Sympathetic nervous system- anatomy

Question 201 of 560

An 18 year old lady with troublesome hyperhidrosis of the hands and arms is due to undergo a sympathectomy to treat the condition. Which of the following should the surgeons divide to most effectively treat her condition?

Sympathetic ganglia at T1, T2 and T3

Sympathetic ganglia at T2 and T3

Sympathetic ganglia at T1 and T2

Stellate ganglion

Superior cervical ganglion

To treat hyperhidrosis the sympathetic ganglia at T2 and T3 should be divided. Dividing the other structures listed would either carry a risk of Horners syndrome or be ineffective. Please rate this question:

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Sympathetic nervous system- anatomy

The cell bodies of the pre-ganglionic efferent neurones lie in the lateral horn of the grey matter of the spinal cord in the thoraco-lumbar regions. The pre-ganglionic efferents leave the spinal cord at levels T1-L2. These pass to the sympathetic chain. Lateral branches of the sympathetic chain connect it to every spinal nerve. These post ganglionic nerves will pass to structures that receive sympathetic innervation at the periphery. Sympathetic chains These lie on the vertebral column and run from the base of the skull to the coccyx.

Cervical

region

Lie anterior to the transverse processes of the cervical vertebrae and posterior to the carotid sheath.

Thoracic Lie anterior to the neck of the upper ribs and and lateral sides of the lower thoracic

http://emrcs.com/question/question.php?q=0#left-panel

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region vertebrae.They are covered by the parietal pleura

Lumbar

region

Enter by passing posterior to the medial arcuate ligament. Lie anteriorly to the

vertebrae and medial to psoas major.

Sympathetic ganglia

Superior cervical ganglion lies anterior to C2 and C3. Middle cervical ganglion (if present) C6 Stellate ganglion- anterior to transverse process of C7, lies posterior to the subclavian artery,

vertebral artery and cervical pleura. Thoracic ganglia are segmentally arranged. There are usually 4 lumbar ganglia.

Clinical importance

Interruption of the head and neck supply of the sympathetic nerves will result in an ipsilateral Horners syndrome.

For treatment of hyperhidrosis the sympathetic denervation can be achieved by removing the second and third thoracic ganglia with their rami. Removal of T1 will cause a Horners syndrome and is therefore not performed.

In patients with vascular disease of the lower limbs a lumbar sympathetomy may be performed, either radiologically or (more rarely now) surgically. The ganglia of L2 and below are disrupted. If L1 is removed then ejaculation may be compromised (and little additional benefit conferred as the preganglionic fibres do not arise below L2.

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Question 202 of 560

A 44 year old lady is recovering following a transphenoidal hypophysectomy. Unfortunately there is a post operative haemorrhage. Which of the following features is most likely to occur initially?

Cavernous sinus thrombosis

Abducens nerve palsy

Bi-temporal hemianopia

Inferior homonymous hemianopia

Central retinal vein occlusion

Theme from April 2014 exam The pituitary is covered by a sheath of dura and an expanding haematoma at this site may compress the optic chiasm in the same manner as an expanding pituitary tumour. Please rate this question:


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Pituitary Gland

The pituitary gland is located within the sella turcica within the sphenoid bone in the middle cranial fossa. It is covered by a dural fold and weighs around 0.5g. It is attached to the hypothalamus by the infundibulum. The anterior pituitary receives hormonal stimuli from the hypothalamus by way of the hypothalamo-pituitary portal system. It develops from a depression in the wall of the pharynx (Rathkes pouch). Anterior pituitary hormones

Growth hormone

Thyroid stimulating hormone ACTH Prolactin LH and FSH Melanocyte releasing hormone


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Posterior pituitary hormones

Oxytocin

Anti diuretic hormone

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Question 203 of 560

During a right hemicolectomy the caecum is mobilised. As the bowel is retracted medially a vessel is injured, posterior to the colon. Which of the following is the most likely vessel?

Right colic artery

Inferior vena cava

Aorta

External iliac artery

Gonadal vessels

The gonadal vessels and ureter are important posterior relations that are at risk during a right hemicolectomy. Please rate this question:


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Caecum

Location Proximal right colon below the ileocaecal valve

Intraperitoneal

Posterior relations Psoas

Iliacus

Femoral nerve

Genitofemoral nerve

Gonadal vessels

Anterior relations Greater omentum

Arterial supply Ileocolic artery


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Lymphatic drainage Mesenteric nodes accompany the venous drainage

The caecum is the most distensible part of the colon and in complete large bowel obstruction with a competent ileocaecal valve the most likely site of eventual perforation.

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Question 204 of 560

A 53 year old man with a carcinoma of the lower third of the oesophagus is undergoing an oesophagogastrectomy. As the surgeons mobilise the lower part of the oesophagus, where are they most likely to encounter the thoracic duct?

Anterior to the oesophagus

On the left side of the oesophagus

On the right side of the oesophagus

Immediately anterior to the azygos vein

Posterior to the oesophagus

The thoracic duct lies posterior to the oesophagus and passes to the left at the level of the Angle of Louis. It enters the thorax at T12 together with the aorta. Please rate this question:


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Thoracic duct

Continuation of the cisterna chyli in the abdomen. Enters the thorax at T12. Lies posterior to the oesophagus for most of its intrathoracic course. Passes to the left at T5. Lymphatics draining the left side of the head and neck join the thoracic duct prior to its

insertion into the left brachiocephalic vein.

Lymphatics draining the right side of the head and neck drain via the subclavian and jugular trunks into the right lymphatic duct and thence into the mediastinal trunk and eventually the right brachiocephalic vein.

Its location in the thorax makes it prone to injury during oesophageal surgery. Some surgeons administer cream to patients prior to oesophagectomy so that it is easier to identify the cut ends of the duct.

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Question 205 of 560

Which of the following represents the root values of the sciatic nerve?

L4 to S3

L1 to L4

L3 to S1

S1 to S4

L5 to S1

Theme from April 2014 exam The sciatic nerve most commonly arises from L4 to S3. Please rate this question:


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Sciatic nerve

The sciatic nerve is formed from the sacral plexus and is the largest nerve in the body. It is the continuation of the main part of the plexus arising from ventral rami of L4 to S3. These rami converge at the inferior border of piriformis to form the nerve itself. It passes through the inferior part of the greater sciatic foramen and emerges beneath piriformis. Medially, lie the inferior gluteal nerve and vessels and the pudendal nerve and vessels. It runs inferolaterally under the cover of gluteus maximus midway between the greater trochanter and ischial tuberosity. It receives its blood supply from the inferior gluteal artery. The nerve provides cutaneous sensation to the skin of the foot and the leg. It also innervates the posterior thigh muscles and the lower leg and foot muscles. The nerve splits into the tibial and common peroneal nerves approximately half way down the posterior thigh. The tibial nerve supplies the flexor muscles and the common peroneal nerve supplies the extensor muscles and the abductor muscles. Summary points

Origin Spinal nerves L4 - S3


Articular Branches Hip joint

Muscular branches in

upper leg

Semitendinosus

Semimembranosus

Biceps femoris

Part of adductor magnus

Cutaneous sensation Posterior aspect of thigh (via cutaneous nerves)

Gluteal region

Entire lower leg (except the medial aspect)

Terminates At the upper part of the popliteal fossa by dividing into the tibial and

peroneal nerves

The nerve to the short head of the biceps femoris comes from the common peroneal part of the sciatic and the other muscular branches arise from the tibial portion.

The tibial nerve goes on to innervate all muscles of the foot except the extensor digitorum brevis (which is innervated by the common peroneal nerve).

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Question 206 of 560

The common peroneal nerve, or its branches, supply the following muscles except:

Peroneus longus

Tibialis anterior

Extensor hallucis longus

Flexor digitorum brevis

Extensor digitorum longus

Flexor digitorum is supplied by the tibial nerve.

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Common peroneal nerve

Derived from the dorsal divisions of the sacral plexus (L4, L5, S1 and S2).

This nerve supplies the skin and fascia of the anterolateral surface of the leg and the dorsum of the

foot. It also innervates the muscles of the anterior and peroneal compartments of the leg, extensor

digitorum brevis as well as the knee, ankle and foot joints.

It is laterally placed within the sciatic nerve. From the bifurcation of the sciatic nerve it passes

inferolaterally in the lateral and proximal part of the popliteal fossa, under the cover of biceps femoris

and its tendon. To reach the posterior aspect of the fibular head. It ends by dividing into the deep

and superficial peroneal nerves at the point where it winds around the lateral surface of the neck of


the fibula in the body of peroneus longus, approximately 2cm distal to the apex of the head of the

fibula. It is palpable posterior to the head of the fibula.

Branches

In the thigh Nerve to the short head of biceps

Articular branch (knee)

In the popliteal fossa Lateral cutaneous nerve of the calf

Neck of fibula Superficial and deep peroneal nerves

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Question 207 of 560

An 83 year old lady presents with a femoral hernia and undergoes a femoral hernia repair. Which of the following forms the posterior wall of the femoral canal?

Pectineal ligament

Lacunar ligament

Inguinal ligament

Adductor longus

Sartorius



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Femoral canal

The femoral canal lies at the medial aspect of the femoral sheath. The femoral sheath is a fascial tunnel containing both the femoral artery laterally and femoral vein medially. The canal lies medial to the vein. Borders of the femoral canal

Laterally Femoral vein

Medially Lacunar ligament

Anteriorly Inguinal ligament

Posteriorly Pectineal ligament


Image showing dissection of femoral canal

Image sourced from Wikipedia

Contents

Lymphatic vessels

Cloquet's lymph node

Physiological significance Allows the femoral vein to expand to allow for increased venous return to the lower limbs. Pathological significance

As a potential space, it is the site of femoral hernias. The relatively tight neck places these at high risk of strangulation.

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http://en.wikipedia.org/wiki/Femoral%20canal

http://d2zgo9qer4wjf4.cloudfront.net/images_eMRCS/swb036b.jpg


Question 208 of 560

A 45 year man presents with hand weakness. He is given a piece of paper to hold between his thumb and index finger. When the paper is pulled, the patient has difficulty maintaining a grip. Grip pressure is maintained by flexing the thumb at the interphalangeal joint. What is the most likely nerve lesion?

Posterior interosseous nerve

Deep branch of ulnar nerve

Anterior interosseous nerve

Superficial branch of the ulnar nerve

Radial nerve

Theme from January 2012 exam This is a description of Froment's sign, which tests for ulnar nerve palsy. It mainly tests for the function of adductor pollicis. This is supplied by the deep branch of the ulnar nerve. Remember the anterior interosseous branch (of the median nerve), which innervates the flexor pollicis longus (hence causing flexion of the thumb IP joint), branches off more proximally to the wrist. Please rate this question:


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Ulnar nerve

Origin

C8, T1

Supplies (no muscles in the upper arm)

Flexor carpi ulnaris Flexor digitorum profundus


Flexor digiti minimi Abductor digiti minimi Opponens digiti minimi Adductor pollicis

Interossei muscle Third and fourth lumbricals Palmaris brevis

Path

Posteromedial aspect of upper arm to flexor compartment of forearm, then along the ulnar. Passes beneath the flexor carpi ulnaris muscle, then superficially through the flexor retinaculum into the palm of the hand.


Branches

http://en.wikipedia.org/wiki/Ulnar%20nerve

http://d2zgo9qer4wjf4.cloudfront.net/images_eMRCS/swb103b.png


Branch Supplies

Muscular branch Flexor carpi ulnaris

Medial half of the flexor digitorum profundus

Palmar cutaneous branch (Arises near the middle of the forearm)

Skin on the medial part of the palm

Dorsal cutaneous branch Dorsal surface of the medial part of the hand

Superficial branch Cutaneous fibres to the anterior surfaces of the

medial one and one-half digits

Deep branch Hypothenar muscles

All the interosseous muscles

Third and fourth lumbricals

Adductor pollicis Medial head of the flexor pollicis brevis

Effects of injury

Damage at the wrist Wasting and paralysis of intrinsic hand muscles (claw hand)

Wasting and paralysis of hypothenar muscles

Loss of sensation medial 1 and half fingers

Damage at the elbow Radial deviation of the wrist

Clawing less in 4th and 5th digits

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Question 209 of 560

Which of the following statements relating to the right phrenic nerve is false?

It lies deep to the prevertebral layer of deep cervical fascia

Crosses posterior to the 2nd part of the subclavian artery

It runs on the anterior surface of the scalene muscle

On the right side it leaves the mediastinum via the vena cava hiatus at a level of T8

The right phrenic nerve passes over the right atrium



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Phrenic nerve

Origin

C3,4,5

Supplies

Diaphragm, sensation central diaphragm and pericardium

Path

The phrenic nerve passes with the internal jugular vein across scalenus anterior. It passes deep to prevertebral fascia of deep cervical fascia.

Left: crosses anterior to the 1st part of the subclavian artery.


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Right: Anterior to scalenus anterior and crosses anterior to the 2nd part of the subclavian artery.

On both sides, the phrenic nerve runs posterior to the subclavian vein and posterior to the internal thoracic artery as it enters the thorax.

Right phrenic nerve

In the superior mediastinum: anterior to right vagus and laterally to superior vena cava

Middle mediastinum: right of pericardium It passes over the right atrium to exit the diaphragm at T8

Left phrenic nerve

Passes lateral to the left subclavian artery, aortic arch and left ventricle

Passes anterior to the root of the lung Pierces the diaphragm alone

Image showing the passage of the phrenic nerve in the neck


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http://en.wikipedia.org/wiki/Phrenic%20nerve



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Question 210 of 560

Which of the following cranial foramina pairings are incorrect?

Carotid canal and internal carotid artery.

Foramen ovale and mandibular nerve.

Optic canal and ophthalmic artery.

Optic canal and ophthalmic nerve.

Foramen rotundum and maxillary nerve.

Question derived from 2010 and 2011 exams

The optic canal transmits the optic nerve. The ophthalmic nerve traverses the superior orbital

fissure.



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Foramina of the base of the skull

Foramen Location Contents

Foramen ovale Sphenoid Otic ganglion

V3 (Mandibular nerve:3rd branch of


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bone trigeminal)

Accessory meningeal artery

Lesser petrosal nerve

Emissary veins

Foramen spinosum Sphenoid

bone

Middle meningeal artery

Meningeal branch of the Mandibular nerve

Foramen rotundum Sphenoid

bone

Maxillary nerve (V2)

Foramen lacerum/

carotid canal

Sphenoid

bone

Base of the medial pterygoid plate.

Internal carotid artery*

Nerve and artery of the pterygoid canal

Jugular foramen Temporal

bone

Anterior: inferior petrosal sinus

Intermediate: glossopharyngeal, vagus, and accessory nerves.

Posterior: sigmoid sinus (becoming the internal jugular vein) and

some meningeal branches from the occipital and ascending

pharyngeal arteries.

Foramen magnum Occipital

bone

Anterior and posterior spinal arteries

Vertebral arteries

Medulla oblongata

Stylomastoid

foramen

Temporal

bone

Stylomastoid artery

Facial nerve

Superior orbital

fissure

Sphenoid

bone

Oculomotor nerve (III)

Recurrent meningeal artery

Trochlear nerve (IV)

Lacrimal, frontal and nasociliary branches of ophthalmic nerve (V1)


Abducent nerve (VI)

Superior ophthalmic vein

*= In life the foramen lacerum is occluded by a cartilagenous plug. The ICA initially passes into the

carotid canal which ascends superomedially to enter the cranial cavity through the foramen lacerum.

Base of skull anatomical overview


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http://en.wikipedia.org/wiki/Foramina%20of%20the%20skull



Question 211 of 560

A 22 year old man is involved in a fight and sustains a stab wound in his upper forearm. On examination there is a small, but deep laceration. There is an obvious loss of pincer movement involving the thumb and index finger with minimal loss of sensation. The most likely nerve injury is to the:

Ulnar nerve

Radial nerve

Anterior interosseous nerve

Axillary nerve

Median nerve

The anterior interosseous nerve is a motor branch of the median nerve just below the elbow. When damaged it classically causes:

Pain in the forearm Loss of pincer movement of the thumb and index finger (innervates the long flexor muscles

of flexor pollicis longus & flexor digitorum profundus of the index and middle finger)

Minimal loss of sensation due to lack of a cutaneous branch



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Median nerve

The median nerve is formed by the union of a lateral and medial root respectively from the lateral (C5,6,7) and medial (C8 and T1) cords of the brachial plexus; the medial root passes anterior to the third part of the axillary artery. The nerve descends lateral to the brachial artery, crosses to its medial side (usually passing anterior to the artery). It passes deep to the bicipital aponeurosis and the median cubital vein at the elbow. It passes between the two heads of the pronator teres muscle, and runs on the deep surface of flexor digitorum superficialis (within its fascial sheath). Near the wrist it becomes superficial between the tendons of flexor digitorum superficialis and flexor


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carpi radialis, deep to palmaris longus tendon. It passes deep to the flexor retinaculum to enter the palm, but lies anterior to the long flexor tendons within the carpal tunnel. Branches

Region Branch

Upper arm No branches, although the nerve commonly communicates with the

musculocutaneous nerve

Forearm Pronator teres

Flexor carpi radialis

Palmaris longus

Flexor digitorum superficialis

Flexor pollicis longus Flexor digitorum profundus (only the radial half)

Distal forearm

Palmar cutaneous branch

Hand

(Motor)

Motor supply (LOAF)

Lateral 2 lumbricals

Opponens pollicis

Abductor pollicis brevis

Flexor pollicis brevis

Hand

(Sensory)

Over thumb and lateral 2 ½ fingers

On the palmar aspect this projects proximally, on the dorsal aspect only the

distal regions are innervated with the radial nerve providing the more

proximal cutaneous innervation.

Patterns of damage Damage at wrist

e.g. carpal tunnel syndrome paralysis and wasting of thenar eminence muscles and opponens pollicis (ape hand

deformity)

sensory loss to palmar aspect of lateral (radial) 2 ½ fingers

Damage at elbow, as above plus:

unable to pronate forearm weak wrist flexion

ulnar deviation of wrist

Anterior interosseous nerve (branch of median nerve)

leaves just below the elbow results in loss of pronation of forearm and weakness of long flexors of thumb and index

finger

Topography of the median nerve


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http://en.wikipedia.org/wiki/Median%20nerve



Question 212 of 560

A 66 year old man is undergoing a left nephro-ureterectomy. The surgeons remove the ureter, which of the following is responsible for the blood supply to the proximal ureter?

Branches of the renal artery

External iliac artery

Internal iliac artery

Direct branches from the aorta

Common iliac artery

Theme from April 2014 exam The proximal ureter is supplied by branches from the renal artery. For the other feeding vessels - see below. Please rate this question:


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Ureter

25-35 cm long Muscular tube lined by transitional epithelium Surrounded by thick muscular coat. Becomes 3 muscular layers as it crosses the bony pelvis Retroperitoneal structure overlying transverse processes L2-L5 Lies anterior to bifurcation of iliac vessels

Blood supply is segmental; renal artery, aortic branches, gonadal branches, common iliac and internal iliac

Lies beneath the uterine artery

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Question 213 of 560

Which of the following structures does not pass behind the lateral malleolus?

Peroneus brevis tendon

Sural nerve

Short saphenous vein

Peroneus longus tendon

Tibialis anterior tendon

Theme from April 2014 exam Tibialis anterior tendon passes anterior to the medial malleolus. Please rate this question:


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Lateral malleolus

Structures posterior to the lateral malleolus and superficial to superior peroneal retinaculum

Sural nerve Short saphenous vein

Structures posterior to the lateral malleolus and deep to superior peroneal retinaculum

Peroneus longus tendon Peroneus brevis tendon

The calcaneofibular ligament is attached at the lateral malleolus

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Question 214 of 560


A 78 year old man presents with symptoms consistent with intermittent claudication. To assess the severity of his disease you decide to measure his ankle brachial pressure index. To do this you will identify the dorsalis pedis artery. Which of the following statements relating to this vessel is false?

It originates from the peroneal artery

It is crossed by the tendon of extensor hallucis brevis

Two veins are usually closely related to it

It passes under the inferior extensor retinaculum

The tendon of extensor hallucis longus lies medial to it.

The dorsalis pedis artery is a direct continuation of the anterior tibial artery. Please rate this question:


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Foot- anatomy

Arches of the foot The foot is conventionally considered to have two arches.

The longitudinal arch is higher on the medial than on the lateral side. The posterior part of the calcaneum forms a posterior pillar to support the arch. The lateral part of this structure passes via the cuboid bone and the lateral two metatarsal bones. The medial part of this structure is more important. The head of the talus marks the summit of this arch, located between the sustentaculum tali and the navicular bone. The anterior pillar of the medial arch is composed of the navicular bone, the three cuneiforms and the medial three metatarsal bones.

The transverse arch is situated on the anterior part of the tarsus and the posterior part of the metatarsus. The cuneiforms and metatarsal bases narrow inferiorly, which contributes to the shape of the arch.

Intertarsal joints


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Sub talar joint Formed by the cylindrical facet on the lower surface of the body of the

talus and the posterior facet on the upper surface of the calcaneus. The

facet on the talus is concave anteroposteriorly, the other is convex. The

synovial cavity of this joint does not communicate with any other joint.

Talocalcaneonavicular

joint

The anterior part of the socket is formed by the concave articular

surface of the navicular bone, posteriorly by the upper surface of the

sustentaculum tali. The talus sits within this socket

Calcaneocuboid joint Highest point in the lateral part of the longitudinal arch. The lower

aspect of this joint is reinforced by the long plantar and plantar

calcaneocuboid ligaments.

Transverse tarsal joint The talocalcaneonavicular joint and the calcaneocuboid joint extend

across the tarsus in an irregular transverse plane, between the talus and

calcaneus behind and the navicular and cuboid bones in front. This plane is termed the transverse tarsal joint.

Cuneonavicular joint Formed between the convex anterior surface of the navicular bone and the concave surface of the the posterior ends of the three cuneiforms.

Intercuneiform joints Between the three cuneiform bones.

Cuneocuboid joint Between the circular facets on the lateral cuneiform bone and the

cuboid. This joint contributes to the tarsal part of the transverse arch.

A detailed knowledge of the joints is not required for MRCS Part A. However, the contribution they

play to the overall structure of the foot should be appreciated Ligaments of the ankle joint and foot


Muscles of the foot

Muscle Origin Insertion Nerve

supply

Action

Abductor

hallucis

Medial side of the calcaneus,

flexor retinaculum, plantar aponeurosis

Medial side of

the base of the

proximal

phalanx

Medial

plantar nerve

Abducts the great toe

Flexor

digitorum

brevis

Medial process of the

calcaneus, plantar

eponeurosis.

Via 4 tendons

into the

middle

phalanges of

the lateral 4 toes.

Medial

plantar

nerve

Flexes all the joints of

the lateral 4 toes except

for the interphalangeal joint.

Abductor

digit

minimi

From the tubercle of the

calcaneus and from the

plantar aponeurosis

Together with

flexor digit

minimi brevis

into the lateral

side of the

Lateral

plantar

nerve

Abducts the little toe at

the metatarsophalangeal

joint

http://en.wikipedia.org/wiki/Talocalcaneal%20articulation



base of the

proximal

phalanx of the

little toe

Flexor

hallucis

brevis

From the medial side of the

plantar surface of the cuboid

bone, from the adjacent part

of the lateral cuneiform bone

and from the tendon of tibialis posterior.

Into the

proximal

phalanx of the

great toe, the

tendon

contains a

sesamoid bone

Medial

plantar

nerve

Flexes the

metatarsophalangeal

joint of the great toe.

Adductor hallucis

Arises from two heads. The

oblique head arises from the

sheath of the peroneus longus

tendon, and from the plantar

surfaces of the bases of the

2nd, 3rd and 4th metatarsal

bones. The transverse head

arises from the plantar

surface of the lateral 4

metatarsophalangeal joints

and from the deep transverse metatarsal ligament.

Lateral side of

the base of the

proximal

phalanx of the

great toe.

Lateral

plantar

nerve

Adducts the great toe

towards the second toe.

Helps maintain the

transverse arch of the

foot.

Extensor

digitorum brevis

On the dorsal surface of the

foot from the upper surface of

the calcaneus and its

associated fascia

Via four thin

tendons which

run forward

and medially

to be inserted

into the

medial four

toes. The

lateral three

tendons join

with hoods of

extensor

digitorum

longus.

Deep

peroneal

Extend the

metatarsophalangeal

joint of the medial four

toes. It is unable to

extend the

interphalangeal joint

without the assistance of

the lumbrical muscles.

Nerves in the foot

Lateral plantar nerve

Passes anterolaterally towards the base of the 5th metatarsal between flexor digitorum brevis and flexor accessorius. On the medial aspect of the lateral plantar artery. At the base of the 5th metatarsal it splits into superficial and deep branches. Medial plantar nerve Passes forwards with the medial plantar artery under the cover of the flexor retinaculum to the interval between abductor hallucis and flexor digitorum brevis on the sole of the foot. Plantar arteries Arise under the cover of the flexor retinaculum, midway between the tip of the medial malleolus and the most prominent part of the medial side of the heel.

Medial plantar artery. Passes forwards medial to medial plantar nerve in the space between abductor hallucis and flexor digitorum brevis.Ends by uniting with a branch of the 1st plantar metatarsal artery.

Lateral plantar artery. Runs obliquely across the sole of the foot. It lies lateral to the lateral plantar nerve. At the base of the 5th metatarsal bone it arches medially across the foot on the metatarsals

Dorsalis pedis artery This vessel is a direct continuation of the anterior tibial artery. It commences on the front of the ankle joint and runs to the proximal end of the first metatarsal space. Here is gives off the arcuate artery and continues forwards as the first dorsal metatarsal artery. It is accompanied by two veins throughout its length. It is crossed by the extensor hallucis brevis

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Question 215 of 560

Which of the following is not a content of the anterior triangle of the neck?

Vagus nerve

Submandibular gland

Phrenic nerve

Internal jugular vein

Hypoglossal nerve

The phrenic nerve is a content of the posterior triangle. The anterior triangle contains the carotid sheath and its contents. Please rate this question:


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Anterior triangle of the neck

Boundaries

Anterior border of the Sternocleidomastoid

Lower border of mandible Anterior midline

Sub triangles (divided by Digastric above and Omohyoid)

Muscular triangle: Neck strap muscles

Carotid triangle: Carotid sheath Submandibular Triangle (digastric)


Contents of the anterior triangle

Digastric triangle Submandibular gland

Submandibular nodes

Facial vessels Hypoglossal nerve

Muscular triangle Strap muscles

External jugular vein

Carotid triangle Carotid sheath (Common carotid, vagus and internal jugular vein) Ansa cervicalis

Nerve supply to digastric muscle

Anterior: Mylohyoid nerve Posterior: Facial nerve


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http://en.wikipedia.org/wiki/Anterior%20triangle%20of%20the%20neck



Question 216 of 560

A 32 year old attends neurology clinic complaining of tingling in his hand. He has radial deviation of his wrist and there is mild clawing of his fingers, with the 4th and 5th digits being relatively spared. What is the most likely lesion?

Ulnar nerve damage at the wrist

Ulnar nerve damage at the elbow

Radial nerve damage at the elbow

Median nerve damage at the wrist

Median nerve damage at the elbow

The ulnar paradox- the higher the lesion, the less the clawing of the fingers seen clinically.

At the elbow the ulnar nerve lesion affects the flexor carpi ulnaris and flexor digitorum profundus. Please rate this question:


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Ulnar nerve

Origin

C8, T1


Flexor carpi ulnaris Flexor digitorum profundus Flexor digiti minimi

Abductor digiti minimi Opponens digiti minimi Adductor pollicis


Interossei muscle Third and fourth lumbricals Palmaris brevis

Path



Branches

Branch Supplies




Branch Supplies

Muscular branch Flexor carpi ulnaris

Medial half of the flexor digitorum profundus

Palmar cutaneous branch (Arises near the middle of the forearm)








Adductor pollicis Medial head of the flexor pollicis brevis

Effects of injury






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Question 217 of 560

A 22 year old man is undergoing an endotracheal intubation. Which of the following vertebral levels is consistent with the origin of the trachea?

C2

T1

C6

C4

C3

The trachea commences at C6. It terminates at the level of T5 (or T6 in tall subjects in deep inspiration). Please rate this question:


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Trachea

Trachea

Location C6 vertebra to the upper border of T5 vertebra (bifurcation)

Arterial and venous supply Inferior thyroid arteries and the thyroid venous plexus.

Nerve Branches of vagus, sympathetic and the recurrent nerves

Relations in the neck

Anterior(Superior to Isthmus of the thyroid gland

Inferior thyroid veins


inferior) Arteria thyroidea ima (when that vessel exists)

Sternothyroid

Sternohyoid

Cervical fascia

Anastomosing branches between the anterior jugular

veins

Posterior Oesophagus.

Laterally Common carotid arteries

Right and left lobes of the thyroid gland

Inferior thyroid arteries

Recurrent laryngeal nerves

Relations in the thorax Anterior

Manubrium, the remains of the thymus, the aortic arch, left common carotid arteries, and the deep cardiac plexus

Lateral

In the superior mediastinum, on the right side is the pleura and right vagus; on its left side are the left recurrent nerve, the aortic arch, and the left common carotid and subclavian arteries.

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Question 218 of 560

A young child undergoes a difficult craniotomy for fulminant mastoiditis and associated abscess. During the procedure the trigeminal nerve is severely damaged within Meckels cave. Which deficit is least likely to be present?

Anaesthesia over the ipsilateral anterior aspect of the scalp

Loss of the corneal reflex

Weakness of the ipsilateral masseter muscle

Anaesthesia of the anterior aspect of the lip

Anaesthesia over the entire ipsilateral side of the face

The angle of the jaw is not innervated by sensory fibres of the trigeminal nerve and is spared in this type of injury. Remember the trigeminal nerve provides motor innervation to the muscles of mastication. The close proximity of the site of injury to the motor fibres is likely to result in at least some compromise of motor muscle function. Please rate this question:


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Trigeminal nerve

The trigeminal nerve is the main sensory nerve of the head. In addition to its major sensory role, it also innervates the muscles of mastication. Distribution of the trigeminal nerve

Sensory Scalp

Face

Oral cavity (and teeth)

Nose and sinuses

Dura mater


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Motor Muscles of mastication

Mylohyoid

Anterior belly of digastric

Tensor tympani

Tensor palati

Autonomic connections (ganglia) Ciliary

Sphenopalatine

Otic

Submandibular

Path

Originates at the pons Sensory root forms the large, crescentic trigeminal ganglion within Meckel's cave, and

contains the cell bodies of incoming sensory nerve fibres. Here the 3 branches exit.

The motor root cell bodies are in the pons and the motor fibres are distributed via the mandibular nerve. The motor root is not part of the trigeminal ganglion.

Branches of the trigeminal nerve

Ophthalmic nerve Sensory only

Maxillary nerve Sensory only

Mandibular nerve Sensory and motor

Sensory

Ophthalmic Exits skull via the superior orbital fissure

Sensation of: scalp and forehead, the upper eyelid, the conjunctiva and cornea of

the eye, the nose (including the tip of the nose, except alae nasi), the nasal

mucosa, the frontal sinuses, and parts of the meninges (the dura and blood vessels).

Maxillary

nerve

Exit skull via the foramen rotundum

Sensation: lower eyelid and cheek, the nares and upper lip, the upper teeth and

gums, the nasal mucosa, the palate and roof of the pharynx, the maxillary,

ethmoid and sphenoid sinuses, and parts of the meninges.

Mandibular

nerve

Exit skull via the foramen ovale

Sensation: lower lip, the lower teeth and gums, the chin and jaw (except the angle of the jaw), parts of the external ear, and parts of the meninges.

Motor Distributed via the mandibular nerve. The following muscles of mastication are innervated:

Masseter Temporalis

Medial pterygoid Lateral pterygoid

Other muscles innervated include:

Tensor veli palatini

Mylohyoid Anterior belly of digastric Tensor tympani

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Question 219-221 of 560

Theme: Nerve lesions

A. Iliohypogastric nerve

B. Ilioinguinal nerve

C. Lateral cutaneous nerve of the thigh

D. Femoral nerve

E. Saphenous nerve

F. Genitofemoral nerve Please select the most likely nerve implicated in the situation described. Each option may be used once, more than once or not at all.

219. A 42 year old woman complains of a burning pain of her anterior thigh which worsens on

walking. There is a positive tinel sign over the inguinal ligament.

You answered Iliohypogastric nerve

The correct answer is Lateral cutaneous nerve of the thigh

The lateral cutaneous nerve supplies sensation to the anterior and lateral aspect of the

thigh. Entrapment is commonly due to intra and extra pelvic causes. Treatment involves

local anaesthetic injections.

220. A 29 year old woman has had a Pfannenstiel incision. She has pain over the inguinal

ligament which radiates to the lower abdomen. There is tenderness when the inguinal

canal is compressed.


The correct answer is Ilioinguinal nerve

221. A 22 year man is shot in the groin. On examination he has weak hip flexion, weak knee

extension, and impaired quadriceps tendon reflex, as well as sensory deficit in the

anteromedial aspect of the thigh.


The correct answer is Femoral nerve

This is a classical description of a femoral nerve injury.



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Nerve lesions during surgery

A variety of different procedures carry the risk of iatrogenic nerve injury. These are important not only from the patients perspective but also from a medicolegal standpoint. The following operations and their associated nerve lesions are listed here:

Posterior triangle lymph node biopsy and accessory nerve lesion. Lloyd Davies stirrups and common peroneal nerve. Thyroidectomy and laryngeal nerve. Anterior resection of rectum and hypogastric autonomic nerves.

Axillary node clearance; long thoracic nerve, thoracodorsal nerve and intercostobrachial nerve.

Inguinal hernia surgery and ilioinguinal nerve. Varicose vein surgery- sural and saphenous nerves. Posterior approach to the hip and sciatic nerve.

Carotid endarterectomy and hypoglossal nerve.

There are many more, with sound anatomical understanding of the commonly performed procedures the incidence of nerve lesions can be minimised. They commonly occur when surgeons operate in an unfamiliar tissue plane or by blind placement of haemostats (not recommended).

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Question 222 of 560

Which of the following is not a branch of the external carotid artery?

Facial artery

Lingual artery

Superior thyroid artery

Mandibular artery

Maxillary artery

External carotid artery branches mnemonic:

'Some Angry Lady Figured Out PMS'

Superior thyroid (superior laryngeal artery branch)

Ascending pharyngeal

Lingual

Facial (tonsillar and labial artery)

Occipital

Posterior auricular

Maxillary (inferior alveolar artery, middle meningeal artery)

Superficial temporal



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External carotid artery

The external carotid commences immediately lateral to the pharyngeal side wall. It ascends and lies

anterior to the internal carotid and posterior to the posterior belly of digastric and stylohyoid. More

inferiorly it is covered by sternocleidomastoid, passed by hypoglossal nerves, lingual and facial

veins.

It then pierces the fascia of the parotid gland finally dividing into its terminal branches within the

gland itself.

Surface marking of the carotid

This is an imaginary line drawn from the bifurcation of the common carotid passing behind the angle

of the jaw to a point immediately anterior to the tragus of the ear.

Branches of the external carotid artery

It has six branches, three in front, two behind and one deep.

Three in front Superior thyroid

Lingual

Facial

Two behind Occipital

Posterior auricular

Deep Ascending pharyngeal

It terminates by dividing into the superficial temporal and maxillary arteries in the parotid gland.


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http://en.wikipedia.org/wiki/External%20carotid%20artery



Question 223 of 560

A 23 year old man is stabbed in the groin, several structures are injured and the adductor longus

muscle has been lacerated. Which of the following nerves is responsible for the innervation of

adductor longus?

Femoral nerve

Obturator nerve

Sciatic nerve

Common peroneal nerve

Ilioinguinal nerve

The adductors are innervated by the obturator nerve



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Adductor longus

Origin Anterior body of pubis

Insertion Middle third of linea aspera


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Action Adducts and flexes the thigh, medially rotate the hip

Innervation Anterior division of obturator nerve (L2, L3, L4)

The schematic image below demonstrates the relationship of the adductor muscles


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http://en.wikipedia.org/wiki/Adductor%20longus%20muscle



Question 224 of 560

Which of the following statements relating to the basilar artery and its branches is false?

The superior cerebellar artery may be decompressed to treat trigeminal neuralgia

Occlusion of the posterior cerebral artery causes contralateral loss of the visual field

The oculomotor nerve lies between the superior cerebellar and posterior cerebral arteries

The posterior inferior cerebellar artery is the largest of the cerebellar arteries arising from

the basilar artery

The labyrinthine branch is accompanied by the facial nerve

The posterior inferior cerebellar artery is the largest of the cerebellar arteries arising from the vertebral artery. The labyrinthine artery is long and slender and may arise from the lower part of the basilar artery. It accompanies the facial and vestibulocochlear nerves into the internal auditory meatus. The posterior cerebral artery is often larger than the superior cerebellar artery and it is separated from the vessel, near it's origin, by the oculomotor nerve. Arterial decompression is a well established therapy for trigeminal neuralgia. Please rate this question:


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Circle of Willis

The two internal carotid arteries and two vertebral arteries form an anastomosis known as the Circle of Willis on the inferior surface of the brain. Each half of the circle is formed by: 1. Anterior communicating artery 2. Anterior cerebral artery 3. Internal carotid artery 4. Posterior communicating artery 5. Posterior cerebral arteries and the termination of the basilar artery The circle and its branches supply; the corpus striatum, internal capsule, diencephalon and midbrain.


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Vertebral arteries

Enter the cranial cavity via foramen magnum Lie in the subarachnoid space

Ascend on anterior surface of medulla oblongata Unite to form the basilar artery at the base of the pons

Branches:

Posterior spinal artery

Anterior spinal artery Posterior inferior cerebellar artery

Basilar artery Branches:

http://en.wikipedia.org/wiki/Circle%20of%20Willis



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Anterior inferior cerebellar artery Labyrinthine artery Pontine arteries Superior cerebellar artery

Posterior cerebral artery

Internal carotid arteries

Branches:

Posterior communicating artery

Anterior cerebral artery Middle cerebral artery Anterior choroid artery

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Question 225 of 560

Which of the following muscles does not recieve any innervation from the sciatic nerve?

Semimembranosus

Quadriceps femoris

Biceps femoris

Semitendinosus

Adductor magnus

The sciatic nerve is traditionally viewed as being a nerve of the posterior compartment. It is known to contribute to the innervation of adductor magnus (although the main innervation to this muscle is from the obturator nerve). The quadriceps femoris is nearly always innervated by the femoral nerve. Please rate this question:


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Sciatic nerve

The sciatic nerve is formed from the sacral plexus and is the largest nerve in the body. It is the continuation of the main part of the plexus arising from ventral rami of L4 to S3. These rami converge at the inferior border of piriformis to form the nerve itself. It passes through the inferior part of the greater sciatic foramen and emerges beneath piriformis. Medially, lie the inferior gluteal nerve and vessels and the pudendal nerve and vessels. It runs inferolaterally under the cover of gluteus maximus midway between the greater trochanter and ischial tuberosity. It receives its blood supply from the inferior gluteal artery. The nerve provides cutaneous sensation to the skin of the foot and the leg. It also innervates the posterior thigh muscles and the lower leg and foot muscles. The nerve splits into the tibial and common peroneal nerves approximately half way down the posterior thigh. The tibial nerve supplies the flexor muscles and the common peroneal nerve supplies the extensor muscles and the abductor muscles. Summary points

Origin Spinal nerves L4 - S3


Articular Branches Hip joint

Muscular branches in

upper leg

Semitendinosus

Semimembranosus

Biceps femoris

Part of adductor magnus

Cutaneous sensation Posterior aspect of thigh (via cutaneous nerves)

Gluteal region

Entire lower leg (except the medial aspect)

Terminates At the upper part of the popliteal fossa by dividing into the tibial and

peroneal nerves

The nerve to the short head of the biceps femoris comes from the common peroneal part of the sciatic and the other muscular branches arise from the tibial portion.

The tibial nerve goes on to innervate all muscles of the foot except the extensor digitorum brevis (which is innervated by the common peroneal nerve).

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Question 226 of 560

A 23 year old man is involved in a fight and is stabbed in his upper arm. The ulnar nerve is transected. Which of the following muscles will not demonstrate compromised function as a result?

Flexor carpi ulnaris

Medial half of flexor digitorum profundus

Palmaris brevis

Hypothenar muscles

Pronator teres

M edial lumbricals A dductor pollicis F lexor digitorum profundus/Flexor digiti minimi I nterossei A bductor digiti minimi and opponens Innervates all intrinsic muscles of the hand (EXCEPT 2: thenar muscles & first two lumbricals - supplied by median nerve)

Pronator teres is innervated by the median nerve. Palmaris brevis is innervated by the ulnar nerve Please rate this question:


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Ulnar nerve

Origin

C8, T1



Flexor carpi ulnaris Flexor digitorum profundus Flexor digiti minimi Abductor digiti minimi

Opponens digiti minimi Adductor pollicis Interossei muscle Third and fourth lumbricals Palmaris brevis

Path






Branches

Branch Supplies

Muscular branch Flexor carpi ulnaris Medial half of the flexor digitorum profundus

Palmar cutaneous branch (Arises near the

middle of the forearm)








Adductor pollicis

Medial head of the flexor pollicis brevis

Effects of injury






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Question 227 of 560

Which of the structures listed below overlies the cephalic vein?

Extensor retinaculum

Bicipital aponeurosis

Biceps muscle

Antebrachial fascia

None of the above

The cephalic vein is superficially located in the upper limb and overlies most the fascial planes. It pierces the coracoid membrane (continuation of the clavipectoral fascia) to terminate in the axillary vein. It lies anterolaterally to biceps. Please rate this question:


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Cephalic vein

Path

Dorsal venous arch drains laterally into the cephalic vein

Crosses the anatomical snuffbox and travels laterally up the arm At the antecubital fossa connected to the basilic vein by the median cubital vein Pierces deep fascia of deltopectoral groove to join axillary vein

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Question 228 of 560

Which of the following pairings are incorrect?

Aortic bifurcation and L4

Transpyloric plane and L1

Termination of dural sac and L4

Oesophageal passage through diaphragm and T10

Transition between pharynx and oesophagus at C6

Vena cava T8 (eight letters) Oesophagus T10 (ten letters) Aortic hiatus T12 (twelve letters)

It terminates at S2, which is why it is safe to undertake an LP at L4/5 levels. The spinal cord itself terminates at L1. Please rate this question:


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Levels

Transpyloric plane Level of the body of L1

Pylorus stomach Left kidney hilum (L1- left one!)

Fundus of the gallbladder Neck of pancreas Duodenojejunal flexure Superior mesenteric artery Portal vein Left and right colic flexure

Root of the transverse mesocolon


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2nd part of the duodenum Upper part of conus medullaris Spleen

Can be identified by asking the supine patient to sit up without using their arms. The plane is located where the lateral border of the rectus muscle crosses the costal margin. Anatomical planes

Subcostal plane Lowest margin of 10th costal cartilage

Intercristal plane Level of body L4 (highest point of iliac crest)

Intertubercular plane Level of body L5

Common level landmarks

Inferior mesenteric artery L3

Bifurcation of aorta into common iliac arteries L4

Formation of IVC L5 (union of common iliac veins)

Diaphragm apertures Vena cava T8

Oesophagus T10

Aortic hiatus T12

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Question 229 of 560

A 22 year old man is involved in a fight. He sustains a laceration to the posterior aspect of his wrist. In the emergency department the wound is explored and the laceration is found to be transversely orientated and overlies the region of the extensor retinaculum, which is intact. Which of the following structures is least likely to be injured in this scenario?

Dorsal cutaneous branch of the ulnar nerve

Tendon of extensor indicis

Basilic vein

Superficial branch of the radial nerve

Cephalic vein

The extensor retinaculum attaches to the radius proximal to the styloid, thereafter it runs obliquely and distally to wind around the ulnar styloid (but does not attach to it). The extensor tendons lie deep to the extensor retinaculum and would therefore be less susceptible to injury than the superficial structures. Please rate this question:


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Extensor retinaculum

The extensor rentinaculum is a thickening of the deep fascia that stretches across the back of the wrist and holds the long extensor tendons in position. Its attachments are:

The pisiform and triquetral medially The end of the radius laterally

Structures related to the extensor retinaculum

Structures superficial to the Basilic vein

Dorsal cutaneous branch of the ulnar nerve


retinaculum Cephalic vein

Superficial branch of the radial nerve

Structures passing deep to the

extensor retinaculum

Extensor carpi ulnaris tendon

Extensor digiti minimi tendon

Extensor digitorum and extensor indicis tendon

Extensor pollicis longus tendon

Extensor carpi radialis longus tendon

Extensor carpi radialis brevis tendon

Abductor pollicis longus and extensor pollicis

brevis tendons

Beneath the extensor retinaculum fibrous septa form six compartments that contain the extensor muscle tendons. Each compartment has its own synovial sheath. The radial artery

The radial artery passes between the lateral collateral ligament of the wrist joint and the tendons of the abductor pollicis longus and extensor pollicis brevis. Image illustrating the topography of tendons passing under the extensor retinaculum


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http://en.wikipedia.org/wiki/Extensor%20retinaculum%20of%20the%20hand



Question 230 of 560

Which of the following is not a content of the porta hepatis?

Portal vein

Hepatic artery

Cystic duct

Lymph nodes

None of the above

The cystic duct lies outside the porta hepatis and is an important landmark in laparoscopic cholecystectomy. The structures in the porta hepatis are:

Portal vein Hepatic artery Common hepatic duct

These structures divide immediately after or within the porta hepatis to supply the functional left and right lobes of the liver. The porta hepatis is also surrounded by lymph nodes, that may enlarge to produce obstructive jaundice and parasympathetic nervous fibres that travel along vessels to enter the liver. Please rate this question:


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Liver

Structure of the liver

Right lobe Supplied by right hepatic artery

Contains Couinaud segments V to VIII (-/+Sg I)

Left lobe Supplied by the left hepatic artery


Contains Couinaud segments II to IV (+/- Sg1)

Quadrate lobe Part of the right lobe anatomically, functionally is part of the left

Couinaud segment IV

Porta hepatis lies behind

On the right lies the gallbladder fossa

On the left lies the fossa for the umbilical vein

Caudate lobe Supplied by both right and left hepatic arteries

Couinaud segment I

Lies behind the plane of the porta hepatis

Anterior and lateral to the inferior vena cava

Bile from the caudate lobe drains into both right and left hepatic ducts

Detailed knowledge of Couinaud segments is not required for MRCS

Between the liver lobules are portal canals which contain the portal triad: Hepatic Artery, Portal Vein, tributary of Bile Duct.

Relations of the liver

Anterior Postero inferiorly

Diaphragm Oesophagus

Xiphoid process Stomach

Duodenum

Hepatic flexure of colon

Right kidney

Gallbladder

Inferior vena cava

Porta hepatis

Location Postero inferior surface, it joins nearly at right angles with the left sagittal fossa, and

separates the caudate lobe behind from the quadrate lobe in front

Transmits Common hepatic duct

Hepatic artery

Portal vein

Sympathetic and parasympathetic nerve fibres

Lymphatic drainage of the liver (and nodes)

Ligaments

Falciform ligament 2 layer fold peritoneum from the umbilicus to anterior liver surface

Contains ligamentum teres (remnant umbilical vein)

On superior liver surface it splits into the coronary and left

triangular ligaments

Ligamentum teres Joins the left branch of the portal vein in the porta hepatis

Ligamentum

venosum

Remnant of ductus venosus

Arterial supply

Hepatic artery

Venous

Hepatic veins

Portal vein

Nervous supply

Sympathetic and parasympathetic trunks of coeliac plexus

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Question 231 of 560

Which of the following structures is not closely related to the carotid sheath?

Sternothyroid muscle

Sternohyoid muscle

Hypoglossal nerve

Superior belly of omohyoid muscle

Anterior belly of digastric muscle

At its lower end the carotid sheath is related to sternohyoid and sternothyroid. Opposite the cricoid cartilage the sheath is crossed by the superior belly of omohyoid. Above this level the sheath is covered by the sternocleidomastoid muscle. Above the level of the hyoid the vessels pass deep to the posterior belly of digastric and stylohyoid. Opposite the hyoid bone the sheath is crossed obliquely by the hypoglossal nerve. Please rate this question:


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Common carotid artery

The right common carotid artery arises at the bifurcation of the brachiocephalic trunk, the left common carotid arises from the arch of the aorta. Both terminate at the level of the upper border of the thyroid cartilage (the lower border of the third cervical vertebra) by dividing into the internal and external carotid arteries. Left common carotid artery This vessel arises immediately to the left and slightly behind the origin of the brachiocephalic trunk. Its thoracic portion is 2.5- 3.5 cm in length and runs superolaterally to the sternoclavicular joint. In the thorax The vessel is in contact, from below upwards, with the trachea, left recurrent laryngeal nerve, left margin of the oesophagus. Anteriorly the left brachiocephalic vein runs across the artery, and the cardiac branches from the left vagus descend in front of it. These structures together with the thymus and the anterior margins of the left lung and pleura separate the artery from the manubrium.


In the neck The artery runs superiorly deep to sternocleidomastoid and then enters the anterior triangle. At this point it lies within the carotid sheath with the vagus nerve and the internal jugular vein. Posteriorly the sympathetic trunk lies between the vessel and the prevertebral fascia. At the level of C7 the vertebral artery and thoracic duct lie behind it. The anterior tubercle of C6 transverse process is prominent and the artery can be compressed against this structure (it corresponds to the level of the cricoid). Anteriorly at C6 the omohyoid muscle passes superficial to the artery. Within the carotid sheath the jugular vein lies lateral to the artery. Right common carotid artery The right common carotid arises from the brachiocephalic artery. The right common carotid artery corresponds with the cervical portion of the left common carotid, except that there is no thoracic duct on the right. The oesophagus is less closely related to the right carotid than the left. Summary points about the carotid anatomy Path

Passes behind the sternoclavicular joint (12% patients above this level) to the upper border of the thyroid cartilage, to divide into the external (ECA) and internal carotid arteries (ICA). Relations

Level of 6th cervical vertebra crossed by omohyoid

Then passes deep to the thyrohyoid, sternohyoid, sternomastoid muscles. Passes anterior to the carotid tubercle (transverse process 6th cervical vertebra)-NB

compression here stops haemorrhage. The inferior thyroid artery passes posterior to the common carotid artery. Then : Left common carotid artery crosses the thoracic duct, Right common carotid artery

crossed by recurrent laryngeal nerve


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http://en.wikipedia.org/wiki/Common%20carotid%20artery



Question 232 of 560

A 21 year old develops tonsillitis. He is in considerable pain. Which of the following nerves is responsible for the sensory innervation of the tonsillar fossa?

Facial nerve

Trigeminal nerve

Glossopharyngeal nerve

Hypoglossal nerve

Vagus

The glossopharyngeal nerve is the main sensory nerve for the tonsillar fossa. A lesser contribution is made by the lesser palatine nerve. Because of this otalgia may occur following tonsillectomy. Please rate this question:


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Tonsil

Anatomy

Each palatine tonsil has two surfaces, a medial surface which projects into the pharynx and a lateral surface that is embedded in the wall of the pharynx.

They are usually 25mm tall by 15mm wide, although this varies according to age and may be almost completely atrophied in the elderly.

Their arterial supply is from the tonsillar artery, a branch of the facial artery.

Its veins pierce the constrictor muscle to join the external palatine or facial veins. The external palatine vein is immediately lateral to the tonsil, which may result in haemorrhage during tonsillectomy.

Lymphatic drainage is the jugulodigastric node and the deep cervical nodes.

Tonsillitis


Usually bacterial (50%)- group A Streptococcus. Remainder viral. May be complicated by development of abscess (quinsy). This may distort the uvula.

- Indications for tonsillectomy include recurrent acute tonsillitis, suspected malignancy, enlargement causing sleep apnoea. - Dissection tonsillectomy is the preferred technique with haemorrhage being the commonest complication. Delayed otalgia may occur owing to irritation of the glossopharyngeal nerve.

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Question 233 of 560

A man has an incision sited that runs 8cm from the deltopectoral groove to the midline. Which of the

following is not at risk of injury?

Cephalic vein

Shoulder joint capsule

Axillary artery

Pectoralis major

Trunk of the brachial plexus

Theme from April 2012 Exam

This region will typically lie medial to the joint capsule. The diagram below illustrates the plane that

this would transect and as it can be appreciated the other structures are all at risk of injury.

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Pectoralis major muscle

http://en.wikipedia.org/wiki/Deltopectoral%20triangle




Origin From the medial two thirds of the clavicle, manubrium and sternocostal angle

Insertion Lateral edge of the bicipital groove of the humerus

Nerve supply Lateral pectoral nerve

Actions Adductor and medial rotator of the humerus

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Question 234 of 560

A surgeon is due to perform a laparotomy for perforated duodenal ulcer. An upper midline incision is to be performed. Which of the following structures is the incision most likely to divide?

Rectus abdominis muscle

External oblique muscle

Linea alba

Internal oblique muscle

None of the above

Theme from September 2011 Exam Upper midline abdominal incisions will involve the division of the linea alba. Division of muscles will not usually improve access in this approach and they would not be routinely encountered during this incision. Please rate this question:


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Abdominal incisions

Midline incision Commonest approach to the abdomen

Structures divided: linea alba, transversalis fascia, extraperitoneal fat,

peritoneum (avoid falciform ligament above the umbilicus)

Bladder can be accessed via an extraperitoneal approach through the

space of Retzius

Paramedian

incision

Parallel to the midline (about 3-4cm)

Structures divided/retracted: anterior rectus sheath, rectus (retracted),

posterior rectus sheath, transversalis fascia, extraperitoneal fat,

peritoneum


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Incision is closed in layers

Battle Similar location to paramedian but rectus displaced medially (and thus

denervated)

Now seldom used

Kocher's Incision under right subcostal margin e.g. Cholecystectomy (open)

Lanz Incision in right iliac fossa e.g. Appendicectomy

Gridiron Oblique incision centered over McBurneys point- usually appendicectomy

(less cosmetically acceptable than Lanz

Gable Rooftop incision

Pfannenstiel's Transverse supra pubic, primarily used to access pelvic organs

McEvedy's Groin incision e.g. Emergency repair strangulated femoral hernia

Rutherford

Morrison

Extraperitoneal approach to left or right lower quadrants. Gives excellent

access to iliac vessels and is the approach of choice for first time renal

transplantation.


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http://emrcs.com/question/question.php?q=0



Question 235 of 560

A 59 year old man is undergoing an extended right hemicolectomy for a carcinoma of the splenic flexure of the colon. The surgeons divide the middle colic vein close to its origin. Into which of the following structures does this vessel primarily drain?

Superior mesenteric vein

Portal vein

Inferior mesenteric vein

Inferior vena cava

Ileocolic vein

The middle colonic vein drains into the SMV, if avulsed during mobilisation then dramatic haemorrhage can occur and be difficult to control. Please rate this question:


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Transverse colon

The right colon undergoes a sharp turn at the level of the hepatic flexure to become the transverse colon.

At this point it also becomes intraperitoneal. It is connected to the inferior border of the pancreas by the transverse mesocolon.

The greater omentum is attached to the superior aspect of the transverse colon from which it can easily be separated. The mesentery contains the middle colic artery and vein. The greater omentum remains attached to the transverse colon up to the splenic flexure. At this point the colon undergoes another sharp turn.

Relations

Superior Liver and gall-bladder, the greater curvature of the stomach, and the lower end of the

spleen

Inferior Small intestine


Anterior Greater omentum

Posterior From right to left with the descending portion of the duodenum, the head of the pancreas,

convolutions of the jejunum and ileum, spleen

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Theme: Nerve Injury

A. Median nerve

B. Ulnar nerve

C. Radial nerve

D. Musculocutaneous nerve

E. Axillary nerve

F. Anterior interosseous nerve

G. Posterior interosseous nerve For each scenario please select the most likely underlying nerve injury. Each option may be used once, more than once or not at all.

236. A 10 year old boy is admitted to casualty following a fall. On examination there is

deformity and swelling of the upper arm. The ability to flex the fingers of the affected

limb is impaired. However, there is not sensory impairment. Imaging confirms a

displaced supra condylar fracture

You answered Median nerve

The correct answer is Anterior interosseous nerve

Supracondylar fractures may be complicated by neurovascular compromise. The anterior

interosseous nerve is most commonly affected. It has no sensory supply so the defect is

motor alone.

237. A well toned weight lifter attends clinic reporting weakness of his left arm. There is

weakness of flexion and supination of the forearm.


The correct answer is Musculocutaneous nerve

Musculocutaneous nerve compression due to entrapment of the nerve between biceps and

brachialis. Elbow flexion and supination of the arm are affected. This is a rare isolated

injury.

238. An 18 year old girl sustains an Holstein-Lewis fracture. Which nerve is at risk?


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The correct answer is Radial nerve

Proximal lesions affect the triceps. Also paralysis of wrist extensors and forearm

supinators occur. Reduced sensation of dorsoradial aspect of hand and dorsal 31/2

fingers. Holstein-Lewis fractures are fractures of the distal humerus with radial nerve

entrapment.



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Brachial plexus

Origin Anterior rami of C5 to T1

Sections of the

plexus

Roots, trunks, divisions, cords, branches

Mnemonic:Real Teenagers Drink Cold Beer

Roots Located in the posterior triangle

Pass between scalenus anterior and medius

Trunks Located posterior to middle third of clavicle

Upper and middle trunks related superiorly to the subclavian artery

Lower trunk passes over 1st rib posterior to the subclavian artery

Divisions Apex of axilla

Cords Related to axillary artery

Diagram illustrating the branches of the brachial plexus


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Cutaneous sensation of the upper limb


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http://en.wikipedia.org/wiki/Brachial%20plexus

http://en.wikipedia.org/median%20nerve





Question 239 of 560

A 23 year old man is stabbed in the chest approximately 10cm below the right nipple. In the emergency department a abdominal ultrasound scan shows a large amount of intraperitoneal blood. Which of the following statements relating to the likely site of injury is untrue?

Part of its posterior surface is devoid of peritoneum.

The quadrate lobe is contained within the functional right lobe.

Its nerve supply is from the coeliac plexus.

The hepatic flexure of the colon lies posterio-inferiorly.

The right kidney is closely related posteriorly.

The right lobe of the liver is the most likely site of injury. Therefore the answer is B as the quadrate lobe is functionally part of the left lobe of the liver. The liver is largely covered in peritoneum. Posteriorly there is an area devoid of peritoneum (the bare area of the liver). The right lobe of the liver has the largest bare area (and is larger than the left lobe). Please rate this question:


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Liver

Structure of the liver

Right lobe Supplied by right hepatic artery

Contains Couinaud segments V to VIII (-/+Sg I)

Left lobe Supplied by the left hepatic artery

Contains Couinaud segments II to IV (+/- Sg1)

Quadrate lobe Part of the right lobe anatomically, functionally is part of the left

Couinaud segment IV

Porta hepatis lies behind


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On the right lies the gallbladder fossa

On the left lies the fossa for the umbilical vein

Caudate lobe Supplied by both right and left hepatic arteries

Couinaud segment I

Lies behind the plane of the porta hepatis

Anterior and lateral to the inferior vena cava

Bile from the caudate lobe drains into both right and left hepatic ducts

Detailed knowledge of Couinaud segments is not required for MRCS

Between the liver lobules are portal canals which contain the portal triad: Hepatic Artery, Portal Vein, tributary of Bile Duct.

Relations of the liver

Anterior Postero inferiorly

Diaphragm Oesophagus

Xiphoid process Stomach

Duodenum

Hepatic flexure of colon

Right kidney

Gallbladder

Inferior vena cava

Porta hepatis

Location Postero inferior surface, it joins nearly at right angles with the left sagittal fossa, and

separates the caudate lobe behind from the quadrate lobe in front

Transmits Common hepatic duct

Hepatic artery

Portal vein

Sympathetic and parasympathetic nerve fibres

Lymphatic drainage of the liver (and nodes)

Ligaments

Falciform ligament 2 layer fold peritoneum from the umbilicus to anterior liver surface

Contains ligamentum teres (remnant umbilical vein)

On superior liver surface it splits into the coronary and left

triangular ligaments

Ligamentum teres Joins the left branch of the portal vein in the porta hepatis

Ligamentum

venosum

Remnant of ductus venosus

Arterial supply

Hepatic artery

Venous

Hepatic veins

Portal vein

Nervous supply

Sympathetic and parasympathetic trunks of coeliac plexus

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Question 240 of 560

A 22 year old man is involved in a fight and sustains a skull fracture with an injury to the middle meningeal artery. A craniotomy is performed, and with considerable difficulty the haemorrhage from the middle meningeal artery is controlled by ligating it close to its origin. What is the most likely sensory impairment that the patient may notice post operatively?

Parasthesia of the ipsilateral external ear

Loss of taste sensation from the anterior two thirds of the tongue

Parasthesia overlying the angle of the jaw

Loss of sensation from the ipsilateral side of the tongue

Loss of taste from the posterior two thirds of the tongue

The auriculotemporal nerve is closely related to the middle meningeal artery and may be damaged in this scenario. The nerve supplied sensation to the external ear and outermost part of the tympanic membrane. The angle of the jaw is innervated by C2,3 roots and would not be affected. The tongue is supplied by the glossopharyngeal nerve. Please rate this question:


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Middle meningeal artery

Middle meningeal artery is typically the third branch of the first part of the maxillary artery, one of the two terminal branches of the external carotid artery. After branching off the maxillary artery in the infratemporal fossa, it runs through the foramen spinosum to supply the dura mater (the outermost meninges) .

The middle meningeal artery is the largest of the three (paired) arteries which supply the meninges, the others being the anterior meningeal artery and the posterior meningeal artery.

The middle meningeal artery runs beneath the pterion. It is vulnerable to injury at this point, where the skull is thin. Rupture of the artery may give rise to an extra dural hematoma.

In the dry cranium, the middle meningeal, which runs within the dura mater surrounding the brain, makes a deep indention in the calvarium.

The middle meningeal artery is intimately associated with the auriculotemporal nerve which wraps around the artery making the two easily identifiable in the dissection of human cadavers and also easily damaged in surgery.


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Question 241 of 560

A 72 year old man presents with haemoptysis and undergoes a bronchoscopy. The carina is noted to be widened. At which level does the trachea bifurcate?

T3

T5

T7

T2

T8

The trachea bifurcates at the level of the fifth thoracic vertebra. Or the sixth in tall subjects. Please rate this question:


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Trachea

Trachea

Location C6 vertebra to the upper border of T5 vertebra (bifurcation)

Arterial and venous supply Inferior thyroid arteries and the thyroid venous plexus.

Nerve Branches of vagus, sympathetic and the recurrent nerves

Relations in the neck

Anterior(Superior to

inferior)

Isthmus of the thyroid gland

Inferior thyroid veins

Arteria thyroidea ima (when that vessel exists)


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Sternothyroid

Sternohyoid

Cervical fascia

Anastomosing branches between the anterior jugular

veins

Posterior Oesophagus.

Laterally Common carotid arteries

Right and left lobes of the thyroid gland

Inferior thyroid arteries

Recurrent laryngeal nerves

Relations in the thorax

Anterior

Manubrium, the remains of the thymus, the aortic arch, left common carotid arteries, and the deep cardiac plexus

Lateral

In the superior mediastinum, on the right side is the pleura and right vagus; on its left side are the left recurrent nerve, the aortic arch, and the left common carotid and subclavian arteries.

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Question 242 of 560

A 23 year old man is injured during a game of rugby. He suffers a fracture of the distal third of his

clavicle, it is a compound fracture and there is evidence of arterial haemorrhage. Which of the

following vessels is most likely to be encountered first during subsequent surgical exploration?

Posterior circumflex humeral artery

Axillary artery

Thoracoacromial artery

Sub scapular artery

Lateral thoracic artery

Similar theme in September 2011 Exam

The thoracoacromial artery arises from the second part of the axillary artery. It is a short, wide trunk,

which pierces the clavipectoral fascia, and ends, deep to pectoralis major by dividing into four

branches.



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Thoracoacromial artery

The thoracoacromial artery (acromiothoracic artery; thoracic axis) is a short trunk, which arises from

the forepart of the axillary artery, its origin being generally overlapped by the upper edge of the

Pectoralis minor.

Projecting forward to the upper border of the Pectoralis minor, it pierces the coracoclavicular fascia


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and divides into four branches: pectoral, acromial, clavicular, and deltoid.

Branch Description

Pectoral

branch

Descends between the two Pectoral muscles, and is distributed to them and to the breast,

anastomosing with the intercostal branches of the internal thoracic artery and with the

lateral thoracic.

Acromial

branch

Runs laterally over the coracoid process and under the Deltoid, to which it gives branches; it

then pierces that muscle and ends on the acromion in an arterial network formed by

branches from the suprascapular, thoracoacromial, and posterior humeral circumflex

arteries.

Clavicular

branch

Runs upwards and medially to the sternoclavicular joint, supplying this articulation, and the

Subclavius.

Deltoid

branch

Arising with the acromial, it crosses over the Pectoralis minor and passes in the same

groove as the cephalic vein, between the Pectoralis major and Deltoid, and gives branches

to both muscles.

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Question 243 of 560

The following are true of the femoral nerve, except:

It is derived from L2, L3 and L4 nerve roots

It supplies sartorius

It supplies quadriceps femoris

It gives cutaneous innervations via the saphenous nerve

It supplies adductor longus

Adductor longus is supplied by the obturator nerve. Please rate this question:


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Femoral nerve

Root values L2, 3, 4

Innervates Pectineus

Sartorius

Quadriceps femoris

Vastus lateralis/medialis/intermedius

Branches Medial cutaneous nerve of thigh

Saphenous nerve

Intermediate cutaneous nerve of thigh

Path Penetrates psoas major and exits the pelvis by passing under the inguinal ligament to enter the


femoral triangle, lateral to the femoral artery and vein.


Mnemonic for femoral nerve supply (don't) M I S V Q Scan for PE M edial cutaneous nerve of the thigh I ntermediate cutaneous nerve of the thigh S aphenous nerve V astus Q uadriceps femoris S artorius PE ectineus

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http://en.wikipedia.org/wiki/Femoral%20nerve



Question 244 of 560

Where is the vomiting centre located?

Medulla oblongata

Substantia nigra

Antrum of stomach

Pons

Midbrain

ABC's of Non- GI causes of vomiting Acute renal failure Brain (Increased ICP) Cardiac (Inferior MI) DKA Ears (labyrinthitis) Foreign substances (Tylenol, theo, etc) Glaucoma Hyperemesis Gravidarum Infections (pyelonephritis, meningitis)



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Vomiting

Reflex oral expulsion of gastric (and sometimes intestinal) contents - reverse peristalsis and abdominal contraction The vomiting centre is in part of the medulla oblongata and is triggered by receptors in several locations:


Labyrinthine receptors of ear (motion sickness) Over distention receptors of duodenum and stomach Trigger zone of CNS - many drugs (e.g., opiates) act here Touch receptors in throat

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Question 245 of 560

Which of the following nerves conveys sensory information from the laryngeal mucosa?

Glossopharyngeal

Laryngeal branches of the vagus

Ansa cervicalis

Laryngeal branches of the trigeminal

None of the above

The laryngeal branches of the vagus supply sensory information from the larynx. Please rate this question:


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Larynx

The larynx lies in the anterior part of the neck at the levels of C3 to C6 vertebral bodies. The laryngeal skeleton consists of a number of cartilagenous segments. Three of these are paired; arytenoid, corniculate and cuneiform. Three are single; thyroid, cricoid and epiglottic. The cricoid cartilage forms a complete ring (the only one to do so). The laryngeal cavity extends from the laryngeal inlet to the level of the inferior border of the cricoid cartilage. Divisions of the laryngeal cavity

Laryngeal vestibule Superior to the vestibular folds

Laryngeal ventricle Lies between vestibular folds and superior to the vocal cords

Infraglottic cavity Extends from vocal cords to inferior border of the cricoid cartilage


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The vocal folds (true vocal cords) control sound production. The apex of each fold projects medially into the laryngeal cavity. Each vocal fold includes:

Vocal ligament

Vocalis muscle (most medial part of thyroarytenoid muscle)

The glottis is composed of the vocal folds, processes and rima glottidis. The rima glottidis is the narrowest potential site within the larynx, as the vocal cords may be completely opposed, forming a complete barrier. Muscles of the larynx

Muscle Origin Insertion Innervation Action

Posterior cricoarytenoid

Posterior aspect

of lamina of

cricoid

Muscular process of arytenoid

Recurrent Laryngeal

Abducts vocal fold

Lateral cricoarytenoid

Arch of cricoid Muscular process of arytenoid

Recurrent laryngeal

Adducts vocal fold

Thyroarytenoid Posterior aspect

of thyroid

cartilage

Muscular process of arytenoid

Recurrent laryngeal

Relaxes vocal fold

Transverse and

oblique

arytenoids

Arytenoid cartilage

Contralateral arytenoid

Recurrent laryngeal

Closure of

intercartilagenous

part of the rima glottidis

Vocalis Depression

between lamina

of thyroid

cartilage

Vocal ligament

and vocal process

of arytenoid

cartilage

Recurrent

laryngeal

Relaxes posterior

vocal ligament, tenses anterior part

Cricothyroid Anterolateral part of cricoid

Inferior margin

and horn of

thyroid cartilage

External laryngeal

Tenses vocal fold

Blood supply

Arterial supply is via the laryngeal arteries, branches of the superior and inferior thyroid arteries. The superior laryngeal artery is closely related to the internal laryngeal nerve. The inferior laryngeal artery is related to the inferior laryngeal nerve. Venous drainage is via superior and inferior laryngeal veins, the former draining into the superior thyroid vein and the latter draining into the middle thyroid vein, or thyroid venous plexus. Lymphatic drainage

The vocal cords have no lymphatic drainage and this site acts as a lymphatic watershed.

Supraglottic part Upper deep cervical nodes

Subglottic part Prelaryngeal and pretracheal nodes and inferior deep cervical nodes

The aryepiglottic fold and vestibular folds have a dense plexus of lymphatics associated with them and malignancies at these sites have a greater propensity for nodal metastasis. Topography of the larynx


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http://en.wikipedia.org/wiki/Larynx



Question 246 of 560

Which of the following nerves passes through the greater sciatic foramen and innervates the perineum?

Pudendal

Sciatic

Superior gluteal

Inferior gluteal

Posterior cutaneous nerve of the thigh

3 divisions of the pudendal nerve:

Rectal nerve

Perineal nerve Dorsal nerve of penis/ clitoris

All these pass through the greater sciatic foramen.

The pudendal nerve innervates the perineum. It passes between piriformis and coccygeus medial to the sciatic nerve. Please rate this question:


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Gluteal region

Gluteal muscles

Gluteus maximus: inserts to gluteal tuberosity of the femur and iliotibial tract Gluteus medius: attach to lateral greater trochanter Gluteus minimis: attach to anterior greater trochanter

All extend and abduct the hip


Deep lateral hip rotators

Piriformis Gemelli

Obturator internus Quadratus femoris

Nerves

Superior gluteal nerve (L5, S1) Gluteus medius

Gluteus minimis

Tensor fascia lata

Inferior gluteal nerve Gluteus maximus

Damage to the superior gluteal nerve will result in the patient developing a Trendelenberg gait. Affected patients are unable to abduct the thigh at the hip joint. During the stance phase, the weakened abductor muscles allow the pelvis to tilt down on the opposite side. To compensate, the trunk lurches to the weakened side to attempt to maintain a level pelvis throughout the gait cycle. The pelvis sags on the opposite side of the lesioned superior gluteal nerve.

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Question 247 of 560

Which of the following is true in relation to the sartorius muscle?

Innervated by the deep branch of the femoral nerve

Inserts at the fibula

It is the shortest muscle in the body

Forms the Pes anserinus with Gracilis and semitendinous muscle

Causes extension of the knee

It is innervated by the superficial branch of the femoral nerve. It is a component of the pes anserinus. Please rate this question:


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Sartorius

Longest strap muscle in the body Most superficial muscle in the anterior compartment of the thigh

Origin Anterior superior iliac spine

Insertion Medial surface of the of the body of the tibia (upper part). It inserts anterior to gracilis and semitendinosus

Nerve Supply Femoral nerve (L2,3)

Action Flexor of the hip and knee, slight abducts the thigh and rotates it laterally

It assists with medial rotation of the tibia on the femur. For example it


would play a pivotal role in placing the right heel onto the left knee ( and

vice versa)

Important

relations

The middle third of this muscle, and its strong underlying fascia forms the roof of

the adductor canal , in which lie the femoral vessels, the saphenous nerve and the

nerve to vastus medialis.

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Theme: Nerve lesions

A. Sciatic nerve

B. Peroneal nerve

C. Tibial Nerve

D. Obturator nerve

E. Ilioinguinal nerve

F. Femoral nerve

G. None of the above Please select the most likely nerve injury for the scenario given. Each option may be used once, more than once or not at all

248. A 56 year old man undergoes a low anterior resection with legs in the Lloyd-Davies

position. Post operatively he complains of foot drop.

You answered Sciatic nerve

The correct answer is Peroneal nerve

Positioning legs in Lloyd- Davies stirrups can carry the risk of peroneal nerve

neuropraxia if not done carefully.

249. A 23 year old man complains of severe groin pain several weeks after a difficult inguinal

hernia repair.

You answered Sciatic nerve

The correct answer is Ilioinguinal nerve

The ilioinguinal nerve may have been entrapped in the mesh causing a neuroma.

250. A 72 year old man develops a foot drop after a revision total hip replacement.

Sciatic nerve

This may be done by a number of approaches, in this scenario a posterior approach is the

most likely culprit.


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Lower limb- Muscular compartments

Anterior compartment

Muscle Nerve Action

Tibialis anterior Deep peroneal nerve

Dorsiflexes ankle joint, inverts foot

Extensor digitorum

longus

Deep peroneal

nerve

Extends lateral four toes, dorsiflexes ankle

joint

Peroneus tertius Deep peroneal nerve

Dorsiflexes ankle, everts foot

Extensor hallucis longus Deep peroneal

nerve

Dorsiflexes ankle joint, extends big toe

Peroneal compartment

Muscle Nerve Action

Peroneus longus Superficial peroneal nerve Everts foot, assists in plantar flexion

Peroneus brevis Superficial peroneal nerve Plantar flexes the ankle joint

Superficial posterior compartment

<muscle< b="" style="box-sizing: border-

box;"></muscle<> Nerve Action

Gastrocnemius Tibial

nerve

Plantar flexes the foot, may also

flex the knee


<muscle< b="" style="box-sizing: border-

box;"></muscle<> Nerve Action

Soleus Tibial nerve

Plantar flexor

Deep posterior compartment

Muscle Nerve Action

Flexor digitorum longus Tibial Flexes the lateral four toes

Flexor hallucis longus Tibial Flexes the great toe

Tibialis posterior Tibial Plantar flexor, inverts the foot

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Sympathetic nervous system- anatomy