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
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
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
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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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.
Image sourced from Wikipedia
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)
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.
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
Image sourced from Wikipedia
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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
Foramen Location Contents
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)
Foramen Location Contents
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
Image sourced from Wikipedia
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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
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
Image sourced from Wikipedia
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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
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
Image sourced from Wikipedia
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
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
Image sourced from Wikipedia
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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
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.
Image sourced from Wikipedia
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)
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 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
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.
You answered Iliohypogastric nerve
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.
You answered Iliohypogastric nerve
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.
Image sourced from Wikipedia
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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
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
Image sourced from Wikipedia
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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.
Image sourced from Wikipedia
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:
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
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.
Image sourced from Wikipedia
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)
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 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
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
Image sourced from Wikipedia
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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
Image sourced from Wikipedia
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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.
Image sourced from Wikipedia
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Pectoralis major muscle
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
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.
Image sourced from Wikipedia
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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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Question 236-238 of 560
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.
You answered Median nerve
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?
You answered Median nerve
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
Image sourced from Wikipedia
Cutaneous sensation of the upper limb
Image sourced from Wikipedia
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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
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.
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)
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
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.
Image sourced from Wikipedia
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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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
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
Image sourced from Wikipedia
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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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Question 248-250 of 560
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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