Mid-Block Anatomy Review:Upper Extremity Clinical Correlates and Radiology

October 29, 2010

During a fight a man is stabbed in the lateral chest beneath the right arm. The wound does not enter the chest cavity. Physical examination reveals that the vertebral (medial) border of the patient's scapula projects posteriorly and is closer to the midline on the injured side. On return visit the patient complains that he cannot reach as far forward (such as to reach for a door knob) as he could before the injury. The nerve injured which caused these symptoms is the: 1. axillary2. long thoracic3. musculocutaneous4. radial5. suprascapular

During a fight a man is stabbed in the lateral chest beneath the right arm. The wound does not enter the chest cavity. Physical examination reveals that the vertebral (medial) border of the patient's scapula projects posteriorly and is closer to the midline on the injured side. On return visit the patient complains that he cannot reach as far forward (such as to reach for a door knob) as he could before the injury. The nerve injured which caused these symptoms is the: 1. axillary2. long thoracic3. musculocutaneous4. radial5. suprascapular

Long thoracic nerve serratus anterior, loss of protraction of the scapula which counteracts trapezius and the rhomboids, powerful retractors of the scapula– Derived from the nerve roots of C5-7– Vulnerable to iatrogenic injury during surgical

procedures due to location on superficial side of serratus anterior

• Test clues: woman post surgery for breast cancer

MOVEMENTS OF PECTORAL (SHOULDER) GIRDLE ON TRUNK

Action Muscles involved Innervation Major Segmentsof innervation

Elevation Levator scapulae Dorsal scapular C4,5Trapezius, upper part Accessory C1- C5Rhomboid major and minor Dorsal scapular C5

Depression Pectoralis minor Medial pectoral C7,8Trapezius, lower part Accessory C1- C5 Latissimus dorsi Thoracodorsal C6,7,8Pectoralis major, sternocostal part Medial pectoral C6-T1

Protraction Serratus anterior Long thoracic C5,6,7Pectoralis minor Medial pectoral C7,8

Retraction Rhomboid major and minor Dorsal scapular C5Trapezius, middle fibers Accessory C1- C5

Lateral rotation Serratus anterior, lower half Long thoracic C5,6,7of scapula (in abduction) Trapezius, upper and lower parts Accessory C1- C5

Medial rotation Rhomboid major and minor Dorsal scapular C5of scapula (in adduction) Levator scapulae Dorsal scapular C4,5

Pectoralis minor Medial pectoral C7, 8

Scapular movements

ElevationDepression

ProtractionRetraction

Lateral rotation(during abduction)Medial rotation(during adduction)

A man suffers a penetrating wound through the anterior axillary fold, with resulting damage to one of the main terminal branches of the brachial plexus. Among the effects is a significant weakening of flexion of the elbow. One or more other effects to be expected is (are):

1. Loss of cutaneous sensation on the tips of several fingers2. Only loss of cutaneous sensation on the anterolateral surface of the forearm3. Only weakening of flexion at the shoulder4. Weakening of flexion at the shoulder and loss of cutaneous sensation on the anterolateral surface of the arm5. Weakening of flexion at the shoulder and loss of cutaneous sensation on the anterolateral surface of the forearm

A man suffers a penetrating wound through the anterior axillary fold, with resulting damage to one of the main terminal branches of the brachial plexus. Among the effects is a significant weakening of flexion of the elbow. One or more other effects to be expected is (are):

1. Loss of cutaneous sensation on the tips of several fingers2. Only loss of cutaneous sensation on the anterolateral surface of the forearm3. Only weakening of flexion at the shoulder4. Weakening of flexion at the shoulder and loss of cutaneous sensation on the anterolateral surface of the arm5. Weakening of flexion at the shoulder and loss of cutaneous sensation on the anterolateral surface of the forearm

Flexion at the elbow: biceps brachii and brachialis musculocutaneous nerve

Functions of the musculocutaneous nerve: Motor: arm and forearm flexors

(Coracobrachialis, Biceps brachii, brachialis.Sensory: lateral antebrachial cutaneous

nerve innervation to the anterolateral surface of the forearm

Lesion: loss of cutaneous sensation on the anterolateral surface of the forearm, severe weakness in flexion of forearm, weakening of flexion at the shoulder - pectoralis major intact, a powerful arm flexor.

C5, C6 anterior arm muscles:Biceps brachii, Brachialis,Coracobrachialis

MC piercescoracobrachialis

A person sustains a left brachial plexus injury in an auto accident. After initial recovery the following is observed: 1) the diaphragm functions normally, 2) there is no winging of the scapula, 3) abduction cannot be initiated, but if the arm is helped through the first 45 degrees of abduction, the patient can fully abduct the arm. From this amount of information and your knowledge of the formation of the brachial plexus where would you expect the injury to be: 1. axillary nerve 2. posterior cord 3. roots of plexus 4. superior trunk 5. suprascapular nerve

A person sustains a left brachial plexus injury in an auto accident. After initial recovery the following is observed: 1) the diaphragm functions normally, 2) there is no winging of the scapula, 3) abduction cannot be initiated, but if the arm is helped through the first 45 degrees of abduction, the patient can fully abduct the arm. From this amount of information and your knowledge of the formation of the brachial plexus where would you expect the injury to be: 1. axillary nerve 2. posterior cord 3. roots of plexus 4. superior trunk 5. suprascapular nerve

-If the diaphragm is functioning normally, you know that the phrenic nerve is probably uninjured, which means that the C5 root has not been damaged

-Since the scapula is not winged, there was no damage to the long thoracic nerve or the C5-7 nerve roots.

-Since the patient cannot initiate abduction of the arm, you know that the suprascapular nerve is injured and supraspinatus has been denervated.

-The patient can abduct the arm once it is lifted to 45 degrees, so the deltoid muscle and the axillary nerve must be intact.

Taking the answer choices one by one: -The axillary nerve is ok, because deltoid is functioning-The posterior cord of the brachial plexus must also be intact, since this cord gives off the axillary nerve-The roots of the brachial plexus are ok, since the phrenic nerve and long thoracic nerve (which are derived from the roots) are still functioning-The superior trunk of the brachial plexus must also be undamaged, since this trunk contributes to the posterior cord which is intact. -So, this means that the injury must be to the suprascapular nerve.

A man riding a motorcycle hit a wet spot in the road, lost control, and was thrown from his bike. He landed on the right side of his head and the tip of his shoulder, bending his head sharply to the left and stretching the right side of his neck. Subsequent neurological examination revealed that the roots of the 5th and 6th cervical nerves had been torn away from the spinal cord.

Following the above injury, which of the movements of the arm at the shoulder would you expect to be totally lost? 1. adduction 2. abduction 3. flexion 4. extension 5. medial rotation

A man riding a motorcycle hit a wet spot in the road, lost control, and was thrown from his bike. He landed on the right side of his head and the tip of his shoulder, bending his head sharply to the left and stretching the right side of his neck. Subsequent neurological examination revealed that the roots of the 5th and 6th cervical nerves had been torn away from the spinal cord.

Following the above injury, which of the movements of the arm at the shoulder would you expect to be totally lost? 1. adduction 2. abduction 3. flexion 4. extension 5. medial rotation

Erb-Duchenne Palsy: Injuries to the upper roots of the brachial plexus (C5 and C6) (MOST COMMON BP INJURY!!)

Damage to:Suprascapular-rotator cuff (which ones?!?)Axillary-deltoid, teres minor Musculocutaneous-biceps, brachialis, coracobrachialisUpper and lower subscapular nerves-subscapularis, teres majorLateral pectoral nerve-weakness in pec major

Paralysis: rotator cuff muscles,, and deltoid, subscapularis and teres major, weakness in pec minor Limb will be:

-medially rotated by an unopposed latissimus and pectoralis major muscles-pronated due to a loss of biceps- adducted due to loss of supraspinatus and deltoid

As far as extension and flexion go: Extension occurs through the actions of the triceps which is innervated by the radial nerve. This nerve should still be intact. Flexion of the arm is not totally lost if biceps brachii and coracobrachialis are denervated, because pectoralis major is not completely lost.

Patient has Erb’s paralysis withA “waiter’s tip” hand position:Shoulder/ anterior armmuscles mainly affected

Following the above injury there would most likely be diminished cutaneous sensation over what part of the upper limb?

1. the back of the shoulder 2. the pectoral region 3. the top of the shoulder and the lateral side of the arm 4. the medial side of the arm and forearm 5. the tip of the little finger

Following the above injury there would most likely be diminished cutaneous sensation over what part of the upper limb?

1. the back of the shoulder 2. the pectoral region 3. the top of the shoulder and the lateral side of the arm 4. the medial side of the arm and forearm 5. the tip of the little finger

-C5 and C6 dermatomes: top of the shoulder and lateral side of the arm

-T1 and C8 dermatomes cover the medial side of the arm, with C8 extending to the tip of the little finger.

-The back of the shoulder is covered by numerous dermatomes, including C6, C7, C8, and T1

-Pectoral region is covered by T1, T2, and T3 dermatomes.

During an industrial accident, a sheet metal worker lacerates the anterior surface of his wrist at the junction of his wrist and hand. Examination reveals no loss of hand function, but the skin on the thumb side of his palm is numb. Branches of which nerve must have been severed? 1. Lateral antebrachial cutaneous 2. Medial antebrachial cutaneous 3. Median 4. Radial 5. Ulnar

During an industrial accident, a sheet metal worker lacerates the anterior surface of his wrist at the junction of his wrist and hand. Examination reveals no loss of hand function, but the skin on the thumb side of his palm is numb. Branches of which nerve must have been severed? 1. Lateral antebrachial cutaneous 2. Medial antebrachial cutaneous 3. Median 4. Radial 5. Ulnar

Median nerve: enters the hand by crossing over the anterior side of the wrist. -Sensory: skin of the radial 3.5 fingers of the palm.

Lateral and medial antebrachial cutaneous nerves:

-Sensory innervation to the anterior side of the forearm

Radial nerve: -Sensory: radial side of the

dorsum of the hand not the palmar side of the hand

Ulnar nerve:-Sensory: medial (ulnar)

side of both the dorsum and palm of the hand

The nerve which passes through the quadrangular space of the posterior shoulder innervates which muscle? 1. Deltoid 2. Infraspinatus 3. Subscapularis 4. Supraspinatus 5. Teres major

The nerve which passes through the quadrangular space of the posterior shoulder innervates which muscle? 1. Deltoid 2. Infraspinatus 3. Subscapularis 4. Supraspinatus 5. Teres major

The quadrangular space:medial: tendon of the long head of

the tricepslateral: humerussuperior: teres minor inferior: teres major

The posterior circumflex humeral artery and the axillary nerve traverse this space. The axillary nerve innervates 2 muscles: deltoid and teres minor.

Infraspinatus and supraspinatus are both innervated by the suprascapular nerve, off the superior trunk of the brachial plexus. Subscapularis is innervated by the upper and lower subscapular nerves, off the posterior cord of the brachial plexus. Teres major is also innervated by the lower subscapular nerve.

Which of the following is not a direct branch of the axillary artery? 1. anterior circumflex humeral 2. posterior circumflex humeral 3. thoracoacromial 4. thoracodorsal 5. subscapular

Which of the following is not a direct branch of the axillary artery? 1. anterior circumflex humeral 2. posterior circumflex humeral 3. thoracoacromial 4. thoracodorsal 5. subscapular

The thoracodorsal and circumflex scapular arteries are branches of the subscapular artery, which comes directly off the third segment of the axillary artery. The anterior and posterior circumflex humeral arteries are also direct branches of the third segment of the axillary artery. The thoracoacromial artery is a branch of the second part of the axillary artery.

While putting metal panels on the roof of a barn, one of the panels slips out of the hands of the man on the roof. During an attempt to catch the panel, a worker below is struck by its sharp edge. The panel hits across the anterior surface of his right arm at midlength and the impact severs all of the tissue to the bone. When examined in the emergency room it is noted that the patient can only weakly flex his elbow and the lateral side of his forearm is numb. In addition to the muscles, which nerve is injured? 1. axillary 2. median 3. musculocutaneous 4. radial 5. ulnar

While putting metal panels on the roof of a barn, one of the panels slips out of the hands of the man on the roof. During an attempt to catch the panel, a worker below is struck by its sharp edge. The panel hits across the anterior surface of his right arm at midlength and the impact severs all of the tissue to the bone. When examined in the emergency room it is noted that the patient can only weakly flex his elbow and the lateral side of his forearm is numb. In addition to the muscles, which nerve is injured? 1. axillary 2. median 3. musculocutaneous 4. radial 5. ulnar

The musculocutaneous nerve innervates biceps brachii and coracobrachialis--muscles which flex the arm. Since this man cannot flex his arm, it appears that the musculocutaneous nerve has been damaged. He had also lost sensation over the lateral part of his forearm, indicating that the lateral antebrachial cutaneous nerve has been damaged. This nerve is a branch of the musculocutaneous nerve.

The axillary nerve innervates deltoid and teres minor--an injury to this nerve would prevent the patient from abducting his arm.

The median nerve innervates the muscles that permit flexion at the wrist and some muscles in the hand, especially of the thumb.

The radial nerve innervates the extensors of the arm, elbow, wrist, and hand.

The ulnar nerve innervates muscles of the hand, primarily. The listed symptoms do not match injuries to any of these other nerves.

A 19-year-old woman was thrown while riding a bicycle. She attempted to break her fall with an out-stretched hand and suffered a fracture. In the emergency room, an examination reveals an inability (Q extend [he hand at the wrist.

What might have been the site of a fracture that caused the muscle weakness?

A. ClavicleB. Hook of the hamateC. Styloid process of the radiusD. Midshaft of the humerusE. Scaphoid

A 19-year-old woman was thrown while riding a bicycle. She attempted to break her fall with an out-stretched hand and suffered a fracture. In the emergency room, an examination reveals an inability (Q extend [he hand at the wrist.

What might have been the site of a fracture that caused the muscle weakness?

A. ClavicleB. Hook of the hamateC. Styloid process of the radiusD. Midshaft of the humerusE. Scaphoid

The radial nerve is commonly lesioned as a result of a spiral fracture of the midshaft of the humerus.

Your patient suffers from compression of a nerve. The patient has weakness of pronationand flex ion at the index and middle fingers at the distal interphalangeal joints and an inability to form the letter 0 by touching the tip of the thumb to the tip of the index finger.There are no sensory deficits.

What nerve may has been compressed?

A Recurrent branch of the median nerveB. Deep branch of the radial nerveC. Deep branch of the ulnar nerveD. Anterior interosseous branch of the median nerveE. Superficial branch of the radial nerve

Your patient suffers from compression of a nerve. The patient has weakness of pronationand flex ion at the index and middle fingers at the distal interphalangeal joints and an inability to form the letter 0 by touching the tip of the thumb to the tip of the index finger.There are no sensory deficits.

What nerve may has been compressed?

A Recurrent branch of the median nerveB. Deep branch of the radial nerveC. Deep branch of the ulnar nerveD. Anterior interosseous branch of the median nerveE. Superficial branch of the radial nerve

A lesion of the anterior interosseous branch of the median nerve would account for these symptoms.

A man who works as a cartoonist for a living begins to develop pain and paresthesias in his right hand at night. The altered sensation is most evident on the palmar aspects of the index and middle fingers.

What else might you expect to see in the patient?

A. Atrophy of the thenar eminenceB. Weakness in the ability to extend the thumbC. Radial deviation of the hand at me wrist during wrist flexionD. Altered sensation in skin over the anatomic snuffboxE. Inability to spread and oppose the fingers

A man who works as a cartoonist for a living begins to develop pain and paresthesias in his right hand at night. The altered sensation is most evident on the palmar aspects of the index and middle fingers.

What else might you expect to see in the patient?

A. Atrophy of the thenar eminenceB. Weakness in the ability to extend the thumbC. Radial deviation of the hand at me wrist during wrist flexionD. Altered sensation in skin over the anatomic snuffboxE. Inability to spread and oppose the fingers

The patient has carpal tunnel syndrome. Choices B and D result from radial nerve lesions. Choice E results from an ulnar nerve lesion. Choice C results from a median nerve lesion at the wrist.

What deficit would you expect in this patient?

A) Partial loss of sensation on the palm of the handB) Inability to extend wristC) Inability to flex wristD) Inability to flex the elbowE) Inability to abduct shoulder past 30 degrees

What deficit would you expect in this patient?

A) Partial loss of sensation on the palm of the handB) Inability to extend wristC) Inability to flex wristD) Inability to flex the elbowE) Inability to abduct shoulder past 30 degrees

What deficit would you expect in this patient?

A) Partial loss of sensation on the palm of the hand

B) Inability to extend wristC) Inability to flex wristD) Inability to flex the elbowE) Inability to abduct shoulder past 30

degrees

What deficit would you expect in this patient?

A) Partial loss of sensation on the palm of the hand

B) Inability to extend wristC) Inability to flex wristD) Inability to flex the elbowE) Inability to abduct shoulder past 30

degrees

What structure is MOST at risk of being damaged?

A) Median NerveB) Radial NerveC) Ulnar NerveD) Deep Brachial Artery

What structure is MOST at risk of being damaged?

A) Median NerveB) Radial NerveC) Ulnar NerveD) Deep Brachial Artery

What Structure Lies Medial to the arrow?

A) Femoral NerveB) Femoral ArteryC) Femoral VeinD) Empty SpaceE) Lymphatics

What Structure Lies Medial to the arrow?

A) Femoral NerveB) Femoral ArteryC) Femoral VeinD) Empty SpaceE) Lymphatics

What is the Arrow pointing to?

A) PiriformisB) Superior GemellusC) Inferior GemellusD) Obturator InternusE) Quadratus Femoris

What is the Arrow pointing to?

A) PiriformisB) Superior GemellusC) Inferior GemellusD) Obturator InternusE) Quadratus Femoris

What is tagged?

A) Superior Gluteal ArteryB) Superior Gluteal NerveC) Inferior Gluteal ArteryD) Inferior Gluteal NerveE) Inferior Gluteal Vein

What is tagged?

A) Superior Gluteal ArteryB) Superior Gluteal NerveC) Inferior Gluteal ArteryD) Inferior Gluteal NerveE) Inferior Gluteal Vein

What innervates the tagged structure?

A) Dorsal RamiB) Dorsal Scapular NerveC) Thoracodorsal NerveD) Suprascapular NerveE) Axillary Nerve

What innervates the tagged structure?

A) Dorsal RamiB) Dorsal Scapular NerveC) Thoracodorsal NerveD) Suprascapular NerveE) Axillary Nerve

What nerve was lesioned in this patient?

A) Lower Subrascapular nerveB) Infrascapular nerveC) Axillary NerveD) Long Thoracic NerveE) Upper Subscapular Nerve

What nerve was lesioned in this patient?

A) Lower Subrascapular nerveB) Infrascapular nerveC) Axillary NerveD) Long Thoracic NerveE) Upper Subscapular Nerve

What nerve is most likely to be compromised by this injury?

A. Median N.B. Ulnar N.C. Radial N. D. Axillary. N.

• Do we see the fracture?• What bone are we looking

at?• Where in the bone is the

fracture? (does that ring a bell?)

• Where are the nerves in the arm?

What nerve is most likely to be compromised by this injury? Mid-shaft humeral fracture=radial nerve injury

A. Median N.B. Ulnar N.C. Radial N. D. Axillary. N.

What nerve is most likely affected by this injury?

A. Median N.B. Ulnar N.C. Radial N.D. Axillary N.

• Where is the problem? (trace the bones)

• What bones are no longer aligned?

• What nerves are located in that area?

What sensory deficit will this person experience?

A. Cutaneous numbness in the upper back

B. Numbness over the left chest

C. Numbness over the anterior seratus muscle

D. Numbness over the lateral aspect of the shoulder

• Medial epicondyle—ulnar nerve• Lumbar disc injury• Hip fx—AVN• Scaphoid fx—AVN • Other ideas!?