Nervous Anatomy

Question 1

What muscles are innervated by the musculocutaneous nerve?

Answer 1

The 3 muscles of the anterior brachium: biceps, brachialis, and coracobrachialis.

Question 2

What are the cervical root contributions to the musculocutaneous nerve and from which cord does it branch?

Answer 2

C5, C6, and C7. Lateral cord.

Question 3

What part of the skin does the sensory branch of the musculocutaneous nerve innervate?

Answer 3

Lateral side of the anterior forearm.

Question 4

What are the 4 potential sites of compression for the median nerve at the elbow and forearm?

Answer 4

1. Ligament of Struthers: anomalous ligament in 1-2% of population running from supracondylar process of humerus to medial epicondyle. 2. Lacertus fibrosus or bicipital aponeurosis: fibrous band of tissue running from distal biceps tendon to flexor-pronator mass. 3. Between the superficial and deep heads of the prontor teres. 4. Deep to the fibrous arch of the FDS 6.5 cm distal to the medial epicondyle.

Question 5

The palmar cutaneous branch of the median nerve branches off proximal to the carpal tunnel. What part of the skin does it innervate? What is the clinical significance?

Answer 5

The thenar eminence. People with carpal tunnel syndrome will have unaffected sensation to the thenar eminence as opposed to people with more proximal median nerve compression.

Question 6

From which nerve does the Anterior Interosseous Nerve branch? What muscles does it innervate?

Answer 6

The median nerve. It innervates FPL, FDP to index and middle fingers, and pronator quadratus.

Question 7

What are 2 potential sites of compression for the suprascapular nerve? What is the clinical significance of each?

Answer 7

The suprascapular notch, which can result in weakness of supraspinatus and infraspinatus. Also the spinoglenoid notch which would affect only infraspinatus. Suprascapular nerve palsy is not uncommon in young athletes who perform overhead smashing motions (volleyball spike).

Question 8

Which specific nerve branch innervates the palmaris brevis?

Answer 8

Superficial branch of ulnar nerve

Question 9

Which specific nerve innervates the pronator quadratus?

Answer 9

Anterior Interosseous nerve

Question 10

Which specific nerve branch innervates the adductor pollicis?

Answer 10

The deep branch of the ulnar nerve

Question 11

Which specific nerve innervates the extensor indicis?

Answer 11

The posterior interosseous nerve

Question 12

Which specific nerve innervates the brachioradialis?

Answer 12

The radial nerve

Question 13

The anamolous Ligament of Struthers can be a compression site of which nerve?

Answer 13

The median nerve

Question 14

The arade of Struthers can be a compression site of which nerve?

Answer 14

The ulnar nerve.

Question 15

What 4 sites, proximal to distal, form potential proximal compression sites of the median nerve?

Answer 15

Ligament of Struthers (present in 1-13% of population), bicipital aponeurosis, pronator teres, FDS arch.

Question 16

The superior trunk of the brachial plexus arrises from which rami?

Answer 16

C5 and C6 anterior rami

Question 17

The middle trunk of the brachial plexus arrises from which rami?

Answer 17

C7 anterior rami

Question 18

The inferior trunk of the brachial plexus arrises from which rami?

Answer 18

C8 and T1 anterior rami

Question 19

Which 2 nerves arise directly from the superior trunk of the brachial plexus?

Answer 19

The suprascapular nerve (lateral branch of superior trunk) and the subclavius nerve (anterior branch of superior trunk)

Question 20

What are the motor and sensory functions of the suprascapular nerve?

Answer 20

The suprascapular nerve innervates 2 RC muscles, supraspinatus and infraspinatus. It also provides sensory innervation to the AC and GH joints.

Question 21

What function has the subclavius nerve?

Answer 21

The subclavius nerve innervates the sublavian muscle.

Question 22

Which 2 nerves arise directly from the C5 ventral root of the brachial plexus?

Answer 22

Dorsal scapular nerve and phrenic nerve.

Question 23

What function has the dorsal scapular nerve?

Answer 23

It provides motor innervation to the rhomboids and the levator scapulae.