Brachial Plexus

Question 1

Dorsal Scapular Nerve

Answer 1

Comes off root from ventral ramus C5 and innervates rhomboid major and rhomboid minor

Question 2

Root

Answer 2

5 from ventral rami of spinal nerves

Question 3

Long Thoracic Nerve

Answer 3

Comes off root from ventral rami C5, C6, C7

Question 4

Trunk

Answer 4

3 - Upper, Middle, Lower

Question 5

Division

Answer 5

3 Anterior & 3 Posterior

Question 6

Cord

Answer 6

3 - Lateral, Posterior, Medial

Question 7

Terminal Branches

Answer 7

4 - Musculocutaneous, Ulnar, Radial, Median

Question 8

Nerve to the subclavius

Answer 8

Comes from the Upper trunk and ventral rami C5, C6. Supplies subcalvius

Question 9

Suprascapular nerve

Answer 9

Comes from the Upper trunk and ventral rami C5, C6. Supplies supraspinatus and infraspinatus

Question 10

Lateral pectoral nerve

Answer 10

Comes from the lateral cord and ventral rami C5, C6, C7. Supplies pectoralis major

Question 11

Medial pectoral nerve

Answer 11

Comes from medial cord and ventral rami C8, T1, Supplies pectoralis minor and pectoralis major

Question 12

Medial brachial cutaneous nerve

Answer 12

Comes from medial cord and ventral rami C8, T1. Pierces the fascia of the proximal arm and supplies the skin on the lower medial arm.

Question 13

Medial antebrachial cutaneous nerve

Answer 13

Comes from medial cord and ventral rami C8, T1. Descends towards the middle of the forearm where it pierces the antebrachial fascia and supplies the skin on the medial forearm

Question 14

Upper subscapular nerve

Answer 14

Comes from the posterior cord and ventral rami C5-T1. Supplies the subscapularis

Question 15

Thoracodorsal nerve

Answer 15

Comes from posterior cord and ventral rami C5-T1. Supplies latissimus dorsi

Question 16

Lower subscapular nerve

Answer 16

Comes from the posterior cord and ventral rami C5-T1. Divides into two muscular branches, one supplying subscapularis and the other supplying teres major.

Question 17

Axillary nerve

Answer 17

Comes from the posterior cord and ventral rami C5-T1. It passes inferiorly to the shoulder, passes around the surgical neck of the humerus, and supplies teres minor and deltoid.

Question 18

Musculocutaneous nerve

Answer 18

Continuation of the lateral cord and ventral rami C5, C6, C7. Supplies coracobrachialis, biceps brachii, and brachialis. Becomes lateral antebrachial cutaneous nerve (LAC) and cutaneously supplies the skin of the lateral forearm.

Question 19

Median nerve

Answer 19

Formed by branches of the lateral and medial cords and ventral rami C5-T1. Supplies no innervation to the arm. Travels through the cubital fossa and gives off the anterior interosseous nerve. Supplies pronator teres, flexor carpi radialis, palmaris longus, and flexor digitorum superficialis. Proximal to the flexor retinaculum, it gives off a palmar branch that cutaneously innervates the skin of the lateral palm. The median nerve then travels the carpal canal and enters the hand. Here it provides muscular innervation to lumbricals 1 & 2. It also provides cutaneous innervation to the lateral 3.5 digits anteriorly and their tips posteriorly

Question 20

Anterior Interosseous nerve

Answer 20

Arises from the median nerve within the cubital fossa. Innervates 2.5 muscles: Flexor digitorum profundus (lateral half), flexor pollicis longus, pronator quadratus.

Question 21

Ulnar nerve

Answer 21

Continuation of the medial cord and ventral rami C8, T1. Supplies no innervation to the arm and passes posterior to the medial epicondyle. It supplies 1.5 muscles of the forearm: flexor carpi ulnaris, and flexor digitorum profundus (medial half). It gives off a dorsal branch that cutaneously innervates the dorsum of the hand and the medial 1.5 digits. It also gives off a palmar branch the innervates the skin of the medial palm. The ulnar nerve passes anterior to the flexor retinaculum and through Guyon’s canal. Lateral to the pisiform bone, it divides into terminal branches: superficial branch of the ulnar nerve and deep branch of the ulnar nerve.

Question 22

Superficial branch of the ulnar nerve

Answer 22

Courses deep to palmaris brevis and innervates it. It supplies the skin of the medial 1.5 digits anteriorly.

Question 23

Deep branch of the ulnar nerve

Answer 23

Courses around the hook of the hamate to innervate 14.5 hand muscles: abductor digit minimi, flexor digit minimi brevis, opponens digiti minimi, lumbricals 3 &4, dorsal interossei (1-4), palmar interossei (1-4), adductor pollicis, and flexor pollicis brevis.

Question 24

Radial nerve

Answer 24

Continuation of the posterior cord. Courses medial to lateral in the radial groove of the humerus. Innervates triceps brachii in the posterior arm. Passes through the lateral side of the cubital fossa and innervates 3 forearm muscles: brachioradialis, extensor carpi radialis longus, anconeus. It then divides into two terminal branches: superficial branch and deep branch.

Question 25

Superficial branch of the radial nerve

Answer 25

The nerve passes over the anatomical snuffbox and enters the hand to provide cutaneous innervation to the proximal portion of the lateral 3.5 digits posteriorly and the dorsum of the hand. No muscular innervation.

Question 26

Deep branch of the radial nerve

Answer 26

Innervates extensor carpi radialis brevis and changes to posterior interosseous nerve (PIN).

Question 27

Posterior interosseous nerve

Answer 27

Innervates 8 forearm muscles: Extensor digitorum, extensor digit minimi, extensor carpi ulnaris, supinator, abductor pollicis longus, extensor pollicis brevis, extensor pollicis longus, extensors indicis. Does not enter the hand.

Question 28

Cubital fossa

Answer 28

Lateral: Brachioradialis
Medial: Pronator teres
Superior: Imaginary line between the medial and lateral epicondyles
Floor: supinator and brachialis
Contents (lateral to medial): Radial nerve and its terminal branches, tendon of the biceps brachii, brachial artery and its terminal branches, median nerve