The brachial plexus

Question 1

Name the different sections of the brachial plexus.

Answer 1

(Real Teenagers Drink Cold Beer)

Roots - Trunks - Divisions - Cords - Branches

Question 2

Name the 5 roots of the brachial plexus.

Answer 2

anterior rami of C5, C6, C7, C8 and T1 nerves

Question 3

Name the 3 trunks of the brachial plexus.

Answer 3

superior, middle and inferior

Question 4

Name the 3 cords of the brachial plexus.

Answer 4

lateral, posterior and medial

Question 5

Name the 5 main nerves arising from the brachial plexus, and their origin.

Answer 5

(3 Musketeers, 2 Assassins, 4 Men, 5 Rats and 2 Unicorns)

1. musculocutaneous nerve:
   
   • terminal branch of lateral cord
   • C5, C6, C7
2. axillary nerve
   
   • terminal branch of posterior cord
   • C5, C6
3. median nerve:
   
   • terminal branch of lateral and medial cords
   • C6, C7, C8, T1
4. radial nerve
   
   • terminal branch of posterior cord
   • C5, C6, C7, C8, T1
5. ulnar nerve
   
   • terminal branch of medial cord
   • C8, T1

Question 6

Which nerve arises directly from the C5, C6 and C7 roots?

Which structures does it innervate?

Answer 6

long thoracic nerve

innervates serratus anterior

Question 7

Which nerve arises from the lateral cord?

Which structures does it innervate?

Answer 7

lateral pectoral nerve

innervates pectoralis major (+ some pec. minor)

Question 8

Which nerve arises from the medial cord?

Which structures does it innervate?

Answer 8

medial pectoral nerve

innervates pectoralis minor (+ some pec. major)

Question 9

Which structures does the musculocutaneous n. innervate?

Answer 9

1. muscles of anterior arm compartment: coracobrachialis, brachialis and biceps brachii
2. skin of lateral aspect of arm (via lateral cutaneous n. of forearm (C6, C7))

Question 10

Which structures does the axillary n. innervate?

Answer 10

1. GH joint
2. teres minor and deltoid
3. skin over inferior part of deltoid (via superior lateral cutaneous n. of arm)

Question 11

Which structures does the median n. innervate?

Answer 11

1. muscles of anterior forearm compartment (except for flexor carpi ulnaris and ulnar 1/2 of flexor digitorum profundus), and 5 intrinsic muscles in thenar 1/2 of palm
2. palmar skin (via palmar cutaneous branches)

Question 12

Which structures does the radial n. innervate?

Answer 12

1. muscles of posterior compartments of arm and forearm
2. skin of :
   - posterior and inferolateral arm (via inferior lateral and posterior cutaneous nerves of arm)
   - posterior forearm (via posterior cutaneous n. of forearm)
   - dorsum of hand lateral to axial line of digit 4 (via superficial branch)

Question 13

Which structures does the ulnar n. innervate?

Answer 13

1. flexor carpi ulnaris and ulnar 1/2 of flexor digitorum profundus, and most intrinsic muscles of hand
2. skin of hand medial to axial line of digit 4

Question 14

What are the cords of the brachial plexus named in relation to?

Answer 14

axillary artery (2nd part)