Upper Limb - Nerves (1)

Question 1

What are the origins of the brachial plexus?

Answer 1

The anterior rami of C5-C8, and most of the anterior ramus of T1.

Question 2

What are the four categories of branching of the brachial plexus?

Answer 2

Starting from the C5-T1 ventral rami: Roots –> Trunks –> Divisions –> Cords

Question 3

Which branches of the brachial plexus traverses beneath the clavicle?

Answer 3

The divisions.

Question 4

What is similar about all three trunks of the brachial plexus?

Answer 4

They all divide into one anterior and one posterior division each. For all three trunks, the posterior division goes into the Posterior Cord.

Question 5

Describe the basic anatomical location of the Roots and Trunks of the brachial plexus.

Answer 5

The Posterior Triangle of the neck. (between the anterior scalene and the middle scalene muscles)

Question 6

Describe the relationship between the axillary artery and the brachial plexus.

Answer 6

The cords of the brachial plexus are named according to their anatomical relation to the axillary artery. The posterior cord runs posterior to the axillary artery, the lateral cord runs laterally, and the medial cord runs medially.

Question 7

What are the two terminal nerves that come off the brachial plexus at the level of its roots? Explain.

Answer 7

1. Dorsal scapular nerve, branching off the C5 root, innervating the rhomboid muscles.
2. Long thoracic nerve, branching off the C5, C6, C7 roots, innervating the serratus anterior muscle.

Question 8

What are the two nerves that come off the superior trunk of the brachial plexus?

Answer 8

1. Subclavian nerve

2. Suprascapular nerve, innervating the supraspinatus and the infraspinatus muscles.

Question 9

Explain the mnemonic: My Aunty Raped My Uncle.

Answer 9

This mnemonic explains the terminal nerves of the brachial plexus. From lateral to medial, in order: Musculocutaneous (from lateral cord), Axillary (posterior cord), Radial (posterior cord), Median (both lateral and medial cords), Ulnar (medial cord).

Question 10

Which is the only generation of brachial plexus branches that do NOT give off terminal nerve branches?

Answer 10

Divisions.

Question 11

What is the mnemonic ULTRA with regard to the brachial plexus?

Answer 11

This describes the five terminal nerve branches coming off the posterior cord.
Upper and Lower subscapular nerves. Thoracodorsal nerve. Radial nerve. Axillary nerve.

Question 12

What is the only side-branching terminal nerve coming off the lateral cord of the brachial plexus?

Answer 12

Lateral pectoral nerve.

Question 13

Apart from the Ulnar nerve, what are the three other terminal nerves coming off the medial cord of the brachial plexus?

Answer 13

1. Medial pectoral nerve
2. Medial brachial cutaneous nerve (arm)
3. Medial antebrachial cutaneous nerve (forearm)

Question 14

Describe some common ways that the brachial plexus can be injured.

Answer 14

Fall onto a shoulder, with the head facing the other way, whereby the head and neck then stretch away from the shoulder, stretching or rupturing supraclavicular parts of the brachial plexus. Obstetric injuries: Erb’s palsy, caused by the neck stretching in similar way.

Question 15

What is the innervation to the muscles of the thenar compartment of the hand?

Answer 15

Recurrent branch of median nerve.