Anatomy Week 11 - Brachial plexus

Question 1

What forms the brachial plexus?

Answer 1

The brachial plexus is formed from anterior
rami of 5 nerve roots (C5, C6, C7, C8, T1). These nerve roots form Trunks, Divisions, Cords and Nerves.
Rugby (Roots) Teams (Trunks) Drink (Divisions) Cold (Cords) Beers (Branches)

Question 2

What nerve roots form the upper/superior trunk?
Middle trunk?
Lower/inferior trunk?

Answer 2

• C5-C6 form the upper/superior
• C7– forms middle trunk
• C8-T1 form lower/inferior trunks

Question 3

List the nerve branches that originate from the roots.

Answer 3

1. Dorsal Scapular
2. Phrenic nerve
3. Long thoracic

Question 4

Where does the Dorsal Scapular originate and what does it innervate?

Answer 4

Originates: Root branches of C5.
Innervates: Rhomboid muscles and Levator scapulae.

Question 5

Where does the Phrenic nerve originate and what does it innervate?

Answer 5

Origin: Root - C3-C5 (C4 main contributor)
Innervates: No nerve supply to the arm.
Motor supply to the diaphragm and sensation to the central tendon.

Question 6

Where does the Long thoracic originate and what does it innervate?

Answer 6

Origin: Root C5 - C7
Innervates: No nerve supply to the arms.
Serratus anterior muscle.

Question 7

List the nerve branches that originate from the trunks.

Answer 7

1. Suprascapular
2. Subclavius

Question 8

Where does the Suprascapular originate and what does it innervate?

Answer 8

Origin: Trunk (upper) C5 - C6
Innervates: Supraspinatus and infraspinatus muscle.

Question 9

Where does the Subclavius originate and what does it innervate?

Answer 9

Origin: Trunk (upper) C5 - C6.
Innervates: Subclavius muscle.

Question 10

List the nerve branches that originate from cords in the brachial plexus.

Answer 10

1.Subscapular superior
2. Subscapular inferior
3. Lateral Pectoral
4. Medial Pectoral
5.Thoracodorsal nerve
6.Medial cutaneous nerve of the arm
cord
7.Medial cutaneous nerve of the forearm

Question 11

Where does the Subscapular superior and inferior originate and what does it innervate?

Answer 11

Origin: Posterior cord branches of C5 and C6.
Innervates: Subscapularis muscles and Teres major.

Question 12

Where does the Lateral pectoral originate and what does it innervate?

Answer 12

Origin: Branches of lateral cord.
Innervate: Pectoralis major.

Question 13

Where does the Medial pectoral originate and what does it innervate?

Answer 13

Origin: Branches of medial cord.
Innervate: Pectoralis minor.

Question 14

Where does the Thoracodorsal nerve originate and what does it innervate?

Answer 14

Origin: Posterior cord (C6 - C8)
Innervates: Latissimus dorsi.

Question 15

Where does the Medial cutaneous nerve of the arm originate and what does it innervate?

Answer 15

Origin: C8 - T1
Innervates: Sensory skin on the upper part of the medial surface of the arm and floor of the axilla.

Question 16

Where does the Medial cutaneous nerve of the forearm originate and what does it innervate?

Answer 16

Origin: C8 - T1
Innervates: Sensory skin over biceps brachii, skin over anterior and medial surface of the forearm.