Week 11 - Brachial Plexus

Question 1

What spinal nerve roots form the brachial plexus?

Answer 1

C5, C6, C7, C8 and T1 (Anterior Rami)

Question 2

What is the mnemonic to remember the organisation of the brachial plexus?

Answer 2

“Rugby Teams Drink Cold Beers”
(Roots → Trunks → Divisions → Cords → Branches/Nerves).

Question 3

Which roots combine to form the trunks of the brachial plexus?

Answer 3

C5-C6 → Upper trunk

C7 → Middle trunk

C8-T1 → Lower trunk

Question 4

C5-C6 combine to from what trunk of the brachial plexus

Answer 4

Upper trunk

Question 5

C7 combine to form what trunks of the brachial plexus

Answer 5

Middle trunk

Question 6

C8-T1 roots combine to form what trunk of the brachial plexus

Answer 6

Lower trunk

Question 7

What do trunks divide into?

Answer 7

Anterior and posterior divisions

Question 8

How are the cords of the brachial plexus formed?

Answer 8

Lateral cord: anterior divisions of upper & middle trunks

Posterior cord: all three posterior divisions

Medial cord: anterior division of the lower trunk

Question 9

How are cords named in relation to the axillary artery?

Answer 9

Based on their position relative to it: lateral, medial, and posterior.

Question 10

What nerves originate from the roots of the brachial plexus?

Answer 10

1.Dorsal Scapular Nerve (C5)

2. Phrenic Nerve (C3–C5, mainly C4)
3. Long Thoracic Nerve (C5–C7)

Question 11

What is the dorsal scapular’s origin and innervation.

Answer 11

Origin: root - branches of C5 rami

Innervation: Rhomboid muscles and levator scapulae

Question 12

What is the Phrenic nerve’s origin and innervation.

Answer 12

Origin: Root - C3-C5 (C4 main contributor)

Innervation: No nerve supply to arms. Motor supply to the diaphragm. sensation to the central tendon. In the thorax - the mediastinal pleura and pericardium

Question 13

What is the long thoracic origin and innervation?

Answer 13

Origin: root - form anterior rami of C5-C7

Innervation: Serratus anterior muscle, no nerve supply to arms

Question 14

What is the function of the Phrenic Nerve?

Answer 14

Motor: Diaphragm

Sensory: Central tendon of diaphragm, mediastinal pleura, pericardium

Question 15

Which nerves arise from the upper trunk (C5-C6)?

Answer 15

Suprascapular Nerve

Subclavius Nerve

Question 16

what is the origin and innervation of the Suprascapular?

Answer 16

Origin: Trunk (upper) - C5-C6

Innervation: Supraspinatus and infraspinatus muscle

Question 17

What is the origin an innervation of the Subclavius?

Answer 17

Origin: Trunk (upper) C5-C6

Innervation: Subclavius muscle

Question 18

What are the nerves from the posterior cord?

Answer 18

Upper Subscapular Nerve

Lower Subscapular Nerve

Thoracodorsal Nerve

Question 19

What is the origin and innervation of the subscapular superior and Subscapular inferior

Answer 19

Origin: posterior cord - branches of C5 and C6 rami

Innervation: Subscapularis muscle and Teres Major

Question 20

What do the Subscapular Nerves innervate?

Answer 20

Subscapularis (upper & lower) and teres major (lower).

Question 21

What does the Thoracodorsal Nerve innervate?

Answer 21

Latissimus dorsi (C6–C8).

Question 22

What are the nerves from the lateral cord

Answer 22

Lateral Pectoral Nerve

Question 23

What is the origin and innervation of the lateral pectoral?

Answer 23

Origin: branches of lateral cords (C5-C7)

Innervation: Pectoralis Major

Question 24

What are the nerves from the medial cord?

Answer 24

Medial Pectoral Nerve

Medial Cutaneous Nerve of Arm

Medial Cutaneous Nerve of Forearm

Question 25

What is the origin and innervation of the Medial Pectoral

Answer 25

Origin: Branches medial cords (C8-T1) Innervation: Pectoralis minor

Question 26

What does the Medial Pectoral Nerve innervate?

Answer 26

Pectoralis major and minor (C8–T1).

Question 27

What does the Medial Cutaneous Nerve of Arm innervate?

Answer 27

Sensory to skin of the medial arm (C8–T1).

Question 28

What does the Medial Cutaneous Nerve of Forearm innervate?

Answer 28

Sensory to skin of the medial forearm (C8–T1).

Question 29

What is the origin and innervation of the thoracodorsal nerve

Answer 29

Origin: Posterior cord (C6-C8) Innervation: Latissimus dorsi