Brachial Plexus

Question 1

Define plexus

Answer 1

Branching network of nerves in the PNS

Question 2

Brachial Plexus

Answer 2

Arises from the ventral rami of C5-T1 nerve roots

Question 3

Segments of Brachial Plexus

Answer 3

Roots: ventral rami of C5-T1
Trunks: upper - roots of C5 and C6
Middle - C7 root
Lower - C8 and T1 root
Divisions: anterior and posterior
Cords: lateral, posterior, medial
Branches: musculocutaneous, axillary, median, radial, ulnar

Question 4

Axillary Nerve

Answer 4

Posterior cord of brachial plexus
C5 and C6
Innervates Deltoid and teres minor

Question 5

Thoracodorsal (middle subscapular)

Answer 5

Posterior cord of brachial plexus
C6, C7, C8
Innervates Latissimus Dorsi

Question 6

Upper subscapular

Answer 6

Posterior cord of brachial plexus
C5, C6
Innervates upper fibers of subscapularis

Question 7

Lower subscapular

Answer 7

Posterior cord of brachial plexus
C5, C6
Lower fibers of subscapularis and teres major

Question 8

Lateral pectoral nerve

Answer 8

At or proximal to the lateral cord
C5, C6, C7
Pectoralis major and occasionally pectoralis minor

Question 9

Medial pectoral nerve

Answer 9

At or proximal to the medial cord
C8, T1
Pectoralis major (sternocostal head) and pectoralis mino

Question 10

Suprascapular

Answer 10

Upper trunk
C5, C6
Supraspinatus and infraspinatus

Question 11

Subclavian

Answer 11

Upper trunk
C5, C6
Subclavius

Question 12

Dorsal scapular

Answer 12

C5 nerve root
C5
Rhomboids and levator scapulae

Question 13

Long thoracic

Answer 13

Proximal to trunks
C5, C6, C7
Serratus anterior

Question 14

Musculocutaneous

Answer 14

Lateral cord
C5, C6, C7
Coracobrachialis, biceps brachii, brachialis

Question 15

Median Nerve

Answer 15

Lateral cord and medial cord
C6, C7, C8, T1
Muscles of anterior forearm compartment

Question 16

Radial nerve

Answer 16

Posterior cord
C5, C6, C7, C8, T1
All muscles of posterior compartments of arm and forearm

Question 17

Ulnar nerve

Answer 17

Medial cord
C8, T1, often C7
Flexor carpi ulnaris and ulnar half of flexor digitorum profundus; most intrinsic muscles of hand

Question 18

Injuries to the superior parts of the brachial plexus

Answer 18

C5 and C6
Usually result from excessive stretching of the angle between the neck and the shoulder. This could occur from being thrown off a horse or motorcycle and landing in a way that separates the neck and shoulder. This stretches or ruptures superior parts of the brachial plexus or avulses (tears) the roots from the spinal cord. Injury to the superior trunk is apparent by the characteristic position of the limb. “Waiter’s tip position” where the limb hangs by the side in medial rotation.
This can also occur during during delivery if the newborn undergoes excessive stretching of the neck.

Question 19

Erb-Duchenne palsy

Answer 19

Injury to the superior parts of the brachial plexus causes paralysis of the muscles of the shoulder and arm supplied by C5 and C6.
Usual clinical appearance: an upper limb with an adducted shoulder, medially rotated arm, and extended elbow. Lateral aspect of the upper limb also experiences loss of sensation.

Question 20

What can cause chronic microtrauma to the superior trunk of the brachial plexus?

Answer 20

Carrying a heavy backpack. It can produce motor and sensory deficits in distribution of the musculocutaneous and radial nerves.

Question 21

Klumpke paralysis

Answer 21

Injury to the inferior parts of the brachial plexus. Occurs when the upper limb is pulled suddenly superiorly. Injures the inferior portion C8 and T1.
A claw hand results because the short muscles of the hand are affected.