Application of information related to structures of the brachial plexus (MA)

Question 1

Injury to C5 nerve root

Answer 1

Phrenic nerve (motor and sensory to diaphragm); dorsal scapular nerve (supplies the rhomboids and levator scapulae); long thoracic nerve (serratus anterior); subclavius nerve (subclavius muscle); suprascapular nerve (supraspinatus and infraspinatus muscles); pectoralis major and minor muscles (via the medial and lateral pectoral nerves); coracobrachialis, brachialis, and biceps brachii (via the musculocutaneous nerve); C5, C6, and C7 form the lateral root that form the median nerve that controls most forearm flexors; upper and lower subscapular nerves supply the subscapularis and teres major; axillary nerve supplies the motor function of deltoid and teres minor; the radial nerve (derives from all 5 roots) supplies motor innervation of the triceps brachii, anconeus, extensor muscles of the forearm

Question 2

Injury to C6 nerve root

Answer 2

Long thoracic nerve (serratus anterior); subclavius nerve (subclavius muscle); suprascapular nerve (supraspinatus and infraspinatus muscles); pectoralis major and minor muscles (via the medial and lateral pectoral nerves); coracobrachialis, brachialis, and biceps brachii (via the musculocutaneous nerve); C5, C6, and C7 form the lateral root that form the median nerve that controls most forearm flexors; upper and lower subscapular nerves supply the subscapularis and teres major; axillary nerve supplies the motor function of deltoid and teres minor; thoracodorsal nerve innervates latissimus dorsi; the radial nerve (derives from all 5 roots) supplies motor innervation of the triceps brachii, anconeus, extensor muscles of the forearm

Question 3

Injury to C7 nerve root

Answer 3

Long thoracic nerve (serratus anterior); pectoralis major and minor muscles (via the medial and lateral pectoral nerves); coracobrachialis, brachialis, and biceps brachii (via the musculocutaneous nerve); C5, C6, and C7 form the lateral root that form the median nerve that controls most forearm flexors; thoracodorsal nerve innervates latissimus dorsi; the radial nerve (derives from all 5 roots) supplies motor innervation of the triceps brachii, anconeus, extensor muscles of the forearm

Question 4

Injury to C8 nerve root

Answer 4

Thoracodorsal nerve innervates latissimus dorsi; the radial nerve (derives from all 5 roots) supplies motor innervation of the triceps brachii, anconeus, extensor muscles of the forearm; medial pectoral nerve which supplies the pectoralis minor and part of pectoralis major; ulnar nerve which supplies motor control to flexor carpi ulnaris, medial belly of flexor digitorum profundus

Question 5

Injury to T1 nerve root

Answer 5

The radial nerve (derives from all 5 roots) supplies motor innervation of the triceps brachii, anconeus, extensor muscles of the forearm; medial pectoral nerve which supplies the pectoralis minor and part of pectoralis major; ulnar nerve which supplies motor control to flexor carpi ulnaris, medial belly of flexor digitorum profundus

Question 6

What 2 cords come together to form the median nerve?

Answer 6

Lateral and medial cords

Question 7

Where does the brachial plexus originate from?

Answer 7

Anterior rami of spinal nerves C5-T1

Question 8

What roots from the superior trunk?

Answer 8

C5 and C6

Question 9

What roots form the middle trunk?

Answer 9

C7 only

Question 10

What roots form the inferior trunk?

Answer 10

C8 and T1