Brachial Plexus

Question 1

Where does brachial plexus come from?

Answer 1

5 spinal roots from the neck (C5, C6, C7, C8, T1), that combine into 3 trunks (superior, middle, inferior) and go through the axilla becoming 6 divisions and recombine into three cords (lateral, posterior, medial), and end in upper limb and 5 branches (MAMUR)

Question 2

Where is posterior cord located?

Answer 2

beneath axillary artery

Question 3

What branches off of C5?

Answer 3

dorsal scapular

Question 4

What branches off c5, c6, c7?

Answer 4

Long Thoracic Nerve

Question 5

What branches of superior trunk (c5, c6)?

Answer 5

suprascapular nerve and nerve to subclavius

Question 6

What nerve branches of Lateral cord?

Answer 6

lateral pectoral and musculocutaneous

Question 7

What nerves branch off posterior cord?

Answer 7

axillary, radial, lower subsacpular, thoracodorsal, and upper subscapular

Question 8

What nerves branch off medial cord?

Answer 8

ulnar, medial brachii cutaneous, medial antebrachial cutaneous, and medial pectoral

Question 9

What two things does musculocutaneous nerve innervate?

Answer 9

Muscles of anterior arm and skin of lateral anterior forearm

Question 10

What is musculocutaneous nerve path?

Answer 10

branches from lateral cord, pierces coracobrachialis muscle, runs through it and innervates muscles of anterior arm (so all bicep muscles). Then it goes deep to biceps brachii terminating in lateral anterior skin

Question 11

What 3 things does median nerve innervate?

Answer 11

most anterior forearm muscles, 5 muscles of palm, and skin thumb to half middle finger

Question 12

What’s path of median nerve?

Answer 12

branches from lateral and medial cords, runs through anterior arm with brachial artery, pierces the pronator teres and branches. It branches into anterior interosseous branch which ends in quadratus muscle, goes through carpal tunnel, and branches to thumb innervating skin of palm, thumb- 1/2 ring finger

Question 13

What does ulnar nerve innervate?

Answer 13

1/2 muscles of the anterior forearm, most hand muscles anteriorly and posteriorly, and the skin of posterior skin of half ring and pinky finger

Question 14

What is path of ulnar nerve?

Answer 14

branches from medial cord, runs posterior to medial epicondyle of humerus, returns to anterior forearm with ulnar artery innervating 1 and 1-2 the the muscles. terminates in skin of dorsal palm and thumb/ring finger

Question 15

What does axillary nerve innervate?

Answer 15

deltoid, teres minor, skin over shoulder

Question 16

What is path of axillary nerve?

Answer 16

branches off posterior cord to quadrangular space, wraps around neck of humerus and runs with PHCA

Question 17

What does radial nerve innervate?

Answer 17

innervates all muscles of posterior arm, forearm, skin of posterior arm, forearm, and some hand

Question 18

What is path of radial nerve?

Answer 18

branches of posterior cord, runs in radial groove posterior to brachial artery, travels in triangular interval, then over lateral humeral epicondyle. Deep radial nerve pierces the supinator becoming interosseous nerve. Superficial radial branches go to posterior and dorsal hand and runs with radial artery.

Question 19

Avulsion vs Rupture

Answer 19

Avulsion is complete tear at spinal root and rupture is complete tear of a peripheral nerve which causes complete loss of function ( motor and sensory)

Question 20

What are symptoms of pinched or damaged nerves?

Answer 20

partial loss of function or tingling

Question 21

What happens if you rupture your radial nerve?

Answer 21

Complete loss of posterior arm and forearm (extensors) and sensory loss of the posterior arm/forearm/dorsal hand

Question 22

What happens if you had a partial tear in your radial nerve?

Answer 22

weakness in the forearms (extensors and numbness of posterior forearm/hand

Question 23

What happens if you get pinched nerve or neuroma of radial nerve?

Answer 23

only sensory deficits on the posterior aspect of forearm and dorsal hand

Question 24

Erb duchane Palsy

Answer 24

Injury to upper brachial plexus (C5, C6) causing avulsion. Usually in infants during delivery, causes waiter’s arm

Question 25

Erb-duchenne palsy

Answer 25

paralysis of deltoid, teres minor, supra/infraspinatus, brachialis, and biceps brachii. Presents as adducted shoulder, medially rotated arm, extended elbow, flexed wrist (because median and ulnar still intact)

Question 26

How does lower brachial plexus injury occur (Klumpke Paralysis)?

Answer 26

less frequent, pulling of upper limb superiorly, flexed arm, lateral rotation, supinated forearm, flexed wrist snd digits

Question 27

Coracobrachialis attachments, innervation, and function?

Answer 27

innervated by musculocutaneous nerve, attaches to the coracoid process, and medial humerus. It does flexion of humerus, adduction, and resists dislocation

Question 28

Brachialis attachments, innervations, and function

Answer 28

Distal half of humerus (anterior) and coronoid process of unla. Innervated by musculocutaneous and radial nerve. Does flexion at the elbow

Question 29

Biceps brachii attachments, innervations, and function

Answer 29

Long head: Attaches to supraglenoid tubercle on scapula, radial tuberosity, and bicipital groove. Short head attaches to coracoid process, radial tuberosity, and bicipital aponeurosis. Innervated by musculocutaneous and does flexion of forearm at elbow and supination

Question 30

Where do the triceps brachii heads attach?

Answer 30

Long head attaches to infraglenoid tubercle of scapula, lateral head attaches to posterior surface of humerus, and medial head attaches posterior inferior surface of humerus. Distally all attach to proximal end of olecranon

Question 31

What innervates triceps brachii and what are the actions?

Answer 31

Radial nerve innervates triceps brachii and they do extension and long head resists dislocation

Question 32

What does anconeus attach to, innervate, and do?

Answer 32

Attaches to lateral epicondyle, lateral olecranon and superior/posterior ulna. Innervated by radial nerve, and does extension of the forearm at the elbow

Question 33

What does brachioradialis attach to, innervated by, and action?

Answer 33

Attach to supracondylar ridge and lateral distal radius. Innervated by radial nerve does flexion at elbow

Question 34

What are four major arteries of the arm?

Answer 34

Brachial which is continuation of axillary, deep brachial inserts in coracobrachialis. At cubital fossa the brachial artery branches into the ulnar and radial artery.

Question 35

What forms the anastomosis of elbow?

Answer 35

Collaterals which are superior the elbow and head down, and recurrrents which are inferior to the elbow and head up

Question 36

What are the four collaterals?

Answer 36

2 from deep brachial are the radial and middle collateral, and two from the brachial are superior ulnar and inferior ulnar collateral.

Question 37

What are the 4 recurrents?

Answer 37

1 radial artery recurrent, interosseous, anterior ulnar, and posterior ulnar are ulnar artery recurrents.

Question 38

What are the borders of antecubital fossa?

Answer 38

line from epicondyle to epicondyle, brachioradialis, pronator teres, and brachialis and supinator more deep

Question 39

What are the CUTANEOUS innervations?

Answer 39

Question 40

What are nerve distributions?

Answer 40

C5 is dorsal scapular nerve, C5, C6 combine to form superior trunk and suprascapular nerve. Superior trunk and middle trunk combine to form lateral cord from roots C5, C6, C7. Every root goes to posterior cord.