9.27.16 Arm

Question 1

What dermatomes do the C6, C7, and C8 innervate?

Answer 1

C6: lateral arm, forearm, thumb
C7: back of arm, back of forearm, 2nd and 3rd digits
C8: medial arm, forearm, hypothenar

Question 2

What are the 3 muscles of the anterior arm?

Answer 2

1. Biceps brachii (long head and short head)
2. Brachialis
3. Coracobrachialis

Question 3

What is the origin and insertion of biceps brachii?

Answer 3

Origin of long head: supraglenoid tubercle of scapula
Origin of short head: tip of coracoid process of scapula
Insertion: radial tuberosity, fascia of forearm via bicipital aponeurosis

Question 4

What innervates biceps brachii?

Answer 4

Musculocutaneous nerve (C5, C6)

Question 5

What is the function of biceps brachii?

Answer 5

Flexes and supinates forearm at elbow

Question 6

What supplies the biceps brachii?

Answer 6

Muscular branches of brachial artery

Question 7

What is the origin and insertion of brachialis?

Answer 7

Origin: distal half of anterior surface of humerus
Insertion: Coronoid process and tuberosity of ulna

Question 8

What innervates brachialis?

Answer 8

Musculocutaneous nerve and radial nerve (C7)

Question 9

What is the function of brachialis?

Answer 9

Flexes forearm at elbow

Question 10

What supplies brachialis?

Answer 10

Radial recurrent artery, muscular branches of brachial artery

Question 11

What is the origin and insertion of coracobrachialis?

Answer 11

Origin: tip of coracoid process of scapula
Insertion: Middle third of medial surface of humerus

Question 12

What innervates coracobrachialis?

Answer 12

Musculocutaneous nerve

Question 13

What is the function of coracobrachialis?

Answer 13

Flexes and adducts arm at shoulder

Question 14

What supplies coracobrachialis?

Answer 14

Muscular branches of brachial artery

Question 15

The tendon of the long head of the biceps runs over the head of the ___ in a synovial sheath that follows the tendon as far as the surgical neck. The tendon is held in place in the ___ by the transverse humeral ligament and the tendon of the ___ muscle.

Answer 15

Humerus; intertubercular groove; pectoralis major

Question 16

What is the origin and insertion of triceps brachii?

Answer 16

Origin of long head: infraglenoid tubercle of scapula
Origin of lateral head: upper half of posterior humerus
Origin of medial head: distal 2/3 of medial and posterior humerus
Insertion: posterior surface of olecranon process of ulna

Question 17

What innervates triceps brachii?

Answer 17

Radial nerve

Question 18

What is the function of triceps brachii?

Answer 18

Extends forearm at elbow; long head stabilizes head of abducted humerus and extends and adducts arm at shoulder

Question 19

What supplies triceps brachii?

Answer 19

Branch of profunda brachii artery

Question 20

The ___ head is the least active of the triceps muscle and aids primarily in ___ the arm.

Answer 20

Long; extending

Question 21

The ___ head is the workhorse of forearm extension.

Answer 21

Medial

Question 22

The ___ head is typically the strongest generator of force, but functions primarily against ___.

Answer 22

Lateral; active resistance

Question 23

The ___ is the continuation of the axillary artery at the inferior border of the teres major muscle; it terminates in the ___, where it divides into what 2 arteries?

Answer 23

Brachial artery; cubital fossa; radial and ulnar arteries

Question 24

The brachial artery lies successively on three muscles, gives three main branches, is in contact with three important nerves, and is associated with three veins. Name all of these.

Answer 24

Muscles: long head of the triceps, coracobrachialis, brachialis muscles
Branches: deep brachial (profunda brachii; runs in radial groove posteriorly), superior ulnar collateral, inferior ulnar collateral artieres
Nerves: radial, ulnar, and median
Veins: 2 venae comitantes (brachial veins) and basilic vein

Question 25

True or false - bifurcation location is not constant and may take place at a high level in the arm.

Answer 25

True

Question 26

The brachial artery lies ___ to both the triceps and brachialis muscles; its pulsations can be felt throughout its course.

Answer 26

Anterior

Question 27

What are the 4 nerves of the arm?

Answer 27

1. Musculocutaneous - anterior compartment
2. Radial - posterior compartment
3. Ulnar - no branches in arm
4. Median - no branches in arm

Question 28

Describe the path of the musculocutaneous nerve (C5-C7).

Answer 28

Pierces the coracobrachialis muscle and continues as the lateral antebrachial cutaneous nerve

Question 29

What does the musculocutaneous nerve innervate?

Answer 29

Coracobrachialis, biceps, and brachialis muscle

Question 30

What happens when the musculocutaneous nerve is injured?

Answer 30

Great loss of flexion of the elbow (not completely due to the brachioradialis and flexor forearm muscles)

Question 31

Describe the path of the radial nerve (C5-C8; T1).

Answer 31

Passes in the radial groove on the back of the humerus with the deep brachial artery, pierces the lateral intermuscular septum, and divides into superficial and deep branches in front of the lateral epicondyle.

Question 32

What does the radial nerve innervate in the arm?

Answer 32

Triceps, brachioradialis, the skin of the posterior arm and forearm

Question 33

Describe the path of the ulnar nerve (C8, T1).

Answer 33

Found medial to axillary and brachial arteries to the middle of the arm, pierces the medial intermuscular septum, and runs with the superior ulnar collateral artery to a groove behind the medial epicondyle of the humerus.

Question 34

A sharp blow to the medial side of the elbow with result in ___ and a shock-like feeling in the hand and forearm.

Answer 34

Paraesthesia

Question 35

Describe the path of the median nerve (C5-C8-; T1).

Answer 35

Runs lateral to, then crosses, and finally, is medial to the brachial artery. It passes through the cubital fossa deep to the bicipital aponeurosis.

Question 36

What is the triangular-shaped, fat-filled depression of the anterior elbow?

Answer 36

Cubital fossa

Question 37

The cubital fossa is ideal for ___.

Answer 37

Drawing blood

Question 38

What are the boundaries of the cubital fossa?

Answer 38

Superior: imaginary line connecting the medial and lateral epicondyles
Medial: forearm flexors originating from the medial epicondyle
Lateral: forearm extensors originating from the lateral epicondyle
Floor: brachialis and supinator muscles
Roof: brachial and antebrachial fascia and reinforced by the bicipital aponeurosis, which serves to protect the deep arteries and nerves in the area

Question 39

What are the deep contents of the cubital fossa?

Answer 39

Terminal part of the brachial artery (branches into ulnar and radial arteries), deep veins in the area, tendon of the biceps brachii muscle, median nerve, radial nerve