Muscles of the Upper Arm

Question 1

How many muscles are in the upper arm?

Answer 1

4

Question 2

How many muscles are in the anterior compartment of the upper arm?

Answer 2

3

Question 3

How many muscles are in the posterior compartment of the upper arm?

Answer 3

1

Question 4

Name the muscles in the anterior compartment of the upper arm

Answer 4

Biceps Brachii
Brachialis
Coracobrachialis

Question 5

Which nerve innervates the muscles of the anterior compartment of the upper arm and what is its nerve root?

Answer 5

Musculocutaneous Nerve

C5, C6, C7

Question 6

Describe Biceps Brachii

Answer 6

A two-headed muscle, the majority of the muscle mass is located anteriorly to the humerus, but has no attachment to the humerus itself.
As the tendon of biceps brachii enters the forearm, a connective tissue sheet is given off called the bicipital aponeurosis. This forms the roof of the cubital fossa and blends with the deep fascia of the anterior forearm.

Question 7

Name the origin and insertion of Biceps Brachii

Answer 7

Origin - Long head - supraglenoid tubercle of the scapula, Short head - coracoid process of the scapula.
Insertion - Both heads insert into the radial tuberosity and the fascia of the forearm via the bicipital aponeurosis.

Question 8

What is the function of Biceps Brachii?

Answer 8

Supination of the forearm

Flexion of the arm at the elbow and the shoulder

Question 9

Describe Brachialis

Answer 9

Lies deep to the Biceps Brachii, and is found more distally than the other muscles of the arm. It forms the floor of the cubital fossa.

Question 10

Name the origin and insertion of Brachialis

Answer 10

Origin - medial and lateral surfaces of the humeral shaft

Insertion - ulna tuberosity, just distal to the elbow joint

Question 11

What is the function of Brachialis?

Answer 11

Flexion at the elbow

Question 12

Which other nerve innervates Brachialis in addition to the musculocutaneous nerve?

Answer 12

Radial nerve

Question 13

Describe Coracobrachialis

Answer 13

Lies deep to the biceps brachii in the arm

Question 14

Name the origin and insertion of Coracobrachialis

Answer 14

Origin - coracoid process
Insertion - passes through the axilla and attaches the medial side of the humeral shaft at the level of the deltoid tubercle

Question 15

What is the function of Coracobrachialis?

Answer 15

Flexion of the arm at the shoulder

Weak adduction

Question 16

Which is a common tendon to rupture?

Answer 16

The long head of the biceps brachii is one of the more common tendons to rupture

Question 17

What does rupturing of the tendon of the long head of biceps brachii present as?

Answer 17

This produces a characteristic sign on flexing the elbow - a bulge where the muscle belly is - called the Popeye Sign. The patient would not notice much weakness in the upper limb due to the action of the brachialis and supinator muscles.

Question 18

Which muscle lies in the posterior compartment of the arm?

Answer 18

Triceps brachii

Question 19

Describe Triceps Brachii

Answer 19

Has 3 heads

The medial head lies deeper than the other two, which cover it.

Question 20

What is the arterial supply to the posterior compartment of the upper arm?

Answer 20

Profunda brachii artery

Question 21

Name the origin and insertion of the triceps brachii

Answer 21

Origin - long head - infraglenoid tubercle
lateral head - humerus, superior to the radial
groove
medial head - humerus, inferior to the radial
groove
Insertion - the heads converge into one tendon and insert into the olecranon of the ulna

Question 22

What is the function of Triceps Brachii?

Answer 22

Extension of the arm at the elbow

Question 23

What is the innervation of Triceps Brachii?

Answer 23

Radial nerve, C5-T1