Anterior Arm and Musculocutaneous Nerve

Question 1

Identify the structures labelled 1-19

Answer 1

1- Greater tuberosity

2- Intertubercular groove

3- Shaft of humerus

4- Radial fossa

5- Lateral epicondyle

6- Capitulum

7- Trochlea

8- Medial epicondyle

9- Coronoid fossa

10- Deltoid tuberosity

11- Surgical neck

12- Anatomical neck

13- Anatomical neck

14- Surgical neck

15- Medial epicondyle

16- Condyles

17- Olecranon fossa

18- Radial groove

19- Greater tubercle

Question 2

What are the main muscles of the anterior compartment of the arm?

Answer 2

Biceps brachii

Coracobrachialis

Brachialis

Question 3

What is the most anterior muscle of the anterior arm?

Answer 3

Biceps brachii

Question 4

What are the attachments of biceps brachii?

Answer 4

Arises from the scapula by two heads

Heads unite ay the distal third of the upper arm

Forms short tendon that is inserted into the tuberosity of the radius

Question 5

On which joints does the biceps brachii act?

Answer 5

Shoulder

Elbow

Radio-ulnar

Question 6

What are the names of the two heads of biceps brachii?

Answer 6

Long head and short head

Question 7

From where does each head of biceps brachii arise?

Answer 7

Short head- arises from coracoid process

Long head- arises from the supraglenoid tubercle and runs in bicipital groove of humerus

Question 8

What action does biceps brachii have on each of the joints it acts on?

Answer 8

Flexes the shoulder and elbow joints

Powerful supinator of the radio-ulnar joint

Question 9

What is the nerve supply to biceps brachii?

Answer 9

Musculocutaneous nerve (C5-6)

Question 10

From which cord of the brachial plexus does the musculocutaneous nerve arise?

Answer 10

The lateral cord

Question 11

What are the attachments of the coracobrachialis muscle?

Answer 11

Originates at tip of coracoid process

Inserted into medial margin of humerus at about its middle

Question 12

What action does coracobrachialis have on the shoulder joint?

Answer 12

Flexes and adducts the shoulder joint

Question 13

What is the nerve supply of coracobrachialis?

Answer 13

Musculocutaneous nerve

Question 14

What are the attachments of the brachialis muscle?

Answer 14

Arises from the front of the distal half of the shaft of the humerus

Inserted into coronoid process of ulna

Lies partly under biceps brachii

Question 15

What action does brachialis have on the elbow joint?

Answer 15

Flexes the elbow joint in all positions

Question 16

What nerve supplies the brachialis muscle?

Answer 16

Musculocutaneous nerve

Question 17

What is the course of the musculocutaneous nerve in the arm?

Answer 17

Enter arm by perforating coracobrachialis

Descends between biceps and brachialis

Continues as lateral cutaneous nerve of forearm

Question 18

What is the root value of the musculocutaneous nerve?

Answer 18

C5-7

Question 19

Which three muscles are supplied by the musculocutaneous nerve?

Answer 19

Biceps brachii

Brachialis

Coracobrachialis