arm muscles: attachments, nerve supply and actions

Question 1

Anterior muscles of the arm

Answer 1

Biceps Brachii
Coracobrachialis
Brachialis

Question 2

nerve supply of anterior arm muscles

Answer 2

Musculocutaneous nerve supplies all muscles in this group

Question 3

main actions of the anterior muscles of the arm

Answer 3

Predominantly flexors of the glenohumeral and elbow joints, biceps is also a supinator of the forearm

Question 4

proximal and distal attachments, nerve supply, actions of biceps brachii

Answer 4

PA-
Short head: coracoid process of the scapula
Long head: supraglenoid tubercle of the scapula
DA- Radial tuberosity. Fascia of the forearm via the bicipital aponeurosis
N/S- Musculocutaneous nerve
A- Both heads: Supinate the forearm and flex the elbow joint (when the forearm is supinated)
Short head also resists dislocation of the glenohumeral joint

Question 5

proximal and distal attachments, nerve supply, actions of coracobrachialis

Answer 5

PA- Coracoid process of the scapula
DA- Medial aspect of the humerus (middle third)
N/S- Musculocutaneous nerve (pierces this muscle)
A- Flexes and adducts the glenohumeral joint. Also resists dislocation of the glenohumeral joint

Question 6

proximal and distal attachments, nerve supply, actions of brachialis

Answer 6

PA- Anterior aspect of the humerus (distal half)
DA- Ulnar tuberosity
N/S- Musculocutaneous nerve
A- Flexes the elbow joint in all positions

Question 7

posterior muscles of the arm

Answer 7

Triceps Brachii
Anconeus

Question 8

posterior muscles of the arm nerve supply

Answer 8

radial nerve

Question 9

main actions of the posterior muscles of the arm

Answer 9

extensors of the elbow joint

Question 10

proximal and distal attachments, nerve supply, actions of triceps brachii

Answer 10

PA-
Long head: infraglenoid tubercle of the scapula
Lateral head: posterior aspect of the humerus, superior to the radial groove
Medial head: posterior aspect of the humerus, inferior to the radial groove
DA- Olecranon process of the ulna
N/S- Radial nerve
A- All heads: Extend the elbow joint
Long head also prevents dislocation of the glenohumeral joint

Question 11

proximal and distal attachments, nerve supply, actions of anconeus

Answer 11

PA- Lateral epicondyle of the humerus
DA- Olecranon process of the ulna
N/S- Radial nerve
A- Weakly extends the elbow joint