What are the muscles of the anterior compartment of the upper arm?
Biceps, coracobrachialis and brachialis
Innervation to anterior compartment of the upper arm
Arterial supply to the anterior compartment of the upper arm
Muscular branches of the brachial artery
Biceps brachii attachments
Long head origionates from the supraglenoid tubercle of the scapula, and the short head origionates from the coracoid precess of the scapula. Both heads insert distally into the radial tuberosity and the fascia of the forearm via the biceptial aponeurosis.
Biceps brachii function
Supination of the forearm. It also flexes the arm at the elbow and at the shoulder.
Biceps brachii innervation
Musculocutaneous nerve. The biceps tendon reflex tests spinal cord segment C6.
Origionates from the coracoid process of the scapula. The muslce passes through the axilla , and attaches the medial side of the humeral shaft, at the level of the deltiod tubercle.
Flexion of the arm at the shoulder and weak adduction.
Origionates from the medial and lateral surfaces of the humeral shaft and inserts into the ulna tuberosity, just distal to the elbow joint.
Flexion at the elbow
Posterior compartment of the upper arm
Contains the triceps brachii muscle, which has three heads. The medial head lies deeper than the other two which cover it.
Arterial supply to posterior compartment of the upper arm
Profunda brachii artery
Triceps brachii attachments
- Long head - origionates from the infraglenoid tubercle.
- Lateral head - origionates from the humerus, superior to the radial groove.
- Medial head - origionates from the humerus, inferior to the radial groove.
- Distally, the heads converge into one tendon and insert into the olecranon of the ulna.
Triceps brachii function
Extension of the arm at the elbow
Triceps brachii innervation
Radial nerve. A tap on the triceps tendon tests spinal segment C7. In some individuals, the long head of the triceps brachii is innervated by the axillary nerve.