Upper Limb - Arm Anatomy (PDF)

The brachium, or arm, extends from the shoulder to the elbow. The deep fascia of the arm, in the form of lateral and medial intermuscular septae, creates two muscular compartments: The anterior compartment contains exor muscles and is innervated by the...

The brachium, or arm, extends from the shoulder to the elbow. The deep fascia of the arm, in the form of lateral and medial intermuscular septae, creates two muscular compartments: The anterior compartment contains exor muscles and is innervated by the musculocutaneous nerve. The posterior compartment contains extensor muscles and is innervated by the radial nerve. Biceps Brachii Muscle Has two heads of origin: ◦ Short head: originates from the coracoid process of the scapula. ◦ Long head: originates from the supraglenoid tubercle of the scapula. Inserts at the radial (bicipital) tuberosity. Innervated by the musculocutaneous nerve. Its primary function is supination of the forearm; when the forearm is supinated, it also exes the forearm. Blood supply: muscular branches of the brachial artery. Biceps Tendon Re ex Test Assesses the integrity of the musculocutaneous nerve and the C5–C6 spinal cord segments. An excessive, diminished, or prolonged (hung) response may indicate central or peripheral nervous system disease or a metabolic disorder. Procedure: ◦ Gently ex the arm at the elbow. ◦ Tap the biceps tendon with a re ex hammer. ◦ Locating the tendon with your thumb and striking your thumb with the hammer ensures accuracy. Brachialis Muscle fl fl fl fl fl  Origin: anterior surface of the humerus. Insertion: coronoid process and the ulnar (brachial) tuberosity of the ulna. Innervation: musculocutaneous nerve. Primary function: exion of the forearm. Blood supply: radial recurrent artery. Coracobrachialis Muscle Origin: coracoid process of the scapula. Insertion: medial surface of the humerus. Innervation: musculocutaneous nerve. Function: exes and adducts the arm. Blood supply: muscular branches of the brachial artery. The musculocutaneous nerve pierces the coracobrachialis muscle. Triceps Brachii Muscle Has three heads of origin: ◦ Long head: originates from the infraglenoid tubercle of the scapula. ◦ Lateral head: originates from the posterior surface of the humerus. ◦ Medial head: also originates from the posterior surface of the humerus. Insertion: olecranon process of the ulna. Innervation: radial nerve. Primary function: extends the forearm. Blood supply: muscular branches of the brachial artery. Olecranon Bursa Located between the olecranon and the triceps tendon. Anconeus Muscle Origin: lateral epicondyle of the humerus. Insertion: olecranon process of the ulna. Innervation: radial nerve. fl fl  Function: assists the triceps brachii muscle. Blood supply: posterior interosseous recurrent artery.