Lab3 - Module 1 - Anatomy of the Arm: Page 3 of 9
Muscles of the Anterior Arm
| Begin with the bones of the upper extremity. |
| Add the Coracobrachialis muscle. This muscle is important mainly as a landmark; the musculocutaneous nerve pierces it. |
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Origin - tip of the coracoid process of the scapula. It originates as a conjoined tendon with the origin of the short-head of the biceps brachii muscle. Insertion - middle 1/3 of the medial surface of the body of the humerus. Innervation - musculocutaneous nerve Actions - flexes the arm at the shoulder and aids in adduction of the arm. Blood supply - muscular branches of the brachial artery. |
| Add the Brachialis muscle. It lies deep to the biceps muscle on the anterior side of the humerus. The brachialis is the main flexor of the forearm at the elbow. |
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Origin - distal ½ of the anterior surface of the humerus Insertion - ulnar tuberosity of the ulna. Innervation - Musculocutaneous nerve Action - flexes the forearm at the elbow joint – Does NOT play a role in pronation or supination. Blood supply - muscular branches from the brachial artery |
| Add the Biceps Brachii muscle. As the name indicates it has two heads of origin. The long head and the short head. You can identify these the short head on the 3D cadaver by using the Highlight Tool. |
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Origin - Short head – tip of the coracoid process of the scapula. It originates as a conjoined tendon with the origin of the coracobrachialis muscle. Long head – supraglenoid tubercle of the scapula. The tendon of the long head crosses the head of the humerus within the capsule of the glenohumeral joint and descends in the intertubercular (bicipital) groove of the humerus. Insertion - radial tuberosity on the radius bone. The biceps brachii also inserts via the bicipital aponeurosis, a triangular, membranous band which runs from the biceps tendon across the cubital fossa into the deep fascia over the flexor muscles in the medial side of the forearm. The bicipital aponeurosis affords protection for the brachial artery and median nerve in the cubital fossa, as well as lessening the pressure of the biceps tendon on the radial tuberosity during pronation and supination of the forearm. Innervation - Musculocutaneous nerve Actions - flexion and supination of the forearm. The biceps is a powerful supinator (accounting for about 60% of supination strength). Blood supply - muscular branches from the brachial artery. |