![]() This muscle helps to depress, abduct, and downwardly rotate the scapula. Pectoralis minor (sometimes shortened to pec minor) lies deep to (underneath) pectoralis major, along the ribs. Today’s muscle, pectoralis minor, starts on the third, fourth, and fifth ribs and ends at the coracoid process. I thought I would use the coracoid process of the scapula, which I identified last week, as a jumping-off point for the next couple of muscles. Additionally, sometimes the tendons that attach at the radius are completely separated they can also be bifurcated. Although its name is the two-headed arm muscle, about 10-12% of arms have a biceps brachii with 3 heads the muscle has been observed to have from 1-5 heads. There is a lot of variation in this muscle. It also flexes the elbow and (more weakly) the shoulder. A mnemonic device for remembering this is “holding a bowl of soup (supination) or prone (pronation) to spill it.” Because of its attachment on the tuberosity of the radius, the biceps brachii is a strong supinator muscle. Supination is turning the forearm so that the palm is face-up pronation is turning the forearm so that the palm is face-down. Both of these joints are pivot joints, and they allow for movements in the forearm known as supination and pronation. “I’ve never heard of them!” The radius and the ulna are the two bones of the forearm they touch (articulate) at both ends: near the elbow (proximal) and near the wrist (distal). The two heads come together into a single muscle body, and then insert as a tendon on the radius.īiceps brachii affects three joints: the shoulder (glenohumeral joint), the elbow (humeroulnar joint), and the radioulnar joints. The longer head also originates on the scapula, on the supraglenoid tubercle–this is a small protrusion of the scapula just above where the humerus and scapula interface (which is the glenoid fossa) this origination is deep in the shoulder joint (so the outline of the longer head–on top–in the picture here is more of an approximation). The shorter head of the biceps originates on the coracoid process of the scapula, making this the third muscle we’ve identified that has an insertion there. Literally, biceps brachii is the two-headed arm muscle. Interestingly, this is the muscle that gave “muscle” its name: in both Latin and Greek, the word for muscle comes from the word for mouse, because biceps brachii, when flexed, looks like a little mouse. This week’s muscle is another well-known one: biceps brachii.
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