The biceps brachii muscle originates from two points on the scapula (shoulder blade) and inserts on the radius bone in the forearm. Here's a more detailed breakdown:
Origins:
The biceps brachii has two heads, each with a different origin:
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Long Head: Originates from the supraglenoid tubercle of the scapula. This is located just above the glenoid fossa, the socket that articulates with the humerus (upper arm bone) to form the shoulder joint. The tendon of the long head travels through the intertubercular groove of the humerus.
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Short Head: Originates from the coracoid process of the scapula. The coracoid process is a bony projection on the anterior (front) aspect of the scapula.
Insertion:
Both the long and short heads of the biceps brachii converge to form a single muscle belly, which then inserts distally (further down the arm) in two ways:
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Radial Tuberosity: The primary insertion is on the radial tuberosity, a bony prominence on the proximal (near) end of the radius bone in the forearm.
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Bicipital Aponeurosis: A secondary insertion is via the bicipital aponeurosis. This is a broad, flat tendon that extends from the biceps tendon and merges with the deep fascia of the forearm, specifically the flexor muscles.
In summary, the biceps brachii muscle's two heads originate on the scapula (shoulder blade) and converge to insert on the radius bone and forearm fascia, allowing it to flex the elbow and supinate the forearm.
