Both heads join on the middle of the humerus, to form a single muscle mass usually near the insertion of the deltoid , to form a common muscle belly. Distally , biceps ends in two tendons: the stronger attaches to the radial tuberosity on the radius , while the other, the bicipital aponeurosis , radiates into the ulnar part of the antebrachial fascia. 
The tendon that attaches to the radial tuberosity is partially or completely surrounded by a bursa ; the bicipitoradial bursa , which ensures frictionless motion between the biceps tendon and the proximal radius during pronation and supination of the forearm. 
Two muscles lie underneath the biceps brachii. These are the coracobrachialis muscle , which like the biceps attaches to the coracoid process of the scapula, and the brachialis muscle which connects to the ulna and along the mid-shaft of the humerus. Besides those, the brachioradialis muscle is adjacent to the biceps and also inserts on the radius bone, though more distally.
Traditionally described as a two-headed muscle, biceps brachii is one of the most variable muscles of the human body and has a third head arising from the humerus in 10% of cases (normal variation) — most commonly originating near the insertion of the coracobrachialis and joining the short head — but four, five, and even seven supernumerary heads have been reported in rare cases. 
The distal biceps tendons are completely separated in 40% and bifurcated in 25% of cases. 
The long head of the biceps brachii muscle is the larger of the two muscle bodies that forms the entire biceps brachii muscle. The biceps brachii gets its name from the Latin words for “two-headed” and “arm” which describe its structure and location. The long and short heads of the biceps brachii work together to achieve the same functions.
The long head extends from its origin on the superglenoid tubercle of the scapula and passes over the head of the humerus before merging with the short head..
The abductor digiti minimi muscle of hand creates abduction of the little finger. Abduction refers to movement of a limb away from the central line of the body or of a digit away from the axis of a limb. Muscles, then, that carry out this type of movement are called abductor muscles.
The abductor pollicis brevis muscle is one of the three muscles of the thenar eminence of the hand and serves to pull the thumb away from the palm. Abduction refers to movement of a limb away from the central line of the body or of a digit away from the axis of a limb. Muscles that carry out this type of movement are called abductor muscles.
The abductor pollicis longus muscle is a long, thin muscle of the forearm that serves to pull the thumb away from the palm. Abduction refers to movement of a limb away from the central line of the body or of a digit away from the axis of a limb. Muscles, then, that carry out this type of movement are called abductor muscles.
The biceps brachii muscle (biceps) is a large, thick muscle of the upper arm consisting of two heads.
Both heads unite to one large muscle at the anterior side of the humerus and attach to the radial tuberosity . A fibrous membrane emerging from the distal part of the muscle (bicipital aponeurosis, also lacertus fibrosus) inserts at the deep fascia of forearm. In terms of innervation, this muscle is supplied by the musculocutaneous nerve (C5-C6), a branch of the brachial plexus .
The surface anatomy of the anterior side of the upper arm is essentially formed by the biceps. While both its origin tendons are covered by the deltoid its insertion tendon can be easily seen and palpated at the crook of the arm. The space between the biceps and triceps forms two grooves (medial and lateral bicipital grooves). Within the medial bicipital groove course the brachial artery and both the ulnar and median nerves while the lateral bicipital groove contains the radial nerve .
Learning anatomy is a massive undertaking, and we’re here to help you pass with flying colours.
Difference Between Pronation and Supination - 0:38
© 2017. SuperStarFloraluk.com