The biceps brachii, or simply biceps in common parlance, is, as the name implies, a two-headed muscle. The biceps lie on the upper arm between the shoulder and the elbow. Both heads arise on the scapula and join to form a single muscle belly which is attached to the upper forearm. While the biceps crosses both the shoulder and the elbow joints, its main function is at the latter where it flexes the elbow and supinates the forearm. Both these movements are used when opening a bottle with a corkscrew: first biceps unscrews the cork (supination), then it pulls the cork out (flexion).
Proximally (towards the body), the short-head of the biceps originates from the coracoid process at the top of the scapula. The long-head originates from the supraglenoid tubercle just above the shoulder joint from where its tendon passes down along the intertubercular groove of the humerus into the joint capsule of the shoulder joint. When the humerus is in motion, the tendon of the long-head is held firmly in place in the intertubercular groove by the greater and lesser tubercles and the overlying transverse humeral ligament. During the motion from external to internal rotation, the tendon is forced medially against the lesser tubercle and superiorly against the transverse ligament.
Both heads join on the middle of the humerus, usually near the insertion of the deltoid, to form a common muscle belly. Distally (towards the fingers), biceps ends in two tendons: the stronger attaches to (inserts into) the radial tuberosity on the radius, while the other, the bicipital aponeurosis, radiates into the ulnar part of the antebrachial fascia.
Two additional 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.
As mentioned above, the bicep contains two muscle heads, the bicep long-head (1) (outer) and the bicep short-head (2) (inner).
The short- head (inner) of the bicep is where you will find most of the mass/bulk of the muscle and the long-head (outer) is what actually creates the ''bicep peak''. When flexing the bicep muscle the long-head (outer) actually rises up and sits on top/above of the short-head (inner). So achieving muscle hypertrophy (increase in muscle size) in the bicep long-head will create a bigger bicep peak.
See pic below.
The best exercises to perform to build your bicep peak are the exercises which put more activation on the bicep long-head. Now you must remember that whatever bicep exercise you perform both muscle heads will be activated, there is no way to isolate only one head at a time. However depending on the exercise you perform the amount of stress and activation applied will not be equal on both muscle heads. Below is a list of some exercises which will really emphasize your bicep long-head and help you create a good bicep peak.
- Close grip barbell curls
- Hammer curls
- Concentration curls
- Spider curls
- Close grip preacher curls
- Cross body hammer curls
Yes the bicep peak is a genetic trait, if you have a big bicep long-head you will have a good bicep peak shape to your biceps, however regardless of your genetics you can still build a good bicep peak through way of training, just make sure you focus a lot of your bicep training on your bicep long-head!
All the best and good luck with your bicep peaks!