The Triceps Brachii
(Latin for “three-headed muscle of the arm)

(red – the long head, yellow – the lateral head, green – the medial head)

The long head has its origin on the infraglenoid tubercle (bottom edge) of the scapula (shoulder blade). The medial head originates proximally from the dorsal (back) surface of the humerus (upper arm bone). The lateral head also originates from the dorsal surface of the humerus, but lateral (further to the outside) and proximal (closer to the trunk) to the groove of the radial nerve.
The fibres come together to form a single tendon which inserts onto the ulna. (The bone on the little finger side of the hand).

The triceps is an extensor muscle of the elbow joint and an antagonist of the biceps and brachialis muscles. This means it straightens the arm when engaged. It can also fixate the elbow joint when the forearm and hand are used for fine movements, e.g., when writing.

With its origin on the scapula, the long head also works the shoulder joint and is involved in retroversion (backwards rotation) and adduction (moving the arm towards the body) of the arm. It helps stabilise the shoulder joint at the top of the humerus

The triceps can be worked through either isolation or compound elbow extension movements and can contract statically to keep the arm straightened against resistance.

For yoga poses that work on the Triceps or that need the muscle to be more effective come back next week to read the next post in this series.

If you have any questions or remarks please leave a comment below and we will answer this as soon as possible.