肱三頭肌

Also known as triceps, tri, triceps brachii

The triceps, or triceps brachii (Latin for "three-headed muscle of the arm"), is a large muscle on the back of the upper limb of many vertebrates. It consists of three parts: the medial, lateral, and long head. All three heads cross the elbow joint. However, the long head also crosses the shoulder joint. The triceps muscle contracts when the elbow is straightened and expands when the elbow is bent. The long head gets a further contraction when the arm is behind the torso due to how it crosses the shoulder joint. It is the muscle principally responsible for extension of the elbow joint (straigh

Key facts

Muscle.Name: Triceps
Muscle.Latin: musculus triceps brachii
Muscle.Image: Triceps brachii.png
Muscle.Caption: Triceps brachii seen from behind.
Muscle.Image2: Triceps brachii muscle06.png
Muscle.Caption2: Triceps brachii seen from behind. Three different colors represent three different bundles which compose triceps.
Muscle.Origin: Long head: infraglenoid tubercle of scapula Lateral head: above the radial grooveMedial head: below the radial groove
Muscle.Insertion: Olecranon process of ulna
Muscle.Blood: Deep brachial artery, posterior circumflex humeral artery (long head only)
Muscle.Nerve: Radial nerve
Muscle.Action: Extends forearm, long head extends, adducts arm, extends shoulder