Triceps brachii origin and insertion

Triceps brachii runs from the scapula and humerus to the ulna. It has three heads: the long head, the lateral head and the medial head.

What are the origin and insertion of triceps brachii?

Triceps brachii arises from the infraglenoid tubercle (long head), the back of the humerus above the radial groove (lateral head) and the back of the humerus below the radial groove (medial head). It inserts on the olecranon. Its main action is elbow extension. It is supplied by the radial nerve (C6, C7, C8). The attachments, actions and nerve follow Gray (1918).

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Every attachment and its bone

Origins 3

Origins of triceps brachii, with the bone each is on
Attachment	Bone	Part
Infraglenoid tubercle	Scapula	Long head
Back of the humerus above the radial groove	Humerus	Lateral head
Back of the humerus below the radial groove	Humerus	Medial head

Insertion 1

Insertion of triceps brachii, with the bone each is on
Attachment	Bone	Part
Olecranon	Ulna	All heads

Actions

The actions of triceps brachii, and which are its main ones
Action	What moves	Main or assisting
Elbow extension	The forearm straightens	Main action
Shoulder extension, long head	The arm swings back	Assists

Each action is stated in the anatomical position: standing, arms by the sides, palms forward.

Innervation

The radial nerve (C6, C7, C8).

Lifts that use triceps brachii

A prime mover produces the lift’s main joint action against the load; a synergist assists that action, or adds a secondary action the lift needs. Each role is the one the lift’s own page gives, for the technique that page states.

Prime mover in 6

Lifts in which triceps brachii is a prime mover, with what it does there
Lift	What it does there
Flat bench press	Elbow extension, all three heads
Incline bench press	Elbow extension, all three heads
Push-up	Elbow extension, all three heads
Parallel-bar dip	Elbow extension, all three heads
Standing overhead press	Elbow extension, all three heads
Cable triceps pushdown	Elbow extension, all three heads The long head also crosses the shoulder, which is held still here.

Sources

Gray (1918), Myology, the muscles and fasciae of the arm

Each lift role is from that lift’s page in muscles worked by exercise, which names the sources it follows.

See it in 3D

Visualiser · Biology Muscle Origin, Insertion and Action Explorer Paint a muscle’s origin and insertion on real 3D bones, or click a bone to see what attaches to it. Visualiser · Biology Upper Limb Muscles Explorer 114 upper limb muscle meshes, by compartment. Visualiser · Biology Muscles Worked by Exercise 3D Explorer Choose a lift and a real body lights its prime movers, synergists and stabilisers, front and back, with the same muscles in 3D.