Deltoid origin and insertion

The deltoid runs from the clavicle and scapula to the humerus. It has three parts: the clavicular part, the acromial part and the spinal part.

What are the origin and insertion of the deltoid?

The deltoid arises from the lateral third of the clavicle, the acromion and the spine of the scapula. It inserts on the deltoid tuberosity. Its main action is shoulder abduction (acromial part). It is supplied by the axillary nerve (C5, C6). The attachments, actions and nerve follow Gray (1918).

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Every attachment and its bone

Origins 3

Origins of the deltoid, with the bone each is on
Attachment	Bone	Part
Lateral third of the clavicle	Clavicle	Clavicular part
Acromion	Scapula	Acromial part
Spine of the scapula	Scapula	Spinal part

Insertion 1

Insertion of the deltoid, with the bone each is on
Attachment	Bone	Part
Deltoid tuberosity	Humerus	All parts

Actions

The actions of the deltoid, and which are its main ones
Action	What moves	Main or assisting
Shoulder abduction, acromial part	The arm lifts out to the side	Main action
Shoulder flexion, clavicular part	The arm swings forward	Assists
Medial rotation, clavicular part	With the elbow bent, the forearm swings in	Assists
Shoulder extension, spinal part	The arm swings back	Assists
Lateral rotation, spinal part	With the elbow bent, the forearm swings out	Assists

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

Innervation

The axillary nerve (C5, C6).

Lifts that use the deltoid

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 7

Lifts in which the deltoid is a prime mover, with what it does there
Lift	Part	What it does there
Flat bench press	Anterior deltoid	Shoulder flexion and horizontal adduction
Incline bench press	Anterior deltoid	Shoulder flexion More active as the bench is raised (Barnett et al. 1995).
Push-up	Anterior deltoid	Shoulder flexion and horizontal adduction
Parallel-bar dip	Anterior deltoid	Shoulder flexion from behind the body
Standing overhead press	Anterior deltoid	Shoulder flexion, raising the bar overhead
Bent-over barbell row	Posterior deltoid	Pulling the upper arms back
Dumbbell lateral raise	Lateral deltoid	Shoulder abduction

Synergist in 6

Lifts in which the deltoid is a synergist, with what it does there
Lift	Part	What it does there
Standing overhead press	Lateral deltoid	Raising the arm as the elbows flare
Pull-up	Posterior deltoid	Shoulder extension
Chin-up	Posterior deltoid	Shoulder extension
Lat pulldown	Posterior deltoid	Pulling the upper arm back
Dumbbell lateral raise	Anterior deltoid	Shoulder abduction
Dumbbell lateral raise	Posterior deltoid	Shoulder abduction

Its parts are also stabilizers in the front squat (anterior deltoid), barbell biceps curl (anterior deltoid), cable triceps pushdown (posterior deltoid) and front plank (anterior deltoid).

Sources

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

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.