Deltoid Muscle – Anterior and Middle Heads

Author: Scott A. Sheffield MS

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The deltoid muscle (derived its name from the Greek letter delta) is a large, triangular shoulder muscle occupying the upper arm and the shoulder giving it this rounded shape. The deltoid consists of three sets of fibers: anterior, middle, and posterior.

image descriptionDeltoid Muscle - Anterior and Middle Heads

An image showing the Deltoid Muscle (highlighted) attached to the upper limb along with other muscles (Pectoralis major, Lattisimus dorsi, Biceps brachii, Brachioradialis)
An image showing the Deltoid Muscle (highlighted) attached to the upper limb along with other muscles (Coracobrachialis, Latissimus dorsi, Biceps brachii, Brachioradialis)
An image showing the Deltoid Muscle (highlighted) attached to the upper limb along with other muscles (Subscapularis, Latissimus dorsi)
An image showing the Deltoid muscle attached to the upper limb
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image descriptionAttachments of Deltoid Muscle: Origin & Insertion

Origin: (proximal attachments)
a. Anterior (clavicular) head: anterior surface of the lateral clavicle.
b. Middle (acromial) head: acromion process and spine of the scapula.

Insertion: (distal attachments)
a. Deltoid tuberosity of the humerus.

Learn the muscles of the shoulder even faster with these handy muscle anatomy reference charts!

An image showing the Deltoid Muscle (highlighted) attached to the upper limb along with other muscles (Pectoralis major, Lattisimus dorsi, Biceps brachii, Brachioradialis)
An image showing the Deltoid muscle attached to the upper limb
An image showing the Origin and insertion of the deltoid muscle on the upper limb
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Actions of Deltoid Muscle:

Anterior Head:

a. at the (glenohumeral) shoulder joint.

b. Medially rotates the arm at the glenohumeral shoulder joint.

Middle Head:
a. Abducts the arm at the glenohumeral shoulder joint.

Innervation of Deltoid Muscle:

Nerves to the muscle:
Axillary nerve

Nerve roots:
C5 and C6

An image showing the Axillary nerve coming out of the brachial plexus
An image showing the Axillary nerve coming out of the brachial plexus
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