Deltoid

Original Editor - Wendy Walker

Lead Editors - Lucinda hampton, Sai Kripa, Wendy Walker, Naomi O'Reilly, Joao Costa, Chrysolite Jyothi Kommu, Kim Jackson, Andeela Hafeez, Vidya Acharya, WikiSysop, Uchechukwu Chukwuemeka, Wanda van Niekerk, Aminat Abolade, Admin, Evan Thomas and George Prudden  

Description

The Deltoid muscle is a large triangular shaped muscle which lies over the glenohumeral joint and which gives the shoulder its rounded contour. It is named after the Greek letter delta, which is shaped like an equilateral triangle. It comprises 3 distinct portions each of which produces a different movement of the glenohumeral joint, commonly named the anterior, mid (or lateral) and posterior heads.

Origin

Anterior fibres/head

Lateral third, anterior surface of the clavicle (close to the lateral fibres of pectoralis major).  

Mid/lateral head

Acromion process, superior surface.

Posterior head

Spine of the scapula, posterior border.

Insertion

Fibres from all heads converge to insert into the deltoid tuberosity on the humerus.

The deltoid fascia is continuous with the brachial fascia and connects to the medial and lateral intermuscular septa.

Nerve Supply

Axillary Nerve, C5 & 6, posterior cord of the brachial plexus.

Blood Supply

Deltoid receives its blood supply from the posterior circumflex humeral artery.

Action

All heads of deltoid work together to produce abduction of the shoulder joint.

In addition, the anterior fibres contribute to shoulder horizontal flexion, and internal rotation; the posterior fibres to horizontal extension, as well as external rotation.

Function

An important function of deltoid is the prevention of subluxation or even dislocation of the head of the humerus particularly when carrying a load.

Deltoid is the prime mover of shoulder abduction.

References

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