The Deltoid Muscle
Introduction
muscle that forms the rounded contour of the shoulder.
Delta = triangle.
Frequent site for intra-muscular injections.
Origin
It arises in three sets of fibers:
" Anterior fibres: from the lateral third of the clavicle
" Middle fibres: from acromion
" Posterior fibres: from posterior spine of the scapula,
"
Insertion
fibers converge toward their insertion into V-shaped deltoid tuberosity on the middle of the lateral aspect of the shaft of the humerus.
Nerve supply
Axillary nerve (C5,C6).
Lateral supraclavicular nerve to some extent
Action
Anterior fibres - flexion of shoulder
Lateral fibres - abduction of shoulder
Posterior fibres - extension of shoulder
Structure
Multipennate muscle
Applied anatomy
Since the muscle derives its nerve from C5, C6 roots, in cervical myelopathy and brachial plexus injury the muscle gets wasted.
In cervical spondylosis pain felt in this muscle
One of the common sites for intramuscular injections
