Shoulder Muscles
All muscles of Shoulder Region with their Origin, Insertion, Nerve Supply and Action
Deltoid Muscle
Origin – Anterior fiber: The anterior border and lateral one-third of the clavicle bone. Middle fiber: Lateral border of acromion process and superior surface. Posterior fiber: The posterior border and the spine of the scapula.
Insertion – Three septa of insertion are attached to the deltoid tuberosity of the Humerus.
Nerve Supply – Axillary Nerve (C5, C6).
Action – Powerful abduction of arm at the shoulder joint. Anterior fibers are helpful in the flexion of the shoulder arm and medial rotation. Posterior fibers are helpful in the extension and lateral rotation of the shoulder arm.
Teres major Muscle
Origin – Posterior Surface of the inferior angle of Scapula bone.
Insertion – The medial lip of the bicipital groove of the humerus bone.
Nerve Supply – Lower subscapular Nerve.
Action – Adduction and Extension of Shoulder arm and also medially rotation of arm.
Rotator Cuff Muscles
(A) Supraspinatus:-
Origin – Supraspinous fossa of the scapula bone.
Insertion – Greater tubercle of the humerus bone.
Nerve Supply – Suprascapular Nerve (C5, C6).
Action – Abduction of shoulder arm at 0-15 degree.
(B) Infraspinatus:-
Origin – Infraspinous fossa of the scapula bone.
Insertion – Greater tubercle of the humerus bone.
Nerve Supply – Suprascapular Nerve (C5-C6).
Action – Lateral rotator of the shoulder arm.
(C) Subscapularis:-
Origin – Subscapular fossa of scapula bone.
Insertion – Lesser tubercle of the humerus bone.
Nerve Supply – Upper and lower subscapular nerve (C5, C6).
Action – Medial rotation of shoulder arm.
(D) Teres minor:-
Origin – Posterior surface and lateral border of scapula bone.
Insertion – Greater tubercle of the humerus bone.
Nerve Supply – Axillary Nerve (C5, C6).
Action – Laterally rotation of shoulder arm.