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Teres Major Muscle – Attachments, Action & Innervation

image descriptionTeres Major Muscle

Teres major is a thick and ovoid muscle in the upper arm. Despite their similar names, Teres major has different actions and innervation from the Teres minor. It’s mainly responsible for the medial rotation of the arm and it also contributes to static posture and arm-swinging.

An image showing the Teres major muscle (highlighted) attached to the upper limb along with other muscles (Trapezius, Deltoid, Triceps brachii, Latissimus dorsi)
An image showing the Teres major muscle (highlighted) attached to the upper limb along with other muscles (Infraspinatus, Teres minor, Triceps brachii, Latissimus dorsi)
An image showing the Teres major muscle (highlighted) attached to the upper limb along with other muscles (Triceps brachii, Latissimus dorsi)
An image showing the Teres Major Muscle attached to the upper limb
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Attachments of Teres Major Muscle Origin & Insertion

image descriptionOrigin: (proximal attachments)
Lower lateral border and inferior angle of the scapula.

image descriptionInsertion: (distal attachments)
Medial lip of the intertubercular (bicipital) groove of the anterior humerus.

An image showing the Teres major muscle (highlighted) attached to the upper limb along with other muscles (Trapezius, Deltoid, Triceps brachii, Latissimus dorsi)
An image showing the Teres Major Muscle attached to the upper limb
An image showing the Teres major muscle Origin on the upper limb
An image showing the Teres major muscle Insertion on the upper limb
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Actions of Teres Major:

image descriptiona. Adducts the arm at the shoulder (glenohumeral) joint.

image descriptionb. Medially rotates the arm at the shoulder (glenohumeral) joint.

Arm rotation (medially)
Arm rotation (medially)
Arm rotation (medially)
Arm rotation (medially)
Arm rotation (medially)

image descriptionc. Extends the arm at the shoulder (glenohumeral) joint.

Innervation of Teres Major:

Lower subscapular nerve.
C5, C6, and C7.
An image showing the Lower subscapular nerve coming out of the brachial plexus
An image showing the Lower subscapular nerve coming out of the brachial plexus
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