Home » Anatomy » Upper Extremity Muscles » Shoulder Muscles » Teres Major – Functional Anatomy

Teres Major – Functional Anatomy

Overview

Origin

  • the posterior, inferior edge of the lateral border of the scapula

Insertion

  • medial lip of the bicipital groove of the humerus

Function

  • adducts and medial rotates the humerus when it is lateral to the body,
  • extends the humerus when it is in horizontal flexion (in front of the body

Innervation

  • lower subscapular nerve – C5-C7

Not So Simple

The anatomy of the teres major is both complicated and simple. It is a simple flat muscle that attaches to the scapula’s lower border and inserts on the bicipital groove. Often, but not always, it lives in a sheath with the latissimus dorsi. The latissimus dorsi may or may not also attach to the lower angle of the scapula.

The physiology is also interesting. Teres major works closely with latissimus dorsi in moving the humerus toward the scapula. It may extend the humerus when it is in front of the body. Conversely, it may flex the humerus when it is behind the body. It also assists in medial rotation of the humerus, especially when the humerus is in front of the body.

In addition, the neurovascular bundle of the brachial plexus weaves through here. The entire bundle lies close to the teres major attachment on the humerus allowing most of the nerve fibers to pass anteriorly while others pass over and posteriorly to the teres major.

 

Wikipedia entry to teres major.


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