Teres Major: Location, Function & Innervation

Instructor: Dan Washmuth

Dan has taught college Nutrition, Anatomy, Physiology, and Sports Nutrition courses and has a master's degree in Dietetics & Nutrition.

Do you know much about the teres major, one of the many muscles of the shoulder joint? If not, then be sure to check out this lesson for lots of great facts about this muscle, including its location, innervation, and function!

What's a Teres Major?

Here's a quick, interactive test to see how well you know your teres major muscle. In order to complete this test, you must do the following activities:

  1. Stand up with your arms hanging naturally at your sides
  2. Raise both arms up to your front till they are at your chest level
  3. Now lower your arms back down to your sides
  4. Now bring your hands up to your shoulders by only bending at the elbows
  5. Now raise your arms straight out to your sides

Do you know which of these movements is caused by your teres major muscle? If you said that lowering your arms back down to your sides is caused by your teres major muscle, then you are correct! All the other movements were performed by other muscles of the shoulders and arms.

Are you ready to learn much more about this muscle?

Teres Major: The Armpit Muscle

The teres major is a small muscle of the shoulder joint. Specifically, this muscle begins from the outer border of the scapula (shoulder blade) and then extends under the shoulder joint and attaches near the top of the humerus (long bone of the upper arm).

The teres major muscle is located under the shoulder joint. It is labeled with the number 5 in this picture.
teres major

To feel for this muscle, raise your right arm straight up to the side of your body. With your left hand, feel around the back side of your right armpit. That is roughly the location of the teres major muscle. (Hopefully you have showered recently and you're wearing deodorant if you felt around your armpit!)

Innervation of the Teres Major

Innervation is the process of the brain sending electrical impulses to each muscle of the body through a network of nerves. Each muscle receives these electrical impulses from a specific nerve or group of nerves. The teres major muscle is innervated by the lower subscapular nerve, which contains nerve fibers from the C5 and C6 cervical (neck) nerves. Once this muscle receives an electrical impulse from the lower subscapular nerve, it will contract and move.

What Does the Teres Major Do?

The main function of the teres major is to move the humerus bone or upper arm in three specific directions, and the following chart describes these three movements.

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