Latissimus Dorsi: Origin, Innervation & Blood Supply

Instructor: Dan Washmuth

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

The latissimus dorsi is one of the largest and strongest muscles in the back. Be sure to check out this lesson for more interesting facts about this muscle, including its origin, innervation, and blood supply.

Latissimus Dorsi

Is your latissimus dorsi muscle working correctly? To find out, perform this quick and easy physical assessment test:

  1. Stand up with your arms hanging naturally at your sides.
  2. Raise both arms straight up towards your back as high as you can, then bring them back to your sides.
  3. Now make a big forward circle with each of your arms.
  4. Now bend both elbows to a 90 degree angle and then rotate your hands backward as far as you can.

If you were able to do each of the motions without much difficulty or pain, then it seems like your latissimus dorsi muscles are working just fine!

The latissimus dorsi muscle ('lat' for short) is a large, flat, wide muscle that is located on both sides of the back, right under the armpits. This muscle is one of the largest and strongest muscles of the back.

The latissimus dorsi is one of the largest and strongest muscles in the back.

Latissimus Dorsi: Origin

Since the latissimus dorsi muscle is so wide, it has many points of origin, which is where it's attached to bone. The following chart describes the points of origin of the latissimus dorsi muscle.

Point of Origin Description of Point of Origin
Spinous processes of thoracic vertebrae T7-T12 The spinous processes are the bony prominences that stick in the back of the vertebrae.
Iliac crest The iliac crest is the top, back border of the hip bone.
Thoracolumbar fascia The thoracolumbar fascia is a membrane of connective tissues that is located throughout the back and abdomen areas of the body.
Inferior angle of scapula The bottom point of the scapula (shoulder blade).
9th-12th ribs The bottom three ribs on each side of the rib cage.

One of the points of origin of the latissimus dorsi is the iliac crest, which is the top border of the back hip bone.
iliac crest

It should be noted that the points of origin of the latissimus muscle can vary from person to person. For example, this muscle sometimes originates from vertebrae other than T7-T12. For some people, the latissimus dorsi originates from the first few lumbar vertebrae as well, which are the vertebrae further down in the vertebral column located in the lower back.

Latissimus Dorsi: Innervation & Blood Supply

The latissimus dorsi muscle is innervated, or supplied with nerves and nerve impulses, by the thoracodorsal nerve. The thoracodorsal nerve is a nerve that consists of nerve fibers from several cervical (neck) nerves, including C6, C7, and C8. Each time you used your latissimus dorsi muscles to perform the movements of the physical assessment test at the begging of the lesson, your latissimus dorsi received electrical impulses from the brain through this thoracodorsal nerve.

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