Latissimus Dorsi Muscle

Original Editor - Ahmed Nassef

Top Contributors - Ahmed Nassef, Uchechukwu Chukwuemeka, Wanda van Niekerk and George Prudden  

Description

The latissimus dorsi muscle, whose name means “broadest muscle of the back,” is one of the widest muscles in the human body. Also known as the “lat,” it is a very thin triangular muscle that is not used strenuously in common daily activities but is an important muscle in many exercises such as pull-ups, chin-ups, lat pulldowns, and swimming.[1]

Origin

Latissimus-dorsi.jpg

a. Spinous processes of 7th thoracic to 5th Lumbar vertebrae.

b. Iliac crest of sacrum.

c. Thoracolumbar fascia.

d. Inferior angle of the scapula.

e. Lower three or four ribs.[2]

Insertion

Floor of intertubercular (bicipital) groove of humerus.[2]

Nerve supply

Thoracodorsal nerve (C6 – C8)[3]

Blood supply

Thoracordosal Artery from the axillary artery[3]

Action

Depression, adducts, extends and internally rotates the arm at the shoulder[3]

Primary Actions of the Latissimus Dorsi

1. Adduction of the arm at shoulder

2. Extension of the arm at the shoulder

3. Internal rotation of the arm at the shoulder

Secondary Actions of the Latissimus Dorsi

1. Assists with extension of the trunk

2. Assists with flexion of the trunk

3. Assists with lateral flexion of the trunk

4. Assists with anterior and lateral pelvic tilt

5. Assists with depression of the scapula

6. Assist with protraction of the scapula

7. Assists with deep inspiration and forced expiration [4]

Palpation

The lateral aspect of the latissimus dorsi muscle builds the posterior border of the axilla. It is felt to contract during resisted adduction of the arm. Its insertion lies anteriorly at the crest of the lesser tuberosity.

Latissimus Dorsi Stretches

Begin this latissimus dorsi stretch standing tall with your back straight and hands above your head. Gently lean to one side until you feel a mild to moderate stretch in the side of your upper back and shoulder (figure 2). Hold for 5 seconds and then return to the starting position. Repeat 10 times provided the exercise is pain free. Then repeat the exercise on the opposite side.

References

  1. Heydemann A. Severe murine limb-girdle muscular dystrophy type 2C pathology is diminished by FTY720 treatment. Muscle & Nerve. 2007; 56(3):486-494
  2. 2.0 2.1 Drake R L, Vogl AW, Mitchell A W. Gray's Anatomy for Students. 2nd Edition. Philadelphia:Churchill Livingstone, 2010
  3. 3.0 3.1 3.2 Calais-German B. Anatomy of Movement. Seattle: Eastland Press, 1993.
  4. Schünke M, Schulte E, Schumacher U. Prometheus: Lernatlas der Anatomie. Stuttgart/New York: Georg Thieme Verlag, 2007.