Latissimus dorsi is a fan-shaped muscle on the back and is one of the superficial extrinsic back muscles, the other superficial extrinsic back muscles are the trapezius levator scapulae rhomboid major and rhomboid minor. The name latissimus dorsi comes from the Latin words latissimus meaning the broadest and dorsi referring to the back. It is one of the largest muscles in the body in surface area.
Anatomy of latissimus dorsi
There are places where each end of a muscle attaches to the bone, they are the origin and insertion of a muscle. When it comes to the lats, the origin is complicated, but the insertion is simple. At the top, the alts muscles originates from the bottom six thoracic vertebrae and the last three or four ribs. Part of the origin also includes the thoracolumbar fascia at the level of the lumbar and sacral vertebrae, as well as the back of one-third of the outside part of the top of your hip bone. The origin of the lats includes a bit of the bottom angle of your shoulder blade.
The insertion point for the alts is located on the inner aspect of your upper arm bone, just below the shoulder blade. As the muscle fibers of the lats extend from the origin to the insertion point, they taper into a point which forms into a triangular shape. The latissimus dorsi muscle is innervated by a long scapular nerve known as the thoracodorsal nerve.
Functions of latissimus dorsi
Activities such as chin-ups, rock climbing and swimming extensively make use of latissimus dorsi, strong lats can help your arms pull your body weight up. The lats also help with the breathing process and are called “accessory breathing muscle”, as they enhance the movements of the trunks during inhalation and exhalation. They do this by expanding the circumference of the rib cage when you inhale causing an increase in the volume of the air that enters your lungs. The latissimus dorsi muscles also decrease the circumference of the trunk during exhalation which tends to squeeze more air out.
There are also other functions of latissimus dorsi such as bringing the whole shoulder girdle down called depression which assists in the act of side bending called lateral flexion. So, when both lats are working at the same time they assist in the arching of the spine called hyperextension and also with the tilting of the pelvis anteriorly.
Functionally, the latissimus dorsi muscle belongs to the muscles of the scapular motion. This muscle is able to pull the inferior muscle of the scapula in various directions, producing movements on the shoulder joint, internal rotation, adduction and extension of the arm.
also read: Can You Tear Your Latissimus Dorsi Muscle