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Latissimus Dorsi Muscle – Attachments, Action & Innervation

image descriptionLatissimus Dorsi Muscle:

Latissimus Dorsi is one of four muscles responsible for the thoracobrachial motion. It is large, flat and triangular in shape originating from large parts of the lumbar region and lower thorax to insert on the humerus through a narrow tendon.

An image showing the Latissimus Dorsi Muscle (highlighted) attached along with other muscles (Trapezius, Detloid, Triceps brachii, Gluteus medius, Gluteus maximus)
An image showing the Latissimus Dorsi Muscle (highlighted) attached along with other muscles (Supraspinatus, Infraspinatus, Triceps brachii, Gluteus medius, Gluteus maximus)
An image showing the Latissimus Dorsi Muscle (highlighted) attached along with other muscles (Supraspinatus, Infraspinatus, External oblique)
An image showing the Latissimus Dorsi Muscle attached to the skeleton
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image descriptionAttachments of Latissimus Dorsi: Origin & Insertion

Origin: (proximal attachments)
a. Spinous processes of T7 – L5 vertebrae.
b. Iliac crest of sacrum.
c. Thoracolumbar fascia.
d. Inferior angle of the scapula.
e. Lower three or four ribs.

Insertion: (distal attachments)
Floor of intertubercular (bicipital) groove of humerus.

An image showing the Latissimus Dorsi Muscle (highlighted) attached along with other muscles (Trapezius, Detloid, Triceps brachii, Gluteus medius, Gluteus maximus)
An image showing the Latissimus Dorsi Muscle attached to the skeleton
An image showing the origin and insertion of the Latissimus Dorsi Muscle
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Actions of Latissimus Dorsi:

image descriptiona. Adducts the arm at the shoulder (glenohumeral) joint.

image descriptionb. Medially rotates the arm at the shoulder (glenohumeral) joint.

Arm rotation (medially)
Arm rotation (medially)
Arm rotation (medially)
Arm rotation (medially)
Arm rotation (medially)

image descriptionc. Extends the arm at the shoulder (glenohumeral) joint.

Innervation of Latissimus Dorsi:

Thoracodorsal nerve.
C6, C7, and C8.
An image showing the Thoracodorsal nerve coming out of the brachial plexus
An image showing the Thoracodorsal nerve coming out of the brachial plexus
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