Latissimus dorsi muscle

Dscn1766.jpg (82229 bytes) Dscn1767.jpg (76407 bytes) Lateral view, left side

Cat information:
latissimus dorsi
originspinous processes of T4-T12
        and L1-L6
insertion:  medial surface of humerus
nerve:  thoracodorsal and ventral thoracic
action: 
extends humerus (arm)

18.gif (33903 bytes) Posterior view, right side Posterior view of origin, left side
Anterior view of insertion, right side

Human information:
latissimus dorsi
origin:  aponeurosis from the spinous processes
        of T7-T12 and L1-L5, posterior iliac crest,
        posterior surface of sacrum, inferior 3 or 4
        ribs, and the inferior angle of the scapula
insertion:  medial lip of intertubercular groove of
        the humerus, anterior and parallel with the
        tendon from
pectoralis major
nerve:  thoracodorsal (C6, C7, C8)
action:  extends, hyperextension, retracts (adducts)
        and medially rotates (internal rotation) humerus

Note that the latissimus dorsi is one of the five muscles in the group we refer to as the muscles that move the arm (not including the rotator cuff muscles).  It has the same action as teres major.  Note that the insertion of latissimus dorsi is between the insertion for pectoralis major and teres major.  The above drawings of the origin and insertion might help visualize this information (red is the origin and blue is the insertion).  Thanks to Laura Holder for the excellent drawing of the origin!

COPYRIGHT 2009 by William C. Johnson II
ALL RIGHTS RESERVED!

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