Spinotrapezius muscles (cat only)

Dscn1797.jpg (76285 bytes) Dscn1796.jpg (75901 bytes) Dorsolateral view, left side

Cat information:
spinotrapezius (cat only corresponds
        to the inferior portion of the human trapezius)
origin:  spinous process of T4-T12
insertion:  tuberosity of scapular spine
          and fascia of supraspinatus and
          infraspinatus muscles
nerve:  spinal accessory (XI) and ventral
          rami of cervical spinal nerves 1-4
action:  retracts (adducts) and depresses
          scapula

4.gif (28365 bytes) Posterior view, left side Posterior (superficial) view of origin and insertion, left side
 
Posterior (superficial) view of insertion, right side

Human information:
spinotrapezius (cat only corresponds
        to the inferior portion of the trapezius
        which is pictured above)
origin:  spinous processes of T6-T12
insertion:  medial third of spine of scapula
nerve:  spinal accessory (XI) and ventral
        rami of cervical spinal nerves 3 and 4

action:  retracts (adducts), depresses and
        rotates scapula

This is one of the five muscles that are grouped as muscles of the scapula, or sometimes as muscles that moor the scapula.  The above drawing of the insertion on the clavicle might help visualize this information (blue is the insertion).  The other drawing of the origin and insertion might help visualize this information (red is the origin and blue is the insertion).  This other drawing is for the entire muscle and includes the origin and insertion for all three divisions of the trapezius muscle.  Notice that part of the origin is on a ligament called the ligamentum nuchae, and this portion of the origin is represented by a line between the skull and the spinous process of C7.  Thanks to Laura Holder for the excellent drawing!

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

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