Cleidomastoid muscle (cat only)

Dscn1770.jpg (79711 bytes) Dscn1771.jpg (78259 bytes) Ventrolateral view, left side

Cat information:
 cleidomastoid (cat only corresponds
         to the lateral portion of the
 origin:  mastoid process
 insertion:  clavicle and the raphe lateral to the
 nerve:  spinal accessory (XI) and ventral
   rami of C2 and C3
 action:  elevates clavicle when head is
           fixed, turns head and depresses
           snout when clavicle is fixed

  93.gif (45198 bytes) Anterior view, right side Superior view of origin, right side
Lateral view of insertion, right side

Human information:
cleidomastoid (cat only corresponds
        to the lateral portion of the
origin:  superior surface of the medial third
        of the clavicle
insertion:  lateral surface of the mastoid
        process and the lateral half of the
        superior nuchal line
nerve:  spinal accessory (XI) and
        anterior rami of C2 and C3
action:  bilateral contraction leads to flexion
        of the head; unilateral contraction causes
        rotation of head to the opposite side (contralateral rotation)
        and movement of head toward the ipsilateral
        shoulder (ipsilateral sidebending)

The above drawings of the origin and insertion might help visualize this information (red is the origin, blue the insertion).  Note that only the clavicular portion of the origin has been shown here.  The sternal portion of the origin will be found with the sternomastoid information.

COPYRIGHT 2009 by William C. Johnson II