Acromiotrapezius muscle (cat only)

Dscn1759.jpg (74509 bytes) Dscn1760.jpg (85972 bytes) Dorsolateral view, left side

Cat information:
acromiotrapezius (cat only corresponds
        to the middle portion of the human trapezius)
  origin:  spinous process of the axis to a
        point between the first and fourth
          thoracic vertebrae
  insertion:  metacromion, scapular spine to
          tuberosity, and superficial surface of
  nerve:  spinal accessory (XI) and ventral
          rami of cervicals 1-4
  action:  hold the vertebral border of the two
          scapulae together and retracts
          (adducts) them

3.gif (26994 bytes) Posterior view, left side Posterior (superficial) view of origin and insertion, left side
(superficial) view of trapezius insertion, right side

Human information:
acromiotrapezius (cat only corresponds
        to the middle division of the trapezius
        which is pictured above)
origin:  spinous processes of 7th cervical and
        1st-3rd thoracic vertebrae
insertion:  superior border of the spine of
nerve:  spinal accessory (XI) and  anterior rami
        of C3 and C4

action:  retracts (adducts) and helps in
        elevation of 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 drawings of the origin and insertion might help visualize this information (red is the origin and blue is the insertion).  Both drawings are 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