Veterinary Gross Anatomy-II

Muscles of the back and loin

MUSCLES OF THE BACK AND LOINS

The muscles on either side are arranged in five superimposed layers.

• First layer
  • Trapezius thoracis
  • Latissimus dorsi
• Second Layer
  • Rhomboideus thoracis
• Third Layer
  • Serratus dorsalis anterior
  • Serratus dorsalis posterior
• Fourth Layer
  • Longissimus costarum
  • Longissimus dorsi
• Fifth Layer
  • Levatores costarum
  • Multifidus dorsi
  • Intertransversales lumborum

Horse

• The serratus dorsalis anterior is more extensive and has eight digitations.
• The serratus dorsalis posterior presents seven to eight digitations and the anterior of these overlap those of the serratus dorsalis anterior muscle.
• The levatores costarum is of 17 pairs.

Dog

• The serratus dorsalis anterior arises from the first six or seven dorsal spines and is inserted from the second to the fifth rib. The muscle is very thick and is well developed.
• The serratus dorsalis posterior arises from the lumbo-dorsal fascia. It is inserted to the last three or four ribs thus presenting three or four digitations.
• The levatores costarum is similar to the ox and horse but its lumbar part is not depressed for the lodgement of the middle gluteus.
• The other muscles are similar to the ox.