272 TEE MUSCLES. 



of the last rib, and the fibrous fascia which unites that muscle to the small 

 oblique of the abdomen. By its inferior face, to the psoas magnus. 



Actions. — It draws the last ribs backwards, and inclines the lumbar spine to 

 one side. 



6. Inteetkansversales of the Loins (Fig, 166, 2, 2). 



(^Synonym. — Intertransversales Imnborum — Percivall. ) 



These are very small flat muscles which fill the intervals between the trans- 

 verse processes of the lumbar vertebrae. Their muscular fibres are mixed with 

 tendinous fibres, and are carried from the anterior border of one transverse 

 process to the posterior border of the other. 



They respond, by their superior face, to the longissimus dorsi, and by their 

 inferior face to the quadratus, as well as the psoas magnus. They act by inclin- 

 ing the lumbar region to one side. 



Differential Characters in the Muscles op the Sublumbar Region in ihe other 



Animals. 



In Ruminants and the Pig, the muscles of this region so closely resemble those of 

 Solipeds, that a special description is unnecessary. It may be remarked, however, that the 

 quadratus lumborum in the Sheep is veiy developed, and throws fibres as fur forward as tlie 

 four last ribs. 



In the Dog, the psoas magnus is little developed, and only commences at the third, or even 

 the fourth lumbar vtrtebra ; the iliacus is very slender, particularly in its externa) portion ; 

 otherwise it is scarcely distinct from the psoa^ luagnus, with which it may be said to form one 

 muscle; the psoas parvus is relatively larger than the great; it is not prolonged into the 

 pectoral cavity, and its anterior extremity is confounded with the quadratus lumborum, which 

 is longer and stronger than in all the other animals. 



Comparison of the Sublumbar Muscles of Man with those of Animals. 



In human anatomy, by tlie names of psoas and iliacus are described the psoas magnum and 

 iliacus of animals. The psoas magnus of Man is distinguished from that of Solipeds by its 

 superior iutsertions, whicli do not go lieymul the last dorsal vertebrae. 



The psoa^ parvus is often absent : when present, it is attached, above, to the bodies of the 

 twelve dorsal vertebrae; below, to tlie ilio-pectineal crest. 



The intertransversales have been studied with the muscles of the back. The quadratus 

 lumborum, classed by anthropotoraists with the abdominal muscles, is distinctly divided into 

 three series of fasciculi: ilio-costal fasciculi, which pass from the upper border of the ilium to 

 the twelfth rib; lumbo-costul fasciculi, passing from the transverse processes of the tliree or four 

 last lumbar vertebrae to the twelfth rib; and iUo-lumbar fasciculi, going from the iliac crest to 

 the posterior face of the transverse processes of all the lumbar vertebrae. 



Coccygeal Region. 



This region is composed of four pairs of muscles destined for the movementg 

 of the tail ; three, named the sac.ro-cocci/(/eaI, are disposed longitudinally around 

 the coccygeal vertebrae, which they completely envelop ; the fourth is designated 

 the ischio-coccygeus (compressor coccygeus). 



1. Sacro-coccygeal Muscles (Fig. 167, 1, 2, 3). 



These three muscles are enclosed, with those of the opposite side, in a strong, 

 common aponeurotic sheath, which is continuous with the inferior ilio-sacral 

 and sacro-sciatic ligaments. They commence on the sacrum, are directed back- 

 ' wards and parallel with the coccyx, gradually diminishing in thickness, and are 

 formed by several successive fasciculi terminating in small tendons, which are 



