266 THE MUSCLES. 



sacral and dorso-lumbar spine, and continuous, in front, with the semispinalis 

 colli ; these two muscles, therefore, measure nearly the whole length of the spine. 



Structure. — It is formed by an assemblage of short fasciculi, which are 

 flattened on both sides, tendinous at their extremities, directed obliquely forwards 

 and downwards, and a little inwards, thus crossing at a right angle the spinous 

 processes they cover. 



Attachments. — These fasciculi are attached, below, to the lateral lip of the 

 sacrum, the articular tubercles of the lumbar vertebrae, and the transverse 

 processes of the dorsal vertebrae — origin. They are fixed, above, to the spinous 

 processes of the sacral, lumbar, and dorsal vertebrae, and into that of the last 

 cervical vertebra — termination. It is to be remarked that they do not attain the 

 summits of these spinous processes in the first half of the dorsal region. 



i^e/a^wws.— Outwards, with the lateral sacro-coccygeal and longissimus dorsi 

 muscles, which are confounded with it near its posterior extremity ; inwards, 

 with the sacral spine and the spines of the lumbar and dorsal vertebrae, and with 

 the interspinous ligaments of these three regions. 



Action. — It is an extensor of the spine. 



Differential Characters in the Muscles of the Spinal Region of the Back and 

 Loins in the other Animals. 



A. Ruminants. — In the Ox, Slieep, and Goat, the trapezius is thick and very broad. 



In the Sheep, only the posterior fasciculus of the muscle annexed to the latissimus dorsi is 

 seen. Some of its fibres are prolonged to the anterior border and external face of the latissimus 

 dorsi. In the Camel, the dorsal portion of the trapezius is remarkable for its size. The 

 latissimus dorsi has a thicker and wider body than that of the Hortse ; it descends low on the 

 ribs ; the aponeurotic portion passes beyond the boss or hump. In the longissimus dorsi, the 

 fasciculi are very distinct, even in the midst of the common mass, where the external fasciculi 

 can be clearly seen to become attached separately to the extremities of the transverse processes 

 of the lumbar vertebrae. 



The anterior small serrated muscle is inserted, by its last digitation, into the ninth rib. 

 The posterior serrated is fixed into the four last ribs. 



B. Pig.— Its trapezius is well developed. The latissimus dorsi is voluminous, and is attached 

 to the surface of the ribs, which it covers by digitations from its flesliy portion. It is fixed 

 near the small trochanter to the lip of the bicipital groove. The inferior branch of the 

 hngissimus dorsi of tbis animal is easily divided into two portions, traces of which are found 

 in the Horse : one is formed by the costal fasciculi, the other by the transversal fasciculi. The 

 latter constitutes the muscle to which Bourgelat has given the name of short transversal. 



C. Camivora. — Several of the spinal muscles in tbe Bog resemble those of the Pig ; such 

 are the trapezium, the latissimus dorsi, and the longissimus dorsi. In animals of this group, it 

 is remarked that the anterior serrated is very tiiick and very developed, and that it is attached 

 to the eight ribs succeeding the second by as many well-marked festoons. The posterior has 

 only three digitations, which are attached to tbe three last ribs. The transversalis costarum 

 exactly resembles the sacro-lumbalis of Man ; behind the last rib, it constitutes a thick fleshy 

 body, separated by a fissure from the longissimus dorsi, with which it is attached to the coxa. 

 Lastly, the semispinalis of the back and loins is very strong in the lumbar region, and is 

 prolonged on the coccygeal vertebrae. 



(According to Leyh, the semispinalis muscles are absent in the Horse and Ruminants; 

 they are found in the Pig between tlie spinous processes of the dorsal and lumbar vertebrae, 

 and in Camivora between the spinous processes of the cervical vertebrae.) 



Comparison of the Mdscles of the Back and Neck in Man with the analogous 

 Muscles in the domesticated Animals (Fig. 164). 



It is usual, in human anatomy, to describe by the name of muscles of the back and neck 

 those which correspond to the superior cervical region, and those of the spinal region of the 

 back and loins of the domesticated animals. The muscles of the inferior cervical region are 

 described in Man as muscles of the neck, with the hyoid muscles and the scalenus. 



