MUSCLES OF THE BODY. 131 
distinguished as the Mm. rotatores; no separate layer of this 
sort is to be made out in the cat. 
Mm. interspinales.—Muscle-bundles passing from the 
spinous process of one vertebra to that of the vertebra imme- 
diately craniad or caudad of it. They are best developed in 
the lumbar region. 
Mm. intertransversarii.— Muscle-fibres interconnecting 
the transverse processes. In the lumbar region the inter- 
transversarii mediales connect the accessory and mammillary 
processes; the intertransversarii laterales lying between the 
transverse processes. In other regions only one set of the 
intertransversarii is to be distinguished. 
(6) Dorsal Muscles of the Cervical Region.—The clavotra- 
pezius (Fig. 68, @) and occipitoscapularis (Fig. 73, @) have 
been described in connection with the muscles of the shoulder. 
The remaining muscles of this region may be considered as 
differentiations of the general vertebral musculature (M. ex- 
tensor dorsi communis). 
M. splenius (Fig. 73, .)—A large sheet of muscle cover- 
ing the dorsal part of the side of the neck, beneath the trapezii. 
Origin from the whole cervical ligament and from the fascia 
covering the deeper muscles along a line which extends from 
the first thoracic spinous process caudolaterad for about two 
centimeters. 
Insertion by a thin tendon into the whole lambdoidal ridge. 
Laterad the tendon may be fused with that of the longissimus 
capitis (Fig. 73, ¢). 
Relations.—Outer surface with the sternomastoid (Fig. 
68, ¢), occipitoscapularis (Fig. 73, @), clavotrapezius (Fig. 
68, @), rhomboideus, tendon of the serratus posterior superior 
(Fig. 73, 2), and the levator scapule (Fig. 73, %). Lateral edge 
closely united with the longissimus capitis (Fig. 73, g). Inner 
surface with the longissimus capitis, complexus (Fig. 69, 0), 
and biventer cervicis (Fig. 69, a). 
Action.—Lateral flexor of the head. The two together 
elevate the head. 
M. longissimus capitis (trachelomastoideus) (Fig. 73, ¢; 
Fig. 69, e).—This is a slender muscle lying close against the 
