Stowell.] 96 [March 2, 
and may be traced to the caudad extremity (origin) of the muscle, where 
it is joined by the anastomosing filaments of the cervical nerves (Fig. 
Crv.). From the dorsal border of the nerve at nearly the same point a 
corresponding ramus (Fig. Clv.-Mas. ce.) is given to the cephalic end 
(insertion) of the same muscle ; this ramus also innerves the adjacent 
cephalic extremity of the M. sterno-mastoideus (Fig. Str.-Mas.). 
N. sterno-mastoideus.—Upon the ectal surface of the M. clavo-mast- 
oideus a large ramus from the Accessorius enters the ental surface of the 
superposed. sterno-mastoid muscle. Zhe shorter or dorsal division of this 
ramus (Fig. Ster.-Mas. ce.) lies ectad of the trunk of the Accessorius 
and supplies the cephalic (insertion) third of the muscle, or that portion 
cephalad of the point of init of the nerve; the ventral division (Fig. Str.- 
Mas. ven.) is distributed to the thick ventral border of the caudal two- 
thirds of the same muscle. About 5mm. peripherad, or at the dorsal 
border of the M. sterno-mastoideus, where the muscle is crossed by the 
large trunk of a cervical nerve (2°), a second ramus (Fig. Str.-Mas. dors.) 
is given from the Accessorius to the thin dorsal border of the caudal por- 
tion of the same muscle. This ramus lies ectad of the cervical nerve and 
receives from it a large accession. Since this muscle has two sources of 
nerve-supply, there is throughout the caudal portion of the muscle a more 
or less frequent anastomosis of terminal filaments. 
N. clavo-trapezius cephalicus.—This ramus is given off in connection 
with the dorsal ramus of the N. sterno-mastoideus; it lies entad of an 
artery which supplies the cephalic 20 mm. of the M. clavo-trapezius. The 
nerve enters the ental surface of the ventral border of the muscle, with 
the artery just named, and sends a ramulus 5-10 mm. caudad of the artery 
and is distributed to the cephalic fourth of the muscle; the terminal fila- 
ments of the nerve may be traced to the dorsi-meson. Near its ectal origin 
this nerve receives an anastomotic branch from the second cervical nerve. 
The main nerve trunk lies entad of the M. clavo-trapezius, crosses the 
ectal surface of the M. levator clavicule and continues dorsad of the 
levator muscle upon the ectal surface of the M. splenius. At the ventral 
border of the M. clavo-trapezius the N. accessorius receives a large branch 
from the second cervical nerve which crosses its ectal surface in this region. 
At the dorsal border of the M. levator clavicule it sends a slender ramus 
(Fig. Spl.) to the cephalic portion of the M. splenius. 
N. clavo-trapezius caudalis.—A bout the middle of the M. clavo-trapez- 
ius, a large ramus, the N. clavo-trapezius caudalis, separates from the 
Accessorius and divides into three or four ramuli which enter the ental 
surface of the M. clavo-trapezius to be distributed to that portion of the 
muscle which lies dorsad of the M. levator clavicule. 
Between the clavo-trapezius and the acromio-trapezius muscles, upon 
the side of the neck, and dorsad of the levator muscle, is a narrow inter- 
muscular interval, the hiatus trapezii (Fig. Hi.), filled with adipose, con- 
nective tissue, a large lymphatic, an artery, the accessory nerve and the 
cervical plexus of the second and third myelic nerves. 
