1888. ] 97 [Stowell 
N. acromio-trapezius.—In this hiatus a large ramus (Fig. caudad of 
Hi.) is sent dorsad to the M. acromio-trapezius, which enters the cephalic 
border of the muscle and is distributed by 3-4 termina] ramuli to the dor- 
sal portion of the muscle ; caudad of the hiatus several (two shown in dia- 
gram) rami from the Accessorius enter the ental surface of the muscle. 
Caudad of the hiatus (about 5 mm.) a large accession (Fig. Crv.) is 
received by the N. accessorius, from the cervical plexus. This nerve 
(myelic) accompanies the artery which appears in the hiatus. 
The nerve trunk terminates upon the M. spino-trapezius. The tendon 
ectad of the Delta mesoscapul@ marks the caudal border of the acromio- 
trapezius muscle and the cephalic border of the spino-trapezius ; entad of 
the ventral angle of this tendinous fascia is found the caudal continuation 
of the N. accessorius, now designated as the spino-trapezius nerve. 
N. spino-trapezius.—At the cephalic border of the M. spino-trapezius, 
the accessory nerve divides into dorsal and ventral rami which may be 
traced throughout the muscle. Since the muscle is innerved by the thor- 
acic nerves (myelic) as well as by the terminal rami of the Accessory, the 
terminal filaments of both nerves form an open plexus throughout its 
tissue. 
SUMMARY. 
A. ANATOMICAL. 
Ectal Origin.—The N. accessorius arises from the lateral column of the 
cephalic myel and the caudal medulla dorsad of the area ovalis; the 
myelic roots are apparent as far caudad as the sixth or seventh cervical 
vertebra. 
Entocranial Course.—The aggregation of these numerous roots forms 
a nerve-trunk which increases in volume from the caudal origin cephalad 
to the foramen of exit; the trunk is apposed to the lateral column of the 
myel, lies entad of the dura between the dorsal and the ventral roots of 
the myelic nerves, enters the cranium through the foramen magnum and 
extends cephalad in the cranium to the caudal roots of the N. vagus, where 
it perforates the dura and is associated with the vagus and the glosso- 
pharyngeus nerves in the foramen of exit. 
FPoramen of Exit.—The N. accessorius traverses the foramen jugulare 
with the associated vagus and accessorius nerves, the jugular vein and a 
small arteriole, a ramulus from the A. occipitalis. 
Communicating Rami. 
1. Accession to the G. jugulare (Vagus) centrad of the foramen of 
exit. 
2. Several rami to the Plexus gangliformis, 5-10 mm. peripherad of the 
foramen jugulare (the first of these is the probable accession to the N. 
glosso-pharyngeus). 
8. Accession to the G. inferius (Vagus). 
4. With cervical nerves. 
PROC. AMER. PHILOS. 800. xxv. 127. M. PRINTED APRIL 18, 1888. 
