98 {March 2, 
Stowell. ] 
Principal Rami—their Ectal Origins and Distributions. 
N. clavo-mastoideus. 
1. Caudal ramus; origin at the ental surface of the M. clavo-mastoideus 
as the nerve perforates the muscle. 
2. Cephalic ramus ; origin opposite the dorsal border of the muscle. 
These rami are distributed to the caudal and the cephalic portions of the 
muscle respectively. 
NV. sterno-mastoideus. 
1. Dorsi-cephalic ramus ; origin at the ectal surface of the M. clayo- 
mastoideus, distribution to the cephalic third of the muscle. 
2, Ventral ramus; origin in common with the preceding, distribution 
to the thick ventral two-thirds of. the muscle. 
3. Dorsi-caudal ramus ; origin at the dorsal border of the M. sterno- 
mastoideus in connection with the cephalic clavo-trapezius nerve, distribu- 
tion to the thin dorsal border of the caudal two-thirds of the muscle. 
NV. clavo-trapeeius. 
1. Ocphalic ramus ; origin in common with the dorsi-caudal ramus of 
the sterno-mastoid nerve, distribution to the cephalic fourth of the M. 
clavo-trapezius ; this nerve joins its platetrope in the dorsi-meson. 
2, Caudal ramus; origin about the middle of the M. clavo-trapezius, 
distribution by 3-4 palmate ramuli to the ental surface of the caudal por- 
tion of the muscle. 
N. acromio-trapezius. 
1. Cephalic ramus ; origin in the Hiatus trapezii, distribution to the 
cephalic portion of the acromio-trapezius muscle; this is the large nerve 
and extends to the dorsi-meson. 
2, Other rami ; several (two prominent) other rami supply the caudal 
portion of the muscle. 
N. spino-trapezius. 
The terminal rami of the Accessorius unite with the thoracic myelic 
nerves in an open plexus to the M. spino-trapezius. 
Myelic Accessions. 
Two large accessions from the myelic nerves are received by the trunk 
of the Accessorius, the cephalic is just caudad of the cephalic clavo-trap- 
ezius nerve, the caudal is just caudad of the hiatus-trapezii. 
B. PHYSIOLOGICAL. 
The N. accessorius is the motor nerve of the sterno-mastoid, the clavo- 
mastoid, and the trapezius muscles ; it is possibly the source of the motor 
fibre of the Vagus nerve; it seems to be exclusively motor ; its distribu- 
tion and physiological experiments indicate the absence of sensibility ; it 
is antagonistic to movements of respiration (Cl. Bernard); it controls 
laryngeal phonation (Cl. Bernard); it is cardio-inhibitory (Heidenhain). 
EXPLANATION OF DIAGRAM. 
The diagram seeks to present the principal rami and relations of the 
nerve, Actual measurements and perspective are sacrificed to clearness 
