IX. STUDY OF THE SPINAL CORD AND PERIPHERAL 
NERVOUS SYSTEM 
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A. GROSS ANATOMY. 
Study demonstration dissections of cat or other small mammal 1 
showing the whole spinal cord and spinal nerve roots (i) in situ , 
and (2) removed from the neural canal. Examine, also, short 
lengths of the spinal cord of some larger mammal (calf, lamb, or 
pig), with the dura mater removed in order to show better the 
external surface of the cord and the relation of the nerve roots 
to it. From these various preparations note the relation of the 
dura mater, arachnoid, and pi a mater to the cord and to the 
nerve roots; the general form of the cord with its cervical and 
- lumbar enlargements and its gradually tapering posterior end 
forming the filum terminate which, together with the more 
posterior pairs of spinal nerves, forms the tail-like structure known 
as the cauda equina; the ventral median fissure, and the dorsal 
median sulcus; the less sharply marked dorsal and ventral lateral 
sulci, the lines along which the dorsal and ventral nerve roots, 
respectively, leave the cord; the segmental arrangement of nerve 
roots corresponding to the intervertebral spaces, the more anterior 
roots passing out almost at right angles, while the more posterior 
ones have a very oblique posterior course; the presence of a 
ganglion on the dorsal (sensory) root; the point of union of the 
two roots. Draw. 
From more detailed dissections of a limited region, study the 
dorsal and ventral rami of each nerve, the former distributed 
mainly to the skin and skeletal muscles, the latter to the deeper 
1 New born or very young kittens furnish excellent material for these prepara¬ 
tions. They should be skinned while fresh, and the roof of the cranial cavity 
removed. The abdomen also should be laid open by a longitudinal slit. They 
should then be hardened for several weeks in 5% formalin made up with 30% alcohol 
(see p. 75) instead of water. When thoroughly hardened they may be washed out 
for a day or two in water and then dissected. They may be kept from year to year 
in 70% alcohol, or in 5% formalin. 
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