IC NERVE (tenth pair) escapes from the brain
through the foramen lacerum. It sends branches to the larynx, pharynx,
oesophagus, lungs, spleen, pancreas, liver, stomach, and intestines.
(Fig. 132.)

753. The SPINAL ACCESSORY NERVE (eleventh pair) has its origin in the
respiratory tract of the spinal cord. It connects with the ninth and
tenth pairs of nerves, and is distributed to the muscles about the
neck.

754. The HYPO-GLOSSAL NERVE (twelfth pair) passes from the brain,
through a small opening, (_con'dy-loid foramen_.) It ramifies upon the
muscles of the tongue, and is its motor nerve.

_Observation._ The cranial nerves, with the exception of the
olfactory, optic, and auditory, connect with each other by means of
filaments. They also send connecting nervous filaments to the upper
spinal nerves, (cervical,) and the sympathetic nerve.

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751. Describe the glosso-pharyngeal nerve. 752. The pneumogastric
nerve. 753. The spinal accessory nerve. 754. The hypo-glossal nerve.

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CHAPTER XXXVII.

ANATOMY OF THE NERVOUS SYSTEM, CONTINUED.

755. The spinal column contains the spinal cord, the roots of the
spinal nerves, and the membranes of the cord.

756. The SPINAL CORD extends from the medulla oblongata to the second
lumbar vertebra, where it terminates in a rounded point. It presents a
difference of diameter in different parts of its extent, and exhibits
three enlargements. The uppermost of these is the medulla oblongata.
There is no distinct demarkation between this enlargement and the
spinal cord. The next corresponds with the origin of the nerves
distributed to the upper extremities; the third enlargement is
situated near the termination of the cord, and corresponds with the
attachment of the nerves which are intended for the supply of the
lower extremities.

757. An anterior and posterior fissure divides the spinal cord into
two lateral cords. These are united by a thin layer of white
substance. The lateral cords are each divided by furrows into three
distinct sets of fibres, or columns; namely the _anterior_, _lateral_,
and _posterior_ columns. The anterior are the motor columns; the
posterior are the columns of sensation; the lateral columns are
divided in their function between motion and sensation. They contain
the fasciculus described, by Sir Charles Bell, as the respiratory
tract.

[Illustration: Fig. 128. A section of the brain and spinal