eal nerves lie between the level of the
eleventh thoracic and first lumbar vertebrae. Injuries of the lower
thoracic and upper lumbar vertebrae, therefore, may produce complete
paralysis within the area of distribution of the lumbar and sacral
plexuses. The anaesthesia reaches to about the level of the umbilicus.
There is incontinence of urine and faeces from the first. Priapism is
absent. Bed-sores and other trophic changes are common, and there is
the usual risk of complications in relation to the urinary tract.

_Conus Medullaris._--A lesion confined to the conus medullaris may
result from a fall in the sitting position. It is attended with slight
weakness of the legs, anaesthesia involving a saddle-shaped area over
the buttocks and back of the thighs, the perineum, scrotum, and penis.
The urethra and anal canal are insensitive, and there is paralysis of
the levatores ani, the rectal and the vesical sphincters. The testes
retain their sensation.

_Cauda Equina._--As the cord terminates opposite the lower border of
the first lumbar vertebra, injuries below this level implicate the
cauda equina. The extent of the motor and sensory paralysis varies
with the level of the lesion and with the particular nerves injured.
Sometimes it is complete, sometimes, selective. As a rule all the
muscles of the lower extremity are paralysed, except those supplied by
the femoral (anterior crural), obturator, and superior gluteal nerves.
The perineal and penile muscles are also implicated. There is
anaesthesia of the penis, scrotum, perineum, lower half of the buttock,
and the entire lower extremity, except the front and lateral aspects
of the thigh, which are supplied by the lateral cutaneous nerve and
the cutaneous branches of the femoral (anterior crural). There is
incontinence of urine and faeces. The prognosis is more favourable than
in lesions affecting the cord itself, and the only risk to life is the
occurrence of infective complications.

#Partial Lesions of the Cord and Nerve Roots.#--Partial lesions, such
as bruises, lacerations, or incomplete ruptures, are always attended
with haemorrhage into the substance of the cord, and usually result
from distortions or incomplete fractures and dislocations of the
spine, or from bullet wounds. They are comparatively rare.

When the _nerve roots_ alone are injured, sensory phenomena
predominate. Formication, radiating pains, and neuralgia are present
in the area of distribution of the