i bc27f85be50b71b1 (80 page)

Sensory and motor input of

Ipsilateral ataxia and

Lateral portion

trunk

discoordination or tremor of

Sensory and motor input of

extremities

extremities for coordination

of gait

Posterior lobe

Medial and lateral portions

Sensory and motor input for

Ipsilateral ataxia and

coordination of motor skills

discoordination of the trunk

and postural tone

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6

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Table 4-2. Continued

N

a..

co

Brain Structure

Substructure

Function

Dysfunction

Flocculonodular

Flocculus nodule

Sensory input from ears

Ipsilateral facial sensory loss

Sensory and motor input from

and Horner's syndrome. nysn

>

eyes and head for coordina�

tagmus, visual overshooting

'"

'"

rion of balance and eye and

Loss of balance

:t

>

head movement

15

1')

ADH

o

= antidiuretic hormone; eN = cranial nerve; ICP = intracranial pressure.

"

Sources; Data from KW Lindsay, I Bone, R Callander (cds). Neurology and Neurosurgery Illustrated (2nd ed). Edinburgh, UK: Churchill Ci

Livingstone, 1991; S Gilman, SW Newman (cds). Manter and Gatz's Essentials of Clinical Neuroanaromy and Neurophysiology (7th ed),

'"

Philadelphia: FA Davis, 1989; JA Kiernan (ed). Introduction to Human Neuroscience. Philadelphia: Lippincott, 1987; EN Marieb fed). Human

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:t

Anatomy and Physiology (5th ed). San Francisco: Benjamin-Cummings. 2001; and L Thelan, J Davie, M Lough reds). Critical Care Nursing:

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Diagnosis and Managemenr (2nd ed). St. Louis: Mosby. 1994.

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NERVOUS SYSTEM

269

Meninges

The meninges are three layers of connective tissue that cover the brain

and spinal cord. The dura marer, rhe outermost layer, lines the skull

(periosteum) and has four major folds (Table 4-3). The arachnoid, the

middle layer, loosely encloses the brain. The pia mater, the inner layer,

covers the convolutions of the brain and forms a portion of the choroid plexus in the ventricular system. The three layers create very important anatomic and potential spaces in the brain, as shown in

Figure 4-2 and described in Table 4-4.

Ventricular System

The ventricular system nourishes the brain and acts as a cushion

by increasing the buoyancy of the brain. It consists of four ventricles and a series of foramen, through which cerebrospinal fluid (CSF) passes to surround rhe CNS. CSF is a colorless, odorless

solution produced by rhe choroid plexus of all ventricles. CSF circulares in a pulse-like fashion through the ventricles and around the spinal cord with the beating of ependymal cilia rhar line the

ventricles and intracranial blood volume changes that occur with

breathing and cardiac systole] The flow of CSF under normal conditions, as shown in Figure 4-3, is as follows4:

Table 4-3. Dural Folds

Falx cerebri

Vertical fold that separates the two cerebral hemi·

spheres ro prevent horizontal displacement of

these structures

Falx cerebelli

Vertical fold that separates the two cerebellar

hemispheres to prevent horizontal displacement

of these structures

Tentorium cerebelli

Horizontal fold that separates occipital lobes from

the cerebellum to prevent vertical displacement

of these Structures

Diaphragm sellae

Horizontal fold that separates that subarachnoid

space from the sella turcica and is perforated by

the stalk of the pituitary gland

Source: Data from JL Wilkinson (ed). Neuroanatomy for Medical Srudents (3rd ed).

Oxford, UK: Butterworth-Heinemann, 1998.

270

AClJTE CARE HANDBOOK FOR PHYSICAL THERAPISTS

Figure 4-2. Coronal section o( cranial meninges showing a venous sinus and

dural (old. ( With permission from PA Young, PH Young. Basic Clinical Nellroallatomy. Phi/adelphia: \Vil/iams & \Vi/kills, 1997;8.)

•

From the lateral ventricles via the interventricular foramen to

the third ventricle

• From the third ventricle to the fourth ventricle via the cerebral

aqueduct

• From the fourth ventricle to the cisterns, subarachnoid space,

and spinal cord via the median and lateral apertures

Table 4-4. Dural Spaces

Epidural (extradural) space

Potential space between the skull and outer

dura mater.

Subdural space

Potential space between [he dura and [he

arachnoid mater; a split in the dura contains the venous sinus.

Subarachnoid space

Anaromic space between the arachnoid and

pia ll1!lter containing cerebrospinal Auid

and the vascular supply of the cortex.