ASSESSING NEUROLOGIC SYSTEM

CNS

CNS

encompasses the brain and spinal cord, which are covered by meninges, three layers of connective tissue that protect and nourish the CNS.

Subarachnoid Space

sur rounds the brain and spinal cord.

Subarachnoid Space

is filled with cerebrospinal fluid (CSF).

CSF

is formed in the ventricles of the brain and flows through the ventricles into the space.

CSF

This fluid-filled space cushions the brain and spinal cords, nourishes the CNS, and removes waste materials.

neurons

Electrical activity of the CNS is governed by ____________ located throughout the sensory and motor neural pathways.

Upper Motor Neurons

influence lower motor neurons, located mostly in the peripheral nervous system.

Brain

Located in the cranial cavity.

Cerebrum, Diencephalon, Brain Stem, Cerebellum

The brain has four major divisions:

corpus callosum

The cerebrum is divided into the right and left cerebral hemi spheres, which are joined by the ___________________________.

corpus callosum

a bundle of nerve fibers responsible for communication between the hemispheres.

gray matter

The lobes are com posed of a substance known as ___________________.

gray matter

mediates higher-level functions such as memory, perception, communi cation, and initiation of voluntary movements.

cerebral cortex

Consisting of aggregations of neuronal cell bodies, gray matter rims the sur faces of the cerebral hemispheres, forming the __________________________.

Diencephalon

lies beneath the cerebral hemispheres and consists of the thalamus and hypothalamus.

Hypothalamus

responsible for regulating many body functions including water balance, appetite, vital signs (temperature, blood pressure, pulse, and respiratory rate), sleep cycles, pain perception, and emotional status.

Brain Stem

Located between the cerebral cortex and the spinal cord.

midbrain, pons, medulla oblongata

The brain stem consists of mostly nerve fibers and has three parts:

Midbrain

serves as a relay center for ear and eye reflexes, and relays impulses between the higher cerebral centers and the lower pons, medulla, cerebellum, and spinal cord.

Pons

links the cerebellum to the cerebrum and the midbrain to the medulla. It is responsible for various reflex actions.

Medulla Oblongata

contains the nuclei for cranial nerves, and has centers that control and regulate respiratory function, heart rate and force, and blood pressure.

Cerebellum

located behind the brain stem and under the cerebrum, also has two hemispheres.

Cerebellum

its primary functions include coordination and smoothing of voluntary movements, maintenance of equilibrium, and maintenance of muscle tone.

Spinal Cord

located in the vertebral canal and extends from the medulla oblongata to the first lumbar vertebra.

F, S-shaped

T or F:

The inner part of the cord has an M-shaped appearance and is made up of two pairs of columns (dorsal and ventral) consisting of gray matter.

Spinal Cord

conducts sensory impulses up ascending tracts to the brain, conducts motor impulses down descending tracts to neurons that stimulate glands and muscles throughout the body, and is responsible for simple reflex activity.

Reflex Activity

involves various neural structures.

Stretch Reflex

The simplest type of reflex arc—involves one sensory neuron (afferent), one motor neuron (efferent), and one synapse.

Knee Jerk

is elicited by tapping the patellar tendon.

Spinothalamic and Posterior Columns

Sensory impulses travel to the brain by way of two ascending neural pathways:

Frontal Lobe

Directs voluntary, skeletal actions

Frontal Lobe

Also influences communication (talking and writ ing), emotions, intellect, reasoning ability, judgment, and behavior.

Broca’s Area

responsible for speech.

Parietal Lobe

Interprets tactile sensations, including touch, pain, temperature, shapes, and two-point discrimination.

Occipital Lobe

Influences the ability to read with understanding and is the primary visual receptor center.

Temporal Lobe

Receives and interprets impulses from the ear.

Wernicke’s Area

which is responsible for interpreting auditory stimuli.

Spinothalamic Tract

Sensations of pain, temperature, and crude and light touch travel by way of the _____________________.

Posterior Columns

sensations of position, vibration, and fine touch travel by way of the

Motor Impulses

are conducted to the muscles by two descending neural pathways: the pyramidal (corticospinal) tract and extrapyramidal tract.

pyramidal tract

The motor neurons of the _______________________ originate in the motor cortex and travel down to the medulla, where they cross over to the opposite side then travel down the spinal cord, where they synapse with a lower motor neuron in the anterior horn of the spinal cord.

Extrapyramidal Tract

consist of those motor neurons that originate in the motor cortex, basal ganglia, brain stem, and spinal cord outside the pyramidal tract.

PNS

consists of 12 pairs of cranial nerves and 31 pairs of spinal nerves.

Somatic, Autonomic

These nerves are categorized as two types of fibers:

Somatic Fibers

carry CNS impulses to voluntary skeletal muscles

Autonomic Fibers

carry CNS impulses to smooth, involuntary muscles (in the heart and glands).

SNS

mediates conscious, or voluntary, activities

I - Olfactory

Carries smell impulses from nasal mucous membrane to brain.

II - Optic

Carries visual impulses from eye to brain.

III - Oculomotor

Contracts eye muscles to control eye movements (interior lateral, medial, and superior), constricts pupils, and elevates eyelids.

IV - Trochlear

Contracts one eye muscle to control inferomedial eye movement.

V - Trigeminal

Carries sensory impulses of pain, touch, and temperature from the face to the brain. Influences clenching and lateral jaw movements (biting, chewing).

VI - Abducens

Controls lateral eye movements.

VII - Facial

Contains sensory fibers for taste on anterior two-thirds of tongue, and stimulates secretions from salivary glands (submaxillary and sublingual) and tears from lacrimal glands.

VIII - Acoustic

Contains sensory fibers for hearing and balance.

IX - Glossopharyngeal

Contains sensory fibers for taste on posterior third of tongue and sensory fibers of the pharynx that result in the gag reflex when stimulated.

X - Vagus

Carries sensations from the throat, larynx, heart, lungs, bronchi, gastrointestinal tract, and abdominal viscera. Promotes swallowing, talking, and production of digestive juices.

XI - Spinal Accessory

Innervates neck muscles (sternocleidomastoid and trapezius) that promote move ment of the shoulders and head rotation. Also promotes some movement of the larynx.

XII - Hypoglossal

Innervates tongue muscles that promote the movement of food and talking

Sympathetic NS

is activated during stress and elicits responses such as decreased gastric secretions, bronchiole dilatation, increased pulse rate, and pupil dilatation.

Sympathetic NS

functions to restore and maintain normal body functions, for example, by decreasing heart rate.

Aura

forewarns the client that a seizure is about to occur.

Anticonvulsants

must be distributed at a therapeutic level in the blood to be effective.

Fasciculations

(continuous, rapid twitching of resting muscles) may be seen in lower motor neuron disease.

Tremors

(involuntary contraction of opposing groups of muscles) are typical in degenerative neurologic disorders, such as Parkinson’s disease (3–6 per second while muscles are at rest or “pin rolling” between thumb and opposing finger), or in cerebellar disease and multiple sclerosis (variable rate, and especially with intentional movement).

Tics

(involuntary repetitive twitching movements) may be seen in Tourette’s syndrome, habit psychogenic tics, or tardive dyskinesias.

Myoclonus

(sudden jerks of arms or legs) may occur normally when falling asleep as a single jerk. However, severe jerking is often seen with grand mal seizures.

Chorea

(sudden rapid, jerky voluntary and involuntary movements of limbs, trunk or face) is seen in Huntington’s disease and Sydenham’s chorea).

Athetosis

(twisting, writhing, slow continuous movements) is seen in cerebral palsy

Mental Status Examinations

provide information about cerebral cortex function.

Papilledema

(swelling of the optic nerve) results in blurred optic disc margins and dilated, pulsating veins.

Optic Atrophy

occurs with brain tumors

Ptosis

drooping of the eyelid) is seen with weak eye muscles such as in myasthenia gravis

Nystagmus

rhythmic oscillation of the eyes

Paralytic Strabismus

paralysis of the oculomotor, trochlear, or abducens nerves

Anesthesia

absence of touch sensation

Hypesthesia

decreased sensitivity to touch

Hyperesthesia

increased sensitivity to touch

Analgesia

absence of pain sensation

Hypalgesia

decreased sensitivity to pain

Hyperalgesia

increased sensitivity to pain

hyporeflexia

Absent or markedly decreased (_____________________) deep tendon reflexes

Brown-Sequard Syndrome

A hemisection of the spinal cord resulting in ipsilateral loss of strength and proprioception and contralateral loss of pain and temperature.