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• Classic-Fiction

Number Name Function

I Olfactory Sense of smell

II Optic Vision

III Oculomotor Pupillary constriction, opening the eye, and most extraocular movements

IV Trochlear Downward, inward movement of the eye

VI Abducens Lateral deviation of the eye

V Trigeminal Motor – temporal and masseter muscles (jaw clenching), also lateral movement of the jaw

Sensory – facial. The nerve has three divisions: (1) ophthalmic, (2) maxillary and (3) mandibular

VII Facial Motor – facial movements, including those of facial expression, closing the eye, and closing the mouth

Sensory – taste for salty, sweet, sour and bitter substances on the anterior twothirds of the tongue

VIII Acoustic Hearing (cochlear division) and balance (vestibular division)

IX Glossopharyngeal Motor – pharynx

Sensory – posterior portions of the eardrum and ear canal, the pharynx, and the posterior tongue, including taste (salty, sweet, sour, bitter)

X Vagus Motor – palate, pharynx and larynx

Sensory – pharynx and larynx

XI Spinal accessory Motor – the sternomastoid and upper portion of the trapezius

XII Hypoglossal Motor – tongue

The peripheral nerves

In addition to cranial nerves, the peripheral nervous system also includes spinal and peripheral nerves that carry impulses to and from the cord. Thirtyone pairs of nerves attach to the spinal cord: eight cervical, 12 thoracic, five lumbar, five sacral and one coccygeal. Most peripheral nerves contain both sensory and motor fibres (Bickley and Szilagyi 2009).

Related theory

Changes in neurological status can be rapid and dramatic or subtle, developing over minutes, hours, days, weeks or even months depending on the insult (Aucken and Crawford 1998). Therefore the frequency of neurological observations will depend upon the patient’s condition and the rapidity with which changes are occurring or expected to occur.

Neurological function is assessed by observing five critical areas:

level of consciousness

pupillary activity

motor function

sensory function

vital signs.

Level of consciousness

Consciousness is a state of awareness of self and the environment and is dependent upon two components:

arousability

awareness.

(Carlson 2002a)

Arousability

This depends on the integrity of the reticular activating system (RAS) (Figure 12.28). The core of nuclei which make up the RAS extends from the brainstem to the thalamic nuclei in the cerebral hemispheres. Thus cognitive ability depends on the ability of the cerebral cortex to permit reciprocal stimulation and conscious behaviour. Consciousness therefore depends on the intactness of the cerebral cortex and the RAS and their ability to communicate effectively (Carlson 2002b, Fairley and McLernon 2005).

Figure 12.28 Reticular activating system.

Awareness

This requires an intact cerebral cortex to interpret sensory input and respond accordingly. This is the content of the consciousness (Bateman 2001, Scherer 1986).

Levels of consciousness may vary and are dependent on the location and extent of any neurological damage (Aucken and Crawford 1998). Previous and/or coexisting problems should be heeded when noting levels of consciousness, for example deafness, hemiparesis/hemiplegia.

Alterations in level of consciousness can vary from slight to severe changes, indicating the degree of brain dysfunction (Aucken and Crawford 1998). Consciousness ranges on a continuum from alert wakefulness to deep coma with no apparent responsiveness. Therefore, nurses must ensure that families and friends are involved at initial history taking and throughout care so as to chronicle accurately any change in neurological symptoms.

Terms such as ‘fully conscious’, ‘semiconscious’, ‘lethargic’ or ‘stuporous’ used to describe levels of consciousness are subjective and open to misinterpretation. Thus, level of consciousness is often measured using the Glasgow Coma Scale (GCS) (see Assessment and recording tools).

Application of painful stimuli

Painful stimuli should be employed only if the patient does not respond to firm and clear commands. It is always important that