Suzanne D'Anna1 Cranial and Spinal Nerves

Suzanne D'Anna2 Cranial Nerves n emerge from the brain n emerge through holes in the cranium - cranial foramina n 12 pairs of cranial nerves n Contains: - sensory fibers (afferent) - motor fibers (efferent) - both sensory and motor fibers

Suzanne D'Anna3 Cranial Nerves (cont.) I Olfactory IIOptic IIIOculomotor IVTrochlear VTrigeminal VIAbducens VII Facial VIII Vestibulocochlear IX Glossopharyngeal X Vagus XI Accessory XII Hypoglosseal

Suzanne D'Anna4 I Olfactory n sensory nerve n Function: - smell (olfactory bulbs) anosmia - loss of sense of smell

Suzanne D'Anna5 II Optic n sensory nerve n Function: - vision (retina) anopsia - defective vision

Suzanne D'Anna6 III Oculomotor n mixed nerve (primarily motor) n Functions: - eyeball movement (4 eyeball muscles and 1 eyelid muscle) - lens accommodation - pupil constriction - muscle proprioception

Suzanne D'Anna7 III Oculomotor (cont.) n Injury or lesion may cause: - strabismus - squinting - ptosis - drooping of upper eye lid - diplopia - loss of accommodation for near vision and double vision

Suzanne D'Anna8 IV Trochlear n mixed nerve (primarily motor) n Functions: - eyeball movement (superior oblique muscles) - muscle proprioception

Suzanne D'Anna9 V Trigeminal n mixed nerve n Functions: - sensations ( face, scalp, teeth, lips, eyeballs, nose and throat lining) - general sensations from the tongue - proprioception (face and scalp) - chewing (muscles of mastication)

Suzanne D'Anna10 VIAbducens n mixed nerve (primarily motor) n Functions: - eyeball movement (lateral rectus muscle) - muscle proprioception

Suzanne D'Anna11 VII Facial n mixed nerve n Functions: - taste (anterior 2/3 of tongue) - proprioception (face and scalp) - facial expression (muscles of the face) n Injury: Bell’s palsy - loss of taste, inability to close eyes

Suzanne D'Anna12 VIII Vestibulocochlear n sensory nerve n Functions: - balance (vestibular apparatus of the internal ear) - hearing (cochlea of internal ear)

Suzanne D'Anna13 VIII Vestibulocochlear (cont.) n Injury may cause: - tinnitus - ringing of the ear or deafness - vertigo - feeling of rotation, dizziness - ataxia and nystagmus - involuntary rapid movement of the eyeball

Suzanne D'Anna14 IX Glossopharyngeal n mixed nerve n Functions: - taste (posterior 1/3 of the tongue) - proprioception for swallowing (throat muscles) - blood pressure receptors (carotid sinuses)

Suzanne D'Anna15 X Vagus n mixed nerve n Functions: - chemoreceptors (blood oxygen concentration, aortic bodies) - pain receptors (respiratory and digestive tracts) - sensations (external ear, larynx, and pharynx) - taste (tongue)

Suzanne D'Anna16 X Vagus (cont.) n Functions: - heart rate and stroke volume (pacemaker and ventricular muscles) - peristalsis (smooth muscles of the digestive tract) - airflow (smooth muscles in bronchial tubes) - speech and swallowing (muscles of larynx and pharynx)

Suzanne D'Anna17 XI Accessory n mixed nerve (primarily motor) n Function: - head rotation (trapezius and sternocleidomastoid muscles

Suzanne D'Anna18 XII Hypoglosseal n mixed nerve (primarily motor) n Functions: - speech and swallowing (tongue and throat muscles)

Suzanne D'Anna19 Classification of Spinal Nerves n all emerge from spinal cord n emerge through holes formed by notches on adjoining vertebrae n 31 pairs n all mixed nerves (containing both sensory and motor) n named and numbered according to region and level of spinal cord from which they emerge

Suzanne D'Anna20 Classification of Spinal Nerves (cont.) n 8 pairs of cervical nerves - first cervical pair emerges between atlas (first cervical vertebra) and occipital bone - first 7 emerge above vertebra of the same number - 8th emerges between 7th cervical vertebra and 1st thoracic vertebra

Suzanne D'Anna21 Classification of Spinal Nerves (cont.) n 12 pairs of thoracic nerves n 5 pairs of lumbar nerves n 5 pairs of sacral nerves n 1 pair of coccygeal nerves - all emerge below vertebra of the same number - emerge through intervertebral foramina

Suzanne D'Anna22 Plexuses (plexus = braid) network of adjacent nerves n cervical plexus: C1 - C5 n brachial plexus: C5 - T1 n lumbar plexus: L1 - L4 n sacral plexus: L4 - S4

Suzanne D'Anna23 Brachial Plexus C 4 C 5 C 6 C 7 C 8 T 1

Suzanne D'Anna24 Lumbo-Sacral Plexus

Suzanne D'Anna25 Dermatomes n specific segment of skin which each spinal nerve innervates n knowledge can help physician determine which segment of the spinal cord or which spinal nerve is affected