1. Objectives 1. Review: Be able to label and identify the function of the cranial nerves 2. List and define disorders of the nervous tissue 3. Define nerve and associated definitions 4. Be able to identify and know functions of structures shown on sagittal section of the central nervous system

3. Cranial Nerves 1. Olfactory nerve – nose to brain, sense of smell 2. Trigeminal nerve – sensations of face, scalp, and teeth; chewing Ophthalmic branch: eye Maxillary branch: eye to upper jaw and throat Mandibular branch: lower jaw

4. 3. Glossopharyngeal nerve – controls salivation; controls swallowing muscles; taste (posterior third of tongue); sensations of throat; blood pressure sensation 4. Hypoglossal nerve – brain to muscles of tongue; tongue movements (swallowing and speech)

5. 5. Accessory nerve – shoulder movements; turning movements of head 6. Vagus nerve – controls swallowing muscles; control and sensation in various visceral effectors 7. Vestibulocochlear – senses of equilibrium and hearing

6. 8. Facial nerve – controls facial muscles; controls secretion of tears and saliva; taste (anterior two thirds of tongue) 9. Abducens nerve – controls lateral rectus muscle of eye 10. Oculomotor nerve – controls upper eyelid muscles; controls ciliary muscle of the eye and sphincter (ring-shaped muscle) in the iris

7. 11. Optic nerve – vision 12. Trochlear nerve – controls superior oblique muscle of the eye

8. Disorders of Nervous Tissue Multiple sclerosis (MS) – myelin disorder: myelin loss and destruction accompanied by varying degrees of oligodendrocyte injury and death; nerve conduction impaired, speech disturbances, vision impairment, weakness, incoordination Relapsing and chronic Cause: autoimmunity?, viral? No known cure

9. Neuroma – tumor; usually develop from glia, membrane tissues, and blood vessels Some types of neuromas: Glioma – common, usually benign but can still be life-threatening Multiple neurofibromatosis – inherited; fibrous neuromas throughout the body; benign but can be disfiguring; “Elephant Man” disease

10. Note Most malignant tumors of glia and other nervous tissue do not arise there but are secondary tumors resulting from the metastasis of cancer cells from the breast, lung, and other organs

11. Nerves A nerve is a group of peripheral nerve fibers (axons) bundled together like the strands of a cable Nerves usually have a white, myelin sheath so called the white matter of the PNS Bundles of axons in CNS, called tracts, may also be myelinated: White matter of CNS

12. Gray matter – tissue composed of cell bodies and unmyelinated axons and dendrites Each axon in a nerve is surrounded by a thin wrapping of fibrous connective tissue called endoneurium Fascicles – groups of wrapped axons

13. Each fascicle is surrounded by a thin, fibrous perineurium The whole nerve is covered by a tough, fibrous sheath called the epineurium Endo---Peri----Epi Axon---fascicle----whole nerve

14. Sagittal Section of the CNS 1. Skull 2. Pineal gland-third ventricle; produces melatonin Ventricle: cavity with cerebrospinal fluid Melatonin: hormone that regulates puberty and menstrual cycle; “third eye” (responds to light and body’s internal clock) 3. Cerebellum-second largest part of brain; production of normal movements; muscle coordination, equilibrium, posture

15. 4. Midbrain-one of the three parts of the brain stem; relay for visual and auditory impulses 5. Spinal cord – gray and white matter do NOT intermingle; gray matter forms the interior of the cord and white matter surrounds it 6. Medulla- enlarged upward extension of the spinal cord; bits of white and gray matter mix to form the reticular (net-like) formation; cardiac, respiratory, and vasomotor control 7. Reticular formation

16. 8. Pons – part of brainstem; consists of white matter and scattered bits of gray matter; influences respiration 9. Pituitary gland – endocrine gland that secretes many important hormones 10. Hypothalamus- regulation of body temperature, water balance, sleep-cycle control, appetite, sexual arousal

17. 11. Cerebral cortex – outer part of cerebrum ( largest and most upper part of the brain; sensory perception, emotions, willed movements, consciousness, memory) Ridges called convolutions or gyri Grooves called sulci Deepest sulci called fissures Longitudinal fissure divides cerebrum into right and left halves (hemispheres)

18. 12. Thalamus – emotions and alerting, arousal mechanisms 13. Corpus callosum – connects lower portion of the right and left hemispheres of the cerebrum