Cranial Nerves -TBI-PNS

Cranial Nerves, TBI, PNS Traumatic Brain Injuries (TBI) ● Concussion ○ slight or mild brain injury ○ bleeding & tearing of nerve fibers happened ○ recovery likely with some memory loss ○ obvious bruising to the brain ● Contusion ○ A more severe TBI ○ nervous tissue destruction occurs ○ nervous tissue does not regenerate ○ commonly affects frontal lobe ● Laceration (Cerebral Hematoma and Edema) ○ Swelling from the inflammatory response ○ May compress and kill brain tissue ○ Subdural Hematoma ■ Collection of blood below the dura ● Ischemia ○ low blood supply to a part of the body ○ result to the creation of reactive oxygen species (main molecules involved in free radicals} Cerebrovascular Accident (CVA) ● ● ● ● aka stroke ruptured blood vessel supplying a region of the brain brain tissue supplied with oxygen from that blood source dies loss of some functions or death Alzheimer’s Disease ● ● ● progressive degenerative brain disease structural changes in the brain - abnormal protein deposits, twisted fibers within neurons memory loss, irritability, confusion, hallucinations and death Spinal Cord ● ● ● from medulla oblongata to the region of T12 cauda equina (below T12) - collection of spinal nerves enlargements occur in the cervical and lumbar regions Anatomy ● C1-C7 - cervical; T1-T12 - thoracic; L1-L5 lumbar; sacrum & coccyx - sacral ● ● Exterior white matter - conduction tracts Internal gray matter - mostly cell bodies ○ Dorsal (posterior) horns ■ connects to the white matter ■ center most ○ Anterior (ventral) horns ● Central canal - filled with cerebrospinal fluid ● Meninges - covers the spinal cord ● Nerves leave at the level of each vertebrae ○ Dorsal root - associated with dorsal root ganglia; collections of cell bodies outside the CNS ○ Ventral root - send motor command from the spinal cord to the muscles Peripheral Nervous System (PNS) ● ● ● Nerves and ganglia outside the CNS Nerve - bundle of neuron fibers Neuron fibers - bundled by connective tissue Structure of a Nerve ● ● ● ● ● ● Endoneurium - surrounds each fiber Fascicles - group of fibers bounded by perineurium Epineurium - bounds the fascicles Mixed nerves - both sensory and motor fibers Afferent (sensory) nerves - carry impulses toward the CNS Efferent (motor) nerves - carry impulses away from the CNS Cranial Nerves ● I. brain has no cranial nerves; no pain receptors Olfactory Nerve - located on the inferior surface of the cribriform plate and superior nasal conchae A. Anosmia - loss of the sense of smell B. pure sensory nerve; functions for the sense of smell II. Optic nerve - visual signals are relayed from rods and cones to bipolar cells to ganglion cells A. Anopia - blindness due to a defect in or loss of one or both eyes B. pure sensory; vision III. Oculomotor Nerve - widest distribution among extrinsic eye muscle A. motor; opening and moving the eyes, adjusting pupil width IV. Trochlear Nerve A. motor; tested in common with CN III for the ability to follow moving objects V. Trigeminal Nerve - three branches (ophthalmic, maxillary, mandibular) leave the cranium through the superior orbital fissure, foramen rotundum, and foramen ovale A. Neuralgia (pain) - relayed via one or more branches, caused by conditions such as inflammation, lesions B. both sensory and motor nerve (mixed); conducts sensory impulses from the skin of the face and mucosa of the nose and mouth; chewing VI. Abducens Nerve A. motor; rolls the eyes laterally VII. Facial Nerve A. mixed; facial expressions and sense of taste VIII. Vestibulocochlear Nerve - vestibular branch carries impulses for equilibrium; cochlear branch carries impulses for hearing A. sensory; balance and hearing IX. Glossopharyngeal Nerve - sensory axons supply the taste buds A. Dysphagia - difficulty in swallowing; Aptyalia - reduced secretion of saliva; Ageusia - loss of taste sensation Cranial Nerves, TBI, PNS B. X. XI. XII. mixed; swallowing, saliva production, and taste sensations Vagus Nerve - widely distributed in the head, neck, thorax, and abdomen A. Vagal neuropathy - interruptions of sensations from many organs in the thoracic and abdominal cavities; Tachycardia - increased heart rate B. mixed; digestion, blood pressure, heart rate, breathing, mood, saliva production, and etc. Accessory Nerve - exits the cranium through the jugular foramen A. Paralysis of the sternocleidomastoid and trapezius muscles - unable to raise the shoulders and difficulty in turning the head B. motor; controlling shoulder and neck movement Hypoglossal Nerve - exits the cranium through the hypoglossal canal A. Dysarthria - difficulty in speaking B. motor; tongue movement, speaking, eating, and swallowing Spinal Nerves ● A pair of spinal nerves at the level of each vertebrae ● C1-C7 - cervical; T1-T12 - thoracic; L1-L5 lumbar; sacrum & coccyx - sacral Autonomic Nervous System ● involuntary branch of the nervous system ● motor nerves ● Sympathetic and Parasympathetic divisions Parasympathetic (housekeeping activities) Sympathetic “fight-or-flight” conserves energy response to unusual stimulus maintains daily necessary body functions takes over to increase activities “D” division digestion, defecation, diuresis “E” division exercise, excitement, emergency, embarrassment Development Aspects of the Nervous System ● formed during the first month of embryonic development ● hypothalamus - one of the last areas to develop ● no more neurons formed after birth; growth and maturation continue for several years ● reaches maximum weight as a young adult ● can always grow dendrites