Lecture 18 - Cranial Nerves and Autonomics PDF

PAS 313 – Human Anatomy Lecture 18: Cranial Nerves and Autonomics Dr. Joseph Costa, PhD Department of Pathology & Anatomical Sciences 1 What are the cranial Nerves? 12 peripheral nervous structures Within cranium Enter/exit brain stem...

PAS 313 – Human Anatomy Lecture 18: Cranial Nerves and Autonomics Dr. Joseph Costa, PhD Department of Pathology & Anatomical Sciences 1 What are the cranial Nerves? 12 peripheral nervous structures Within cranium Enter/exit brain stem directly CNs innervate craniofacial, thoracic, abdominal structures,...... and the special sensory organs I. Olfactory II. Optic III. Oculomotor IV. Trochlear V. Trigeminal VI. Abducens VII. Facial VIII. Vestibulocochlear IX. Glossopharyngeal X. Vagus XI. Spinal Accessory XII. Hypoglossal Note the ROMAN NUMERALS used to number the nerves 5  Mnemonics Classical: On old Olympus's towering top a Finn and German viewed some hops Modern On, On, On, They Traveled And Found Voldemort Guarding Very Ancient Horcruxes Miscellaneous I. Olfactory Nerve Sense of Smell Small nerves in nasal cavity roof Pass through cribriform plate of ethmoid 7  II. Optic Nerve Vision Retina Formed by axons of the ganglionic cells in the retina of the eye Optic nerve 8 III. Oculomotor Nerve IV. Trochlear Nerve VI. Abducens Nerve Control skeletal muscles that move the eyeball 9  Oculomotor N. also supplies autonomic impulses that constrict pupil and change the shape of lens 10 V. Trigeminal Nerve: Three nerve bundles Sensation for skin of the face and teeth and cavities of head. 11 Trigeminal nerve also innervates the muscles of mastication Masseter Temporalis Medial pterygoid Lateral Pterygoid 12 VII. Facial Nerve Motor to muscles of facial expression Taste from anterior 2/3 of tongue 13  Sublingual gland Lacrimal gland Submandibula r gland Facial nerve: Tears and Saliva Lacrimal glands (tears) Salivary glands (not the parotid) 14 VIII. Vestibulocochlear Nerve: 15 IX. Glossopharyngeal Nerve Autonomics to Parotid gland (salivation) Taste/touch Posterior 1/3 of Tongue 16 X. Vagus Nerve: Somatic Motor/Sensory Sensory and motor to epithelium and muscles of pharynx and larynx 17 X. Vagus Nerve: Parasympathetics to heart and airway 18 X. Vagus Nerve: Autonomics control of smooth muscle and gland secretion in digestive system 19  XI. Spinal Accessory Nerve Motor to 2 muscles: Sternocleidomastoi d Trapezius 20 XII. Hypoglossal nerve: Muscles of the tongue Styloglossus Intrinsic Tongue mm. Genioglossu s Hyoglossus 21  Summary Review the Cranial Nerves and their Function. Although the they have many functions, you are only responsible for knowing those functions listed in this lecture. You should anticipate questions on a quiz or exam that ask you to apply these functions to a clinical situation as discussed during this lecture. 22 Autonomic Nervous System  The autonomic Nervous System Visceral motor Acts on Cardiac muscle Smooth muscle Glands Unconscious NOT VOLUNTARY “Automatic” Fight/Flight response  Autonomic Components in Central and Peripheral Nervous systems Central Nervous Peripheral Nervous System system Limbic system Peripheral nerves Hypothalamus Cranial nerves Brainstem Spinal nerves Spinal Cord  ANS: Two Neuron Chain Ganglion = Collection of nerve cell bodies Sympathetic + parasympathetic Impulses carried on two types of neurons 1. Preganglionic 2. Postganglionic Preganglionic: Cell bodies inside CNS Axon begins in CNS, exits, and then synapses with........Postganglionic: Exclusively in PNS (cell body & axon) This neuron goes to target tissue E.g. Heart, blood vessels, GI tract,  SOMATIC Motor AUTONOMIC Motor Conscious & Voluntary Not under conscious control: Involuntary SINGLE neuron to effector(s) TWO neuron chain: (MOTOR UNIT) pre & post ganglionic Thick/heavily myelinated Preganglionic=myelinated Postganglionic =unmyelinated Rapid conduction of impulse Slow conduction of an impulse Innervates Skeletal muscle Smooth muscle, Cardiac & Glands Always Stimulatory May be Stimulatory or Inhibitory  Sympathetic Nervous System Differs from parasympathetic: Location of pre/postganglionic neurons Neurotransmitter used Effects on body Preganglionic locations: Grey matter of Thorax/lumbar spinal cord “Thoracolumbar” system All thoracic nerves (T1-T12) Upper lumbar nerves (L1,L2)  Sympathetic Nervous System: Component location Preganglionic synapses within sympathetic Chain (AKA paravertebral chain) Linked “chain” of ganglia just outside spinal cord Sympathetic Nervous System: Component location HOWEVER SOME neurons go THROUGH the chain, but DON’T synapse. In head, neck, & thorax: Synapse in chain In abdomen and Pelvis: Synapse in other ganglia found in those cavities Example: Nerves to digestive organs  SYMPATHETIC DIVISION Neurotransmitter: Preganglionic: Acetylcholine Postganglionic: Epinephrine and Norepinephrine General Effects “ Fight or Flight ” response Ex. Increase heart rate, cease peristalsis, sweating, etc. Active during vigorous exercise, excitement, stress Blood shunted to skeletal muscle Short term response Requires increased energy  Adrenal Medulla Also contributes to sympathetic response Suprarenal glands (AKA adrenaline glands) sit on top of kidneys Cells inside act as postganglionic neurons Secrete Epinephrine AND norepinephrine Travel through bloodstream as hormones “Adrenaline surge” Sympathetic Pathway Summary 1. From brain (ex. Limbic system) 2. Descend to specific level of spinal cord 3. Exit the spinal cord 4. Enter sympathetic chain AND THEN One of the following A) Synapse in chain B) Pass through chain and synapse in abdominal/pelvic ganglion C) Synapse with postganglionic neurons in adrenal medulla PARASYMPATHETIC DIVISION “CranioSacral” Preganglionic neuron locations 1. Nuclei of Cranial Nerves in the Brainstem III Oculomotor XII Facial IX Glossopharyngeal X Vagus 2. Nuclei in Sacral region of Spinal Cord Postganglionic neuron locations Close to the organ innervated Ex., eye, glands & visceral organs of neck, thoracic & abdominal cavity  PARASYMPATHETIC DIVISION “CranioSacral” Neurotransmitters: Preganglionic=Acetylcholine Postganglionic=Acetylcholine General Effect: “Resting/Digesting” Active when body is at rest Blood shunted toward internal organs Long term response Conserves energy Regular heartbeat, breathing rate,  SYMPATHETIC PARASYMPATHETIC HEART RATE ▲ HEART RATE ▼ SMOOTH MUSCLE OF SMOOTH MUSCLE OF BRONCHIOLES : DILATE BRONCHIOLES : CONSTRICT URINARY BLADDER : FILL URINARY BLADDER : EXPEL DIGESTIVE MOVEMENT ▼ DIGESTIVE MOVEMENT ▲ SWEAT GLANDS ▲ SWEAT GLANDS neutral ARRECTOR PILI M. ▲ ARRECTOR PILI M. neutral EYE : DILATE EYE : CONSTRICT