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Chapter 14: Peripheral Nervous System. PowerPoint by John McGill Supplemental Notes by Beth Wyatt. Nervous System Organization. I. SPINAL NERVES. OVERVIEW DEFINITION Nerves That Extend Off the Spinal Cord (Emerge From the Spinal Cavity) NUMBER: 31 Pair. Spinal Nerves.
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Chapter 14: Peripheral Nervous System PowerPoint by John McGill Supplemental Notes by Beth Wyatt
I. SPINAL NERVES • OVERVIEW • DEFINITION • Nerves That Extend Off the Spinal Cord (Emerge From the Spinal Cavity) • NUMBER: 31 Pair
I. SPINAL NERVES • C1-C8 • CERVICAL NERVES • T1-T12 • THORACIC NERVES • L1-L5 • LUMBAR NERVES • SACRAL NERVES • S1-S5 • COCCYGEAL NERVES • 1 PAIR
SPINAL NERVES are IDENTIFIED BY LETTERS AND NUMBERS • They are NOT “named.” • LETTERS • INDICATE REGIONS OF VERTEBRAL COLUMN • NUMBERS • INDICATE HOW MANY OF EACH TYPE (EACH PAIRED)
SPINAL NERVES are IDENTIFIED BY LETTERS AND NUMBERS • THE LETTERS AND NUMBERS INDICATE WHERE THE NERVES EXIT SPINAL CAVITY • C1-C7 Exit Above C1-C7 Vertebrae • C8 Exits Below C7 Vertebra • Thoracics and Lumbars Exit Below Their Respective Vertebrae • Sacrals Exit Through Openings in Sacrum • Coccygeals Pass Over Coccyx
CAUDA EQUINA ( Horse’s Tail ) • Describes the Appearance of the Bottom of the Spinal Cord • Reason: Spinal Cord Ends at Bottom of the 1st Lumbar Vertebra;
CAUDA EQUINA ( Horse’s Tail ) • Means That Lumbar, Sacral, and Coccygeal Nerves Hang in a Bundle at the Bottom of the SC Before Exiting at Their Respective Locations • Causes the Bottom of the Spinal Cord to Resemble a Cauda Equina
SPINAL NERVES ARE MIXED NERVES • The spinal nerves carry both sensory and motor messages and are called “mixed nerves.”
SPINAL NERVE STRUCTURE • NERVE ROOTS: Join Spinal Nerves to Spinal Cord • VENTRAL ROOTS • NF OF EFFERENT NEURONS • DORSAL ROOTS • NF OF AFFERENT NEURONS
RAMI (RAMUS) • The Major Branches of a Spinal Nerve • Each Spinal Nerve Has 2 Rami
RAMI (RAMUS) DESCRIPTION • The spinal nerve trunk emerges laterally from the intervertebral foramen • The trunk divides into two major branches (The anterior (ventral) and posterior (dorsal) primary rami (ramus, singular)) • The posterior primary rami go to the back. • The anterior primary rami go to the sides and front of the body, and to the upper and lower members.
DORSAL RAMUS • AREAS SUPPLIED • Provides Nerve Supply to Posterior Head, Neck, and Trunk • Contains Both Afferent and Efferent (Somatic) Nerve Fibers
VENTRAL RAMUS (More Complex) • AREAS SUPPLIED • Lateral and Anterior Neck and Trunk as well as Extremities • Contains Both Afferent and Efferent (Somatic & Autonomic) Nerve Fibers
VENTRAL RAMUS (More Complex) • NERVE PLEXUSES are only found on ventral rami • DEFINITION • Complex Nerve Network • The Ventral Rami of Most Spinal Nerves Form Plexuses (Not T2 ‑ T12) • Formed when the Ventral Rami of Several Spinal Nerves Exchange Fibers • (Fibers Recombine) to Form New Nerves that Supply Specific Areas
VENTRAL RAMUS (Comments from the text) • Fibers of several rami join to form individual nerves. • Each nerve emerging from a plexus contains all the fibers that innervate a body region. • Destination is basis for nerve’s name. • The plexus reduces the number of nerves needed to supply a body part. • Since plexi are composed of fibers from different spinal nerves, damage to one spinal nerve does not mean a complete loss of function in a body region • But Instead, Partial Loss of Function in Several Areas
MAJOR PLEXUSES (ALL ARE PAIRED): CERVICAL PLEXUS • CERVICAL PLEXUS • Formed by the Ventral Rami of C1‑C4 and a Branch of Ventral Ramus of C5 • Provides Nerve Supply to Neck and Upper Shoulders and Part of Head
MAJOR PLEXUSES (ALL ARE PAIRED):BRACHIAL PLEXUS • BRACHIAL PLEXUS • Formed by the Ventral Rami of C5‑T1 • Provides Nerve Supply to Lower Shoulders and Arms
MAJOR PLEXUSES (ALL ARE PAIRED): LUMBAR PLEXUS • LUMBAR PLEXUS • Formed by the Ventral Rami of L1‑L4 • SACRAL PLEXUS • Formed by the Ventral Rami of L4, L5, & S1‑S4 • *Note: Together the Lumbar and the Sacral Plexuses (also the Coccygeal Plexus) Are Known as the Lumbosacral Plexus that Provides Nerve Supply to the Lower Trunk and the Legs
Plexus Notes • * Coccygeal Plexus: Formed by S4, S5, and Coccygeal Nerves
GENERALIZATIONS ABOUT SPINAL NERVES • Spinal Nerves Are Not Named; • However, the Nerves That Emerge From Plexuses Often Are Named • Examples: Phrenic Nerve, Sciatic Nerve • There is a Close Relationship Between Where a Spinal Nerve Exits the Spinal Cavity and the Area the Nerve Supplies
CRANIAL NERVES • DEFINITION • Nerves That Attach to the Undersurface of the Brain (Mainly the Brainstem) • 12 Pair
CRANIAL NERVES • IDENTIFICATION • By Names and Numbers • NAMES • MAY INDICATE NERVE’S FUNCTION • MAY INDICATE AREA THE NERVE SUPPLIES • NUMBERS • ROMAN NUMERALS • ORDER IN WHICH NERVE EMERGES FROM ANTERIOR TO POSTERIOR
NERVE TYPES • Some Cranial Nerves Are Mixed, Some Are Sensory, Some Are Motor • Saying to Remember Nerve Types: Some Say Marry Money, But My Brothers Say Bad Business Marry Money • MIXED NERVES: V, VII, IX, X • SENSORY NERVES: I, II, VIII • MOTOR NERVES: III, IV, VI, XI, XII
NAMES, NUMBERS, FUNCTIONSCRANIAL NERVE I • OLFACTORY NERVE • Sensory • Function: Smell
CRANIAL NERVE II • OPTIC NERVE • Sensory • Function: Vision
CRANIAL NERVE III • OCULOMOTOR NERVE • Motor • Functions: • Eye Movements • Regulation of Pupil Size • Accomodation
CRANIAL NERVE IV • TROCHLEAR NERVE • Motor • Function: Eye Movements
CRANIAL NERVE V • TRIGEMINAL NERVE • Mixed • Functions: • Sensory: Sensations of Head and Face • Motor: Chewing
CRANIAL NERVE VI • ABDUCENS NERVE • Motor • Function: Lateral Eye Movements
CRANIAL NERVE VII • FACIAL NERVE • Mixed • Functions: • Sensory: Taste • Motor: • Facial Expressions • Secretion of Saliva and Tears
CRANIAL NERVE VIII • Vestibulocochlear • Sensory Functions: Hearing and Equilibrium
CRANIAL NERVE IX • GLOSSOPHARYNGEAL NERVE • Mixed • Functions: • Sensory: Taste (and General Sensations of Tongue) • Motor: Swallowing, Secretion of Saliva • NOTE: This nerve is also involved in the reflexes of BP andrespiration.
CRANIAL NERVE X • X VAGUS NERVE • Mixed • Functions: • Sensory: Sensations in Organs Supplied • Motor: Movements of Organs Supplied (i.e., Slows Heart, Increases Peristalsis)
CRANIAL NERVE XI • ACCESSORY NERVE Motor • Functions: • Turning Movements of Head • Shoulder Movements • Movements of Organs Supplied • Voice Production
CRANIAL NERVE XII • HYPOGLOSSAL NERVE • Motor • Function: Tongue Movements
On Old Olympus‘ Tiny Tops A Friendly Viking Grew Vines And Hops” Saying Used to Remember the Names of the Cranial Nerves • On • Old • Olympus‘ • Tiny • Tops • A • Friendly • Viking • Grew • Vines • And • Hops”
Only • Old • Octopi • Trade • Tracks • At • Friendly • Vertebrate • Grasslands • In • Vagus • Ad • Hoc