Transcript Ch. 14 The Peripheral Nervous System

Ch. 14
The Peripheral Nervous System
Objectives
• Know the divisions of the PNS
• Know the various types of general sense
receptors
• Be able to describe the cranial nerves
• Be able to define a nerve plexus
• Be able to describe the nerve plexus
Divisions of Nervous System
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Structures of PNS
• Sensory receptors
– Detect sensor information from the environment
• Nerves and ganglia
– Bundles of axons
• Mixed nerves
• Motor endings
– Innervate the effector
Sensory Receptors
• Modality (stimulus detected)
– Thermoreceptors, photoreceptors, nociceptors
• Origin (location)
– Exteroceptors
– Interoceptors
– Proprioceptors
• Structure
– General
• Free nerve endings
• Encapsulated nerve endings
– Special
General Sense Receptors
Unencapsulated Receptors
• Free nerve endings
– Pain, warmth, cold
Encapsulated Receptors
• Tactile (Meissners) corpuscles
– Phasic, light touch, texture
• Krause end bulbs
• Tactile discs
– Tonic, light touch, texture
– Merkel cells
• Hair receptors
– Monitor movement
– tactile, mucus membranes
• Lamellated (Pacinian) corpuscles
– Phasic, deep pressure, stretch,
tickle, vibration
• Bulbous (Ruffini) corpuscles
– Tonic, heavy touch, pressure, joint
movment, skin stretching
General Sense Receptors
Cranial Nerves
Cranial Nerves
• Olfactory, Optic, Oculomotor, Trochlear,
Trigeminal, Abducens, Facial, Vestibulocochlear,
Glossopharyngeal, Vagus, Accessory, Hypoglossal
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• Functions (sensory, motor, both)
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Cranial Nerves
• Olfactory nerve
– Sensory (smell)
– Passes through cribriform plate
• Optic nerve
– Sensory (vision)
– Passes through optic canal
• Oculomotor nerve
– Motor (extrinsic eye muscles, iris and ciliary bodies)
– Passes through superior orbital fissure
• Trochlear nerve
– Motor (extrinsic eye muscle)
– Passes through superior orbital fissure
Cranial Nerves
• Trigeminal nerve
– Sensory/motor
– Three divisions
• Ophthalmic (general senses)
– Superior orbital fissure
• Maxillary (general senses)
– Foramen rotundum
• Mandibular (S/M)
– Foramen ovale
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Cranial Nerves
• Abducens nerve
– Motor (extrinsic eye muscle)
– Passes through superior orbital fissure
• Facial nerve
– Sensory/Motor
– Five branches on face (facial muscles)
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Temporal
Zygomatic
Buccal
Mandibular
Cervical
– Various glands (motor)
– Taste sensation
– Internal acoustic meatus and stylomastoid foramen
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Cranial Nerves
• Vestibulocochlear nerve
– Sensory (hearing and equilibrium)
– Passes through internal acoustic meatus
• Glossopharyngeal nerve
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–
Sensory/Motor
Passes through jugular foramen
Innervates pharyngeal muscles and parotid gland
Taste
• Vagus
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–
–
–
–
Sensory/Motor
Passes through jugular foramen
Autonomic motor control of viscera
Voluntary control of pharynx and larynx
General sensory info from viscera
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Cranial Nerves
• Accessory nerve
– Motor (sternocleidomastoid and trapezius)
– Rootlets enter via foramen magnum, exits through
jugular foramen
• Hypoglossal nerve
– Motor (tongue)
– Passes though the hypoglossal canal
Spinal Nerves
• Root
– Sensory
– motor
• Spinal Nerve
– mixed
• Ramus
– mixed
Nerve Plexus
• Network of spinal nerves
(ventral rami) that join and
branch off (exception T2-T12)
• Four plexuses
– Cervical, brachial, lumbar, sacral
• Primarily serve to innervate limbs
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Cervical Plexus
• Innervation of the neck (C1-C4)
• Cutaneous innervation, some motor
• Phrenic nerves
– Somatic motor and sensory innervation of
diaphragm
– Necessary for respiration
Brachial Plexus
• Innervation of upper limb
• Rami from C5-T1
– Converge to form 3 trunks
• Upper, middle, lower
– Trunks split into divisions
• Anterior and posterior
– Divisions converge to form 3
cords
• Lateral, posterior, medial
– Cords split into 5 nerves
• Musculocutaneous, Median,
Ulnar, Radial, Axillary
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Lumbar Plexus
• Rami of L1-L4
• Innervation of lower limb
– Anterior and medial thigh
• Femoral nerve
Sacral Plexus
• Rami from L4-S4
• Innervation of lower limb,
buttocks, pelvis, and
perineum
• Sciatic nerve
– Tibial and common fibular
nerves
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