PNS Structure of Nerves Cranial Nerves Spinal Nerves Sensory receptors Motor control.
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Transcript of PNS Structure of Nerves Cranial Nerves Spinal Nerves Sensory receptors Motor control.
PNS
Structure of NervesStructure of Nerves Cranial NervesCranial Nerves Spinal Nerves Spinal Nerves Sensory receptorsSensory receptors Motor controlMotor control
Structure & Classification of Structure & Classification of NervesNerves
Classification:Classification:Sensory, Motor, Mixed, Cranial & Spinal nerves; Ganglia
Cranial NervesCranial Nerves
• 12 pair of nerves
– arise from brain
– exit through foramina leading to muscles, glands and sense organs in head & neck
• Input & output ipsilateral except CN II and IV
I: Olfactory Nerve
II: Optic Nerve
III: Oculomotor Nerve & IV: Trochlear Nerve
V: Trigeminal Nerve
VI: Abducens Nerve
VII: Facial Nerve
VIII: Vestibulocochlear Nerve
IX: Glossopharyngeal Nerve
X: Vagus Nerve
XI: Accessory Nerve
XII: Hypoglossal Nerve
Cranial Nerve Disorders
• Trigeminal neuralgia (tic douloureux)Trigeminal neuralgia (tic douloureux)– recurring episodes of intense stabbing pain in trigeminal nerve
area
– pain triggered by touch, drinking, washing face
– treatment may require cutting nerve
• Bell’s palsyBell’s palsy– disorder of facial nerve causes paralysis of facial muscles on
one side
– may appear abruptly w/ full recovery w/in 3-5 weeks
Spinal Spinal NervesNerves
- 31 pairs of mixed nerves
- connect to cord via dorsal & ventral roots and rootlets
- away from cord branch into dorsal & ventral rami
- nerve plexuses
- nerve damage
Dermatomes:Dermatomes: skin segment skin segment innervated by cutaneous innervated by cutaneous sensory spinal nervesensory spinal nerve
Sensory ReceptorsSensory Receptors
• Stimulus typeStimulus type:– mechanoreceptor, thermoreceptors, nociceptors,
chemoreceptors & photoreceptors
• SourceSource:– exteroceptors, interoceptors & proprioceptors
• Structural complexityStructural complexity:– simple vs. complex
Organization of Organization of Somatosensory Somatosensory SystemSystem
1. Receptor levelReceptor level: sensory receptors
2. Circuit levelCircuit level: ascending fiber tracts
3. Perceptual levelPerceptual level: cerebral cortex
Hierarchy of Motor ControlHierarchy of Motor Control