1 / 82

The Peripheral Nervous System

14. The Peripheral Nervous System. I. The Peripheral Nervous System (PNS). A. Nerves allow the CNS to receive information and initiate action B. The PNS is functionally divided into sensory and motor divisions C. Sensory (afferent) division 1. somatic sensory 2. visceral sensory

kalil
Download Presentation

The Peripheral Nervous System

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. 14 The PeripheralNervous System

  2. I. The Peripheral Nervous System (PNS) A. Nerves allow the CNS to receive information and initiate action B. The PNS is functionally divided into sensory and motor divisions C. Sensory (afferent) division 1. somatic sensory 2. visceral sensory 3. special sensory (e.g. eye, ear) D. Motor (efferent) division 1. somatic motor 2. visceral motor (Autonomic Nervous System) a. sympathetic division b. parasympathetic division

  3. Central nervous system (CNS) Peripheral nervous system (PNS) Sensory (afferent) division Motor (efferent) division Somatic sensory Visceral sensory Somatic nervoussystem Autonomic nervoussystem (ANS) General: Touch, pain,pressure, vibration,temperature, andproprioception in skin,body wall, and limbs General: Stretch, pain,temperature, chemical changes, and irritationin viscera; nausea andhunger Motor innervation of allskeletal muscles Motor innervation of smooth muscle, cardiacmuscle, and glands Special: Hearing,equilibrium, vision Special: Taste, smell Sympatheticdivision Parasympatheticdivision

  4. II. General Terms A. sensation - awareness of external/internal conditions B. perception - conscious registration of conditions C. stimulus - change that can initiate nerve impulse E. transduction - changing stimulus signal into nerve signal F. adaptation - decreased sensitivity with repeat stimuli a. rapidly adapting - pressure, touch, smell b. slowly adapting - pain, position, blood chemicals G. afterimage - sensation even after stimulus is gone H. modality - distinct property of each sensation

  5. I. receptor (sense organ) - converts stimulus to impulse J. nerve – bundle of axons carrying sensory or motor information a. can be motor only b. can be sensory only c. can be both sensory and motor (most) K. ganglion – collection of nerve cell bodies located outside the CNS a. mostly the autonomic nervous system

  6. III. General Classification of Receptors A. Two main categories of sensory receptors 1. Free nerve endings of sensory neurons a. monitor general sensory information 2. Complete receptor cells a. specialized epithelial cells or small neurons b. monitor most types of special sensoryinformation c. special senses = vision, hearing, smell, taste, balance

  7.  B. Receptors Named by Location   1. exteroreceptors – (“outside”) respond to external environment a. located at or near body surfaces b. include receptors for touch, pressure, pain, and temperature 2. enteroreceptors – (“inside”) respond to internal environment a. located in digestive tube, bladder, and lungs b. monitor a variety of stimuli i. chemical concentration, taste, tissue stretching, temperature 3. proprioreceptors - respond to body position/motion a. located in skeletal muscles, tendons, joints, and ligaments b. monitor degree of stretch c. send inputs on body movement to the CNS

  8. C. Receptors Named by Type of Stimulus Detected   1. mechanoreceptors - any mechanical deviation   a. touch, pressure, vibration, proprioception etc. b. baroreceptors – monitor blood pressure 2. thermoreceptors - changes in temperature 3. nocireceptors - pain; physical or chemical damage 4. photoreceptors - light; rods & cones of the eye   5. chemoreceptors - shapes of different molecules   a. taste, smell, chemicals of blood

  9. IV. General Sensory Receptors A. General sensory receptors (not special – vision, hearing, etc.) 1. widely distributed 2. nerve endings of sensory neurons monitor: a. touch, pressure, stretch, pain, temperature, proprioception B. Divided into two different groups 1. free nerve endings 2. encapsulated nerve endings

  10. C. Free nerve endings 1. abundant in epithelia and underlying connective tissue 2. respond to pain and temperature 3. monitor affective senses (emotional response – e.g. pain!) 4. epithelial tactile complexes (Merkel discs) a. tactile epithelial cell innervated by sensory nerve ending b. slowly adapting receptors for light touch 5. hair follicle receptors—wrap around hair follicles a. rapidly adapting receptors

  11. D. Encapsulated nerve endings 1. consist of one or more end fibers of sensory neurons 2. enclosed in connective tissue 3. mechanoreceptors a. tactile (Meissner’s) corpuscles b. lamellar (Pacinian) corpuscles c. bulbous corpuscles (Ruffini endings) d. proprioceptors

  12. 4. Tactile (Meissner’s) corpuscles a. spiraling nerve ending surrounded by Schwann cells b. occur in the dermal papillae c. rapidly adapting receptors for discriminative touch d. occur in sensitive, hairless areas of the skin 5. Lamellar corpuscles a. nerve ending surrounded by layers of flat Schwann cells b. occur in the hypodermis c. sensitive to deep pressure—rapidly adapting receptors

  13. 6. Bulbous corpuscles a. located in the dermis and respond to pressure b. monitor continuous pressure on the skin - adapt slowly

  14. 7. Proprioceptors a. monitor stretch in locomotory organs Three different types: i. muscle spindles ► measure the changing length of a muscle ► embedded in the perimysium between muscle fascicles ii. intrafusal muscle fibers ► modified skeletal muscle fibers located within muscle spindles iii. anulospiral endings ► located around middle of intrafusal fibers ► stimulated by rate and degree of stretch

  15. c. tendon organs ► are located near the muscle-tendon junction ► monitor tension within tendons d. joint kinesthetic receptors ► sensory nerve endings within the joint capsules i. lamellar corpuscles ii. bulbous corpuscles iii. free nerve endings iv. receptors resembling tendon organs

  16. Extrafusalmuscle fibers (contact) Anulo-spiralendings (primarysensory endings) Musclespindle Intrafusalmuscle fibers Capsule Sensoryfiber Tendon organ (tension) Tendon

  17. V. Cranial Nerves – An Overview A. Attach to the brain and pass through specific foramina of the skull B. Numbered from I to XII (roman numerals) 1. Cranial nerves I and II attach to the forebrain 2. All others attach to the brain stem C. Primarily serve head and neck structures D. vagus nerve (X) is the only cranial nerve that extends into the abdomen

  18. Filaments ofolfactory nerve (I) Optic nerve (II) Oculomotornerve (III) Facial nerve (VII) Trochlearnerve (IV) Vestibulocochlearnerve (VIII) Trigeminalnerve (V) Abducensnerve (VI) Glossopharyngealnerve (IX) Vagus nerve (X) Accessory nerve (XI) Hypoglossal nerve (XII)

  19. Olfactory nerve (I) Optic nerve (II) Oculomotornerve (III) Facial nerve (VII) Trochlearnerve (IV) Vestibulocochlearnerve (VIII) Trigeminalnerve (V) Abducensnerve (VI) Glossopharyngealnerve (IX) Vagus nerve (X) Accessory nerve (XI) Hypoglossal nerve (XII)

  20. The Cranial Nerves Cranial nerves Sensory function Motor function Cranial nerves Sensory function Motor function Somaticsensory(SS) Visceralsensory(VS) Somaticmotor(SM) Visceral motor:parasympathetic(VM) Somaticsensory(SS) Visceralsensory(VS) Somaticmotor(SM) Visceral motor:parasympathetic(VM) Smell VII Facial General General;taste SM VM I Olfactory Vision VIII Vestibulocochlear Hearing;equilibrium II Optic Some SM VM IX Glossopharyngeal General SM VM III Oculomotor General;taste X Vagus General General;taste SM VM IV Trochlear SM General SM V Trigeminal XI Accessory SM SM XII Hypoglossal SM VI Abducens

  21. Create your own memory device: O__________________ F_________________ O__________________ V_________________ O__________________ G_________________ T___________________ V_________________ T___________________ A_________________ A___________________ H_________________

  22. Mike’s memory device (not for a mixed audience) Oh! Feel Oh! Very Oh! Good To V_________________ Touch A_________________ And H_________________

  23. The Cranial Nerves

  24. Olfactory Nerves (I) A. Special visceral sensory - sense of smell B. Olfactory receptor cells located in olfactory epithelium of nasal cavity C. Olfactory bulbs project fibers into the nasal cavity C. Pass through the cribriform foramina of the ethmoid bone

  25. Olfactory Nerves (I)

  26. The Optic Nerves (II) A. Special somatic sensory - vision B. Originate on the retina of the eye C. Pass through the optic canals of the sphenoid bone D. Criss-cross at the optic chiasma

  27. Optic Nerves (II)

  28. The Oculomotor Nerves (III) A. Somatic motor - innervate four extrinsic eye muscles 1. Superior rectus 2. medial rectus 3. inferior rectus 4. inferior oblique B. Visceral motor ► Constricts pupil ► Controls shape of lens C. Pass through the superior orbital fissure

  29. Oculomotor Nerves (III)

  30. The Trochlear Nerves (IV) A. Somatic motor - the superior oblique muscle B. Pass ventrally and laterally around midbrain C. Pass through superior orbital fissure

  31. Trochlear Nerves (IV)

  32. The Trigeminal Nerves (V) A. Largest of the cranial nerves 1. Ophthalmic division (V1) superior oribital fissure 2. Maxillary division (V2) foramen rotundum 3. Mandibular division (V3) foramen ovale B. Cell bodies of sensory neurons located in the trigeminal ganglion C. Mandibular division = motor fibers that innervate chewing muscles

  33. Trigeminal Nerves (V)

  34. The Abducens Nerves (VI) A. Somatic motor - innervates lateral rectus muscle B. Pass through the superior orbital fissure NOTE: III (oculomotor); IV (trochlear) and VI (abducens) = innervation of the muscles of the eye

  35. Abducens Nerves (VI)

  36. The Facial Nerves (VII) A. Special visceral sensory - taste buds on anterior two-thirds of tongue B. Somatic motor - innervate facial muscles C. Visceral motor - innervation of lacrimal glands, submandibular and sublingual salivary glands D. Enter temporal bone through the internal acoustic meatus

  37. Facial Nerves (VII)

  38. The Vestibulocochlear Nerves (VIII) A. Sensory nerve of hearing and equilibrium B. From inner ear - pass through the internal acoustic meatus C. Carries information from vestibular apparatus and cochlea

  39. Vestibulocochlear Nerves (VIII)

  40. The Glossopharyngeal Nerves (IX) A. General visceral sensory 1. posterior one-third of tongue 2. pharyngeal mucosa 3. chemoreceptors in carotid body 4. baroreceptors of carotid sinus B. Somatic motor - elevate pharynx during swallowing C. Visceral motor - innervate the parotid salivary gland D. Fibers pass through the jugular foramen

  41. Glossopharyngeal Nerves (IX)

  42. The Vagus Nerves (X) A. General visceral sensory - from thoracic and abdominal viscera B. Special visceral sensory - taste buds on epiglottis C. Somatic motor - skeletal muscles of the pharynx and larynx D. Visceral motor - parasympathetic innervation to 1. Heart, lungs, abdominal organs E. Fibers exit through the jugular foramen

  43. Vagus Nerves (X)

  44. The Accessory Nerves (XI) A. Somatic motor - innervates trapezius and sternocleidomastoid B. Pass into skull through foramen magnum C. Exit skull through the jugular foramen

  45. Accessory Nerves (XI)

  46. The Hypoglossal Nerves (XII) A. Somatic motor - innervate the tongue muscles B. Exit the skull through hypoglossal canal

More Related