More Related Content
Similar to Chapter 11 and 13a nervous tissue and cranial nerves
Similar to Chapter 11 and 13a nervous tissue and cranial nerves (20)
Chapter 11 and 13a nervous tissue and cranial nerves
- 1. PowerPoint® Lecture Slides prepared by Vince Austin, University of Kentucky
Human Anatomy & Physiology, Sixth Edition
Elaine N. Marieb
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
11
13a
Nervous System (11) and
Cranial Nerves (13a)
- 2. Nervous System
The master controlling and communicating system of the body
Functions
Sensory input – monitoring stimuli occurring inside and outside the
body
Integration – interpretation of sensory input
Motor output – response to stimuli by activating effector organs
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
- 4. Organization of the Nervous System
Central nervous system (CNS)
Brain and spinal cord
Integration and command center
Peripheral nervous system (PNS)
Paired spinal and cranial nerves
Carries messages to and from the spinal cord and brain
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
- 5. Peripheral Nervous System (PNS): Two
Functional Divisions
Sensory (afferent) division
Somatic afferent fibers – carry impulses from skin,
skeletal muscles, and joints to the brain
Visceral afferent fibers – transmit impulses from visceral
organs to the brain
Motor (efferent) division
Transmits impulses from the CNS to effector organs
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
- 6. Motor Division: Two Main Parts
Somatic motor nervous system
Conscious control of skeletal muscles
Autonomic motor nervous system (ANS)
Regulates smooth muscle, cardiac muscle, and glands
Divisions – sympathetic and parasympathetic
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
- 9. Histology of Nerve Tissue
The two principal cell types of the nervous system are:
Neurons – excitable cells that transmit electrical signals
Supporting cells – cells that surround and wrap neurons
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
- 10. Supporting Cells: Neuroglia
The supporting cells (neuroglia or glial cells):
Provide a supportive scaffolding for neurons
Segregate and insulate neurons
Promote health and growth
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
- 11. Astrocytes
Most abundant, versatile, and highly branched glial
cells
They cling to neurons and their synaptic endings, and
cover capillaries
Functionally they:
Support and brace neurons
Anchor neurons to their nutrient supplies
Guide migration of young neurons
Control the chemical environment
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
- 13. Microglia and Ependymal Cells
Microglia – small, ovoid cells with spiny processes
Phagocytes that monitor the health of neurons
Ependymal cells – range in shape from squamous to columnar
They line the central cavities of the brain and spinal column
Help to circulate cerebrospinal fluid with cilia
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
- 14. Microglia and Ependymal Cells
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 11.3b, c
- 15. Oligodendrocytes, Schwann Cells, and Satellite
Cells
oligodendrocytes – branched cells that wrap around nerve
fibers (axons) of neurons in the CNS to form a myelin sheath
Schwann cells – wrap around nerve fibers (axons) of
neurons in the PNS to form a myelin sheath
satellite cells - surround neuron cell bodies in the PNS
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
- 17. Neurons (Nerve Cells)
Structural units of the nervous system
Composed of a body, axon, and dendrites
Long-lived, amitotic, and have a high metabolic rate
Their plasma membrane functions in:
Electrical signaling
Cell-to-cell signaling during development
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
- 18. Neurons (Nerve Cells)
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 11.4b
- 19. Nerve Cell Body (Perikaryon or Soma)
Contains the nucleus and a nucleolus
Is the major biosynthetic center
Is the focal point for the outgrowth of neuronal processes
Has well-developed Nissl bodies (rough ER)
Contains an axon hillock – cone-shaped area from which
axons arise
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
- 20. Processes
Armlike extensions from the soma
Called tracts in the CNS and nerves in the PNS
There are two types: axons and dendrites
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
- 21. Dendrites of Motor Neurons
Short, tapering, and diffusely branched processes
They are the receptive, or input, regions of the neuron
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
- 22. Axons: Structure
Slender processes of uniform diameter arising from the
hillock
Long axons are called nerve fibers
Usually there is only one unbranched axon per neuron
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
- 23. Axons: Function
Generate and transmit action potentials
Secrete neurotransmitters from the axonal terminals
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
- 24. Myelin Sheath
Whitish, fatty (protein-lipoid), segmented sheath around most
long axons
It functions to:
Protect the axon
Electrically insulate fibers from one another
Increase the speed of nerve impulse transmission
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
- 25. Myelin Sheath and Neurilemma: Formation
Formed by Schwann cells in the PNS and oligodendrocytes in
the CNS
A Schwann cell:
Envelopes an axon in a trough
Encloses the axon with its plasma membrane
Has concentric layers of membrane that make up the myelin
sheath
Neurilemma – remaining nucleus and cytoplasm of a Schwann
cell
Nodes of Ranvier: Gaps in the myelin sheath between adjacent
Schwann cells
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
- 26. Myelin Sheath and Neurilemma: Formation
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 11.5a-c
- 27. Axons of the CNS
Both myelinated and unmyelinated fibers are present
Myelin sheaths are formed by oligodendrocytes
Nodes of Ranvier are widely spaced
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
- 28. Regions of the Brain and Spinal Cord
White matter – dense collections of myelinated fibers
Gray matter – mostly nerve cell bodies (soma) and
unmyelinated fibers
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
- 29. Neuron Classification
Structural:
Multipolar — three or more processes
Bipolar — two processes (axon and dendrite)
Unipolar — single, short process
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
- 30. Comparison of Structural Classes of Neurons
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Table 11.1.1
- 31. Comparison of Structural Classes of Neurons
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Table 11.1.2
- 32. Comparison of Structural Classes of Neurons
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Table 11.1.3
- 33. Neuron Classification
Functional:
Sensory (afferent) — transmit impulses toward the CNS
Motor (efferent) — carry impulses away from the CNS
Interneurons (association neurons) — shuttle signals
through CNS pathways
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
- 34. Structure of a Nerve
Nerve – cordlike organ of the PNS consisting of peripheral
axons enclosed by connective tissue
Connective tissue coverings include:
Endoneurium – loose connective tissue that surrounds
axons
Perineurium – coarse connective tissue that bundles
fibers into fascicles
Epineurium – tough fibrous sheath around a nerve
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
- 35. Structure of a Nerve
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 13.3b
- 36. Classification of Nerves
Sensory and motor divisions
Sensory (afferent) only – carry impulse to the CNS
Motor (efferent) only – carry impulses from CNS
Mixed – sensory and motor fibers carry impulses to and
from CNS; most common type of nerve
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
- 37. Peripheral Nerves
Mixed nerves – carry somatic and autonomic (visceral)
impulses
The four types of mixed nerves are:
Somatic afferent and somatic efferent
Visceral afferent and visceral efferent
Peripheral nerves originate from the brain or spinal column
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
- 38. The 12 Cranial Nerves
Twelve pairs of cranial nerves arise from the brain
They may have sensory, motor, or both sensory and motor
functions
Each nerve is identified by a number (I through XII) and a
name
Four cranial nerves carry parasympathetic fibers that serve
muscles and glands
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
- 40. Summary of Function of Cranial Nerves
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 13.5b
- 41. Make up your own memory device!
I. O______________ VII. F_______________
II. O______________ VIII. V______________
III. O_____________ IX. G_______________
IV. T_____________ X. V________________
V. T______________ XI. A________________
VI. A_____________ XII. H_______________
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
- 42. Cranial Nerve I: Olfactory
Functions solely by carrying afferent impulses for
the sense of smell
Arises from the olfactory epithelium
Passes through the cribriform plate of the ethmoid bone
Fibers run through the olfactory bulb and terminate in the
primary olfactory cortex
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
- 43. Cranial Nerve I: Olfactory
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure I from Table 13.2
- 44. Cranial Nerve II: Optic
Functions solely by carrying afferent impulses for vision
Arises from the retina of the eye
Optic nerves pass through the optic canals and converge at
the optic chiasm
They continue to the thalamus where they synapse
From there, the optic radiation fibers run to the visual cortex
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
- 45. Cranial Nerve II: Optic
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure II Table 13.2
- 46. Cranial Nerve III: Oculomotor
Functions in raising the eyelid, directing the eyeball,
constricting the iris, and controlling lens shape
Fibers extend from the ventral midbrain, pass through the
superior orbital fissure, and go to the extrinsic eye muscles
Parasympathetic cell bodies are in the ciliary ganglia
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
- 47. Cranial Nerve III: Oculomotor
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure III from Table 13.2
- 48. Cranial Nerve IV: Trochlear
Functions primarily as a motor nerve that directs the eyeball
Fibers emerge from the dorsal midbrain and enter the orbits
via the superior orbital fissures; innervate the superior
oblique muscle
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
- 49. Cranial Nerve IV: Trochlear
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure IV from Table 13.2
- 50. Cranial Nerve V: Trigeminal
Conveys sensory impulses from various areas of the face
(V1) and (V2), and supplies motor fibers (V3) for mastication
Composed of three divisions: ophthalmic (V1), maxillary
(V2), and mandibular (V3)
Fibers run from the face to the pons via the superior orbital
fissure (V1), the foramen rotundum (V2), and the foramen
ovale (V3)
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
- 51. Cranial Nerve V: Trigeminal
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure V from Table 13.2
- 52. Cranial Nerve VI: Abducens
Functions primarily as a motor nerve innervating the lateral
rectus muscle
Fibers leave the inferior pons and enter the orbit via the
superior orbital fissure
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure VI from Table 13.2
- 53. Cranial Nerve VII: Facial
Motor functions include facial expression, and the
transmittal of autonomic impulses to lacrimal and
salivary glands; Sensory function is taste from the
anterior two-thirds of the tongue
Fibers leave the pons, travel through the internal
acoustic meatus, and emerge through the
stylomastoid foramen to the lateral aspect of the face
Mixed nerve with five major branches
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
- 54. Cranial Nerve VII: Facial
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure VII from Table 13.2
- 55. Cranial Nerve VIII: Vestibulocochlear
Functions are solely sensory – equilibrium and hearing
Fibers arise from the hearing and equilibrium apparatus of
the inner ear, pass through the internal acoustic meatus, and
enter the brainstem at the pons-medulla border
Two divisions – cochlear (hearing) and vestibular (balance)
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
- 56. Cranial Nerve VIII: Vestibulocochlear
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure VIII from Table 13.2
- 57. Cranial Nerve IX: Glossopharyngeal
Motor – innervates part of the tongue and pharynx, and
provides motor fibers to the parotid salivary gland; Sensory
– fibers conduct taste and general sensory impulses from the
tongue and pharynx
Fibers emerge from the medulla, leave the skull via the
jugular foramen, and run to the throat
Nerve IX is a mixed nerve with motor and sensory functions
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
- 58. Cranial Nerve IX: Glossopharyngeal
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure IX from Table 13.2
- 59. Cranial Nerve X: Vagus
Motor - Most motor fibers are parasympathetic fibers to the
heart, lungs, and visceral organs; Sensory function is in taste
The only cranial nerve that extends beyond the head and
neck
Fibers emerge from the medulla via the jugular foramen
The vagus is a mixed nerve
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
- 60. Cranial Nerve X: Vagus
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure X from Table 13.2
- 61. Cranial Nerve XI: Accessory
Primarily a motor nerve:
Supplies fibers to the larynx, pharynx, and soft palate
Innervates the trapezius and sternocleidomastoid, which
move the head and neck
Formed from a cranial root emerging from the medulla and a
spinal root arising from the superior region of the spinal cord
The spinal root passes upward into the cranium via the
foramen magnum
The accessory nerve leaves the cranium via the jugular
foramen
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
- 62. Cranial Nerve XI: Accessory
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure XI from Table 13.2
- 63. Cranial Nerve XII: Hypoglossal
Innervates both extrinsic and intrinsic muscles of the tongue,
which contribute to swallowing and speech
Fibers arise from the medulla and exit the skull via the
hypoglossal canal
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
- 64. Cranial Nerve XII: Hypoglossal
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure XII from Table 13.2