Transcript PowerPoint to accompany Hole’s Human Anatomy and

11.1: Introduction
• The central nervous system (CNS) consists of the brain
and spinal cord.
• The brainstem connects the brain to the spinal cord.
• Communication to the peripheral nervous system (PNS)
is by way of the spinal cord.
1
11.2: Meninges
• The meninges
• Membranes of CNS
• Protect the CNS
• Three (3) layers:
• Dura mater
• “Tough mother”
• Venous sinuses
• Arachnoid mater
• “Spider mother”
• Space contains
cerebrospinal fluid
(CSF)
• Pia mater
• “Little mother”
• Encapsulates blood
vessels
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Skin
Scalp
Subcutaneous tissue
Cranium
Bone of skull
Cerebrum
Dural sinus (superior
sagittal sinus)
Tentorium
cerebelli
Arachnoid
granulation
Dura mater
Cerebellum
Arachnoid
mater
Pia mater
Vertebra
Subarachnoid space
Spinal cord
Falx cerebri
Meninges
(a)
Meninges
Gray matter
White matter
(b)
2
Cerebrum
Meninges of the Spinal Cord
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Spinal cord
Ventral root
Dorsal root
Spinal nerve
Dorsal root
ganglion
Subarachnoid
space
Pia mater
Arachnoid mater
Epidural space
Dura mater
Dorsal root
Dorsal branch
(dorsal ramus)
Spinal
nerve
Ventral branch
(ventral ramus)
Dorsal root
ganglion
Spinal cord
Ventral root
Epidural
space
Thoracic
vertebra
(a)
(b)
Body of
vertebra
3
11.3: Ventricles
and Cerebrospinal Fluid
• There are four (4) ventricles
• The ventricles are interconnected
cavities within cerebral hemispheres and
brain stem
• The ventricles are continuous with the
central canal of the spinal cord
• They are filled with cerebrospinal fluid
(CSF)
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Lateral ventricle
Interventricular
foramen
Third ventricle
Cerebral
aqueduct
Fourth ventricle
To central canal
of spinal cord
• The four (4) ventricles are:
• Lateral ventricles (2)
• Known as the first and
second ventricles
• Third ventricle
• Fourth ventricle
• Interventricular foramen
• Cerebral aqueduct
(a)
Interventricular
foramen
Lateral
ventricle
Third ventricle
Cerebral
aqueduct
Fourth
ventricle
4
(b)
To central canal
of spinal cord
Cerebrospinal Fluid
• Secreted by the choroid plexus
• Circulates in ventricles, central
canal of spinal cord, and the
subarachnoid space
• Completely surrounds the brain
and spinal cord
•Clear fluid similar to blood plasma
• Volume is only about 120 ml.
• Nutritive and protective
• Helps maintain stable ion
concentrations in the CNS
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Arachnoid
granulations
Blood-filled
dural sinus
Choroid plexuses
of third ventricle
Pia mater
Third ventricle
Cerebral aqueduct
Fourth ventricle
Subarachnoid space
Arachnoid mater
Dura mater
Choroid plexus of
fourth ventricle
Central canal of spinal cord
Pia mater
Subarachnoid space
Filum terminale
Arachnoid mater
Dura mater
5
11.4: Spinal Cord
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
• Slender column of nervous
tissue continuous with brain and
brainstem
• Extends downward through
vertebral canal
• Begins at foramen magnum and
ends at L1/L2 interspace
• Conduit for nerve impulses to
and from brain and brainstem
• Center for spinal reflexes
Brainstem
Foramen
magnum
Cervical
enlargement
Cervical
enlargement
Spinal cord
Vertebral
canal
Lumbar
enlargement
Lumbar
enlargement
Conus
medullaris
Cauda
equina
Conus
medullaris
Filum
terminale
6
(a)
(b)
Structure of the Spinal Cord
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Posterior horn
Posterior funiculus
Posterior median
sulcus
White matter
Gray matter
Gray commissure
Lateral funiculus
Dorsal root
of spinal nerve
Central canal
Anterior
funiculus
Dorsal root
ganglion
Ventral root
Anterior
of spinal nerve horn
(a)
Anterior
median
fissure
Portion of
spinal nerve
7
Reflex Arcs
• Reflexes are automatic, subconscious responses to stimuli
within or outside the body
• Simple reflex arc (sensory – motor)
• Most common reflex arc (sensory – association – motor)
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Sensory or
afferent neuron
Receptor
Central
Nervous
System
Motor or
efferent neuron
Effector
(muscle or gland)
12
8
(a)
Reflex Arcs
9
General Components of a
Spinal Reflex
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Spinal cord
Interneuron
Dorsal
1
Receptor
3
2
Sensory neuron
Cell body
of sensory
neuron
White matter
Gray matter
4
Ventral
Motor neuron
Central
canal
5
Effector
(muscle
or gland)
(b)
10
Reflex Behavior
• Example is the knee-jerk reflex
• Simple monosynaptic reflex
• Helps maintain an upright posture
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Axon of sensory
neuron
Cell body of
sensory neuron
Spinal cord
Cell body of
motor neuron
Axon of motor
neuron
Direction of impulse
Effector (quadriceps femoris
muscle group)
Receptor associated with
dendrites of sensory neuron
Patella
Patellar ligament
11
Reflex Behavior
• Example is a withdrawal reflex
• Prevents or limits tissue damage
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Cell body of sensory neuron
Axon of sensory neuron
Direction
of impulse
Dendrite of
sensory
neuron
Pain
receptor
in skin
Tack
Effector (flexor
muscle contracts
and withdraws part
being stimulated)
Interneuron
Axon of
motor neuron
Spinal cord
Cell body of
motor neuron
12
11.5: Brain
• Functions of the brain:
• Major parts of the brain:
• Interprets sensations
• Cerebrum
• Determines perception
• Frontal lobes
• Stores memory
• Parietal lobes
• Reasoning
• Occipital lobes
• Makes decisions
• Temporal lobes
• Coordinates muscular movements
• Insula
• Regulates visceral activities
• Diencephalon
• Determines personality
• Cerebellum
• Brainstem
• Midbrain
• Pons
13
• Medulla oblongata
The Brain
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Gyrus
Skull
Sulcus
Meninges
Cerebrum
Corpus
callosum
Diencephalon
Fornix
Midbrain
Brainstem
Pons
Cerebellum
Medulla
oblongata
Spinal cord
(a)
Fornix
Cerebrum
Midbrain
Pons
Corpus
callosum
Transverse fissure
Diencephalon
Cerebellum
Medulla oblongata
Spinal cord
14
(b)
b: © Martin M. Rotker/Photo Researchers, Inc.
Structure of the Cerebrum
• Corpus callosum
• Connects cerebral
hemispheres (a commissure)
• Gyri
• Bumps or convolutions
• Sulci
• Grooves in gray matter
• Central sulcus of
Rolando
• Fissures
• Longitudinal: separates the
cerebral hemispheres
• Transverse: separates
cerebrum from cerebellum
• Lateral fissure of Sylvius
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Central sulcus
Parietal lobe
Gyrus
Sulcus
Frontal lobe
Lateral sulcus
Occipital lobe
Transverse
fissure
Cerebellar
hemisphere
Temporal lobe
(a)
Central sulcus
Parietal lobe
Central sulcus
Longitudinal
fissure
Parietal lobe
Occipital lobe
(b)
Occipital lobe
Frontal lobe
Insula
Retracted
temporal lobe
(c)
15
Lobes of the Cerebrum
• Five (5) lobes bilaterally:
• Frontal lobe
• Parietal lobe
• Temporal lobe
• Occipital lobe
• Insula aka ‘Island of
Reil’ (functions in
interoceptive awareness
& judging intensity of
pain, among other
things)
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Central sulcus
Parietal lobe
Occipital lobe
Frontal lobe
Insula
Retracted
temporal lobe
(c)
16
Functions of the Cerebrum
• Interpreting impulses
• Initiating voluntary movements
• Storing information as memory
• Retrieving stored information
• Reasoning
• Seat of intelligence and personality
17
Functional Regions of the
Cerebral Cortex
• Cerebral cortex
• Thin layer of gray matter that constitutes the outermost
portion of cerebrum
• Contains 75% of all neurons in the nervous system
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Central sulcus
Motor areas involved with the control
of voluntary muscles
Sensory areas involved with
cutaneous and other senses
Concentration, planning,
problem solving
Frontal eye field
Parietal lobe
Auditory area
Sensory speech area
( Wernicke’s area)
Front lobe
Occipital lobe
Motor speech area
(Broca’s area)
Combining
visual images,
visual recognition
of objects
Lateral sulcus
Visual area
Interpretation of auditory patterns
Cerebellum
18
Temporal lobe
Brainstem
Functions of the Cerebral Lobes
19
Sensory Areas
(post-central sulcus)
• Cutaneous sensory area
• Sensory area for taste
• Near base of the central sulcus
• Sensory area for smell
• Parietal lobe
• Interprets sensations on
skin
• Visual area
• Occipital lobe
• Interprets vision
• Arises from centers deep within
the cerebrum
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Central sulcus
Motor areas involved with the control
of voluntary muscles
Sensory areas involved with
cutaneous and other senses
Concentration, planning,
problem solving
Frontal eye field
Parietal lobe
Auditory area
• Auditory area
• Temporal lobe
• Interprets hearing
Sensory speech area
( Wernicke’s area)
Front lobe
Occipital lobe
Motor speech area
(Broca’s area)
Combining
visual images,
visual recognition
of objects
Lateral sulcus
Visual area
Interpretation of auditory patterns
Cerebellum
Temporal lobe
Brainstem
20
Motor & Sensory Areas
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Arm
Forearm
Trunk
Trunk
Pelvis
Neck
Forearm Arm
Thigh
Pelvis
Thigh
Thumb,
fingers,
and hand
Leg
Foot and
toes
Facial
expression
Hand, fingers,
and thumb
Upper
face
Leg
Foot and
toes
Genitals
Lips
Salivation
Vocalization
Mastication
Teeth and
gums
Swallowing
Tongue and
pharynx
Longitudinal
fissure
(a) Motor area
Longitudinal
fissure
(b) Sensory area
Frontal lobe
Motor area
Sensory area
Central sulcus
Parietal lobe
21
Association Areas
• Regions that are not primary motor or primary sensory areas
• Widespread throughout the cerebral cortex
• Analyze and interpret sensory experiences
• Provide memory, reasoning, verbalization, judgment, emotions
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Central sulcus
Motor areas involved with the control
of voluntary muscles
Sensory areas involved with
cutaneous and other senses
Concentration, planning,
problem solving
Frontal eye field
Parietal lobe
Auditory area
Sensory speech area
( Wernicke’s area)
Front lobe
Occipital lobe
Motor speech area
(Broca’s area)
Combining
visual images,
visual recognition
of objects
Lateral sulcus
Visual area
Interpretation of auditory patterns
Cerebellum
Temporal lobe
Brainstem
22
Association Areas
• Frontal lobe association areas
• Concentrating
• Planning
• Complex problem solving
• Parietal lobe association areas
• Understanding speech
• Choosing words to express
thought
• Temporal lobe association areas
• Interpret complex sensory
experiences
• Store memories of visual scenes,
music, and complex patterns
• Occipital lobe association areas
• Analyze and combine visual
images with other sensory
experiences
23
Hemisphere Dominance
• The left hemisphere is dominant in most individuals
• Dominant hemisphere controls:
• Speech
• Writing
• Reading
• Verbal skills
• Analytical skills
• Computational skills
• Nondominant hemisphere controls:
• Nonverbal tasks
• Motor tasks
• Understanding and interpreting
musical and visual patterns
• Provides emotional and intuitive
thought processes
24
Memory
• Short term memory
• Long term memory
• Working memory
• Changes structure or
• Closed neuronal circuit
function of neurons
• Circuit is stimulated over and
• Enhances synaptic
over
transmission
• When impulse flow ceases,
memory does also unless it
enters long-term memory via
memory consolidation
• Limited to 7 bits of
information
25
Basal Nuclei
• Masses of gray matter
• Deep within cerebral
hemispheres
• Produce dopamine
• Control certain muscular
activities
• Primarily by
inhibiting motor
functions
Basal
nuclei
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Longitudinal
fissure
Right cerebral
hemisphere
Caudate
nucleus
Putamen
Globus
pallidus
Thalamus
Cerebellum
Hypothalamus
Brainstem
Spinal cord
26
Diencephalon
• Between cerebral hemispheres and above the brainstem
• Surrounds the third ventricle
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
• Thalamus
• Epithalamus
• Hypothalamus
• Optic tracts
• Optic chiasm
• Infundibulum
• Posterior pituitary
• Mammillary bodies
• Pineal gland
Superior
colliculus
Corpora quadrigemina
Optic nerve
Inferior
colliculus
Optic chiasma
Pituitary gland
Thalamus
Mammillary body
Third
ventricle
Optic tract
Pons
Cerebral
peduncles
Pineal gland
Fourth
ventricle
Pyramidal tract
Olive
Cerebellar
peduncles
Medulla
oblongata
Spinal cord
(a)
(b)
27
Diencephalon
• Thalamus
• Gateway for sensory impulses heading to cerebral cortex
• Receives all sensory impulses (except smell)
• Channels impulses to appropriate part of cerebral cortex for
interpretation
• Epithalamus
• Functions to connect the limbic system to other parts of the
brain.
•Hypothalamus
• Maintains homeostasis by regulating visceral activities
• Links nervous and endocrine systems (hence some say the
neuroendocrine system)
28
Diencephalon
The Limbic System
• Consists of:
• Portions of frontal lobe
• Portions of temporal lobe
• Hypothalamus
• Thalamus
• Basal nuclei
• Other deep nuclei
• Functions:
• Controls emotions
• Produces feelings
• Interprets sensory impulses
29
Brainstem
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Hypothalamus
Diencephalon
Three parts:
1. Midbrain
2. Pons
3. Medulla Oblongata
Thalamus
Corpus
callosum
Corpora
quadrigemina
Midbrain
Cerebral
aqueduct
Pons
Reticular
formation
Medulla
oblongata
Spinal cord
30
Midbrain
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Superior
colliculus
Corpora quadrigemina
Optic nerve
Inferior
colliculus
Optic chiasma
Pituitary gland
Thalamus
Mammillary body
Third
ventricle
Optic tract
• Between diencephalon and pons
• Contains bundles of fibers that
join lower parts of brainstem and
spinal cord with higher parts of
the brain
• Cerebral aqueduct
• Cerebral peduncles (bundles of
nerve fibers)
• Corpora quadrigemina (centers
for visual and auditory reflexes)
Pons
Cerebral
peduncles
Pineal gland
Fourth
ventricle
Pyramidal tract
Olive
Cerebellar
peduncles
Medulla
oblongata
Spinal cord
(a)
(b)
31
Pons
• Rounded bulge on underside of
brainstem
• Between medulla oblongata and
midbrain
• Helps regulate rate and
depth of breathing
• Relays nerve impulses to and from
medulla oblongata and cerebellum
(bridge)
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Superior
colliculus
Corpora quadrigemina
Optic nerve
Inferior
colliculus
Optic chiasma
Pituitary gland
Thalamus
Mammillary body
Third
ventricle
Optic tract
Pons
Cerebral
peduncles
Pineal gland
Fourth
ventricle
Pyramidal tract
Olive
Cerebellar
peduncles
Medulla
oblongata
Spinal cord
(a)
(b)
32
Medulla Oblongata
• Enlarged continuation of
spinal cord
• Conducts ascending and
descending impulses between
brain and spinal cord
• Contains cardiac,
vasomotor, and respiratory
control centers
• Contains various nonvital
reflex control centers
(coughing, sneezing,
swallowing, and vomiting)
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Superior
colliculus
Corpora quadrigemina
Optic nerve
Inferior
colliculus
Optic chiasma
Pituitary gland
Thalamus
Mammillary body
Third
ventricle
Optic tract
Pons
Cerebral
peduncles
Pineal gland
Fourth
ventricle
Pyramidal tract
Olive
Cerebellar
peduncles
Medulla
oblongata
Spinal cord
(a)
(b)
33
Cerebellum
• Inferior to occipital lobes
Longitudinal
• Posterior to pons and medulla
fissure
oblongata
• Two hemispheres like cerebrum Thalamus
• Vermis connects hemispheres
• Cerebellar cortex (gray matter)
Superior peduncle
• Arbor vitae (white matter)
Pons
Middle peduncle
• Cerebellar peduncles (nerve fiber
Inferior peduncle
Medulla oblongata
tracts)
• Dentate nucleus (largest nucleus in
cerebellum)
• Integrates sensory information
concerning position of body parts
• Coordinates skeletal muscle activity
• Maintains posture
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Corpus callosum
Cerebellum
34
Major Parts of the Brain
35
11.6: Peripheral Nervous System
• Cranial nerves arising from the brain
• Somatic fibers connecting to the skin and skeletal muscles
• Autonomic fibers connecting to viscera
• Spinal nerves arising from the spinal cord
• Somatic fibers connecting to the skin and skeletal muscles
• Autonomic fibers connecting to viscera
36
Nervous System Subdivisions
37
Structure of a Peripheral Nerve
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Fascicle
Peripheral nerve
Epineurium
Motor neuron
ending
Axon
Perineurium
Endoneurium
Node of Ranvier
Schwann cell
Sensory receptor
Myelin sheath
Neurilemma
38
Nerve and Nerve Fiber
Classification
• Sensory nerves
• Conduct impulses into brain or spinal cord
• Motor nerves
• Conduct impulses to muscles or glands
• Mixed (both sensory and motor) nerves
• Contain both sensory nerve fibers and motor nerve fibers
• Most nerves are mixed nerves
• ALL spinal nerves are mixed nerves (except the first pair)
39
Cranial Nerves
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Olfactory bulb
Olfactory (I)
Olfactory tract
Optic (II)
Optic tract
Oculomotor (III)
Trochlear (IV)
Trigeminal (V)
Vestibulocochlear (VIII)
Abducens (VI)
Hypoglossal (XII)
Facial (VII)
Vagus (X)
Glossopharyngeal (IX)
Accessory (XI)
40
Cranial Nerves I and II
• Olfactory nerve (CN I)
• Sensory nerve
• Fibers transmit impulses
associated with smell
• Optic nerve (CN II)
• Sensory nerve
• Fibers transmit impulses
associated with vision
41
Cranial Nerves III and IV
• Oculomotor nerve (CN III)
• Primarily motor nerve
• Motor impulses to muscles
that:
• Raise eyelids
• Move the eyes
• Focus lens
• Adjust light entering eye
• Trochlear nerve (CN IV)
• Primarily motor nerve
• Motor impulses to muscles
that move the eyes
• Some sensory
• Proprioceptors
• Some sensory
• Proprioceptors
42
Cranial Nerve V
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
• Trigeminal nerve (CN V)
• Mixed nerve
• “Three (3) sisters”
• (1) Ophthalmic division
• Sensory from surface of eyes,
tear glands, scalp, forehead, and
upper eyelids
Lacrimal nerve
Ophthalmic
division
Eye
Maxillary
division
• (3) Mandibular division
• Sensory from scalp, skin of
jaw, lower teeth, lower gum,
and lower lip
• Motor to muscles of
mastication and muscles in
floor of mouth
Infraorbital
nerve
Mandibular
division
• (2) Maxillary division
• Sensory from upper teeth,
upper gum, upper lip, palate,
and skin of face
Lacrimal
gland
Maxilla
Lingual
nerve
Inferior
alveolar
nerve
Tongue
Mental
nerve 43
Mandible
Cranial Nerves VI and VII
• Abducens nerve (CN VI)
• Primarily motor nerve
• Motor impulses to muscles
that move the eyes
• Some sensory
•Proprioceptors
• Facial nerve (CN VII)
• Mixed nerve
• Sensory from taste receptors
• Motor to muscles of facial
expression, tear glands, and
salivary glands
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Temporal nerve
Zygomatic nerve
Buccal nerve
Facial nerve
Posterior auricular
nerve
Parotid salivary
gland
Mandibular nerve
Cervical nerve
44
68
Cranial Nerves VIII and IX
• Vestibulocochlear nerve (CN VIII)
• Aka acoustic or auditory nerve
• Sensory nerve
• Two (2) branches:
• Vestibular branch
• Sensory from equilibrium
receptors of ear
• Cochlear branch
• Sensory from hearing
receptors
• Glossopharyngeal nerve (CN IX)
• Mixed nerve
• Sensory from pharynx, tonsils,
tongue and carotid arteries
• Motor to salivary glands and
muscles of pharynx
45
Cranial Nerve X
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
• Vagus nerve (CN X)
• Mixed nerve
• Somatic motor to muscles of speech
and swallowing
• Autonomic motor to viscera of thorax
and abdomen
• Sensory from pharynx, larynx,
esophagus, and viscera of thorax and
abdomen
Meningeal branch
Auricular branch
Pharyngeal branch
Superior ganglion
of vagus nerve
Inferior ganglion
of vagus nerve
Palate
Nerve XI
Superior laryngeal
nerve
Nerve XII
Carotid body
Recurrent laryngeal
nerve
Left vagus
nerve
Cardiac nerves
Lung
Heart
Stomach
Liver
Spleen
Pancreas
Kidney
Small
intestine
46
Large intestine
Cranial Nerves XI and XII
• Accessory nerve (CN XI)
• Primarily motor nerve
• We called this “Spinal” Accessory
because:
• Cranial branch
• Motor to muscles of soft
palate, pharynx and larynx
• Spinal branch
• Motor to muscles of neck
and back
• Some sensory
• Proprioceptor
• Hypoglossal nerve (CN XII)
• Primarily motor
• Motor to muscles of the
tongue
• Some sensory
• Proprioceptor
47
Functions of Cranial Nerves
48
Spinal Nerves
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
• ALL are mixed nerves
(except the first pair)
• 31 pairs of spinal nerves:
• 8 cervical nerves
• (C1 to C8)
• 12 thoracic nerves
• (T1 to T12)
• 5 lumbar nerves
• (L1 to L5)
• 5 sacral nerves
• (S1 to S5)
• 1 coccygeal nerve
• (Co or Cc)
C1
C2
C3
C4
C5
C6
C7
C8
T1
T2
Posterior
view
Cervical
nerves
T3
T4
T5
T6
T7
Thoracic
nerves
T8
T9
T10
T11
T12
L1
Cauda equina
L2
L3
L4
Lumbar
nerves
L5
S1
S2
S3
S4
S5
Co
Sacral
nerves
Coccygeal
nerve
49
Spinal Nerves
• Dorsal root (aka posterior
root)
• Sensory root
• Axons of sensory neurons
are in the dorsal root
ganglion
• Dorsal root ganglion
• Aka DRG
• Cell bodies of sensory
neurons whose axons
conduct impulses inward
from peripheral body parts
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Dorsal root
Dorsal root
ganglion
Dorsal root
Dorsal branch
of spinal nerve
Ventral branch
of spinal nerve
Ventral root
Paravertebral
ganglion
Posterior
median sulcus
Posterior
horn
Visceral branch
of spinal nerve
(b)
Lateral horn
Ventral branch
of spinal nerve (ventral ramus)
Anterior
horn
Central
canal
Dorsal branch
of spinal nerve (dorsal ramus)
Anterior
median
fissure
Paravertebral
ganglion
(a) Ventral root
Spinal nerve
Visceral branch
of spinal nerve
50
Spinal Nerves
• Ventral root (aka anterior root)
• Motor root
• Axons of motor neurons
whose cell bodies are in the
spinal cord
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Dorsal root
Dorsal root
ganglion
Dorsal root
Dorsal branch
of spinal nerve
Ventral branch
of spinal nerve
Ventral root
Paravertebral
ganglion
Posterior
median sulcus
Posterior
horn
• Spinal nerve
• Union of ventral root
and dorsal roots
• Hence we now have a
“mixed” nerve
Visceral branch
of spinal nerve
(b)
Lateral horn
Ventral branch
of spinal nerve (ventral ramus)
Anterior
horn
Central
canal
Dorsal branch
of spinal nerve (dorsal ramus)
Anterior
median
fissure
Paravertebral
ganglion
(a) Ventral root
Spinal nerve
Visceral branch
of spinal nerve
51
Nerve Plexuses
• Nerve plexus
• Complex networks formed by anterior branches of spinal nerves
• The fibers of various spinal nerves are sorted and recombined
• There are three (3) nerve plexuses:
• (1) Cervical plexus – Lies deep within the neck
• (2) Brachial plexus – Lies deep within shoulders
• (3) Lumbosacral plexus – Extends from lumbar region into pelvic
cavity
52
Plexuses
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Posterior view
Musculocutaneous
nerve
Axillary nerve
Radial nerve
Median nerve
Ulnar nerve
Phrenic nerve
C1
C2
C3
C4
C5
C6
C7
C8
T1
Cervical plexus
(C1–C4)
Brachial plexus
(C5–T1)
T2
T3
T4
T5
T6
T7
Intercostal
nerves
T8
T9
T10
T11
T12
Cauda equina
L1
L2
L3
L4
Femoral
nerve
L5
S1
S2
S3
S4
S5
Obturator nerve
Lumbosacral plexus
(T12–S5)
Co
Sciatic nerve
53
11.7: Autonomic Nervous System
• Functions without conscious effort
• Controls visceral activities
• Regulates smooth muscle, cardiac muscle, and glands
• Efferent fibers typically lead to ganglia outside of the CNS
• Two autonomic divisions regulate:
• Sympathetic division (speeds up)
• Prepares body for ‘fight or flight’ situations
• Parasympathetic division (pauses or slows down)
• Prepares body for ‘resting and digesting’ activities
54
Sympathetic Division
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Lacrimal gland
Eye
Parotid gland,
submandibular and
sublingual glands
Blood vessels
Heart
Celiac and
pulmonary
plexuses
Trachea
Lungs
Skin
Celiac
ganglion
Fibers to
skin, blood vessels,
and adipose tissue
Liver
Gallbladder
Superior
mesenteric
ganglion
Stomach
Pancreas
Small intestine
Large intestine
Spinal
cord
Inferior
mesenteric
ganglion
Adrenal gland
Kidney
Sympathetic
chain ganglia
Urinary
bladder
Preganglionic Postganglionic
neuron
neuron
Ovary
Penis
Uterus
Scrotum
55
Parasympathetic Division
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Sphenopalatine
ganglion
Lacrimal
gland
Ciliary ganglion
Cranial
nerve III
Submandibular
and sublingual
glands
Submandibular
ganglion
Cranial
nerve
VII
Eye
Parotid
gland
Otic ganglion
Cranial
nerve IX
Heart
Cranial nerve X
(Vagus)
Trachea
Lung
Cardiac and
pulmonary
plexuses
Liver
Gallbladder
Stomach
Celiac
plexus
Spleen
Pancreas
Superior
hypogastric
plexus
Spinal
cord
Small intestine
Large intestine
Inferior
hypogastric
plexus
Kidney
Pelvic
nerves
Urinary
bladder
Preganglionic Postganglionic
neuron
neuron
Scrotum
Uterus
Penis
Ovary
56
Control of Autonomic
Activity
• Controlled largely by CNS
• Medulla oblongata regulates cardiac, vasomotor and
respiratory activities
• Hypothalamus regulates visceral functions, such as body
temperature, hunger, thirst, and water and electrolyte balance
• Limbic system and cerebral cortex control emotional
responses
57