Ch. 13 Central Nervous System
I. Coverings of CNS (Figs. 13-2, 13-3)
A. Bone (Cranium & Vertebrae)
B. Meninges - membranes; 3 layers
1. ______ (Figs. 13-2, 13-3)
a. strong ______fibrous tissue
b. outer layer & also forms inner periosteum of cranial bones
c. Falx cerebri (Fig. 13-2) - inward extension
1) Superior sagittal sinus - b/t 2 ______hemispheres
d. Falx ______- inward ext that separates 2 halves of cerebellum
e. Tentorium cerebelli -separates cerebellum from ______
f. ______space - outside dura mater but inside bony coverings
2. Arachnoid membrane (Figs. 13-2, 13-3)
a. delicate, cobweb-like layer
b. subdural space - between ______and arachnoid membrane
c. ______space - under arachnoid & outside pia mater
1) contains CSF
3. ______ (Figs. 13-2, 13-3)
a. adheres to outer surface of brain & sp cord
b. delicate c.t., minute blood vessels
a. Filum terminale (Fig. 13-1) - slender filament at S3 level; blends w/ dura mater to form cord that disappears w/ periosteum of coccyx
C. Meningitis - inflammation of ______
1. Most often involves ______& pia meninges
2. Causes - ______(m/c), viral, fungus
3. S/sx - ______, severe HA, stiff ______
4. Dx - CSF sample from subarachnoid space
II. Cerebrospinal Fluid
A. Liquid cushion; similar to plasma
B. Reservoir of circulating fluid à brain monitors for chgs in internal environment
C. Fluid spaces (p. 377)
1. ______space
2. Central canal of sp cord
3. Ventricles (Fig. 13-4) - 4
a. Lg. fluid filled spaces w/in brain
b. Interconnected w/ each other & canal of sp. Cord
c. Lined w/ ependymal cells
d. Lateral ventricles
1) C-shaped
2) In each hemisphere of the ______
e. 3rd Ventricle
1) In diencephalons
2) Interventricular foramen- opening to lateral ventricle
f. 4th Ventricle- where the ______attaches
to the back of the ______.
1) Cerebral Aqueduct- Connects 3rd &
4th, Runs through midbrain
D. Formation & Circulation of CSF (Fig. 13-5)
1. Choroid plexus
a. network of capillaries that project from pia mater into ______& into roofs of ______& 4th ventricles
b. forms CSF from blood plasma
c. covered w/ sheet of ______cells à release CSF into spaces
2. Arachnoid villi - returns CSF to blood
3. Circulation pathway (Fig. 13-5)
a. lateral ventricle à seeps thru opening, ______foramen à 3rd ventricle à
b. through channel, ______aqueduct à 4th ventricleà
c. central canal of cord
d. some from 4th ventricle à cisterna magna, a space continuous w/ ______space à venous blood
E. ______ml - Avg. amt. of CSF in adult
III. Spinal Cord (p. 380)
A. Structure of the spinal cord (Fig. 13-6)
1. Location (Fig. 13-1)
2. Transverse sectional structure (Figs. 13-6, 13-7)
3. Gross structure (Fig. 13-7)
a. dorsal nerve root- carries ______
information to the spinal cord
b. ventral nerve root- carries ______
information out of the spinal cord
B. Functions of the spinal cord- provides conduction
routes to and from the ______and serves as the integrator or ______center
1. Ascending tracts (Fig. 13-7; Table 13-1)-
conduct ______impulses up the cord to the brain
a. Lateral spinothalamic tracts- crude
touch, pain, and ______
b. Anterior spinothalamic tracts- crude touch and ______
c. Fasciculi gracilis and cuneatus- discriminating touch and ______sensation of position and movement of body parts
d. Spinocerebellar tracts- ______kinesthesia
2. Descending tracts (Fig. 13-7; Table 13-2)- conduct ______impulses down the cord from the brain
a. Lateral corticospinal tracts- voluntary movement of ______side of body
b. Anterior corticospinal tracts- voluntary movement of ______side of body
c. Reticulospinal tracts- help maintain ______during skeletal muscle movements
d. Rubrospinal tracts- transmits impulses that coordinate body movements and maintenance of posture
IV. The Brain (p. 383)
A. Major divisions (Fig. 13-8)
1. Brainstem
a. Medulla oblongata- lowest part
b. Pons- in between/ in the middle
c. Midbrain- uppermost part
2. ______
3. Diencephalon
a. Thalamus
b. ______
c. Epithalamus- includes the pineal body/ gland
4. Cerebrum
B. Structure of the brainstem
1. Medulla oblongata (Fig. 13-9)
a. Connects brain to sp. Cord
b. Extension of sp cord above ______
c. Composed of ______(projection tracts) & a network of gray & white matter called the ______
d. Pyramids (Fig. 13-9)
1) Two bulges of white matter located on ______surface
2) Made up of pyramidal tracts descending from motor cortex
e. Olive (Fig. 13-9) - oval projection on each side of ventral surface of medulla, lateral to ______
f. Nuclei - in reticular formation, clusters of neuron cell bodies
1) Vital centers/ control centers
2. Pons (Fig. 13-9)
a. B/t midbrain & medulla ob.
b. Composed of ______matter & reticular formation
c. External white matter - fibers run transversely across pons, thru middle cerebellar peduncles à cerebellum
3. Midbrain (______) (Fig. 13-9)
a. Between ______& pons
b. Cerebral peduncles (Fig. 13-9)
1) Bulges of white matter
2) tracts conduct impulses b/t ______& cerebrum
c. Corpora quadrigemina (Fig. 13-9, B) - lg nuclei in midbrain
1) 2 Inferior colliculi - ______centers
2) 2 Superior colliculi - ______centers
d. Red nucleus (Fig. 13-11; Fig. 13-22)
1) Nucleus involved in muscular control
e. Substantia nigra (Fig. 13-15)
2) Nucleus involved in muscular control
3) Dark pigment in nucleus
C. Functions of the brainstem (p. 386)
1. Performs sensory, motor, and ______functions
2. Important tracts pass through to other parts of the brain; other tracts terminate on brainstem
3. Medulla oblongata reflex center nuclei
a. Vital centers
1) Cardiac center- force & rate of heart contraction
2) ______center - BP (vessel diameter)
3) Respiratory center - Rate/depth of breathing
b. Nonvital centers
1) Vomiting, coughing, ______, hiccuping, and swallowing
4. Pons reflex centers
a. ______center - helps maintain normal breathing rhythms
b. For cranial nerves V, VI, VII and VIII.
5. Midbrain reflex centers
a. Nuclei for cranial nerves III (______reflexes) and IV (______movements)
D. Cerebellum -Structure (Fig. 13-10)
1. ______Fissure - separates from the cerebrum
2. Cortex - outside; gray matter
3. White matter predominates interior
4. ______- "Tree of Life"; pattern of white matter
5. Sulci (grooves) and ______(raised areas)
6. Vermis - separates 2 hemispheres of the cerebellum
7. Cerebellar peduncles (Fig. 13-9) - contains long tract fibers
a. Inferior cerebellar peduncles - tracts that come into cerebellum from ______and cord
1) Ex. Spinocerebellar
b. Middle cerebellar peduncles - tracts to ______from pons
1) Pontocerebellar tracts
c. Superior cerebellar peduncles - tracts from dentate nuclei (cerebellum) à red nucleus (midbrain) à ______
8. Dentate nuclei
a. nuclei in each hemisphere that communicate w/ motor cortex of ______cortex & thalamus
E. Functions of the cerebellum (Fig. 13-11)
1. Coordinates skilled movements
a. Works w/ ______to produce skilled movements
b. Coordinates activities of groups of muscles
2. Helps control posture
a. functions to make movements ______, steady, and efficient at the subconscious level
3. Controls skeletal muscles for ______
a. sensory impulses from equilibrium receptors (ear) à cerebellum
b. cerebellum à motor fibers for contracting muscles for stabilization
F. Diencephalon- located between the cerebrum and the midbrain (p. 388) - thalamus, ______, epithalamus
1. Thalamus (Figs. 13-8, 13-12, 13-15)
a. Structure
1) 80% of diencephalon
2) Lateral masses - mass of gray matter; form wall of ______ventricle
a) Geniculate bodies - grp of nuclei that play a role in processing ______& visual input
3) Joined by Intermediate mass (Fig.13-9)
b. Function
1) Relay station for sensory impulses à primary sensory areas of Cerebral cortex
a) Conscious recognition of sensations (pain, ______, touch)
b) All senses, but ______
c) Relay of sensory action potentials to cerebrum
2) Association of sensations with feelings of ______and ______
3) Part of arousal and ______mechanism
4) Part of complex ______mechanism
2. Hypothalamus (Figs. 13-8, 13-12) - beneath thalamus; forms inferiorlateral walls of 3rd ventricle
a. Structure
1) Supraoptic nuclei
a) Gray matter above & either side of optic chiasma
2) Infundibulum
a) Stalk leading to posterior lobe of ______gland (neurohypophysis)
4) Mamillary bodies
a) Posterior part of hypothalamus
b) Involved in olfactory sense
b. Function - important in homeostasis
1) Autonomic center - main visceral control center of body
a) Regulator & coordinator of autonomic activities.
2) Link between mind and body
a) Major relay station b/t ______& lower autonomic ctrs
b) Route by which emotions can express themselves in changed ______functions
3) Synthesis neurohypophyseal hormones
a) Hormones affect urine volume ______but do play an essential role in maintaining water balance
4) Secretion of releasing hormones
a) Axons secrete chemicals = releasing hormones
b) Control release of certain anterior pituitary hormones, ex. ______hormone
5) Part of arousal or alerting mechanism
a) Maintaining the ______state
6) Appetite center
a) Regulating appetite and "satiety center"
7) ______control site
a) Neurons whose fibers connect w/ autonomic centers for vasoconstriction,
______, & sweating
3. Pineal body (Figs. 13-8; 13-9, B; 13-12)
a. Structure
1) Part of the epithalamus
a) Most dorsal of diencephalons
2) Located superior to corpora quadrigemina
b. Function
1) Regulation of ______clock
2) Production of ______
G. Structure of the cerebrum (p. 390)
1. 60% of brain wt
2. 2 halves - L & R cerebral hemispheres
3. Cerebral cortex
a. gray matter
b. 2-4 mm thick
c. many convolutions (gyri)
1) precentral gyrus, ______gyrus, cingulated gyrus, & ______gyrus
d. ______- shallow grooves
e. ______- deeper grooves
1) Forms 5 lobes/hemisphere: frontal, ______, temporal, ______, insula
2) Lobes named for cranial bone, except insula
3) Longitudinal fissure - separates hemispheres of ______
4) Central sulcus - groove b/t ______& parietal lobes
5) Lateral fissure - outlines temporal lobe; insula (island of ______lies deep in lat. Fissure)
6) ______fissure - separates occipital lobe from parietal lobe
4. Cerebral White Matter (Cerebral tracts and cerebral nuclei)
a. Tracts (Fig. 13-14) - 3 types
1) Projection tracts
a) Extensions of ascending spinothalamic tracts & descending ______tracts
2) ______tracts
a) Most numerous
b) Impulses b/t gyri w/in single hemisphere
3) Commissural tracts (corpus callosum) (Fig. 13-12)
a) Connect corresponding regions of 2 hemispheres
b) Compose the corpus callosum - largest
b. Cerebral Nuclei (Fig. 13-15) - islands of gray matter deep inside white matter (basal ganglia) of each cerebral hemisphere
1) ______nucleus
a) comma-shaped
2) Lentiform nucleus
a) lens like
b) putamen & globus ______
3) ______nucleus
a) ______-shaped
b) tip of caudate nucleus
4) Regulating voluntary ______functions
a) Initiates mm contractions in maintaining ______, walking or other repetitive movements
H. Functions of the cerebral cortex (p. 393)
1. Functional areas of the cortex (Figs. 13-16, 13-17)
a. Certain areas usually have 1 particular function = ______localization
b. Each hemisphere - opposite sides of body
c. Hemispheres not exactly = in function
2. Sensory functions of the cortex (Figs. 13-16; 13-17, A)
a. Somatic senses - touch, temp, pain, propioception
b. Special senses - visual, hearing
c. Postcentral Gyrus - primary somatic ______area
1) Parietal lobe; behind central sulcus
2) General somatic senses
3) Size relates to # of sensory receptors (fig.13-17)
d. Transverse gyrus - Primary ______area & Auditory association area
e. Somatosensory association area - "body perception; many connections w/ prim sensory cortex
f. Visual cortex
1) ______lobe
2) Surrounded by Visual Association Area
g. Wernicke's Area
1) Left temporal lobe
2) Comprehension of written & spoken language
3. Motor functions of the cortex (Figs. 13-16; 13-17, B)
a. Precentral gyrus
1) Primary somatic ______area
2) Voluntary skeletal movements
3) Pyramidal tracts (______tracts) & all other descending motor tracts
4) Homunculus - "little man)
a) Entire body represented on each hemisphere; distorted image
b. Premotor cortex
1) Anterior to primary motor cortex
2) Thought to activate groups of ______simultaneously
3) Learned repetitive movements like typing
c. Broca's area
1) Motor speech
2) Articulation of words
3) Damage (aphasias) - unable to articulate, but can make vocal sounds & understands words heard/read
4. Integrative functions of the cortex
a. Consciousness (Fig. 13-18)
1) Reticular Activating System
a) Network of neurons
b) Consists of centers of reticular formation in ______
c) Impulses from sp. Cord à______à all parts of cerebral cortex
d) w/o excitation of cortical neurons à ______/cannot be arousal
e) functions:
1. arousal or ______system
2. maintaining ______
f) Drugs
1. Depress the Reticular Activating System- induces sleep, ex. ______
2. Stimulates the cerebrum- stimulates the Reticular Activating System, enhances alertness and keeps you awake, ex. ______
b. Memory
1) Short term & long term
2) Temporal, ______, & occipital lobes
3) ______- permanent change in synapses in a specific circuit of neurons
4) Limbic system also plays a key role in memory
c. Limbic System "Emotional Brain”
1) Curving border @ corpus ______; includes cingulated gyrus & hippocampus
2) Many connections w/ higher & lower brain center
3) Functions with other parts of the cerebral cortex to enable us to experience emotions such as ______, fear, sexual feelings, ______, and sorrow
5. Specialization of cerebral hemispheres (p. 396)
a. R & L specialize in ______functions
b. L - language; dominate the control of hand movements like ______; & logic (math)
c. R - certain auditory stimuli (______, coughing, crying); tactile perception; creative (perceiving and visualizing spatial relationships)
V. Somatic Sensory Pathways in the CNS (Fig. 13-21)
A. Primary sensory neurons - axons conduct from periphery to dendrites & cell bodies in CNS (sp cord)à
B. Secondary sensory neurons - axons ascend (ascending tracts) àfrom spinal cord or brainstem àthalamus à
C. Dendrites & cell bodies of Tertiary sensory neurons à axons conduct to sensory areas in cortex
D. Most axons of secondary neurons decussate (cross from one side to another) before reaching the ______
E. Ex. Medial lemniscal system (discriminating touch and pressure, precise localization, 2-point discrimination, weight discrimination, and sense of vibration) & ______pathway (crude touch and pressure)
VI. Somatic Motor Pathways in the CNS (Fig. 13-22)
A. Pyramidal tracts (______tracts) (Fig. 13-22)