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Human Anatomy > Ch. 18 Brain and Cranial Nerves > Flashcards

Ch. 18 Brain and Cranial Nerves Flashcards

1
Q

Support and Protection of Brain

A

cranium
cranial meninges
cerebrospinal fluid (CSF)
blood-brain barrier

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2
Q

Meninges

A

dura matter, arachnoid mater, pia mater

  • dura mater: periosteal and meningeal layers; spinal cord has only one
  • dural venous sinuses: form between two dura matters; drain venous blood from the brain and deliver it into the internal jugular veins
  • no epidural space around brain
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3
Q

Dura Mater

A

3 extensions of dura mater separate parts of the brain

  • falx cerebri: separates the two hemispheres of the cerebrum
  • falx cerebelli: separates the two hemispheres of the cerebellum
  • tentorium cerebelli: separates the cerebrum from the cerebellum
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4
Q

Blood Brain Barrier

A
  • allows glucose and oxygen into brain
  • protects from harmful substances and pathogens
  • proteins and antibodies cannot cross BBB
  • oxygen, carbon dioxide, anesthetic drugs, and alcohol can cross BBB
  • astrocytes are part of BBB
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5
Q

CSF

A
  • clear, colorless that protects the brain and spinal cord against chemical, physical injuries and serve as shock absorber
  • carries oxygen, glucose, and other needed chemicals from blood to neurons and neuroglia
  • circulates through cavities in brain and spinal cord and around brain and spinal cord in the subarachnoid space
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6
Q

CSF Protection

A
  • mechanical protection: CSF serves as shock-absorbing medium that protects the delicate tissues of the brain and spinal cord
  • chemical protection: CSF provides chemical environment for accurate neuronal signaling in neurons that border the fluid
  • circulation: medium for minor exchange of nutrients and waste products between blood and nervous tissue
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7
Q

CSF Production and Circulation

A
  • lateral ventricle
  • septum pellucidum: separate the lateral ventricles
  • third ventricle: midline superior to hypothalamus and thalamus
  • fourth ventricle: between brain stem and cerebellum
  • choroid plexus
  • interventricular formina: CSF formed in choroid plexuses flows into third ventricle through opening
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8
Q

Brain Stem: Medulla

A
  • begins at foramen magnum and extends to inferior of pons
  • Gray matter contains several nuclei that form 2 important centers:
    cardovascular center: inhibitory and accelerator fibers control the rate of heart and blood pressure
    respiratory center: controls rate and depth of breathing; centers of reflexes involved in sneezing, coughing, swallowing and vomiting
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9
Q

Internal Anatomy

A

Inferior Olivary Nucleus: relay impulses from proprioceptors to cerebellum
Gracile and Cutaneous Nuclei: touch, pressure, vibrations, and proprioception

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10
Q

White Matter of MO contains…

A

pyramids: sensory and motor axons that form the bulge within MO forms on anterior aspects of medulla
decussation of the pyramids: crossing of axons from right to left and vice-versa of spinal cord is decussation of pyramids
medial lemniscus: axons in a band of white matter that ascend from MP to the thalamus
gracile and cuneate nuclei: touch, conscious proprioception, pressure, and vibration

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11
Q

Cranial Nerves associated with MO

A

vestibulochoclear, glossopharyngeal, vagus, accessory, hypoglossal

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12
Q

Pons

A
  • bridge that connects parts of the brain with one another
  • connect right and left sides of cerebellum
    ventral region: pontine nuclei: coordination between cerebellum and cerebrum
    dorsal region: ascending and descending tract: between spinal cord and brain
    pontine resp. group:
  • pneumotaxic and apneustic- control breathing
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13
Q

Pons contains nuclei associated with cranial nerves…

A

trigeminal, abducens, facial, vestibulocochlear

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14
Q

Midbrain

A
  • cerebral aqueduct: passes through midbrain and connects third ventricle to fourth ventricle
  • contains both tracts and nuclei
    Anterior:
  • cerebral peduncles: pair of tracts in anterior part of the midbrain and contains axons of sensory neurons that extend from MO to thalamus; axons of corticospinal, coritcopontine, and corticobulbar motor neurons, which conduct nerve impulses from cerebrum to spinal cord, medulla, and pons
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15
Q

Posterior of Midbrain

A

superior colliculi: two superior elevations of midbrain
- reflex centers for certain visual activities; accommodation reflexes such as tracking movements with eyes
inferior colliculi: inferior elevations part of auditory reflex
- relaying impulses from receptors for hearing in the ear to the thalamus
substantia nigra (dopamine): contro subconscious muscle activities; loss of neurons causes Parkinson’s disease
red nuclei: axons of cerebellum and cerebral cortex form synapses in red nuclei
- functions with cerebellum to coordinate muscular movements

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16
Q

Cranial Nerves associated with Midbrain

A

oculomotor and trochlear

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17
Q

Reticular Formation

A
  • broad region of white and gray matter
  • sensory and motor function; RAS consists of sensory axons that project to cerebral cortex
  • maintain consciousness, active during awakening from sleep and maintain attention and alertness
  • descending portion of RAS maintain muscle tone
  • helps regulates heart rate, bp, resp. rate
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18
Q

Cerebellum

A

cerebellar cortex: gray matter in series of slender, parallel ridges called folia
arbor vitae: tracts of white matter deep to gray matter
cerebellar nuclei: gray matter that give rise to axons carrying impulses from cerebellum to other brain centers and spinal cord
vermis: central constricted area
cerebellar hemispheres: separates two lobes
- each hemisphere consists of lobes separated by deep and distinct fissures

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19
Q

Cerebellum Anatomy

A

Flocculonodular lobe: contribute to equilibrium and balance
superior and middle cerebellar peduncles: bundles of axons that conduct impulses between the cerebellum and other parts of the brain
inferior peduncles: carries sensory info from the vestibular apparatus and proprioception into the cerebellum
anterior and posterior lobe: govern subconscious aspects of skeletal muscle movements

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20
Q

Diencephalon

A
  • contains nuclei involved in sensory and motor processing between higher and lower brain centers
  • extends from brain stem to cerebrum and surrounds the third ventricle; includes the thalamus, hypothalamus, and epithalamus
  • projecting is hypophysis, or pituitary gland; optic tracts carrying neurons from the retina enter this region of the brain
21
Q

Thalamus

A
  • bridge of gray mater celled intermediate mass (interthalamic adhesion) joins the right and left halves of the thalamus
    functions: serve as major relay station, relays sensory impulses from spinal cord, brain stem, and midbrain to primary sensory area of cerebral cortex
  • transmits info from cerebellum and basal ganglia to primary motor area of cerebral cortex
  • plays a role in regulation of autonomic activities and maintenance of consciousness
  • crude perception of painful, thermal, and pressure sensations arise at the level of the thalamus
22
Q

7 Groups of Nuclei on each side of thalamus

A

anterior nucleus: emotions, alterness and memory
medial nuclei: emotions, memory, awareness, and cognition
lateral nuclei: expression of emotions
ventral group: contains five nuclei and contribute to motor functions such as movement planning
intralaminar nuclei: pain perception, integratin of sensory and motor info and arousal
midline nucleus: memory and olfaction
reticular nucleus: surround lateral aspect of thalamus next to internal capsule; monitors, filters, and integrates activities of other thalamic nuclei

23
Q

Hypothalamus (4 major regions)

A

mammillary: relay station for reflexes related to sense of smell
tuberal region: widest part; include stalk called infundibulum, which connects pituitary gland to hypothalamus
supraoptic region: superior to optic chiasm and contains paraventricular nucleus, supraoptic nucleus, anterior hypothalamic nucleus, and suprachiamastic nucleus; forms hypothalamohypophyseal tract to posterior pituitary
preoptic region anterior: region contains medial and lateral preoptic nuclei; participate with hypothalamus to regulate certain autonomic activities

24
Q

Hypothalamus Functions

A
  • control of ANS
  • production of hormones
  • regulation of emotional and behavioural patterns
  • regulation of eating and drinking
  • control of body temperature
  • regulation circadian rhythms and state of consciousness
25
Q

Epithalamus

A
  • posterior to thalamus, consists of pineal gland and hebenular nuclei
  • halbenular nucleus involved in olfaction (emotional response)
  • pineal gland is part of endocrine system by secreting melatonin
  • melatonin promotes sleepiness and contribute to set body’s biological clock by inducing sleep and help body adjust to jet lag
26
Q

Circumventricular Organs

A
  • part of diencephalon called circumventricular organs lie in wall of third ventricle and monitor chemical changes in blood because they lack a blood-brain barrier
  • include part of hypothalamus, pineal gland, pituitary gland, and few other nearby structures
  • coordinate homeostatic activities of endocrine and nervous systems such as blood pressure, hunger, thirst, fluid balance
  • site of HIV entrance in brain
27
Q

Cerebrum

A
  • cerebral hemispheres that are separated by falx cerebri
  • outer rim of gray matter and internal white matter and gray matter deep within white matter
  • outer rim of gray matter is cerebral cortex
  • folds are called gyri or convolutions
  • deepest grooves between folds are known as fissures; shallower grooves between folds are termed sulci
28
Q

Lobes of Cerebrum

A

frontal, parietal, temporal, occipital lobes

  • central sulcus: separates frontal from parietal
  • precentral gyrus: located anterior to central sulcus and contains primary motor area of cortex
  • postcentral gyrus: lies posterior to central sulcus, contains primary somatosensory area of cerebral cortex
  • lateral cerebral sulcus: separates frontal lobe from temporal lobe
  • parieto-occipital sulcus: separates parietal lobe from occipital lobe
29
Q

Cerebral White Matter

A
  • consists primarily of myelinated axons in three types
  • association tracts: contains axons that conduct nerve impulses between gyri in same hemisphere
  • commissural tracts: contain axons that conduct nerve impulses from gyri in one cerebral hemisphere to other gyri in other cerebral hemisphere; three important groups: corpus, anterior commissure, and posterior commissure
  • projection tracts: contain axons that conduct nerve impulses from cerebrum to lower parts of CNA or from lower parts of CNS to cerebrum
30
Q

Functional Areas of Cerebrum (Telencephalon-forebrain)

A

cerebrum:

  • motor areas: primary motor area; motor speech area
  • sensory areas: primary somatosensory area; primary visual, auditory, gustatory, olfactory area
  • association areas: somatosensory association area, visual and auditory association area, Wernicke’s area, gnostic area
31
Q

Motor Area (right frontal lobe)

A

primary motor area: located in precentral gyrus of frontal lobe
- neurons of this area control voluntary skeletal muscle activity

32
Q

Left frontal lobe

A

motor speech area (broca’s area): located in inferio-lateral portion of left frontal lobe

  • regulates patterns of breathing
  • control muscular movement necessary for vocalization
33
Q

Sensory Area

A

primary somatosensory area: located postcentral gyrus area of the parietal lobe
- receives somatic sensory info from touch, pain, pressure, proprioceptors
primary visual: located in occipital lobe; recieves and processes incoming visual info
primary auditory: located in temporal; auditory info
primary gustatory: located in insula area; processes taste info
primary olfactory area: temporal lobe; provides conscious awareness of smells and olfactory perception

34
Q

Association Areas

A

somatosensory area: located in parietal lobe and posterior to prim. somatosensory cortex
- integrates and interprets sensations to determine texture, temp., pressure, and shapes of objects
- storage of memories of past experiences
Visual: occipital lobe and surrounds primary visual area; process visual info by analyzing color, movement and form
auditory: temporal lobe; interprets characterisitics of sound and store memories of sound
Wernicke;s: located in left hemisphere; recognizing, understanding and comprehending spoken or written language
Integrative: parietal, occipital and temporal lobes; integrates all sensory, visual and auditory info being processed by association area

35
Q

Limbic System

A
  • olfaction and memory
  • “emotional brain”
  • damage causes memory impairment
36
Q

Cranial Nerves

A
  • 12 pairs of cranial nerves
  • five are mixed nerves because they contain axons of both sensory and motor neurons
  • cell bodies of motor neurons lie in neuclei within the brain; cranial nerves 3, 4 and 6 include both somatic and autonomic motor axons
  • cell bodies of sensory neurons are located in ganglia outside the brain
37
Q

Origin of Cranial Nerves

A 
forebrain: 2 pairs (1&2)
brainstem:
- midbrain 2 pairs (3&4)
- MO 5 pairs (8,9,10,11,12)
- pons 3 pairs (5,6,7)
38
Q

Olfactory Nerve

A
  • sensory
  • axons that conduct nerve impulses for olfaction
  • end in brain in paired masses of gray matter called olfactory bulbs, two extensions of the brain that rest of cribriform plate
  • within bulbs, axon terminals of olfactory receptors form synapses with dendrites
  • make up olfactory tracts, which extend posteriorly from olfactory bulbs
39
Q

Optic Nerve

A
  • sensory
  • contains axons that conduct nerve impulses for vision
  • two optic nerves merge at optic chiasm; axons on medial hald cross and lateral half remain on same side
  • most axons in optic tract end in lateral geniculate nucleus of thalamus
40
Q

Oculomotor Nerve

A
  • motor
  • axons in superior innervate superior rectus and levator palpebrea superior
  • axons inferior supply medial rectus, inferior rectus, and inferior oblique muscles (extrinsic muscles)
41
Q

Trochlear Nerve

A
  • motor; only one that arises from posterior aspect of brain stem
  • somatic motor axons innervate superior oblique muscle of eyeball
  • proprioceptive sensory axons from superior oblique muscle begin in 3 nerve but leave nerve to join opthalmic branch of 5 nerve
42
Q

Abducens

A
  • motor
  • originates in abducens nucleus in pons
  • somatic motor axons extend from nucleus to lateral rectus muscle of eyeball
  • abducens nerve is named so because nerve impulses cause abduction of eyeball
43
Q

Trigeminal Nerve

A
  • mixed cranial nerve and largest
  • 3 branches: ophthalmic, maxillary, and mandibular
  • ophthalmic nerve: smallest branch passes into orbit via superior orbital fissure
  • maxillary nerve: in intermediate size between ophthalmic and manipular nerves and passes through foramen rotunda
  • mandibular nerve: largest branch, passes through foramen ovale
44
Q

Facial Nerve

A
  • mixed cranial nerve
  • nerve impulses propagating along these axons cause contraction of facial expression muscles plus stylohyoid muscle, posterior belly of digastric and stapedius muscle
45
Q

Vestibulocochlear Nerve

A
  • sensory cranial nerve and two branches; vestibular branch and cochlear branch
  • vestibular branch carries impulses for equilibrium and cochlear branch carries impulses for hearing
46
Q

Vagus

A
  • mixed cranial nerve that is distributed from head and neck into thorax and abdomen
  • originate from medulla oblongata
  • axons of autonomic motor neurone (para.) in vagus nerve originate in nuclei and medullar and end in lungs and heart
  • vagal para. axons also supply glands of GI tract and smooth muscle of rest. passageways, esophagus, stomach, gallbladder, small intestine, most large intestine
47
Q

Accessory Nerve

A
  • mixed cranial nerve
  • cranial portion part of vagus nerve
  • motor axons arise in anterior gray horn of first five segments of cervical portion of spinal cord
  • conveys motor impulses to sternocleiodmastoid and trapezius muscles to coordinate head movements
48
Q

Hypoglossal Nerve

A
  • motor cranical nerve
  • comatic motor axons originate in hypoglossal nucelus in medulla oblongata, pass through hypoglossal canal and supply tongue muscles
  • axons conduct nerve impulses for speech and swallowing; sensory axons originate from proprioceptors in tongue muscles begin course toward brain in hypoglossal nerve and end in medulla oblongata

Human Anatomy (24 decks)

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