lect10[1]anatomy

8/10/2019 Lect10[1]Anatomy

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Lecture 10: The Brain and Cranial Nerves

I. General Organization of Brain

A. Brain Stem1. medulla oblongata2. pons

3. midbrain (mesencephalon)

B. Diencephalon1. thalamus2. hypothalamus

C. Cerebrum

D. Cerebellum

II. Specialized Parts of the Brain

A. Meninges1. dura mater - outer layer, very tough2. arachnoid - middle layer3. pia mater - innermost layer, adheres to brain itself

B. Ventricles - Cavities in the Brain1. lateral - (2) in each hemisphere2. third - in slit between thalamic halves3. fourth - between brain stem and cerebellum

i. Foramen of Monro - lateral -> 3rdii. cerebral aqueduct - 3rd -> 4thiii. median & lateral apertures - 4th -> other

C. Cerebrospinal Fluid1. liquid of about 80-150 ml2. flows around brain and through the ventricles3. choroid plexuses - formation of CSF

D. Special Properties of Brain Tissue1. brain uses 20% of oxygen (only 3 pounds!)2. brain uses 30-35% of glucose3. blood- brain barrier -

i. network between capillaries and neurogliaii. only very select molecules get in

III. Brain Stem

A. Medulla Oblongata - just above for. magnum to the pons1. pyramids - carry motor tracts from cerebrum


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2. decussation of pyramids - where tracts cross sides3. reticular formation - arousal and sleep (Quinley)4. cardiac center - heart rhythm5. rhythmicity area - breathing rate6. vasomotor area - dilation of blood vessels7. olive - (inferior and accessory nuclei

i. projects motor fibers to cerebellumii. allows for coordinated motion

8. vestibular nuclear complex - from inner ear,balance

B. Pons - above medulla, anterior to cerebellum1. middle cerebellar peduncles - connect to cerebellum2. pneumotaxic/apneustic areas - breathing

C. Midbrain - above pons to diencephalon1. cerebral peduncles - motor/sensory tracts (ventral)2. superior colliculi - visual stimuli -> motion3. inferior colliculi - auditory stimuli -> motion4. substantia nigra - motor coordination (Parkinsons)5. red nucleus - joining of cerebral/cerebellar tracts6. medial lemniscus - touch, pressure, vibration tracts

IV. Diencephalon - thalamus and hypothalamus

A. Thalamus - relay station between cerebrum and midbrain1. medial geniculate n. - auditory2. lateral geniculate n. - visual3. ventral posterior n. - taste & general sensation4. ventral anterior n. - motor actions5. ventral lateral n. - motor actions and arousal6. anterior n. - emotion and memory7. reticular nucleus - regulates thalamic action

B. Hypothalamus - tiny area below thalamus (sella turcica)1. The MASTER REGULATOR of the body (hormones)2. supraoptic region - above optic chiasm (crossing)3. infundibulum - carries hormones to pituitary gland4. mammillary bodies - olfactory relay

5. Chief functions of Hypothalamusa. regulates most organs through autonomicsb. integrates sensory information from organs

c. relay between Nervous Endocrine Systemsi. antidiuretic hormone - urinationii. oxytocin - uterine contraction/mammary

d. relays thoughts emotions via autonomicse. rage, aggression, passivity (rat studies)f. temperature control/regulation via autonomicsg. feeding/satiety center


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h. thirst centeri. sleep/arousal state with reticular formationj. helps control body rhythms (circadian)

V. Cerebellum - posterior to midbrain, inferior to occipital

A. Structure

1. transverse fissure - separates from occipital lobe2. tentorium cerebelli - dura mater around cerebellum3. anterior/posterior lobes - subconscious motion4. flocularnodular lobe - balance/equilibrium5. falx cerebelli - dura mater between hemispheres6. inf. cereb. peduncles - afferents from medulla7. mid. cereb. peduncles - afferents from pons8. sup. cereb. peduncles - efferents to midbrain

B. Functions

1. maintains equilibrium and posture2. fine tunes voluntary movement ordered by cerebrum

VI. Cerebrum - two hemispheres containing 5 different lobes

A. General Features

1. cerebral cortex - (gray matter) surface, cell bodies2. cerebral tracts - (white matter) beneath, axons3. gyri/convolutions - ridges of cortex4. fissures - deep grooves/valleys between gyri5. sulci - shallow grooves/valleys between gyri6. longitudinal fissure - divide right/left hemispheres7. corpus callosum - tracts connecting right/left8. falx cerebri - dura mater in long. fissure

B. The Lobes of the Cerebral Cortex

1. frontal lobe - under frontal bonea. central sulcus - frontal parietal

i. precentral gyrus - anterior, motor areaii. postcentral gyrus - post., sensory area

b. lateral sulcus - frontal temporal

2. parietal lobe - under parietal bonea. parieto-occipital sulcus

3. temporal lobe - under the temporal bone4. occipital lobe - under occipital bone (vision)5. insula buried deep within the lateral sulcus6. Fiber Tracts - White Matter

a. association fibers - within same hemisphere


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b. commissural fibers - between hemispheresi. corpus callosumii. ant./post. commissures

c. projection fibers - to lower brain & spinal

C. Basal Ganglia - communication cerebrum thalamusD. Limbic System - learning, memory, and emotions

E. Functional Areas of Cortex1. Sensory Areas

a. primary vision - occipital cortexb. primary auditory - temporal cortexc. somatosensory - postcentral gyrus (homunculus)

2. Motor Areas - precentral gyrus3. Association Areas - connect motor and sensory

lect10[1]anatomy

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