CH. 13 - BRAIN & CRANIAL NERVES
I. BRAIN - most complex structure in universe
A. DORSAL BODY CAVITY
1. BRAIN
2. SPINAL CORD
B. BRAIN REGIONS (4) & VENTRICLES (4) (Fig. 13.1, p. 439; Tab. 13.1, p 440)
1. BRAINSTEM a. MIDBRAIN & Cerebral Aqueduct
b. PONS
c. MEDULLA OBLONGATA
d. RETICULAR FORMATION
2. CEREBELLUM - 4th Ventricle
3. DIENCEPHALON - 3rd Ventricle
4. CEREBRUM - 2 Lateral ventricles
II. DEVELOPMENT OF CNS
A. EARLY STAGES (Fig. 13.2, p. 440)
1. ECTODERM – embryonic tissue
2. NEURAL PLATEèGROOVEèNEURAL TUBEèPOUCHES
3. LATERAL EXPANSIONS
4. BRAIN (4 PARTS) & VENTRICLES (4)
B. LATER STAGES (Fig. 13.3 & KNOW Tab. 13.2, p. 441)
YOUNG EMBRYO OLDER EMBRYO ADULT
1. PROSENCEPHALON TELENCEPHALON CEREBRUM &
(Forebrain) Lat. Ventricles (1 & 2)
DIENCEPHALON DIENCEPHALON &
3rd Ventricle
2. MESENCEPHALON MESENCEPHALON MIDBRAIN &
(Midbrain) Cerebral Aqueduct
3. RHOMBENCEPHALON METENCEPHALON PONS & CEREBELLUM &
(Hindbrain) 4th Ventricle
MYELENCEPHALON MEDULLA OBLONGATA
III. BRAINSTEM (Fig. 13.4, p. 443)
- Ascending & descending nerve tracts
- Continuous w/ spinal cord
- Damage hereèvery seriousèdeath
A. MEDULLA OBLONGATA -collection of nuclei-gray matter/bodies
1. PYRAMIDS (2)
a. Descending tracts
b. Voluntary muscle control
c. DECUSSATE - cross over; left brain controls right side
2. OLIVES (2)
a. Balance & coordination
b. Sound volume
3. Nuclei for Cranial nerves V, IXèXII Cranial nerves - Roman
4. Reflexes Spinal nerves - Arabic
a. Heart, vessels, respiration
b. Swallow, vomit, cough, sneeze, hiccup
B. PONS - Superior & anterior to medulla
1. Ascending & Descending tracts
2. PONTINE NUCLEI - a. Sleep
b. Respiration
c. Cerebrum-Cerebellum coordination
3. Nuclei for Cranial nerves Vè IX
C. MIDBRAIN - Superior to pons, smallest part of brainstem
1. TECTUM (roof) = CORPORA QUADRIGEMINA
a. SUPERIOR COLLICULI - visual, auditory & touch reflexes
b. INFERIOR COLLICULI - hearing & helps auditory-visual reflexes
2. TEGMENTUM (floor)
a. Ascending tracts
b. RED NUCLEI - unconscious regulation & coord. of motor
3. CEREBRAL PEDUNCLES -major descending motor tracts
4. SUBSTANTIA NIGRA - “black body” - melanin
a. coordinating movement & muscle tone
b. lesion here = Parkinson’s disease
5. Nuclei for Cranial nerves III, IV & V
D. RETICULAR FORMATION - scattered throughout brainstem
1. Controls arousal from sleep & unconsciousness
2. Retic. activing system - input from face, sound, sight
3. Damageècoma
IV. CEREBELLUM = Little brain (Fig. 13.6, p. 445)
A. Organization like cerebrum
B. 3 Parts:
1. FLOCCULONODULAR LOBE – balance & eye movements
2. CENTRAL VERMIS – fine & smooth motor coordination
3. LATERAL HEMISPHERES – learning skilled movements
C. FUNCTION: “MUSCLE MEMORY”
1. COMPARATOR - “Fine tuner”, smooth, fluid movements
2. Coordination w/cerebrum muscular movements
3. Balance = PROPRIOCEPTION - position of body & parts
4. Learn highly skilled, complex motor movements w/practice
V. DIENCEPHALON - between brainstem & cerebrum, lots of nuclei
- 4 regions (Fig. 13.7, p. 446)
A. THALAMUS - 4/5 of Diencephalon, “Switchboard”
1. Integration of most sensory input - EXCEPT SMELL!
2. 2 lobes connected by INTERMEDIATE MASS - tract
3. MEDIAL GENICULATE BODY - auditory input
4. LATERAL GENICULATE BODY - visual input
5. SENSORY STIMèTHALAMUSèCEREBRUM (EXCEPT SMELL!)
6. Motor fxns in response to moods
B. SUBTHALAMUS - help control motor function
C. EPITHALAMUS
1. HABENULAR NUCLEI - emotional response to smell
2. PINEAL BODY/EPIPHYSIS - “pine-cone” shaped
a. Brain sand - Ca & Mg salts
b. Puberty (?)
c. Sleep/wake (?)
D. HYPOTHALAMUS - many nuclei & tracts, many fxns (Tab. 13.3, p. 447)
1. MAMILLARY BODIES - reflex centers for olfaction
2. INFUNDIBULUM - stalk to HYPOPHYSIS = PITUITARY - helps
control endocrine system
3. IMPUT/AFFERENT from:
a. Viscera
b. Taste
c. Limbic system - emotional response to smell
d. Sexual stimulation
e. Mood
4. OUTPUT/EFFERENT to:
a. A.N.S. - i. Metabolism & heart rate
ii. Body temp: If éèsweat; êèshivering
iii. Urine production
b. Pituitary - electrolyte balance, sex. dev. & fxns, CONTROLS ENDO.
c. Swallowing, regulates hunger & thirst
d. Emotions: fear, rage, feel good, full, etc.
e. Sleep/wake regulation
5. HOMEOSTASIS of appetite, satiety, thirst, rage, mood
a. REMOVEègiant rats up to 30 lbs ! ! !
VI. CEREBRUM (Fig 13.8, p. 449)
- Largest part
- Uniquely human qualities
- Folds é surface area: GYRUS (GYRI) = ridges
SULCUS (SULCI) = grooves
A. 2 HEMISPHERES - L controls R half of body & vice versa
1. Longitudinal fissure splits L & R hemispheres
2. CORPUS CALLOSUM - commissure connects, tracts
3. LEFT= Analytical & speech
4. RIGHT = Artistic & Music
B. 5 LOBES - named after skull bone found under
1. FRONTAL
a. Voluntary motor fxn, motivation, mood, aggression
2. PARIETAL - central sulcus separates from frontal
a. Most sensory input
b. Except smell, hearing & vision
3. OCCIPITAL - Visual reception & integration
4. TEMPORAL - lateral fissure separates from rest of cerebrum
a. Olfactory & Auditory input
b. “Psychic cortex” - Highest level of brain fxn:
- abstract thought, memory & judgment
5. INSULA - deep in lateral fissure; memory & emotional state
C. GRAY MATTER
1. CORTEX - outer surface
2. NUCLEI = BASAL NUCLEI/GANGLIA - deep inside cerebrum
D. WHITE MATTER
1. MEDULLA - between cortex & nuclei
2. TRACTS - connect cortex (Fig. 13.9, p. 450)
a. ASSOCIATION - fibers w/in same hemisphere
b. COMMISSURAL - in CORPUS CALLOSUM, between hemis.
c. PROJECTION - fibers to outside of cerebrum
E. BASAL NUCLEI/GANGLIA - inner gray matter, largest nuclei in brain
1. MIDBRAIN - SUBSTANTIA NIGRA (Fig. 13.10, p. 450)
2. DIENCEPHALON - SUBTHALAMIC NUCLEI
3. CEREBRUM - CORPUS STRIATUM
a. CAUDATE NUCLEUS
b. LENTIFORM NUCLEUS
4. FUNCTION: a. posture & muscle tone
b. Inhibit unwanted muscle activity
F. LIMBIC SYSTEM (Fig. 13.11, p. 451)
1. Many components
2. Influences: a. Mood b. Personality c. Emotions
d. Smell & memory e. Response to pleasure/pain
VII. MENINGES & C.S.F.
A. MENINGES - C.T. layers around C.N.S. (Fig. 13.12, p. 452)
1. DURA MATER - “tough mother”, outermost
a. 2 over brain w/sinuses, contin. w/ periosteum
b. 1 over spinal cord, epidural space between periosteum
2. ARACHNOID LAYER
a. Thin, delicate & web-like
b. SUBARACHNOID SPACE - C.S.F.
3. PIA MATER - “delicate mother”, innermost
a. DENTICULATE ligaments - hold pia to dura in cord
B. VENTRICLES - lined w/Ependyma, w/ CSF (Fig. 13.13, p. 454)
1. LATERAL - 1/hemisphere
a. SEPTUM PELLUCIDUM separates
2. 3rd - Around diencephalon
a. INTERVENTRICULAR FORAMEN connects to laterals
3. 4th - over Pons & Medulla
a. CEREBRAL AQUEDUCT to 3rd ventricle
b. Cont. w/ central canal of spinal cord
C. C.S.F. (Fig. 13.14, p. 455)
1. Derived from plasma of blood
2. CHOROID PLEXUS - produces
a. Invag. of vascular pia into ventricles
b. Lined w/ependymal cells
3. In ventricles, subarachnoid space, sinuses & central canal
4. Pathway: Lateral Vè3rd Vè4th Vèmedian & lateral
foraminaèout to subarachnoid spaceèsagittal sinusè
arachnoid granulationsèblood
VIII. CRANIAL NERVES [I-XII] - ARISE FROM BRAIN (Fig. 13.15, p. 458)
A. FUNCTIONAL ORGANIZATION - *KNOW Tab. 13.4, p. 458
S 1. SENSORY
O I. OLFACTORY
O II. OPTIC
A VIII. AUDITORY
S 2. SOMATOMOTOR
T IV. TROCHLEAR
A VI. ABDUCENS
S XI. SPINAL ACCESSORY
H XII. HYPOGLOSSAL
3. SOMATOMOTOR & SENSORY
V. TRIGEMINAL
4. SOMATOMOTOR & PARASYMPATHETIC
III. OCULOMOTOR
5. SOMATOMOTOR, SENSORY & PARASYMPATHETIC
VII. FACIAL
IX. GLOSSOPHARYNGEAL
X. VAGUS