Download Brain and Cranial Nerves

Insight:
Some cranial nerve disorders
Brain and Cranial Nerves (Ch. 15)
Human Anatomy lecture
I. Overview
(Directional terms:
rostral = toward the forehead
caudal = toward the spinal cord)
A. 3 Major parts – KNOW Fig. 15.1
1. Brain stem
- medulla oblongata
- pons
- midbrain
- diencephalon (many texts disagree and consider this a 4th part on its own)
2. Cerebrum
3. Cerebellum
B. Major landmarks
Cerebrum
• cerebral hemispheres separated by longitudinal fissure
• corpus callosum  thick band of connecting fibers at bottom of
longitudinal fissure
• gyrus (pl. = gyri) = ridge
• sulcus = groove
C. Protection and coverings
1. Same 3 meninges;
2. Dura mater has 2 layers - Fig. 15.3
3. 3 Extensions of dura help anchor (Fig. 15.3 & 15.5)
- falx cerebri- falx cerebelli- tentorium cerebelli-
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D. Cerebrospinal fluid (CSF)
1. Circulates around and within the brain
2. a. 60% produced by choroid plexuses
b. 40% produced by
KNOW Fig. 15.4 & 15.5
3. Pathway:
4. Reabsorbed
5. Functions
 CNS “blood”:

buoyant: 1500g vs. 50g!
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E. Blood supply
1. 4- prong supply through cerebral arterial circle (Review)
2. Brain capillaries less leaky
II. Brain stem
A. Medulla oblongata  Fig. 15.6, but label Fig. 15.23
1. Continuous caudally with spinal cord, rostrally with pons
~ 3 cm
2. Anterior bulges Lateral bulges 3. Functions
- conduction pathway - CNS
- nuclei
B. Pons (= “bridge”)
1. Connects medulla with midbrain; both to cerebellum(via cerebellar peduncles)
2. Nuclei for
“little feet”
C. Midbrain
1. rostral to pons; caudal to diencephalon
2. cerebral peduncles 3. cerebral aqueduct
4. corpora quadrigemina (= “quadruplets”)
- superior colliculi - inferior colliculi 5. several other nuclei,
D. Diencephalon – Fig. 15.11
1. Thalamus (80%)
- 2 large masses bulge medially into 3rd ventricle and laterally into lateral
ventricles
- connected by intermediate mass
- major function
2. Epithalamus – posterior roof
- Pineal gland - neuroendocrine organ
 “pine cone”
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3. Hypothalamus - floor
4. Third ventricle
III. Cerebellum – KNOW Fig. 15.9
A. Structure
1. dorsal to brain stem,
2. central vermis
3. flat folia
 “leaf”
4.
5.
B. Functions (Fig. 15.10)
1. regulates voluntary, skilled movements by comparing intent with performance
2. regulates posture and balance
3. many others, including sensory & motor (only 10% of brain’s mass but 50% of
its neurons – 100 billion!)
IV. Cerebrum  Fig. 15.12
A. Structure
1. cerebral cortex - grows rapidly in the fetus,
- why is gray matter on outside of cerebral/cerebellar cortex but on inside of
spinal cord? 
2. some sulci separate each hemisphere into lobes (named after overlying bone)
-sketch-
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3. white matter - under cortex -- Fig. 15.13
• association tracts• commissural tracts • projection tracts–
4. basal nuclei (ganglia) – Fig. 15.16
5. limbic (= border) system – Fig. 15.15
– bilateral interconnected rings of structures
- includes hippocampus (= seahorse),
B. Functions (NRF text detail)
1. sensory areas –
2. motor areas 3. association areas 4. basal nuclei –
5. limbic system –
V. Cranial nerves
KNOW CHART: Number, Name, Function, Attachment (NRF text detail)
- 12 pairs, part of PNS
- numbered with Roman numerals rostral caudal
- use mnemonic? p. 437
- Insight: p. 431
KNOW FIG. 15.23 -- left side labels and only IVI
- note that “midbrain” should be “hypothalamus”
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CRANIAL NERVE SUMMARY
NUMBER AND NAME
I – olfactory
II – optic
III –oculomotor
SITE OF ATTACHMENT
cerebrum
thalamus
midbrain
IV – trochlear
(“pulley”)
V – trigeminal
(“triplets”)
V1 = ophthalmic
V2 = maxillary
V3 = mandibular
VI – abducens
midbrain
VII – facial
pons
VIII –vestibulocochlear
IX – glossopharyngeal
pons & medulla oblongata
medulla oblongata
X – vagus
(“wanderer”)
medulla oblongata
XI – accessory
(spinal accessory)
medulla oblongata
anterior gray horns, C1-C5
XII – hypoglossal
medulla oblongata
pons
pons
FUNCTION
smell
vision
eyeball & eyelid movement,
pupil constriction, muscle
sense
eyeball movement; muscle
sense
chewing; muscle sense
facial sensation
eyeball movement, muscle
sense
muscles of facial expression,
saliva & tear secretion;
taste, muscle sense
balance & hearing
saliva secretion, taste, blood
pressure regulation
visceral smooth muscle
control, digestive secretion;
visceral sensations, muscle
sense
head, neck & shoulder
movements; swallowing,
muscle sense
tongue movement (swallowing
& speech); muscle sense
NOTE:
1. Which 3 cranial nerves are primarily sensory?
2. There are no pure motor nerves because motor nerves also carry “muscle sense”
(proprioception) from the muscles they serve. However, 5 cranial nerves are primarily motor
and traditionally classified this way. Give the name & number of those 5.
3. Which 3 cranial nerves are involved in taste perception?
4. Which 3 cranial nerves are involved in eyeball movement?
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