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Lecture Notes
The brain contains many reflex control centers, like the spinal cord,
but also contains gray matter that allows conscious activities like cognition,
speaking and walking.
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I. The Brain Protective layers and structures
A. Meininges and layers
Meninges same as spinal cord, in general.
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B. Ventricles:
They are chambers within the brain filled with CSF which is produced here..
They are continuous with each other, the subarachnoid space, and
the central canal of the spinal cord.
C. Cerebrospinal Fluid (CSF):
It circulates within and around the brain and spinal cord.
It cushions to prevent physical injury.
It also helps nourish the brain by transporting nutrients and gases.
Production: CSF is made by the choroid plexus which are
clusters of thin-walled capillaries in the ventricles. Choroid plexus are also
known as the Blood Brain Barrier.
II. Brain Parts/Regions
FOCUS ON FUNCTIONS OF BRAIN STRUCTURES
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A. Brain Stem:
some gray (control centers) and white matter (carry information towards/away
from brain)
All of its functions are autonomic and involuntary.
1) Medulla oblongata:
- continuous with spinal cord at foramen magnum
- heart rate regulation
- respiratory rate regulation
- blood pressure (vasodilation and vasoconstriction) regulation
- vommitting, coughing, sneezing, swallowing
2) Pons:
- inferior to midbrain and anterior to cerebellum
-secondary respiratory control center to medulla oblongata
3)Midbrain:
- inferior to the thalamus
- control center for visual and auditory "startle" reflexes (rapid
movement of head/neck in response to bright lights/loud sounds)
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B. Diencephalon: almost all gray matter (control centers, again)
1) Thalamus:
- relay station for sensory impulses to the cerebral cortex
- memory processing
2) Hypthalamus:
act as control center for regulating below body condition:
- body temperature
- food intake (hunger)
- water balance and thirst
-reproduction
-metabolism
-growth
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3)Pituitary Gland. an extension of the hypothalamus found below the hypothalams.
Triggered by hypothalamus to produce hormones that regulate reproduction, metabolism
and growth.
C. Cerebellum:
- maintains posture and ensures smooth coordinated movements
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D. Cerebrum: largest percentage of total brain mass
1) Cerebral Cortex:
Gyri = ridges or “hills”
Sulci = grooves or “valleys”
Fissures: very deep grooves that separate lobes from each other
and other brain parts.
Cortical functions are generally voluntary and conscious and fall in one of
three functional categories:
- motor
- sensory
- association
Lobes of the cerebral cortex:
a) Prefrontal: intellect, cognition, mood, personality, judgement,
reasoning.
b) Frontal:
- conscious skeletal muscle control of muscles on opposite side (= primary motor
area)
- voluntary eye movements
- motor speech (voluntary movements for speaking)
c) Parietal:
- body sensory information (touch and position) from skin and muscles (= primary
somatosensory cortex)
- gustation/taste
d) Occipital:
-sensory vision
e) Temporal:
-auditory
-olfaction/smell
-balance
2. Corpus Callosum
a white matter tract that allows communication between hemispheres of cerebral
cortex.
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I II. Cranial Nerves: 12 pairs
FOCUS ON THE FUNCTION OF THE NERVES
Most are mixed nerves, having both motor and sensory neurons.
Nerves I, II, and VIII are ONLY sensory.
Functional image of cranial nerves
1) Olfactory (I): smell sensory input
2) Optic (II): vision sensory input
3) Oculomotor (III):Eye Movement
Note (three nerves work together on this)
4) Trochlear (IV): eye movement
5) Trigeminal (V):Chewing movements, Facial sensation ( of the skin) sensory
input
6) Abducens (VI): eye movement
7) Facial (VII):Movement of facial expression muscles, taste (from anterior
2/3 of tongue)
8) Vestibulocochlear (VIII): Hearing (hence "Cochlea"), Equilibrium sensory input
9) Glossopharyngeal (IX): Reception of blood pressure, blood gas levels, Taste ( from posterior 1/3 of tongue)
10) Vagus (X): reception of blood pressure and blood gas chemistry, controls smooth movements in digestive system, decreases cardiac muscle contractions, increases secretion of digestive juices
11) Accessory (XI) and 12) Hypoglossal (XII): Head and Neck Movement, Tongue
movements
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Professor Thomas M. Lancraft
Human Anatomy Courses
at St. Petersburg College
St. Petersburg/Gibbs Campus
6/2006
