Bio 40B
Dr. Kandula

 Part of CNS
 Found in dorsal body cavity
 Continuous with spinal cord at foramen magnum
 The development and uniqueness of brain makes humans “ superior ” to other animals

Enclosed and protected by the cranium and three membranes called meninges
 Dura Mater
 Arachnoid Mater
 Pia Mater

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 Three membranes that surround and protect the brain
 Dura mater outermost tough fibrous membrane
Made up of 2 layers : outer periosteal layer is attached to cranium; inner layer surrounds brain

• There are 3 inward folds of dura mater:
• Falx cerebri: Goes into longitudinal fissure separating two cerebral hemispheres
• Falx cerebelli: Separates the 2 hemispheres of cerebellum
• Tentorium cerebelli: Separates cerebrum from cerebellum

 Arachnoid lies deep to dura mater and is separated from it by subdural space , this space contains small amounts of interstitial fluid. The arachnoid is an avascular layer.
 Pia mater lies deep to the arachnoid layer and is separated from it by the subarachnoid space.
The subarachnoid space contains cerebrospinal fluid . The pia mater is tightly attached to surface of brain.

Made up of 4 parts:
The four parts include: cerebral hemispheres, diencephalon, brainstem and cerebellum.

 In humans the cerebrum is the most prominent part and makes up 70 % of the brain

 Separated into two hemispheres by longitudinal fissure
 Falx cerebri found in fissure
 Corpus callosum (white matter fibers) connects two hemispheres at base of fissure

 Gyri (pl) or gyrus (sing) are ridges
 Sulci (pl) or sulcus (sing) are shallow grooves
– central sulcus,
– parieto-occipital sulcus,
– lateral sulcus
 Fissures are deeper grooves
– longitudinal fissure
– transverse fissure

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Cortex: Thin outer edge of gray matter (neuron cell bodies)
Thick central core of white matter (axons)
Four lobes
– Parietal: receives sensory info
– Frontal: voluntary motor
– Occipital: vision
– temporal: hearing, taste

Important gyri
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Precentral gyrus – primary motor area, ie. all impulses for voluntary muscular activities originate here.
Postcentral gyrus – primary sensory area, ie., all general senses information perceived here

1. Thalamus
 Mostly gray matter
 Relays sensory info to cerebrum
2. Hypothalamus
 “ master gland ” of body
 Controls hormones, temp, emotion, thirst
 Maintains homeostasis
 Controls ANS functions
3. Epithalamus has pineal gland to control day/night cycles.

1.
Medulla oblongata
 White matter of motor and sensory neurons
 This is where neurons cross to opposite side of body pyramids
 Breathing and heart control
2.
Pons means “ bridge ”
 Bridge between medulla and midbrain
 Also contains breathing center/helps regulate breathing
3.
Midbrain
 Corpora quadrigemina ,( superior and inferior colliculi) controls reflexes associated with hearing and vision
 cerebral aqueduct (with CSF)

 Also has 2 hemispheres connected by a body called vermis
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Function: coordination, balance and equilibrium
Folds of gray matter  folia
 White matter arrangement characteristic and called arbor vitae

 Function: cushion/protect brain and spinal cord
 Made by the ependymal cells of choroid plexuses (small capillaries in the ventricles)
 Circulates through subarachoid space and the four ventricles
 Finally, CSF drains out the arachnoid villi back into the blood circulation

Lateral ventricles  foramen of Munro  third ventricle  cerebral aqueduct  fourth ventricle  central canal of spinal cord or subarachnoid space surrounding brain and spinal cord

 Part of the peripheral nervous system
 12 pairs that mostly control head and neck
 Nerves contain motor neurons, sensory neurons, or mixed
 See handout

III
IV
V
I
Number Name
II
VI
Olfactory
Optic
Innervation Type Function
Temporal lobe of brain sensory Smell
Occipital lobe of brain sensory Vision
Occulomotor Eye muscles and ciliary body mixed
Trochlear
Trigeminal
Abducens
Superior oblique muscle of eye mixed touch –pain– temperature to the face; motor division of the nerve supplies the muscles of mastication supply a muscle called the lateral rectus muscle that moves the eye outward. mixed mixed
Movement of eyeball
Movement of eyeball
Touch on face; mastication
Movement of eyeball

Numb er
VII
VIII
Name
Facial
Auditory
Innervation Type
Action motor portion supplies all the facial musculature/ sensory portion, taste to the anterior two-thirds of the tongue; secretory to the lacrimal gland and salivary glands
Temporal lobe of brain mixed facial musculature, taste, and tears & saliva secretion sensory Hearing and equilibrium
IX
X
Glossopharyngeal Pharynx, tongue and salivary glands mixed TASTE POSTERIOR
1/3 TONGUE,
SALIVATION,
SWALLOWING
Vagus Pharynx heart, respiratory tract,
GIT, mixed GASTRIC PANCREATIC
SECRETIONS, GI
MOVEMENT, CARDIAC,
RESPIRATORY AND
VISCERAL REFLEX

Number Name Innervation Type Action
XI
XII
Spinal
Accessory
Muscles of neck and shoulder mixed MUSCLE
MOVEMENT
(sternocleidomastoid, trapezius) AND
VISCERAL REFLEX
Hypoglossal Tongue muscles mixed Tongue movement