Anatomy

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Anatomy Physiology

• Part 2 Nervous System

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The Brain

• 100 billion multipolar neurons
• 3 major components
• The cerebrum largest part (associated with
  sensory motor functions, higher mental
  functions)
• The cerebellum (voluntary muscle movement
  coordination)
• The brain stem (connects regulates viscera)
• Another part of the brain is the diencephalon.
  This is also associated with sensory functions.

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Cerebrum

• There are 2 cerebral hemispheres. This is
  collectively called the cerebrum.
• Gyri are ridges sulci are grooves.
• Fissures are deep grooves
• Fissures divide the cerebrum into lobes.

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• The corpus callosum is a bridge of nerve fibers
  that connect the 2 hemispheres.
• The hemispheres generally mirror each other.

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Cerebrum Lobes

• These are named for the bones they are under.
• Frontal lobe
• Parietal lobe
• Temporal lobe
• Occipital lobe
• Insula

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• There are 3 main areas of the cerebrum
• Cerebral Cortex
• White Matter
• Basal Nuclei

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Cerebrum Cerebral Cortex

• Functions speech, memory, logic, emotional
  responses, voluntary movement
• The cortex includes
• Brocas area vocalization/formation of words
• Speech area language comprehension (meanings of
  words)

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Cerebrum

• White Matter

• Basal Nuclei

• Contains nerve tracts that allow communication to
  occur between hemispheres and brain stem

• a.k.a. basal ganglia
• Gray matter
• Regulate voluntary motor functions

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Diencephalon

• It contains the thalamus, hypothalamus, optic
  tracts pituitary gland, mammillary gland pineal
  gland.
• The thalamus is the central region of message
  relays receiving all sensory info (except smell)
  transmitting the signals to the appropriate
  location.
• It produces awareness of sensations.

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• The hypothalamus maintains homeostasis links
  the NS to the endocrine system. It regulates
• Heart rate blood pressure
• Body temperature
• Water electrolyte balance
• Hunger body weight
• Stomach intestinal secretions movement
• Sleep wakefulness
• Production of stimulants for the pituitary gland

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Diencephalon

• Other glands part of the Diencephalon
• Pituitary gland (hormones)
• Pineal gland (sleep regulation)
• Choroid plexuses (capillaries that secrete CSF)

• The hypothalamus includes the limbic system and
  controls emotional responses expression as a
  result, it guides behavior to increase the chance
  of survival.

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Brain Stem

• Connects the spinal cord to the cerebrum
• Includes the midbrain, pons medulla oblongata
• The midbrain contains reflex centers (visual
  auditory)

Midbrain
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• The pons is between stem oblongata relays
  sensory impulses regulates rate depth of
  breath.
• The medulla oblongata is below the pons

• The medulla oblongata is associated with
  coughing, sneezing, swallowing vomiting
  reflexes.
• It controls heart rate, blood pressure, and
  breathing

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• The reticular formation is a network of nerve
  fibers that are throughout the midbrain, pons
  medulla oblongata.
• This regulates wakefulness (increased activity
  increases awareness decreased activity induces
  sleep).
• If this is injured, this causes unconsciousness
  if the person cannot be aroused, a comatose state
  (coma) results.

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Cerebellum

• Integrates coordinates sensory info skeletal
  muscles helps to maintain posture.
• Injury to this area will cause tremors
  (involuntary movements), inaccurate movements,
  staggering walk, muscle tone loss or equilibrium
  disturbance.

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Protection of CNS Meninges

• The CNS is surrounded by bones, membranes
  fluids (skull contains the cranial cavity which
  contains the brain, etc.).
• The membranes of the CNS are the meninges
  (between bones soft tissues).
• These protect the brain spinal cord.
• There are 3 layers to the meninges dura mater,
  arachnoid mater, pia mater.

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Meninges

• Arachnoid Mater

• Dura Mater

• outermost layer
• found within the cranial cavity, surrounds skull
  bones, extends inward between brain lobes
• Surrounds the spinal cord ends as a sac right
  below the cord (but is not attached to the
  vertebrate).

• Thin membrane without a blood supply
• Between dura mater pia mater
• Covers brain spinal cord

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• Between the arachnoid mater pia mater is the
  subarachnoid space. The cerebrospinal fluid
  (CSF) is contained here.
• This is a clear watery fluid that bathes the
  brain spinal cord.

• Pia Mater
• The innermost layer of the meninges
• Covers the brain spinal cord and follows their
  surfaces closely

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Spinal Cord

• This is a nerve column that goes from the brain
  into the vertebral canal.
• Consists of 31 segments 31 pairs of spinal
  nerves
• There are 2 enlargements the cervical
  enlargement contains the nerves for the upper
  limbs the lumbar enlargement contains the nerves
  for the lower limbs.

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Spinal Cord with Meninges
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PNS Cranial Nerves

• There are 12 pairs of cranial nerves
• 1. Olfactory nerves (I) sense of smell
• 2. Optic nerves(II) vision (eyes to brain)
• 3. Oculomotor nerves (III) eye muscle movement
  (somatic autonomic)
• 4. Trochlear nerves (IV) eye movement smallest
  cranial nerves
• 5. Trigeminal nerves (V) contain ophthalmic,
  maxillary, mandibular nerves mixed nerves
  largest cranial nerves.

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• 6. Abducens nerves (VI) aids in eye muscle
  movement
• 7. Facial nerves (VII) taste receptors
  stimulate salivary tear gland secretions
  (autonomic)
• 8. Vestibulocochlear nerves (VIII) maintain
  equilibrium enable hearing (ear)
• 9. Glossopharyngeal nerves (IX) swallowing
  mixed nerves associated with the tongue
  pharynx.
• 10. Vagus nerves (X) speech swallowing mixed
  (autonomic somatic)
• 11. Accessory nerves (XI) cranial spinal
• 12. Hypoglossal nerves (XII) tongue, speaking,
  chewing swallowing.
• See textbook for summary of cranial nerves.

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PNS Spinal Nerves

• Come from the spinal cord
• Grouped according to their location
• Cervical nerves (C1 to C8) 8 pairs
• Thoracic nerves (T1 to T12) 12 pairs
• Lumbar nerves (L1 to L5) 5 pairs
• Sacral nerves (S1 to S5) 5 pairs
• Coccygeal nerves (Co) 1 pair
• See textbook summary of these spinal nerves.

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Autonomic Nervous System

• Functions independently (autonomous), meaning
  without conscious thought
• Controls visceral functions
• Contains the parasympathetic sympathetic
  divisions
• The parasympathetic division functions during
  restful conditions while the sympathetic division
  functions during emergency, stressful energy
  spending situations.

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• Look up in text or online!
• Know the following
• Huntingtons Disease, Parkinsons Disease,
  Ataxia, Meningitis, Encephalitis, Hydrocephalus,
  Blood brain barrier, Concussion, Contusion,
  Intracranial hemorrhage, cerebral edema, CVA,
  hemiplegia, TIA, Cerebral palsy, Spina bifida,
  and Senility