THE BRAIN

1
THE BRAIN
2
Brain Directional Terms and Landmarks

• Rostral - toward the forehead
• Caudal - toward the spinal cord

3
Superior View of the Brain

• A longitudinal fissure (deep groove) separates 2
  cerebral hemispheres.
• Folds are called gyri and the shallow grooves are
  called sulci.
• The surface layer (cortex) consists of gray
  matter.
• Deeper masses of gray matter are called nuclei.
• Bundles of axons (white matter) are called tracts.

4
Median Section of the Brain
5
MAIN PARTS OF THE BRAIN

• 1. Brain stem - continuous with spinal cord
• - consists of medulla oblongata, pons,
• midbrain
• 2. Cerebellum - posterior to brain stem
• 3. Diencephalon - superior to brain stem
• - consists of thalamus hypothalamus
• 4. Cerebrum - occupies most of cranium

6
MEDULLA OBLONGATA

• Relays impulses between other parts of brain
  spinal cord.
• Functions in consciousness arousal.
• Regulates heart beat, breathing, and blood vessel
  diameter.
• Coordinates swallowing, vomiting, coughing,
  sneezing, and hiccuping.

7
PONS

• Relays impulses from one side of the cerebellum
  to the other between medulla midbrain.
• Helps medulla to control breathing.

8
MIDBRAIN

• Functions include
• relay of motor impulses from cerebral cortex to
  the pons
• relay of sensory impulses from the spinal cord to
  the thalamus

9
CEREBELLUM

• Coordinates skilled movements.
• Regulates posture balance.
• Gray matter is superficial (cortex).
• White matter is deep.
• Has arbor vitae (tracts).

10
DIENCEPHALON

• Epithalamus - contains pineal gland
• Thalamus - functions in cognition, relay of
  sensory input to the cerebral cortex, provision
  of crude perception of touch, pressure, pain,
  temperature
• Subthalamus - helps to control body movements
• Hypothalamus - has many functions

11
HYPOTHALAMIC FUNCTIONS

• Controls integrates activities of the autonomic
  nervous system pituitary gland.
• Regulates emotional behavioral patterns,
  circadian rhythms, body temperature, eating
  drinking behavior, sleep patterns.

12
CEREBRUM

• Cortex has gyri (ridges), shallow grooves (sulci)
  and deep grooves (fissures).
• Gray matter is superficial (cortex).
• White matter is deep.

13
CEREBRUM

• Interprets sensory impulses.
• Controls muscular movement.
• Functions in emotional intellectual processes.

14
Functions of Cerebral Lobes

• Frontal concerned with
• voluntary motor functions,
• planning, mood, smell, and
• social judgement
• Parietal - concerned with sensory reception
  integration of sensory information
• Occipital serves as a visual center
• Temporal concerned with hearing, smell,
  learning, memory, emotional behavior

15
CRANIAL MENINGES

• Continuous with spinal meniniges
• Dura mater - outermost - extensions separate the
  brain into regions
• Arachnoid - middle meninx - avascular - has
  collagen fibers
• Pia mater - innermost - surround blood vessels in
  brain

16
Cranial Meninges
17
EXTENSIONS OF DURA MATER

• Falx cerebri - separates the cerebral hemispheres
• Falx cerebelli - separates the two hemispheres of
  the cerebellum
• Tentorium cerebelli - separates cerebrum from
  cerebellum

18
THE BRAIN BLOOD

• The cerebral arterial circle (circle of Willis)
  carries blood to the brain.
• A blood-brain barrier (BBB) protects brain cells
  from pathogens other harmful substances in
  blood.
• Lipid-soluble substances such as oxygen,carbon
  dioxide, alcohol, and anesthetic agents can pass
  readily into brain tissue.
• Only few water-soluble substances e.g. glucose
  can pass the BBB.

19
CEREBROSPINAL FLUID

• Clear, colorless liquid
• Produced by choroid plexuses (capillaries covered
  by ependymal cells) in walls of brain ventricles.
• Circulates through subarachnoid space through
  cavities within brain spinal cord.

20
CEREBROSPINAL FLUID

• Protects brain spinal cord against chemical
  physical injuries
• Carries oxygen, glucose, and other chemical
  requirements from blood to nerve cells
• Reabsorbed into blood through arachnoid villi

21
Flow of Cerebrospinal Fluid
22
VENTRICLES

• Internal chambers within the CNS
• lateral ventricles found inside cerebral
  hemispheres
• third ventricle is single vertical space under
  corpus callosum
• cerebral aqueduct runs through midbrain
• fourth ventricle is small chamber between pons
  cerebellum
• central canal runs down through spinal cord
• Lined with ependymal cells and containing choroid
  plexus of capillaries that produce CSF

23
CRANIAL NERVES

• 10 of 12 pairs of cranial nerves emerge from the
  brain stem.
• Each nerve is designated by a Roman numeral.

24
Inferior View of the Brain