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THE BRAIN

THE BRAIN. Brain Directional Terms and Landmarks. Rostral - toward the forehead Caudal - toward the spinal cord. 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 .

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THE BRAIN

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  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. THEBRAIN & 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

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