Brain and cranial nerves

  1. What is the Cerebellum
    • •Cerebellum (“little brain”) is
    • located below the posterior portion of cerebrum

    • –Separated from the cerebrum by
    • transverse fissure and tentorium cerebelli

    –Gray matter compose the cortex

    • –White matter predominates in the
    • interior part of cerebellum
  2. what is it's function?
    • –Evaluates how well movements
    • initiated by motor areas are actually being carried out

    • –Together with cerebrum produces
    • skilled movement by coordinating the activities of groups of muscles

    –Control posture

    –Control skeletal muscles to maintain balance
  3. Diencephalon
    •Located between cerebrum and the midbrain

    •Composed of several structures located around third ventricles:

    –Thalamus, hypothalamus, optic chiasm, pineal gland
  4. Thalamus
    –Dumbbell-shaped mass of gray matter

    •Consists of large number of nuclei

    –Each lateral mass forms lateral wall of 3rd ventricle

    –Intermediate mass- joints the two lateral masses

    –Geniculate bodies

    »Responsible for processing of auditory and visual input
  5. Thalamus functions
    •Conscious recognition of the less critical information about the sensation of pain, temperature and touch

    •Relay sensory information to cerebrum

    •Important for the association of sensory impulses with feeling of pleasure/unpleasure

    •Plays a part in arousal mechanism
  6. Hypothalamus
    –Forms floor of the third ventricle and lower part of the lateral wall

    –Four regions:

    •Supraoptic Nuclei

    •Preoptic Nuclei

    •Mammilary Bodies

    •Tuberal Region
  7. Hypothalamus functions

    •Controls and integrates the activities of ANS

    •Synthesize hormones

    •Regulates emotions and behaviour

    •Regulates eating and drinking

    –Feeding centre

    –Satiety centre

    –Thirst centre

    •Controls body temperature

    •Regulate circadian rhythms (sleep and wake cycle)
  8. Epithalamus
    –Pineal gland

    •Size of small pea

    •Secretes the hormone melatonin

    –Melatonin promotes sleeping

    –Habenular nuclei

    •Involved in a emotional response to odour
  9. Cerebrum - cerebral cortex
    •Cerebral Cortex

    –Outer layer of the cerebrum

    •Gyri/convolutions - folds

    •Fissures - deep groves between folds

    –Longitudinal fissures separates the cerebrum into left and right emispheres

    •Sulci- shallow groves between folds

    –Corpus callosum

    •White matter-composed of axons that connect left and right hemispheres of the brain

    •Forms roof of the lateral and 3rd ventricles
  10. Lobes of Cerebrum
    •Each hemisphere is composed of four lobes:

    –Frontal lobe

    –Parietal lobe

    –Temporal lobe

    –Occipital lobe
  11. Cerebral White Matter
    •Composed of myelinated axons

    •Consist of:

    –Association tracts

    •Conduct nerve impulses between Gyri of the same hemisphere

    –Commissural tracts

    •Conduct nerve impulses from gyri in one cerebral hemisphere to corresponding gyri in the other hemisphere

    –Projections tracts

    •Conduct nerve impulses from cerebrum to lower parts of the CNS
  12. Basal Ganglia
    • •Composed of three
    • nuclei:

    –Globus Pallidus


    –Caudate Nucleus
  13. Functions of Basal Ganglia
    • •Function of Basal
    • Ganglia:

    –Initiate and terminates body movement

    –Regulates muscle tone
  14. The Limbic System
    •Limbic system or “emotional brain”

    –Sex, rage, fear, pleasure, pain

    –Integration of recent memory

    –Biological rhythms.

    •Most structures lie on the medial surface of the cerebrum

    –Cingulate gyrus

    –Parahippocampal gyrus


    –Dentate gyrus


    –Septal nuclei
  15. Functional Organization of Cerebral Cortex
    –Primary somatosensory areas:

    •Located posterior to the central sulcus of each hemisphere (postcentral gyrus of each parietal lobe)

    •Cortex contains “somatic sensory map”

    •Somatic senses, including sensation of touch, pressure, vibration, temperature, pain, and proprioception

    –The primary visual area

    –The primary auditory area

    –The primary gustatory area

    –The primary olfactory area
  16. Functional Organization of Cerebral Cortex - Motor area
    –Receives input from the anterior aspect (frontal area) of each hemisphere

    •Primary motor area

    –Precentral gyrus

    –Involved in a control of contraction of muscle/muscle groups

    •Broca’s speech area

    –Located in the frontal lobe close to the lateral cerebral sulcus

    –Important for the articulation of speech
  17. Functional Organization of Cerebral Cortex - association areas
    • –Localized to large areas of
    • occipital, parietal, and temporal lobes, as well as frontal lobes

    •Somatosensory association area

    •Visual association area

    •Facial recognition area

    •Auditory association area

    •The orbitofrontal cortex

    •Wernicke’s area

    •The common integrative area

    •The prefrontal cortex

    •The premotor area

    The frontal eye field area
  18. Hemispheric Lateralization
    •Right and left hemispheres specialize in different functions

    –Both hemispheres communicate with each other to perform complex functions

    –Left Hemisphere

    •Language function

    •Dominant control of certain types of hand movement

    –Right Hemisphere

    •Tactual perception

    •Perception and visualizing of spatial relationships
  19. Cranial Nerves
    •Twelve pairs of cranial nerves

    •Cranial nerves can be identified by name or number (order in which they emerge, anterior to posterior)

    •Composed of axon bundles that contain:

    –Sensory cranial nerves

    –Motor cranial nerves

    –Mixed cranial nerves
  20. Olfactory Nerve (I)
    –Carry the information about the sense of smell

    –Dendrites and cell bodies lie in nasal mucosa

    –Axons terminate in olfactory bulb
  21. Optic Nerve (II)
    –Carry visual information from eyes to the brain

    –Sensory axons terminate in the innermost layer of the retina

    –Enter cranial cavity through the optic foramina

    –Unites at the optic chiasm
  22. Oculomotor Nerve (III)
    • –Fibers originate from cells in the oculomotor nucleus
    • and project to some of the external eye fibres

    –Efferent autonomic fibers

    •Regulate the amount of light entering the eye and focusing on near objects

    –Sensory fiber from proprioceptors in the eye musculature
  23. Trochlear Nerve (IV)
    –Contain afferent fibers from proprioceptors
  24. Trigeminal Nerve (V)
    –Each trigeminal nerve has three branches:

    •Ophthalmic nerve

    •Maxillary nerve

    •Mandibular nerve

    –Composed of sensory and motor fibers

    • •Sensory fibers carry afferent impulses from skin and mucosa of head and teeth to cell bodies in trigeminal
    • ganglion

    •Motor fibers originate in trifacial motor nucleus and project to the muscle of mastication

    –Trigeminal neuralgia
  25. Abducens Nerve (VI)
    • –Motor fibers originate in the pons on the floor of the 4th
    • ventricle and project to the lateral rectus muscles of the eye

    –Contains afferent fibers from proprioceptors in the lateral rectus muscle
  26. Facial Nerve (VII)
    • –Motor fibers originate from a lower part of the point and project to superficial muscles of the face and
    • scalp

    –Autonomic fibers project to submaxillary and sublingual glands

    –Contains sensory fibers from taste buds of the anterior 2/3 of the tongue
  27. Vestibulocochlear Nerve (VIII)
    –Vestibular Nerve

    •Originate in a semicircular canals in inner ear

    •Responsible for the sensation of equilibrium

    –Cochlear Nerve

    •Originate in the organ of Corti in the cochlea of the inner ear

    •Transmit impulses that result in a sense of hearing
  28. Glossopharyngeal Nerve (IX)
    –Composed of sensory, motor and autonomic nerve fibers

    Supply carotid sinus, tongue and pharynx
  29. Vagus Nerve (X)
    –Composed of sensory and motor fibers

    •Sensory fibers supply pharynx, larynx, trachea, heart, carotid body, lungs, bronchi, esophagus, stomach, small intestine, and gallbladder

    •Motor fibers innervate pharynx and larynx

    •Parasympathetic function (heart, lungs, etc.)
  30. Accessory Nerve (XI)
    –Motor nerve “accessory” to the vagus nerve

    –Innervates the thoracic and abdominal viscera, pharynx, larynx, trapezius and sternocleidomastoid
  31. Hypoglossal Nerve (XII)
    –Composed of sensory and motor fibers

    –Sensory fibers from proprioceptors in muscles of the tongue

    –Motor fibers innervate the muscles of the tongue
Card Set
Brain and cranial nerves
chapter 14