Brain and Cranial Nerves PPT

June 16, 2012 | By | Reply More

Brain and Cranial Nerves PPT

Discuss the organization of the brain, including the major structures and their functions

Describe the meninges of the spinal cord and brain, and integrate the formation and flow of CSF with this information.

Describe the structures that constitute the BBB and their functions

Review the cranial nerves, again giving a brief function of each.

Major Brain Subdivisions   

Telencephalon (= Cerebrum)

Diencephalon (Thalamus and hypothalamus)


Metencephalon  (Pons and cerebellum)

Myelencephalon (= Medulla oblongata)

Gray & White Matter Organization

In brain stem similar to spinal cord (nuclei around ventricles, tracts on outside)

In cerebrum and cerebellum: white matter covered with layer of neural cortex (grey)

Cranial Meninges

1. Dura mater – strong, “tough mother”

                a. falx cerebri

                b. falx cerebelli

                c. tentorum cerebelli                        

2. Arachnoid – spidery, holds blood vesse

3. Pia mater – “delicate mother”

Four Ventricles

CSF filled chambers

Communicating with central canal of spinal cord

CSF: Cerebro-Spinal Fluid

Formation in ventricles by specialized ependymal cells of choroid plexuses (~500 mL/day; total volume ~ 150 mL)


 transport medium, in

shock absorption

 buoyancy (floats the brain)

CSF circulation: Ventricles → central canal → subarachnoid space

Reabsorption into circulation via arachnoid granulations into superior sagittal sinus.

Blood Brain Barrier (BBB)

what is it?

3 areas in brain don’t have BBB

  1. •  portion of hypothalamus
  2. •  pineal gland (in diencephalon)
  3. •  choroid plexus


Two hemispheres  separated by longitudinal fissure

Gyrus (gyri) separated by sulcus (sulci)

Major lobes named  after overlaying bones

Cerebral Hemispheres . . .

 . . have functional regions (motor, sensory and association areas)

. . . have some functional differences (in spite of anatomical resemblance)                 → Lateralization of cortical functioning

. . . receive information and generate commands for opposite side of body

Cerebral Cortex and Central White Matter

Gray surface (cortex) with white tracts internally

Commissures – connect corresponding gyri of the two hemispheres

                   1) corpus callosum

                   2)  anterior commissure

Projection tracts (fibers) – connect more or less vertically

Association tracts (fibers) – connect one gyrus to another in the same hemisphere

Basal (or cerebral) Nuclei

Misnomer: basal ganglia

Gray matter internal to the cerebral cortex, below floor of lateral ventricles.

Function: modulate motor output from the cerebral cortex.  Subconscious control of skeletal muscle tone and coordination of learned movement patterns.

Parkinson’s disease is caused by the loss of at least 80% of the dopaminergic neurons in basal nuclei and substantia nigra (resting tremor)



Pineal gland – produces melatonin,             sets diurnal cycles

Thalamus (~12 nuclei)


Just superior to optic chiasma

Infundibulum – connects to pituitary gland

Some functions:

Control of autonomic nervous system

Coordination of nervous and endocrine systems

Secretion of hormones – ADH and oxytocin


= Midbrain

Corpora quadrigemina   = 2 pairs of sensory nuclei

  • Superior colliculi (relay station for visual information)
  • Inferior colliculi (relay station for auditory information

Substantia nigra – regulates motor output

Cerebral peduncles – ascending and descending tracts to thalamus

Nuclei of ori for CN III and IV

Metencephalon:   Cerebellum

Hemispheres and lobes

Cortex -gray surface   with folia – fine ridges and   sulci – grooves between the ridges

Purkinje cells , axons of which become arbor vitae (white matter) in center

Regulation of posture and balance

Metencephalon: Pons
Myelencephalon: Medulla oblongata

Mostly ascending and descending tracts

Nuclei of ori for many cranial nerves

Location of autonomic nuclei involved in respiratory and cardiovascular control

Relay stations for sensory and motor neurons


Cranial Nerves

Twelve pairs:

2 attach to forebrain (Telen- & Diencephalon)

10 attach to brainstem (Mes-, Met- and Myelencephalon)

Names relate to  appearance or function

Classification ?

Olfactory Nerve (= CN or N I)

1º function?


Destination? _____________(By way of cribiform plate of ethmoid)

Only CN directly attached to Cerebrum

Optic Nerve (N II)

1º  fu?


dest? – by way of optic foramen of sphenoid to Diencephalon (optic chiasma)  and to occipital lobe

Oculomotor (N III)

C: Motor

O: Mesencephalon

D: Somatic motor to superior, inferior, medial recti and inferior oblique; visceral motor to intrinsic eye muscles by way of superior orbital fissure

Trochlear (N IV)

C: Motor

O: Mesencephalon

D: superior oblique

 by way of superior orbital fissure

Trigeminal (N V)

C: Mixed

three major branches

                                1. ophthalmic (sensory)

                                2. Maxillary  (sensory)

                                3. Mandibular (mixed)

O: face / nuclei of pons

D: sensory nuclei in pons / muscles of mastication


Facial (N VII)

C: Mixed

O: sensory from taste receptors of anterior 2/3 of tongue / motor from pons

D: Sensory to sensory nuclei of pons / motor muscles of facial expression, visceral motor to tear gland.

Vestibulocochlear (N VIII)

Glossopharyngeal (CN IX)

Vagus (N X)

C: Mixed 

O: Sensation from pharyngeal area and outer ear / motor from medulla

D: Sensory to medulla / visceral motor to thoracic and abdominal cavities and their organs. Major motor pathway for ANS

Accessory (N XI) and

C: Motor

O: Motor nuclei of medulla and spinal cord

D: Swallowing, trapezius & scm muscles

Hypoglossal (N XII)

C: Motor

O: Motor nuclei of medulla

D: Tongue musculatur



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