1. Ch 15: Brain and Cranial Nerves
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.

2. Major Brain Subdivisions
Telencephalon (= Cerebrum)
Diencephalon (Thalamus and hypothalamus)
Mesencephalon
Metencephalon (Pons and cerebellum)
Myelencephalon (= Medulla oblongata)
Brainstem

3. 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)

4. Cranial Meninges 2. Arachnoid - spidery, holds blood vessels
3. Pia mater - "delicate mother"
1. Dura mater - strong, "tough mother"
a. falx cerebri
b. falx cerebelli
c. tentorum cerebelli

5. Longitudinal fissure
Arachnoid granulations: This is where the CSF produced in the choroid plexuses of the ventricles and which has circulated into the subarachnoid space is reabsorbed.

6. Four Ventricles Lined by ependymal cells CSF filled chambers
Communicating with central canal of spinal cord
Lined by ependymal cells

7. CSF: Cerebro-Spinal Fluid
Formation in ventricles by specialized ependymal cells of choroid plexuses (~500 mL/day; total volume ~ 150 mL)
Functions
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.
Fig 15.6
Buoyancy: brain weight in air: about 1.4 kg – in CSF about 50 g (= 97% lighter) because it is only a little denser than the CSF. Protects brain from crushing itself.
Arachnoid granulations only appear at about 3 years of age. Infants are therefore especially sensitive to alterations or hyperactivity of the choroid plexuses.l

8. Blood Brain Barrier (BBB)
what is it?
3 areas in brain don’t have BBB
portion of hypothalamus
pineal gland (in diencephalon)
choroid plexus
Alcohol, nicotine and anesthetics can diffuse through BBB. Blood borne toxins (urea, food toxins, bacterial toxins) cannot get through.
Recent discovery: During prolonged emotional stress the tight junctions of the BBB are opened.

9. Cerebrum Two hemispheres separated by longitudinal fissure
Gyrus (gyri) separated by sulcus (sulci)
Major lobes named after overlaying bones

10. 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
In 90-95% of people left side has more control over language, math and logic. Right side is more involved withy visual-spatial skills, intuition, emotion, artistic and musical skill.

11. 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

12. 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)
Fig 15.11
Substantia nigra is in mesencephalon

13. Diencephalon Epithalamus Thalamus (~12 nuclei) Hypothalamus
Pineal gland - produces melatonin, sets diurnal cycles
Thalamus (~12 nuclei)
Hypothalamus
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
Thalamus = 80% of diencephalon. Gateway (relay station) to the cerebral cortex not just for sensory input but for all info. Processing and editing also takes place. About 12 nuclei
Hypothalamus also about 12 nuclei. Main visceral control center of the body

14. Mesencephalon) = 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

15. 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

16. 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

17. Cranial Nerves Twelve pairs: Classification ?
2 attach to forebrain (Telen- & Diencephalon)
10 attach to brainstem (Mes-, Met- and Myelencephalon)
Names relate to appearance or function
Classification ?

18. Olfactory Nerve (= CN or N I)
1º function?
Origin?
Destination? _____________(By way of cribiform plate of ethmoid)
Only CN directly attached to Cerebrum

19. Optic Nerve (N II) 1º fu? ori?
dest? - by way of optic foramen of sphenoid to Diencephalon (optic chiasma) and to occipital lobe

20. 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

21. Trochlear (N IV) C: Motor O: Mesencephalon D: superior oblique
by way of superior orbital fissure

22. 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

23. Abducens (CN VI)
C: Motor
O: Pons
D: Runs lateral rectus eye muscle

24. 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.

25. Vestibulocochlear (N VIII)D
Vestibulocochlear (N VIII)

26. Glossopharyngeal (CN IX)
C: mixed
O: sensory from posterior 1/3 of tongue / motor from medulla oblongata
D: medulla / muscles for swallowing, parotid gland

27. 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

28. Accessory (N XI) and Hypoglossal (N XII) C: Motor
O: Motor nuclei of medulla and spinal cord
D: Swallowing, trapezius & scm muscles
Hypoglossal (N XII)
O: Motor nuclei of medulla
D: Tongue musculature
Scm = sternocleido mastoid muscle

29. Mnemonic
Out On Our Table Top Are Fruits, Very Green Veggies And Hamburgers
The End