An easy-to-follow complete review of the brain and cranial nerves. Explains each concept in detail, step-by-step. This review guide will help you focus on what is important to learn for midterm and final exams.
The cranial meninges are CT coverings of the brain, continuous with the meninges of the
spinal cord
DURA MATER
Tough fibrous outer layer = periosteal layer which is fused with the periosteum of the
cranial bones ** no epidural space in skull
Sub dural space that contains blood vessels and venous sinuses
Inner meningeal layer that forms dural folds which stabilize the brain, and contain dural
sinuses to drain blood and excess CSF away from the brain
o Falx Cerebri: b/w the cerebral hemispheres in longitudinal fissure, contains the
superior and inferior sagittal sinuses
o Tentorium cerebelli: separates cerebrum from cerebellum, horizontal plane
o Falx cerebelli: separates cerebellar hemispheres, inferior to tentorium cerebelli
ARACHNOID LAYER
Does not dip into surface of brain but covers it, looks like a spider web from the
connections to the pia mater
Subarachnoid space: contains CSF, continuous with subarachnoid space of spinal cord
PIA MATER
Adheres to the astrocytes on the surface of the brain, follows every brain contour
If you tried to remove this, you would cause damage to the surface of the brain
VENTRICLES
LATERAL VENTRICLES
Two C shaped chambers, one in each hemisphere
Separated by septum pellucidum
Interventricular foramen: channel that connects the lateral ventricles to the 3 rd ventricle
RD
3 VENTRICLE
Located b/w the two thalami in the center of the diencephalon
Aqueduct: connects 3rd to 4th ventricle
th
4 VENTRICLE
Sits b/w the surface of the pons and the medulla oblongata, and the cerebellum
Continues on into the spinal cord as the central canal
Has apertures that open up into the subarachnoid space if its going to take that route
CEREBROSPINAL FLUID (CSF)
, Surrounds and protects the neural tissues of the CNS
Transports nutrients and waste through diffusion across ependymal walls
Produced by the choroid plexus, which are capillaries covered in ependymal cells
Path of CSF circulation:
o Lateral ventricles interventricular foramen third ventricle cerebral
aqueduct fourth ventricle 1) continues into central canal of spinal cord or
2) leaves the roof of the fourth through medial and lateral apertures to enter the
subarachnoid space and circulate the brain/spinal cord
Arachnoid villi (granulations): help drain the excess CSF from the subarachnoid space by
allowing it to enter the dural sinuses
BRAINSTEM
MEDULLA OBLONGATA
Communication b/w brain and spinal cord passes through
Coordination of complex autonomic reflexes that control visceral functions
Contain tracts that connect the spinal cord to higher brain regions
o Pyramids: descending motor tracts that carry out our conscious control of our
skeletal muscles from the cerebral cortex **CORTICOSPINAL TRACTS d
o Olive: relays info from the red nucleus
Autonomic reflex centers: subconscious control of function that we don’t have to think
about (ie in the viscera)
o Cardiac – controls HR and contraction
o Vasomotor – controls blood vessel diameter
o Respiratory rhythmicity – controls respiration
Nucleus gracilis and cuneatus: relay for somatic sensory information ascending the
spinal cord in the dorsal columns
Nuclei for cranial nerves VII, IX, X, XI, XII
PONS
Relay centers for the cerebellum
Contains higher respiratory centers (that can exert influence over the respiratory
centers found in the MO)
Reticular formation: contains the RAS which controls our levels of consciousness by
getting input from the ears/eyes/senses
MIDBRAIN
Reticular activating system (RAS) continues up from the pons into this area
Corpora quadrigemina: consists of the superior colliculi (visual relay centers) and
inferior colliculi (auditory relay centers)
Red nucleus: involved in subconscious control of upper limb muscles (tone, posture etc)
o Gives rise to rubrospinal motor tract
Substantia nigra: nuclei that regulate the activity of the basal nuclei
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