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Lecture 1: CNS Overview - Paulman
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Cranial Nerves
o Mnemonics
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On old Olympus' towering top a Fin and German viewed some hops
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Some say marry money but my brother says big brains matter more
o Cranial Nerve I – Olfactory
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Whiff, c diff, sensory sniff
o Cranial Nerve II – Optic
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Sensory nerve for eye
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Central and peripheral sight
o Cranial Nerve III – Oculomotor
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Pupil constricting
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Eyes moving
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Prevent eyelid dropping
o Cranial Nerve IV – Trochlear
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Works superior oblique
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Hard to look down if weak
o Cranial Nerve V – Trigeminal
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Mastication
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Sensory and motor face sensation
o Cranial Nerve VI – Abducens
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Eye abduction
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Motor nerve for motion
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Prevent double vision
o Cranial Nerve VII – Facial
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Facial expression
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Sensory and motor
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2/3 taste sensation
o Cranial Nerve VIII – Vestibulocochlear
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Body balanced
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Used for the ear, sound sensor
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Sensory
Lecture 1: CNS Overview - Paulman
o Cranial Nerve IX – Glossopharyngeal
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Sensory 1/3 back of tongue taste
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Helps us swallow
o Cranial Nerve X – Vagus
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Lets us speak and stay
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Dysphagia
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Sensory and motor
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Longest nerve in body
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Parasympathetic innervation to a large part of body
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Heart, larynx, trachea, bronchi, lungs, liver, gallbladder, stomach,
pancreas, kidney, SI, proximal LI, left colic flexure dividing sacral
parasympathetic supply from cranial supply
o Cranial Nerve XI – Spinal Accessory
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Shrug your shoulders
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Test head resistance
o Cranial Nerve XII – Hypoglossal
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Tongue movement
Lecture 1 – CNS Overview
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Central Nervous System (CNS)
o Brain, spinal cord, meninges
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Neurons and glia
Peripheral Nervous System (PNS)
o Axons, dendrites, ganglia
o Autonomic Nervous system (ANS)
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Part of the PNS
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2 components
o Parasympathetic
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“Always on”
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Vegetative Functions:
Lecture 1: CNS Overview - Paulman
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Respiration, peristalsis, steady heart rate,
glandular secretion
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Smooth muscle and organs only
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None in body wall
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Cranio (4 nerves)-sacral (S2-S4) outflow
(visceral afferent/efferent)
o CN III, VII, IX and X
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Somatic – 1 neuron
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Efferent: controls striated (skeletal) muscle (SE)
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Afferent: Info from body wall and outside world
into CNS (SA)
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Neuron inside CNS, no peripheral
Visceral – 2 neurons
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Efferent: controls smooth muscle, glandular
secretion (VE)
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Afferent: info from organs/tissues into CNS (VA)
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Send info out to sympathetic trunk. In SCG it
synapses in neuron. Effector neuron sends out.
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Found in CNS and PNS
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All in the brain are autonomics
o Sympathetic
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“Always off”
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Fight or flight response
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Increase heart rate, respiration, blood pressure
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Decrease peristalsis, reproductive function, digestion
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Thoraco-lumbar outflow (visceral afferent/efferent)
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T1  L2 (where it synapses)
Brain lobes
o Parietal  initiating action
o Occipital  farthest from eyes, visual cortex
Lecture 1: CNS Overview - Paulman
o Temporal lobe  coordination of sensory input, decision where to send info in brain
to final processing
o Brain stem  cerebellum (coordination and motor function)
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Where info comes into brain and it is organized
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Sending info into right places
o Hemispheres
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Both are mixed with art and logical, some areas are localized
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Left temporal lobe  speech
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Right temporal lobe  music
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Brain connects from side to side by the Corpus callosum (connecting body)
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Mass intermedia and something else (commissure?)
Spinal cord
o Brain matter and cell bodies are on the inside  opposite of the brain
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Skull
o Cranium made of bone, arteries, veins and nerves
o 3 parts
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1 – Outer table – very dense, hard
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2 – Diploe – spongy bone, soft, vascular
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3 – Inner table – very dense, hard
o Not well vascularized from the outside
o Receives most blood from dural arteries
o Fixed in placed with plates/screws post-op
o Bones
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Neurocranium
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Bony shell surrounding brain and meninges
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Calvarium  “Skullcap”
o Made of frontal, parietal and occipital bone
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De novo from mesenchymal cells
Viscerocranium
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Facial skeleton
Lecture 1: CNS Overview - Paulman
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Cartilaginous precursors and ossifies
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Bones arise from pharyngeal arch precursors (Gills, later)
o Borders of the fossae
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Btwn anterior and middle is posterior border of lesser wing of sphenoid
bone and sphenoid limbus (Central)
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Btwn middle and posterior  made of petrous ridges of temporal bones
laterally and posterior clinoid processes of the occipital bone centrally
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Anterior Fossa
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Cribriform plate (CN I)
Middle Fossa
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Optic canal—CN II and ophthalmic artery
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Superior orbital fissure—CN III, IV, V1, VI, ophthalmic veins
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Foramen rotundum—CN V2
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Foramen ovale—CN V3
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Foramen spinosum—middle meningeal artery
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Foramen lacerum—nothing of consequence
Posterior Fossa
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Internal auditory (acoustic) meatus—CN VII, VIII, labyrinthine artery
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Jugular foramen—CN IX, X, XI and superior jugular bulb (and inferior
petrosal sinus)—origin of internal jugular vein
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Hypoglossal canal—CN XII
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Foramen magnum—spinal cord, meninges, CSF, spinal arteries /
veins, vertebral arteries,
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Scalp
o Innervation
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Anterior  CN V
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Posterior  cervical nerves
o SCAL
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Skin
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Connective tissue (dense)
Lecture 1: CNS Overview - Paulman
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Aponeurosis  epicranial aponeurosis, broad flat tendon
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LCT
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Pericranium  inner layer
o Inner layer  pericranium, diff than other periostea, continuous through numerous
opening of skulll with dura matter
o Clinical implications
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Coronal cuts gape badly
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Sagittal ones don’t gape
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Loose areolar layer allows the scalp to move on the skull but also provides a
pathway for things to move around
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Fractures
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Hard to break skull
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Worst case scenario  “Coup-Countrecoup”
o Hit in forehead and distribute waves of impact around skull, so
once waves goes to back, force hits force, cancel each other out
and get fracture in back
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Veins
o Superficial, everything goes to the jugular veins
o Emissary veins
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Connect skull veins to the dural sinuses inside cranial cavity
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Some penetrate from scalp to dural sinuses
o Clinical implications
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Meningitis
Lymphatic
o Many lymph channel, but few nodes which first appear in the collar (of cranial
system)