Download Lec. 3 - VCOMcc

Anatomy Outline Test #1
Lec. 1: Intro
CNS
PNS
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Brain and SC, meninges (neurons and ganglia)
Spinal nerves: 8 cervical, 12 thoracic, 5 lumbar, 5 saccral, 1 coccygeal ((31 pairs)
SC: sensory neurons in dorsal root ganglion
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Axons, dendrites, ganglia
Contains ANS- autonomic Nervous System
o Parasympathetic: always on
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Vegetative fxns: respiration, peristalsis, HR, glandular secretion (homeostastis)
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Smooth muscles and organs only!!
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NONE in body wall or extremities!!
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Cranio-sacral outflow
o Sympathetic
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Always off…unless fight or flight response
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HR, respiration, BP
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peristalsis, reproductive fxn, digestion
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Thoraco-lumbar outflor
Somatic: 1 neuron
o Efferent: controls striated/skeletal muscle (effects things)
o Afferent: information from body wall and outside world into CNS (affects you)
Visceral: 2 neurons (1 in CNS, 1 in ganglia in body)
o No control over
o Efferent: controls smooth muscle, glandular secretion
o Afferent: info from organs and tissues into CNS
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Neuron
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Epineurium: surrounds bundle of fasicles
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Perineurium: covers fascicle (bundle of nerve fibers)
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Endoneurium: covers individual nerve fiber
The Skull
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3 parts of skull bones:
o Outer table: very dense, hard bone
o Diploe: spongy bone, soft, vascular (absorbs impact, distributes force)
o Inner table: very dense, hard bone
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bone receives most blood from dural arteries (doesn’t heal well)
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Neurocranium: bony shell surrounding brain and meninges
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Viscerocranium: fascial skeleton, from pharyngeal arches
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Important Features
o Pterion: “H” shaped, where parietal bone, frontal bone, sphenoid bone, and temporal bone
come together
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Most vulnerable, middle meningeal a. underneath epidural hematoma
o Mastoid Process: not on neonatal skull
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Calvarium, “skullcap”
o 3 bones:
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Frontal bone
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Paired parietal bones
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Occipital bone
o Coronal suture= “crown”, between frontal and parietal bones
o Sagittal suture: between 2 parietal bones
o Lambdoid suture= between occipital bone and parietal bones
o Bregma: where parietal bones meet frontal bone *reference pt for surgery
o Lambda: where parietal bones meet occipital bone
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Skull Issues
o Fractures: depressed fracture (doesn’t require treatment), comminuted fracture, linear
fracture, basilar fracture
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o “Coup-Countrecoup”- back of skull is broken, soft tissue bounces around
The scalp
o Layers= “SCALP”
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Skin, hair follicles
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Connective tissue (dense)
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Aponeurosis/ Epicranial aponeurosis (broad flat tendon between frontal and
occipital belly of occipitofrontalis)
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Loose CT: fatty
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Pericranium: continueous w/ dura mater
o Innervation
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Trigeminal nerve (CN V)
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Spinal Nerves
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Greater occipital (C2), Third occipital (C3), lesser occipital (C2,C3), greater
auricular (C2, C3)
o Arterial Supply
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Multiple anastomoses and tight CT  heavy bleeding!!
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Overlap of carotids
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Coronal cuts worse (muscle pulls wound open)  gaping
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Sagittal cuts don’t gape
o Venous Return
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All drain to jugular vein
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Emissary Veins: connect skull veins and some penetrate scalp  dural sinuses
inside cranial cavity
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**important for infection inside brain from scalp wound= meningitis**
o Lymphatics
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Many channels, FEW nodes
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Nodes in collar
Lec. 2: Neural Development Part 1
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Neurulation: 22-23 days
Notochord induces neuroectoderm  neural plate  neural groove and neural folds  neural crest
and neural tube formation
o Neural crest
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All sensory cells of PNS unipolar neurons of spinal ganglia (DRG)
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sympathetic trunks, sympathetic organ plexuses, pre-aortic ganglia
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schwann cells
Neural canal (lumen of neural tube)- ventricular system, central canal of SC
**rostral neuropore closes first (day 25)  failure to closemeroencephaly/anencephaly
**caudal neuropore closes second (day 27) failure to close spina bifida
Microglia come from mesenchymal cells (in bone marrow) comapred to other neuronal cells
Sulcas limitans: seperates alar from basal plate
Alar Plate Cell bodies = dorsal gray horns  afferent nuclei
“alar=affarent”/sensory neurons
Basal Plate Cell bodies= ventral gray horn and lateral gray horn
Congenital Anomalies of SC:
o Spinal dermal sinus (dimple)
o Spina bifida occulta (tuft of hair)
o Spina bifida cystica
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w/ meningocele
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w/ meningomyelocele (occurs w/ meroencephaly and craniolacunia (deficient
development of calvaria)
o Myeloschisis: most severe type of SB, SC left open (neural folds didn’t fuse)
Brain Development
o Head Fold
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Midbrain flexure, cervical flexure (demarks hindbrain from SC)
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Pontine flexture (thinning of roof of hindbrain myelencephalon and
metencephalon)
o Forebrain (prosencephalon)
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Telencephalon cerebral hemispheres (lat. Ventricles)
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Diencephalon thalamus, epithalamus, hypothalamus (3rd ventricle)
o Midbrain (mesenchephalon)
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Mesencephalon  Midbrain (Aqueduct)
o Hindbrain (Rhombencephalon)
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Metencephalon Pons, cerbellum (4th ventricle)
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Myelencephalon Medulla Oblongata (4th ventricle)
Choroid Plexus, CSF
o Tela choroidea of 4th ventricle: pia mater + ependymal roof  choroid plexus
o Median and Lateral Apertures: absorption of CSF into venous system via arachnoid villi
Midbrain
o Neural canalcerebral aqueduct
o Alar plate Neuroblast tectum colliculi
o Basal plate neuroblast  tegmentum of midbrain, substantia nigra?
Forebrain
o Closure of rostral neuropore, optic vesicles appear (primordial of retina and optic nerves)
Diecephalon
o From lat wall of 3rd ventricle
o Thalamus, hypothalamus, epithalamus
o Pituitary gland (hypophysis): ectoderm derivative
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*2 sources: hypophyseal diverticulum and neurohypophyseal diverticulum
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hypophyseal diverticulum contacts infundibulum(the neurohypophyseal
diverticulum)  pars anterior, pars tuberalis of pituitary gland
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results in adenohypophysis (glandular) or anterior lobe (oral ectoderm)
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and neurohypophysis (nervous part) or posterior lobe (neuroectoderm)
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as hypohyseal diverticulum stalk regresses, can get cysts (accessory anterior lobe
tissue)
Lamina terminalis: most important cerebral commissure (from one hemisphere to other)
Corpus callosum connects neocortical areas
Brain Anomalies
o Cranium Bifidum: cranial meningocele, meningoencephalocele (meninges and brain),
meningohydroencephalocele (brain w/ ventricular system)
o Exencephaly: most of brain extrudes from calvarium
o Anencephaly: common lethal, females
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ALWAYS associated w/ acrania, possible association w/ rachischisis, most common
anomaly in stillborns
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Polyhydramnios
o Microcephaly: calvaria and brain small, normal face size, genetic, environmental factors
(premature synostosis- union of all cranial sutures)
o Agenesis of corpus callosum
o Hydrocephalus (depending on what canal is blockedwhat ventricles are enlarged)
o Holoprosencephaly
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Severe, common, small forebrain (lateral ventricles fuse1 large ventricle)- eyes
abnormally close together
o Hydranencephaly
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Rare, hemispheres absent or membranous sacs, brainstem intact, head grows
excessively after birth
o Arnold-Chiari Malformation
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Most common involving cerebellum
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hydrocephalus tonguelike projection of medulla displacement of vermis of
cerebellum though foramen magnum
Lec. 3: Gross Brain, Meninges, Circulation, and SC
Meninges
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functions:
o supportive framework for vasculature and CSF
o protection for brain and SC- suspended in CSF (bouyancy), and tethered by meninges
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Layers
o Dura mater- Pachymenix (thick membrane)
o Arachnoid and Pia mater- Leptomenix (slender membrane)
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Continous w/ one another
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Pia- directly adherent to brain, makes brain look shiny
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Dura Mater- outermost layer, tough, thick, collagenous membrane, only layer sensitive to pain
o Cranial Dura Mater:
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adherent to inside of calvaria (suture lines, base)
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2 layers tightly fused together (not separated by pathologies)
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Periosteal Layer (periosteum of skull)
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Meningeal Layer
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Pathologies can separate periosteum from bone (epidural/extradural space)
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Specialized Formations
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Venous sinuses
o Endothelial lined spaces between periosteal and meningeal
layers (normal seperation)
o Collect blood from the brain
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Infoldings/Partitions/Septa: inward projections of meningeal layer at
major brain fissures
o Falx cerebri- divides cerebral hemispheres
o Tentorium cerebelli- seperates cerebellum from cerebral
hemispheres
o Falx Cerebelli- divides cerebellar hemispheres
o Diaphragma sellae- covers pituitary gland
o Purpose: division of the cavity into compartments, restrict rotary
displacement of brain
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Innervation
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CN V (trigeminal nerve)
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C2, C3: floor of posterior cranial fossa
o Spinal Dura Mater
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Only 1 meningeal layer (not fused)- otherwise movable vertebra could tear SC)
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But technically, periosteal layer exists (separated by epidural space)
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Leptomeninges
o Continuous, develop from single layer of mesenchyme
o Pia mater: visceral part (covers organ)
o Arachnoid mater: parietal part (adheres to dura mater)
o Joined together by arachnoid trabeculae (tethers)
o Continuous at roots of cranial/spinal nerves
o Arachnoid Mater
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Inner lining of dura (via pressure)
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Cranial/spinal arachonid similar
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Not vascularized
o Subarachnoid cisterns
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Radiological landmarks, CSF sampling sites (Cisterna Magna)
o Pia mater
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Follows arteries into the cerebral cortex
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Highly vascularized
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Spinal Pia
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Thick
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Denticulate ligaments: anchors length of SC to dura mater (bilateral)
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Filum terminale: tethers cord to coccyx
Meningeal Spaces
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Subarachnoid space- true space
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Subdural space and extradural/epidural space- not true spaces (only exists b/c of hemorrhage)
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Extracerebral Hemorrhages
o Between the skull and brain
o Subarachnoid hemorrhage: b/c of ruptured aneurysm (sudden BP causes rupture)
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Headache, stiff neck
o Epidural/extradural hemorrhage: b/c of skull fractures, laceration of middle meningeal a.
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Initial LOC lucid interval (1-5 hrs) decline of consciousness
o Subdural hemorrhage (between dura and arachnoid) b/c of head trauma, ruptures cerebral
vein
CSF
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Partial filtrate of blood, composition similar to plasma
Functions: buoyancy, cushion, chemical stability
Formed in ventricles (arise from embryonic neural tube)
Choroid Plexus
o Specialized ependymal cell protrusions into each ventricle (produce CSF)
o Invagination of the tela choroidea (pia mater + capillaries + ependymal cells) into the
ventricles
CSF circulation
o Lateral ventricles interventricular foramina 3rd ventricle cerebral aqueduct 4th
ventricle median and lateral apertures subarachnoid space (continous w/ SC and
cerebellum)
o CSF returns to blood via arachnoid villi  arachnoid granulations (large cluster) in dural
sinuses
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Herniation of arachnoid mater thorough the meningeal layer of dura mater
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Only 1 layer of endothelium
o Flow maintained by pressure of CSF, ependymal cell cilia, rhythmic pulsations of brain blood
flow
o Hydrocephalus
Lec 4: CNS Vasculature
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Blood supply essential to brain function (brain ischemiaLOC loss of electrical activity
irreversible damage)
Blood Supply to Brain:
o Internal Carotid A. (80% of blood to brain)- ant. And middle fossa
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Cervical part (arise in neck) via common carotid a.
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Petrous part of temporal bone (enters carotid canal)
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Cavernous part- crosses though cavernous sinus (in carotid groove)- emerges
though dural roof
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Cerebral part
o Vertebral A. (20%) – post. Fossa
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Enter skull though foramen magnum, merge together  basilar a.
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Supply blood to post. Brain, branches  brainstem
Arteries of the Brain
o Cerebral a. (3)
Anteror cerebral a. –supply most of medial, superior surface of brain, frontal poles
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Middle cerebral a. – supplies lateral surface of cerebral hemispheres, temporal
poles (via lateral sulcus)
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Posterior cerebral a. – supply inferior surface of brain and occipital poles
o Cerebellar a. (3)
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Posterior Inferior cerebllar a. (PICA): largest branch off vertebral a.
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Anterior Inferior cerebellar a. (AICA): first major branch of basilar a.
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*Labyrinthine a. supplies inner ear
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Superior Cerebellar a.: last major branch of basilar a.
o communicating a. (2)- Anterior and Posterior
o Anterior choroidal a.
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Last branch given off by ICA
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Supplies Optic tract, choroid plexus of lat. Ventricle, and deep brain structures
(CVAs)
o Perforating A. – supply deep cerebral structures (key brain regions)
Circle of Willis/Cerebral Arterial Circle
o *Important anastomosis between A/P blood supplies to the brain. (although limited blood
flow b/c of pressure)
Watershed Zones
o Areas of brain located btwn terminal distributions of adjacent a. (if BP, watershed zones lose
blood flow)
Blood-Brain Barrier
o Function: seperates blood from brain b/c of it’s potential for harmful agents, and variable
composition
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True BBB: microenvironment of neuronal fxn, protects Brain extra-cellular environment
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Formed by regular blood capillaries throughout brain (astrocyte foot providing tight
jxns sealing endothelial cells, and a thick BM)
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Lipid-soluble substances (fats, gases, alcohol) can pass
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Ion regulation
Blood-CSF barrier: protects CSF from blood
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All along arachnoid mater (via tight jxns)
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At choroid plexuses b/c true BBB absent (permeable capillaries)  specialized
choroid ependymal cells provide tight jxns
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Circumventricular organs b/c true BBB absent (around 3rd and 4th ventricles)specialized ependymal cells provide tight jxns
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Circumventricular organs sample blood b/c of leaky capillaries
Venous drainage
o cerebral veins dural venous sinuses basilar plexus of veins or internal jugular veins
o 2 types of Valveless veins  dural venous sinuses
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1. Cerebral veins
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superficial
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deep: Vein of Galen (Great cerebral vein.)
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2. Emissary Veins: connect from scalp to brain
Lec. 5: Intro to Autonomic Nervous System
**In CNS
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A collection of nerve cell bodies= nucleus
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bundle of nerve fibers that connect nuclei = tract
**In PNS
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nerve cell bodies (1 or many)= ganglion
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bundle of nerve fibers+ supporting CT+blood supply = nerve
CNS & PNS
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somatic and visceral divisions
o 1 neuron between CNS and sensory eding/effector organ
o afferent nerves: pain, pressure, movement of limbs, contraction of GIenter SC via dorsal
roots (via sensory nerves)  to brain via SC
o efferent nerves: brain sends signals to initiate responses  secretomotor to glands or muscle
motor response actions generate sensory responses
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reflexes: shortcut from SC muscle motor response (bypass brain)
SC
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cervical nerves # for vertebra below nerve
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all other nerves # for vertebra above nerve
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somatic or visceral fibers (carried by cranial/spinal nerves)
o Somatic fibers
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General sensory afferent fibers (sensory):
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Extroceptive sensations (from skin, pain, and proproception from muscles,
tendons, joints)
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General visceral efferent fibers (motor)
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Transmit impulses to skeletal muscles
o Visceral fibers
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General visceral afferent fibers (sensory)
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Transmit pain or subconscious visceral reflex sensations from visceral
organs to CNS
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General visceral efferent fibers (motor)
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Transmit impulses to smooth muscle and glandular tissues
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Pre-synaptic and post-synaptic fibers
o Sensory fibers: pseudounipolar neurons (cell bodies outside CNS ganglia)
o Motor fibers: multipolar neurons
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Cell bodies of somatic motor and presynaptic visceral motor neurons: gray matter of
SC
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Cell bodies of post-synaptic motor neurons: outside CNS in autonomic ganglia
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fibers leave via vertebral foramen ventral/dorsal rootletsventral nerve root, dorsal nerve root
(dorsal root ganglion) mixed spinal nerve  ventral/dorsal primary ramus
(mixed)motor/sensory nerve  segmental innervation/distribution (myotomes/dermatomes) or
peripheral nerve innervation/distribution (plexuses.)
o dorsal roots- sensory afferent fibers from cell bodies in dorsal root ganglion
(DRG)peripheral sensory endings and post. Horn of SC (gray matter)
o Ventral roots- motor efferent fibers from cell bodies in anterior horn of SC gray
mattereffector organs
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Dorsal/ventral roots- only nerves that can be cut (rhizotomy) for pain
relieve/spastic paralysis
o Dorsal Primary rami:
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Small portion of area on back
o Ventral Primary rami:
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Everything else, trunk, arms, limbs
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Majority merge w/ adjacent anterior rami somatic nerve plexuses
(multisegmental peripheral nerves)
Autonomic nervous system (ANS)
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Motor fibers that stimulate smooth muscle, cardiac muscle, glandular cells
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2-neuron system
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1st presynaptic neuron in gray matter on SC
o synapses w/ 2nd neuron in autonomic ganglia (fibers end in effector organ)
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sympathetic and parasympathetic always separate (originate in CNS but leave in different areas)
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Sympathetic
o Fxns:
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Primary fxn: regulate blood vessels (vasoconstrict mostly)
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Pupil: keep wide (adapt to light)
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Speeds up heart rhythm
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Turns off peristalsis of stomach
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Turns of reproductive organ normal fxn
o Fight or flight, catabolic system
o Thoracolumbar
o Release NE at post-synaptic neurons
o Extend to innervate all body’s blood vessels  reach all parts of body (except nails, cartilage)
o Short pre-synaptic fibers (b/c ganglia are so close to SC)
o Long post-synaptic fibers
o Thoracolumbar outflow (white rami is only on T1-L2/L3)
o Pre-synaptic neuron:
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1 location: interomedial cell column (lateral horn) of T1-L2/L3
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leaves SC though anterior root (motor)anterior ramiwhite ramus
communicanssympathetic ganglion/paravertebral ganglion
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If innervating head, neck, body wall, limbs, thoracic cavity- 3 options
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1. Ascend up sympathetic trunk, synapse w/ post synaptic neuron at
higher paravertebral ganglia (via gray ramus communicans)
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2. Descend in sympathetic trunk, synapse w/ post synaptic neuron at
lower paravertebral ganglia
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3. Immediately synapse w/ post synaptic neuron at that level
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If innervating viscera:
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Pass though trunk and paravertebral ganglia without
synapsingabdominopelvic splanchnic nervepre-vertebral
ganglionviscera or adrenal medulla…etc.
o Post-synaptic neuron:
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2 locations:
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Paravertebral ganglia (in sympathetic trunks/chains)
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Prevertebral ganglia/pre-aortic ganglia
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stimulates contraction of blood vessels, arrector muscles (goosebumps), sweating
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if innervating head, travels on cephalic a. branchcell bodies in superior cervical
ganglion (close to vagus and carotid!!)
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if innervating viscera of thoracic cavity, travels on cardiopulmonary splanchnic n. 
pass though abd. Splanchnic n.  pre-vertebral ganglia cardiopulmonary,
esophageal plexuses
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Parasympathetic
o Fxns: homeostasis/anabolic system
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Keeps pupil contracted
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Maintains normal heart rhythm
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Maintains normal peristalsis of stomach
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Maintains normal fxn of repro organs
o Craniosacral
o Release Ach at post-synaptic neurons
o Long Pre-synaptic neurons
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Starts in brainstem
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Has to travel to ganglia in head or viscera
o Short Post-synaptic neurons (b/c ganglia is in wall of viscera)
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Post synaptic neurons ALWAYS found in ganglia in PNS (head/visceral organs)
o ONLY affect visceral structures (NONE in body wall or limbs)!!
o Outflow (leave in 2 places)
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Cranial parasympathetic outflow
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Gray matter of brainstem, fibers exit CNS in CN III, VII, IX, X (3, 7,9, 10)
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CN III, VII, XI innervates head (4 ganglia)
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CN X innervates thoracic and abdominal viscera (most of GI)
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Sacral parasympathetic outflow
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Gray matter of SC, exit via anterior roots of S2-S4 and pelvic splanchnic n.
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Innervates pelvic viscera
Blue Boxes
o If cell bodies are intact when axons damagedpossible regeneration
o Paresthesia: pressure on a nerve (pins/needles)
o Crushing nerve injury: kills the axons, cell bodies intact, CT coverings intact regenertion
o Cutting nerve injurysurgery
o Anterograde degeneration: degeneration of axons detached from cell bodies (axon and
myelin sheath)
o Compression of vas nervorumischemia of nerveserious, usually permanent paresthesia
Lec. 6: Gross Brain-Internal
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Lateral sulcus/Fissure of Sylvius : seperates temporal lobe from frontal and parietal
Central sulcus: seperates frontal and parietal lobes
Parietal, temporal, frontal opercula-forms opercular cortex, covers insula
Lateral sulcus/Fissure of Sylvius : seperates temporal lobe from frontal and parietal
Frontal Lobe
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Precentral sulcus Broca’s ephasia: punctuated speech, not coherent (motor)
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(Ventral) Orbital gyri: lateral to olfactory sulcus (contains Olfactory bulb, olfactory tract)
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Fxns:Voluntary movements, Executive fxns: personality, insign, forsight (gets inhibited when you
drink/Thenias Gage)
Parietal Lobe
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Language comprehension-Wernicke’s area- can say things but they are gibberish
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Other Fxns: spatial orientation, directing attention
Temporal Lobe
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Fxns: emotional, olfactory processing
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complex aspects of learning/memory
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Wernike’s Area (language comprehension)
Occipital Lobe
o Visual Cortex
Limbic Lobe
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Cingulate gyrus (emotional processing, depression)
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Fxn: emotional responses, drive-related behavior, memory
White Matter
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Corpus Callosum
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White matter, communication between hemispheres
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Centrum Semiovale
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White matter, in dorsal core of frontal/parietal lobes, conveys neural impulses throughout
cerebrum
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Internal Capsule (anterior and posterior limb, Genu)
Brainstem
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All 3 areas contain tegmentum, “hood”: contains the brainstem nuclei (posterior in midbrain)
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Anterior to tegmentum: large ascending and descending tracts
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Tegmentum covered dorsally by tectum only in mesencephalon
PAG Raphe Nuclei
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PAG: periaqueductal gray: important in descending pain control system
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Electrical stimulation of PAGameliorate pain
Opium and derivatives (morphine) control pain by activating this network
Endogenous ligands for opiate receptors (enkephalin and dynorphin)
Friedreich’s Ataxia (problem w/ spinocerbellar tract)
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Inherited degenerative disease
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Lack of coordination in arms (intention tremor) and wide based, reeling gait (ataxia)
Red Nucleus : coordinates muscle tone, body position, gait (lestion produces resting tremor, abnormal
muscle tone, involuntary writhing)
Pontocerebellar angle/Cerbellopontine Angle
o Syndrome: most common neoplasms in the posterior fossa- most are benign (majority
vestibular schwannomas (acoustic neuomas)).
o SS secondary to compression of nearby CN V, VII, VIII
o CN V involved loss of ipsilateral corneal reflex
Reticular Formation
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Autonomic Reflex circuitry (inspiration, expiration, breathing rhythm, HR, BP)
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Hypothalamus- sympathetic control via IML column of SC
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Interuption: Horners Syndrome (Miosis, ptosis, enopthalmos)
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Projections from ARAS (ascending reticular activating system)- maintains consciousness/sleep wake
cycle
o If damaged bilaterally  coma
Type of Neuons
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Noradenergic Neurons
o Locus Cerulus of rostral pons  cerebral cortex
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Dopaminergic Neurons
o in substantia nigra and VTA
o 3 fiber streams
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Nigrostriatal/Mesotriatal (substantia nigracaudate and putamen)
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Mesolimbic: from VTA limbic structures

Mesocortical: from VTAcerebral cortex
o fxn: initiation of movement, motivation, cognition, pleasure, addiction
o Parkinson’s disease
o Antipsychotics used for Schizophrenia: blocks dopamine receptors

Serotonergic Neurons
o In raphe nuclei  widespread innervation
o Sleep/wakefulness, overall arousal
o Descending pain control system
o Antidepressants: enhance effectiveness of transmission of serotonin

Cholinergic Neurons
o Reticular formation, basal forebrain

Substantia innominata: basal nucleus of Meyhert (forbrain cholinergic)
o

Forebrain activity lvl, sleep/wake, learning/memory
Ach receptors
Blood Supply to Brainstem

Vertebral-basilar system

Stroke syndromes: medial or lateral areas commonly affected
Lec. 7: Spinal Cord and Nerve Roots
(combined Paulman and Sarkos tract stuff)
Tracts: axons that have same function (collected into bundles)

Tracts terminating in brain=ascending, affarent, sensory tracts

Tracts from brain to SC= descending, efferent, motor tracts
Spinal Cord Basics

Gray Matter
o Anterior Horn: motor neurons
o Lateral Horn: autonomic neurons (sympathetic or parasympathetic neurons
o Posterior Horn: sensory neurons

White Matter
o Anterior Funiculus
o Lateral Fasciculus
o Anterior Funiculus

Intrinsic Fascicles of SC: interneurons (intrinsic reflex pathways)

Spinal Levels
o Cervical enlargement, Lumbosacral enlargements- bigger ventral horns (b/c of motor
neurons for the head/limbs)

Spinal Nerves
o Branches:

Dorsal Primary Ramus  posterior cutaneous n.  medial and lateral branch

Ventral Primary Ramus Lateral cutaneous n. and anterior cutaneous n.

Spinal Vasculature
o 2 arterial sources

Vertebral a.  1 anterior and 2 posterior spinal arteries

Get reinforcing contribution by segmental medullary arteries

Great Anterior Segmental A. (of Adamkiewicz)- largest (reinforces 2/3
blood supply to SC)

Radicular a. from regional arteries, supply nerve roots, peripheral parts of horns (do
not contibute to spinal a. )

None of the a. supplying SC is sufficient to supply ENTIRE cord! (ischemia
loss of portion of SC)

Venous Drainage
o Longitudinal veins ant. And Post. To cord connect to parallel veinsInternal vertebral
plexus
Spinal Sensory Pathways
o Sensation Modalities

Proprioception

Mechanoreceptors

Myelinated A  and  fibers

Touch

Mechanoreceptors

Pacinian corpuscles

Myelinated A- fibers

Temp

Thermoreceptors

Myelinated A- and unmyelinated C fibers (slow, general temp sense)

Pain

Nocipceptors

Myelinated A- fibers (fast) and unmyelinated C fibers (slow)

Itch
o

Histamine

Unmyelinated C fibers
Mechanical Senses

Proprioception, Touch (receptors in peripheral tissue)= DORSAL COLUMN
TRACT/PCML TRACT

 Primary neuron in DRGenter cord via dorsal horn ascend up sC by
dorsal column nucleus

First synapse in brain stem – dorsal column nucleus @ medulla
o Gracili nucleus
o Cuneate nucleus

2nd neurons decussate to opposite side of CNS

travel up brainstem via medial lemniscus VPN of
thalamussomatosensory cortex

**MS: damage to fasciculus cuneatus of C-spine: loss of
proprioception/Asterogenesis (can’t describe objects w/ touch)

“Protective Senses”

Temp, Pain, Itch= ANTEROLATERAL PATHWAY** A for Anterolateral also
stands for ASAP- decussates ASAP**

Receptors in peripheral tissue (bare nerve endings)

 Primary neuron in DRG

First synapse in dorsal horn of SC

decussate via ventral commissure in SC

Ascend in anterolateral columns

Spinothalamic Tract
o Originates and decussates in SC (transmits pain, temp, itch to
thalamus)
o spinal lemniscusVPN of thalamus
o **Syringomyelia** (if central canal becomes enlarged,
compresses fibers)
o


Causes selective loss of pain and temp in upper limbsfrequent
burns (b/c no pain)
Somatotopic Organization
o Anterior Horn

Medial columnsinnervate muscles of midline

Lateral columnsinnervate muscles of trunk

Contains motor nuclei
o Posterior Horn (slender)- contains cell bodies of secondary sensory neurons (receive
processes from spinal/dorsal root ganglion cells in specific/laminar layers)
Brown-Sequard Syndrome
o A spinal hemi-section
o Axons in the dorsal column are ipsilateral
o Anterolateral system: decussates as it ascends causes loss of pain, temp, itch (1-2 segments
caudal to lesion)
o Loss of mechanical sensations (proprioception, touch) @ level of lesion
Spinal Motor Pathways

Lateral Columns **typically contralateral, decussate in brainstem
o Corticospinal tracts (LCS- CL)- lateral corticospinal= contralateral
o **mnemonic: Cleopatra’s contralateral pyramids**- and her RED RUBYS

Frontal cortex

Decussates @ pyramids

Primary motor pathway for major muscle movements

Contralateral in the cord!!
o Rubrospinal Tract **RED RUBIES*

Cleopathra also has RED Rubies on her necklace (C-spine only!!)

Red nucleus ventral horn of ONLY cervical spine

Ventral Columns** typically ipsilateral, decussate in SC
o Remember “IV” – ipsilateral ventral columns
o Corticospinal Tracts
o
o
o

Motor cortex ventral horn of cervical and thoracic

Ipsilateral in cord until terminal level

Some decussate = bilateral
Reticulospinal Tracts

From medulla/Pons ventral horn

Descent ipsilaterally down cord bilateral motor control

Branches or has interneurons (spinal reflexes)- autonomic fxns
Tectospinal Tracts

Superior colliculusventral horn of c-spine (fxns in upper limb/neck)

Tectum: visual movements/gaze
Vestibulospinal Tracts

Medial nuclei: head/neck position

Lateral nuclei: ipsilateral (interneurons decussate)
Corticobulbar tract* (mostly in head & neck)


Primary motor cortexmotor nuclei in pons and medulla
CN motor fxn
Lec. 8/9: CN



Nuclei for most CN (except CN I and II) are in brainstem or upper spinal cord
CN IV comes off ventral side (not dorsal side)
Motor and sensory usually NOT carried by same nerve
CN I- Olfactory nerve (only have 1 nose)= SVA

Olfactory Organ: contains cell bodies olfactory receptor neurons, possess fine olfactory cilia,
surrounded by fluid by olfactory glands olfactory nerves though cribiform plate of ethmoid
boneolfactory bulb  synapse w/ Mitral cells axons of 2nd neurons form olfactory tract lateral
and medial olfactory striae (distinct fiber bands)  ONLY CN to enter cerebrum directly!!
o Lateral striae temporal piriform complex
o Medial striae though anterior commisure to other side
o Temporal Lobe Epilyptic seizures (start smelling funny things before seizure) b/c of direct
connection
o Reflex vomiting- doesn’t get routed to cortex for interpretation (start throwing up b/c of
smell)
CN II- Optic nerve (2 eyes)= SSA

Optic nerve and eye- direct extensions of developing brain

Retinal receptor cells axons as optic nerves medial half of each retina deccusate in optic chiasm
optic tracts terminate in lateral geniculate nuclei of thalamus visual cortex in occipital lobe

Partial crossing of optic nerve fibers in chiasm- requirement for binocular vision, depth of field
perception
CN III- Oculomotor nerve: chief motor nerve to ocular and extraocular muscles

GSE: somatic motor to 4 extraocular muscles, and levator palpebrae superioris (superior eyelid)
o superior, medial, inferior recti, and inferior oblique
o proprioceptive to these muscles

GVE: parasympathetic motor to the sphincter pupillae and ciliary m.
o Sphincter pupillae: constricts pupil (control light input)
o Ciliary m: changes shape of lens (distance vision)
o Primary neurons in Edinger-Westphal nucleus in midbrain Synapse in ciliary ganglion
short ciliary n. eye muscles
CN IV- Trochlear Nerve

One fxn, one muscle

GSE to superior oblique muscle

Only CN to emerge from posterior/dorsal side of midbrain
CN V- Trigeminal nerve/Sensory N. of Face

Both deep and surface

**CN VII and IX often hitch a ride with CN V (some branches of V carry different modalities)

3 divisions (all GSA fibers, each exit cranial volt though different foramen)


V1: Ophthalmic n. above eye, forehead, temporal region, scalp, bridge of nose
V2: Maxillary n.  innervation to upper teach, nasal cavity
o Trigeminal neuralgia (unbearable pain in face, b/c of pulsating a. running next to it)

V3: Mandibular n.: lower teeth, also carries SVE muscles of mastication
o ONLY CN V branch that has intrinsic motor fibers!!
CN VI- Abducens nerve (Ab- 6 pack)

One fxn, one muscle

GSE to lateral rectus muscle (pulls eye outward)

If damaged, will go cross-eyed
CN VII- Facial Nerve

Multiple modalities!!
o SVE: facial expression muscles
o GVE: parasympathetic to pterygopalatine and submandibular ganglia
o GSA: small region posterior to ear
o SVA: taste to anterior 2/3 tongue

Exits CN vault w/ CN VIII

3 main branches: facial nerve proper, greater superficial petrosal n., chorda tympani nerve

sensory geniculate ganglion in temporal bone (NO SYNAPSES b/c it’s a sensory ganglion!!)

from facial nerve proper (SVE) (Two zebras bit my crotch)
o Temporal
o Zygomatic
o Buccal
o Marginal Mandibular
o Cervical
CN VIII- Vestibulocochlear nerve (8 looks like ear)

Vestibular nerve: SSA fibers= equlibrium, motion (input from semicircular canals, utricle, saccule)
o Ganglia in medulla medial to ICP

Cochlear nerve: SSA fibers = sensory: hearing, sense sound vibrations (input from cochlea)
o Ganglia in medulla lateral to ICP

Innervates inner ear (neuroectoderm)
CN IX- Glossopharyngeal nerve

Multiple Modalities w/ numerous branches!!
o SVA: taste to post 1/3 of tongue
o SVE: 1 muscle- stylopharyngeus (gag reflex when touching tympanic membrane/Qtip)
o GVE: to parotid gland (otic ganglion)
o GSA: middle ear space, pharynx, post tongue and soft palate (trigeminal nucleus; gag reflex)

Exits cranial vault with CN X and XI (and jugular bulb)

Forms part of the pharyngeal plexus of nerves

Carotid body: chemoreceptor (02, CO2)

Carotid sinus: baroreceptor (measures BP)

If damaged, problems adapting to BP
CN X- Vagus Nerve

Multiple Modalities!! (5)
o GSA: lower pharynx, larynx, root of tongue
o GVA: thoracid and abdominal organs
o SVA: epiglottic taste buds
o SVE: motor to soft palate, pharyngeal mm, laryngeal mm
o GVE: parasympathetic to thoracic and abd vicsera

in carotid sheath between jugular and carotid (super strong)

in the neck:

pharyngeal branch: SVE to pharyngeal mm

superior laryngeal: SVE to 1 muscle, GSA to upper larynx, SVA (taste) to epiglottic region

recurrent laryngeal: GSA to inferior larynx, SVE to rest of laryngeal mm.

most below the neck (thoracid/abd viscera)- GVE parasympathetic
CN XI- Accessory Nerve/Spinal accessory nerve

One fxn, 2 muscles

GSE to sternocladomastoid and trapezius muscles

Nucleus in upper 5-6 segments of C spine arises from nerve roots

Joined by branch of CN X while exiting skull
CN XII- Hypoglossal Nerve

GSE to 3 pairs of extrinsic tongue muscles and ALL intrinsic tongue muscles

Hitches a ride with spinal nerves of C1, C2
Blue Boxes

CN injuries: usually b/c of fracture at base of skull, movement of brain can tear/bruise CN

CN 3, 4, 5, 6 prone to compression/injury related to pathologies of cavernous sinus

Olfactory Nerve
o Anosmia: loss of smell (URI, sinus disease, head trauma, aging)
o Olfactory Hallucinations- lesion irritating the lateral olfactory area may cause temporal lobe
epilepsy or uncinate fits

Optic Nerve
o Could be affected my demyelinating diseases (MS)
o Optic Neuritis: lesions of optic n. diminution of viscual acuity
o Visual Field Defects

An optic nerve lesion blindness in temporal and nasal visual fields of ipsilateral
eye

Optic chiasm lesion bitemporal hemianopsia (loss of vision of one half of visual
field in both eyes)

Right optic tract at midline lesion left temporal and right nasal visual fields
(contralateral homonymous hemianopsia)

Most common type of vision loss, strokes

Oculomotor Nerve
o Ipsilateral oculomotor palsy (injury)
o Compression:

Extradural hematoma ipsilateral slowness of the papillary response to light
(compresses superficial fibers first)

Aneurysm of Posterior cerebral/Suerior cerebellar A.

**stopped halfway though on blue boxes…sorry!*