Quiz 1 Flashcards by Akshay Roy-Chaudhury

Q

Gray matter composition

A

Neurons
Axons, dendrities
Glial cells

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Q

White matter composition

A

Primarily myelinated axons

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Q

Multipolar cells

A

Vast majority of neurons

Several dendrites and single axon

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Q

Bipolar cells

A

Single process arising from opposite poles of soma

Retina, olfactory, vestibular/auditory

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Q

Pseudounipolar neurons

A

Found in sensory ganglia and dorsal root ganglia

One cell body with bifurcating process. “T” shaped

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Q

Nissl bodies

A

Clumps of rough ER

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Q

Central chromatolysis

A

Nissl body dispersion following axonal injury

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Q

Axon hillock

A

Funnel shape region of soma

No ER so is pale in Nissl stains

Lowest threshold for AP

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Q

Astrocytes

A

Help maintain BBB

Proliferate in respond to injury (Gliosis)

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Q

Oligodendrocytes

A

Myelin sheath forming cells in CNS

One cell can wrap around multiple axons

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Q

Ependymal cells

A

Lining of brain ventricles, in contact with CSF

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Q

Choroid plexus

A

Specialized secretory epithelium within ventricles

Secrete CSF

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Q

Dorsal root ganglia

A

Sensory ganglia associated with cranial and spinal nerves AND sym/parasym ganglia

Derive from neural crest

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Q

Electrical synapses

A

Direct cytoplasmic continuity via gap junctions

Rapid and synchronous firing of interconnected cells

Typically excitatory

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Q

Excitatory neurotransmitters

A

Glutamate

Aspartate

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Q

Inhibitory neurotransmitters

A

GABA

Glycine

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Q

Biogenic amine neurotransmitters

A

Dopamine
NE
Serotonin

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Q

Synthesis of Dopamine and NE

A

Tyrosine (Tyrosine hydroxylase) –> DOPA (DOPA decarboxylase) –> Dopamine (Dopamine B-hydroxylase) –> NE

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Q

Acetylcholine synthesis

A

Acetyl CoA + Choline

Choline acetyltransferase

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Q

Serotonin synthesis

A

Tryptophan (Tryptophan hydroxylase) –> –> Serotonin

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Q

GABA Synthesis

A

Glutamate (glutamic acid decarb) –> GABA

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Q

Release of NT’s from vesicles

A

Depolarization of terminal membrane –> opening of voltage gated Ca channels –> vesicular movement and release

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Q

Change in post synaptic ion permeability –> Na/Ca influx

A

EPSP

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Q

Change in post synaptic ion permeability –> Cl- influx, K efflux

A

IPSP

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Temporal summation

Graded potentials coming from the same synapse

Spatial summation

Graded potentials coming from multiple presynaptic neurons

Reuptake, NT's that use this process

Glutamate, aspartate, GABA, glycine, NE, Dopamine, Serotonin

Acetylcholine termination

Metabolized by acetylchoinesterase --> Broken down into acetate and choline

Dopamine and NE metabolism

Broken down by MAO and COMT Dopamine --->--> HVA NE --->--> MHPG

Serotonin metabolism

Broken down by MOA Serotonin---> 5HIAA

Nicotinic cholinergic receptor

Ach receptor at motor endplate --> increase permeability to cations --> AP and muscle contraction

NMDA receptor

Glutamate receptor Needs glutamate and slight depolarization

GABA-A receptor

GABA Increases permeability of Cl --> Cl influx and hyperpolarization --> inhibition of signal

Lidocaine

Local anesthetic Na channel blocker Can cause death with systemic doses

Mepivicaine

Local anesthetic Na channel blocker

Procaine

Local anesthetic Na channel blocker

Cocaine

Local anesthetic Na channel blocker Blocks catecholamine reuptake

Novicaine

Local anesthetic Na channel blocker Blocks catecholamine reuptake

Tetracaine

Local anesthetic Na channel blocker Blocks catecholamine reuptake

Benzocaine

Local anesthetic Na channel blocker Blocks catecholamine reuptake

Procaine

Local anesthetic Na channel blocker Blocks catecholamine reuptake

Side effects of local anesthetics

High doses = death because of respiratory block, CV issues, depress SM contraction If cross BBB --> seizures

Tubocurarine

Nicotinic (Ach) antagonist

Atracurium

Nicotinic (Ach) antagonist

Mivicarium

Nicotinic (Ach) antagonist

Vecuronuium

Nicotinic (Ach) antagonist

Pancuronium

Nicotinic (Ach) antagonist

Rocuronium

Nicotinic (Ach) antagonist

Succinylcholine

Nicotinic agonist that desensitizes receptor --> Downregulation

Neuromuscular blocker side effects

Decrease BP and tachycardia Histamine release, respiratory paralysis, death @ high doses

Dantrolene

Block Ca release from SR

Diazepam

GABA-A channel agonist, increase frequency of channel opening

Baclofen

GABA-B agonist G protein inhibitory coupling

Botulinum toxin

Inhibit Ach release at NMJ

Carisoprodol

GABA-A channel agonist, increase channel opening frequency

CN I

Olfactory, sensory 15-20 filaments/side Cilia project into mucosa of nasal cavity where aromatic molecules bind Neurons project into olfactory bulb, not brainstem

CN II

Optic, sensory Cell bodies of neurons in ganglionic cell layer of retina Retina --> optic disc --> optic nerve Does not connect to brainstem

CN III

Oculomotor - eye movement/pupillary constriction Brainstem --> cavernous sinus --> enters orbit through superior orbital fissure Innervates 5/7 extraocular muscles Also carries preganglionic parasymp to innervate ciliary muscle: Lens accomadation, production of aqueous fluid Also post ganglionic parasymp: Pupil constricion

CN IV

Trochlear - eye movements Only CN to arise from dorsal aspect of brainstem Superior oblique muscle

CN V

Trigeminal: Ophthalmic - Forehead, cornea, dura Maxillary - Cheek and upper teeth Mandibular - Lower jaw and teeth sensation, lip, anterior tongue. Muscles of mastication Come from trigeminal ganglion Sensory - Touch Motor - Jaw muscles

CN VI

Abducens - eye movement Brainstem --> cavernous sinus --> s orbital fissure --> lateral rectus muscle to ABDUCT eye

CN VII

Facial - Sensory and motor Sensory - taste Motor - Facial expression muscles and parasympathetic (facial glands)

CN VIII

Vestibulocochlear - Hearing, balance Spiral ganglia for cochlea Vestibular ganglia for balance

CN IX

Glossopharyngeal - taste, motor pharynx Sensory - Oral pharynx, back of tongue. Taste, touch Parasympathetic motor - Parotid gland Motor - Stylopharyngeus muscle

CN X

Vagus Motor - Pharynx/larynx and parasympathetic for viscera Sensory - Thorax and abdomen

CN XI

Accessory Motor Trapezius, sternocleidomastoid Head and neck movement

CN XII

Hypoglossal Motor only Tongue muscles

Sensory pathway to thalamus

Primary afferent --> secondary neuron (crosses midline) --> thalamus --> cerebral cortex

Secondary neuron characteristics

Crosses midline

Shortest distance from sensory to cortex?

3 neurons Primary afferent Secondary neuron Thalamic-cortical neuron

Pain/temperature sensory pathway

Primary afferent --> Secondary neuron in spinal cord (crosses midline) --> Thalamus --> cerebral cortex

Touch/vibration sensory pathway

Primary afferent --> Travel up spinal cord to secondary neuron in brainstem (crosses midline) --> thalamus --> cerebral cortex

Damage to nervous system pre brainstem will show what sided effect to pain and touch

Pain - contralateral because neuron already crossed sides Touch - Ipsilateral because crossing of neurons occurs in brainstem

Sensory pathways to cerebellum

Side of cerebellum is related ipsilaterally to body. Ie right side of cerebellum = right side of body Thalamus not required

LMN

Lower motor neuron Origin in ventral root of spinal cord gray matter Final and direct output to muscle via Ach release and NMJ

LMN releases...

Ach at NMJ Trophic factors - general health of muscle

LMN input - DTR

Primary sensory afferent travels to dorsal horn of spinal cord --> synapse on LMN dendrite --> AP that travels out ventral horn via LMN back to muscle Reflex arc tests sensory AND LMN function

UMN

Upper motor neuron Soma in primary motor cortex or surrounding areas - Important for voluntary movements Often monosynaptic connections to LMN = fast signal transduction

UMN pathways

1. Stop in pontine nucleus of cerebellum --> end message to contralateral portion of cerebellum 2 Travel to spinal cord (cross midline) --> synapse with interneurons that synapse with LMN 3. Travel directly to LMN, crossing midline at spinal medullary junction

UMN and DTR

UMN suppresses DTR and activates LMN

Lesion to UMN = ?

Muscle weakness HYPER-reflexia

Lesion to LMN = ?

Muscle weakness and HYPO-reflexia

UMN damage and babinski sign

UMN damage causes babinski sign - abnormal response of big toe to plantar stimulation Up going big toe and fanning of other toes

Basal ganglia

Gray matter nuclei in brain Motor learning and planing

Basal ganglia lesions

DO NOT cause muscle weakness Interference with motor control causing slowness Basal ganglia connected to motor cortex on same side --> Cause issues on contralateral side of lesion

Cerebellar lesions

No midline crossing of neurons so damage is on ipsilateral side of lesion

Nociceptors

Pain specific sensory neurons

Noxious stimuli

Tissue damaging stimuli

Pain transduction

Noxious stimuli --> chemical signals Noxious pressure --> Nociceptor activation and noxious chemical release --> AP travels to spinal cord AND through dendrites of nociceptor = release of pain neurotransmitters --> immune response

Hyperalgesia

Nociceptors sensitized after numerous stimuli --> More vigorous response

Pain transmission

Peripheral information relayed to spinal cord or brainstem --> thalamus --> cortex Different afferent nerves with different velocities

C fibers

Non myelinated fibers Transmit mechanical, thermal, chemical stimuli C-polymodal nociceptors Associated with second pain

A delta fibers

Thinly myelinated, slower fibers Mechanical and noxious thermal Responsible for first pain

Lissauers tract

Special fiber tract where A-delta and C fibers can travel rostral or caudal through spinal tract before entering dorsal horn

Pain transmission within spinal cord

Fibers communicate via chemical synapse with secondary neuron in superficial layer or spinal cord --> 2nd order neurons cross midline to anterior aspect of spinal cord white matter --> to thalamus --> synapse to somatosensory cortex

Repetitive nociceptor firing and sensitization

2nd order neurons in spinal cord become sensitized and respond at lower thresholds

Pain associated neurotransmitters

Released from nociceptive afferent to second order neuron in spinal cord Glutamate Substance P

Pain modulation

Nervous system changes that allow noxious stimuli to be inhibited System activation = release of endorphins and enkephalins --> pain relief via G protein coupled receptors (block Ca entry into cell)

Descending modulatory system - opioid receptor activation and pathway of pain relief

Receptor activation in midbrain --> neurons project to reticular formation --> Disinhibition of GABAergic inhibitory interneurons --> allows for descending neurons to be active --> dorsal horn of spinal cord along dorsolateral funiculus --> synapse with afferent neurons/second order neurons/endorphin and enkephalin neurons

Descending pain modulatory neuron release/activation

Serotonin (5HT), NE --> inhibit pain NT release, inhibit second order pain transmission Activates opioid containing neurons in dorsal horn --> endorphin/enkephalin release

Sites of opioid action

1. Activate brainstem opioid receptors --> disinhibition of descending neurons 2. Activate opioid receptors on second order pain cells in spinal cord/brainstem --> Prevents ascending transmission of pain 3. Activate opioid receptors of nociceptive pain fibers of central and peripheral terminals to inhibit pain signal transduction

Synaptic plasticity

Changes in process of transmission/transduction Presynaptic - Increase/decrease of transmitter release Postsynaptic - Increase/decrease of response to transmitter

Cellular plasticity

Changes in cell phenotype Up/down regulation of proteins Expression of new proteins Changes in channel subunits Membrane remodeling

Systems plasticity

Reorganization of neural connectivity Long time, usually irreversible Diabetic neuropathy

Opioid mechanism of action

Act at G protein receptor --> decrease AC --> decrease cAMP and PKA Block Ca influx

Gabapentin/Pregabalin

Inhibition of voltage gated Ca channels by binding a2delta protein that delivers channel to membrane

1a and 1b fibers

Largest diameter sensory axons, heavily myelinated. Fastest conduction velocities

A-beta fibers

Heavily myelinated, second largest Touch, pressure, vibration

A delta

Smaller, thinly myelinated Pain, temperature, some touch

C fibers

Smallest, unmyelinated Slowest conduction Slow pain, temp, touch Polymodal

Type I fibers =

Ia, Ib

Type II fibers =

A-beta

Type III fibers =

A-delta

Slowly adapting receptors

Fire spikes as soon as stimulus occurs and dont stop Frequency of spikes decreases (spike frequency adaptation)

Rapidly adapting receptors

Bursts of spikes at beginning and end of stimulus

Spiral endings @ hair follicles

Nerve endings that spiral around hair follicle base Rapidly adapting A beta

Meissner's corpuscles

Encapsulated structures made out of stacked schwann cells Near surface of skin, rapidly adapting A beta Texture stimuli

Merke's disks

Non encapsulated near skin surface Slow adapting A beta Touch stimuli

Pacinian corpuscles

Onion structure Deep in skin, large receptive field Rapid adapting A beta Vibration stimuli

Ruddini endings

Deep in skin all over body and in internal organs Large receptive fields, attached to collagen Slowly adapting, A beta Stretch and sustained pressure

Muscle spindles

Detect muscle length and sudden stretch Normal muscle fibers attached to special muscle fibers with afferent nerves

Nuclear bag fibers

Dynamic activity and static elongation

Nuclear chain fibers

Static elongation only

Muscle spindle fiber afferent nerves

1. Primary afferent that enters spindle and surrounds bag and chain fibers 2. Secondary afferents that innervate chain fibers Nerves From DRG

Muscle spindle motor innervation

1. Large diameter alpha motor neurons that innervate extrafusal fibers 2. Small diameter fibers from gamma motor neurons, supply intrafusal fibers

Golgi tendon organs

Junction between center of muscle and tendon Detects force of muscle Nerve terminals compressed when force produced, ion channels open and AP

Joint afferents

Fire at extreme joint ROM

Neural tube development

Neural folding --> neural tube closure --> Neural crest cells

Plates of neural tube

Alar - posterior, sensory Basal - anterior, motor

Primary vesicles of neural tube

Proencephalon Mesencephalon Rhombencephalon

Proencephalon - divisions and structures

Telencephalon: Cortex, hemispheres, hippocampus, amygdala. Lateral ventricles Diencephalon - Thalamus, hypothalamus, pineal gland - Upward = rathke's - Downward = Posterior pituitary - 3rd ventricle

Mesencephalon

Midbrain Forms cerebral aqueduct

Rhombencephalon

Divides into metencephalon and myelencephalon Forms cerebellum and brainstem 4th ventricle

Anencephaly

Failure of rostral neural tube closure Absent cerebral hemisphere

Spina bifida cystica

Failure of caudal neural tube closure Meningeocele --> meninges protruding Meningiomyelocele --> Neural elements + meninges out

Spina bifida occulta

Failure of vertebral closure but normal spinal cord

Arnold Chiari malformation

Displacement of caudal brainstem and inferior cerebellum through foramen magnum Midbrain tectum beak like

Holoprosencephaly

Failure of proencephalon division Facial anomalies

Lissencephaly

Smooth brain with absence of cerebral convolution Neural migration disorder

Polymicrogyria

Neural migration disorder Small gyri

Neuronal heterotopia

Neural migration disorder Collection of neurons in subcortical white matter

Germinal matrix hemorrhage

Region of proliferating cells next to lateral ventricle Cells migrate out to cortex

Brainstem and neural plates

Wall of rhomboencephalon spreads out to form floor of 4th ventricle --> alar plate ends up lateral to basal plate in medulla and pons

Cervical flexure location

Spinal cord and brainstem

Cephalic flexure location

Midbrain and diencephalon

Periventricular leukomalacia

Necrosis of deep hemispheric white matter adjacent to ventricles Caused by perinatal anoxia Typically involves descending motor tracts --> bilateral spasticity and paralysis

Dura matter

Thick outermost layer of brain connective tissue, continuous with periosteum of skull

Arachnoid matter

Thin cellular, collagenous membrane

Pia matter

Innermost delicate collagenous membrane Attached to surface of CNS

Subarachnoid space

Between arachnoid and pia, filled with CSF Contains large arteries and veins supplying underlying brain

Function of meninges (CT spaces)

Protect CNS, shock absorber Arachnoid membrane linked by tight junctions, blood CSF barrier

Dural reflections

Dura doubles on itself to form partition Falx cerebri (between cerebral hemispheres) Tentorium cerebelli (between cerebellum and cerebral hemispheres)

Dural sinuses

Thin walled endothelium lined venous channels Cerebral veins empty into dural sinuses

Subdural hemorrhage

Between dura and arachnoid Caused by tearing of bridging veins (subarachnoid space-->dural sinuses) Cortical atrophy from aging --> More space for brain to move --> subdural hemorrhage susceptibility

Epidural hemorrhage

Blood between dura and skull

CSF production

Produced by choroid plexus Secretion through active transport across choroid epithelium

CSF function

Flotation of brain Regulates brain ECF Spatial buffer for arterial pulses

CSF production and flow

Produced by choroid plexus in lateral/4th ventricles --> escapes to subarachnoid space through median and lateral apertures on brain surface --> passes through arachnoid villi --> Enters venous sinuses

Arachnoid villi

Protrusions of arachnoid through the dura into sinuses Allows CSF to drain into venous system

Hydrocephalus

Accumulation of excessive CSF in ventricular system Can be caused by blockages in CSF path

Herniation syndrome overview

Increased intracranial pressure --> brain tissue herniating from one area to another --> strangulated/necrotic --> swelling --> necrosis

Cingulate gyrus herniation

Cingulate gyrus herniates medially beneath falx cerebri

Uncal herniation

Medial temporal lobe herniates below tentorium Can compress midbrain and CN III (dilated pupil) Can compress posterior cerebral artery --> infarction

Uncal herniation downward displacement of midbrain/pons

Can tear penetrating arteries/veins --> Duret hemorrhages

Cerebellar tonsils

Herniation into foramen magnum Fatal when respiratory centers in medulla are compressed

Internal carotid pre terminal branches

Posterior communicating artery Anterior choroidal artery

Middle cerebral artery supplies

Lateral surface of hemispheres

Anterior cerebral artery blood supply

Orbital and medial surface of frontal lobe

Perforating/ganglionic arteries

Anterior/middle cerebral artery branches that supply deep structures Basal ganglia and diencephalon

PICA

Posterior inferior cerebellar artery Branch of vertebral artery Supplies posterior inferior cerebellum Also choroid plexus of 4th ventricle

AICA

Anterior inferior cerebellar artery Supplies anterior inferior cerebellum Branch of basilar artery

Venous drainage pathway from CNS

Arteries --> CNS --> capillaries --> veins --> venous sinus

Venous drainage pathway from Choroid plexus

Arteries --> Choroid plexus --> capillaries --> CSF --> venous sinus

Deep veins drain into....

Straight sinus

Superficial veins drain into....

Superior sagittal sinus

Blood flow regulation in brain

Autoregulation Increase BP = increase constriction Decrease BP = decrease constriction

3 barriers in brain

1. Endothelial cell tight junctions 2. Arachnoid barrier (between dura and subarachnoid space) 3. Choroid epithelium

Greater petrosal nerve

Branch of CN VII Motor

Chorda tympani

Sensory of CN VII Tongue taste

Geniculate ganglion

Location of cell bodies for taste Ganglion is far from sensory organ

Terminal portion of CN VII

Motor for face

Pharyngeal arch #1: Cranial nerve, skeleton, muscle

CN 5 - Trigeminal, mandibular branch Malleus, Meckels cartilage, mandible, muscles of mastication

Pharyngeal arch #2: CN, skeleton, muscle

CN 7 - Facial Stapes, styloid process Facial expression muscles

Pharyngeal arch #3: CN, skeleton, muscle

CN 9 - Glossopharyngeal Stylopharyngeus

Pharyngeal Arch #4: CN, skeleton, muscle

CN 10 - Vagus Pharynx and larynx muscles Laryngeal cartilage

Pharyngeal pouches come from..

Endodermal epithelium

Pharyngeal pouch #1

Auditory tube

Pharyngeal pouch #2

Palatine tonsil

Pharyngeal pouch #3

Inferior parathyroid glands Thymus

Pharyngeal Pouch #4

Superior parathyroid glands Parafollicular cells of thyroid

Pharyngeal cleft #1

External auditory meatus Connects to first pharyngeal pouch

Morphine

Mu opioid agonist, opening of K channels and blockage of Ca channels Constipation and decrease respiratory drive

Oxycodone

Mu opioid agonist, opening of K channels and blockage of Ca channels Percocet contains acetominiphen

Hydrocodone

Mu opioid agonist, opening of K channels and blockage of Ca channels Vicodin contains acetominophen

Methadone

Mu opioid agonist, opening of K channels and blockage of Ca channels

Loperamide

Less potent Mu agonist Does not cross BBB, use for diarrhea

Fentanyl

Mu opioid agonist 100x more potent than morphine

Butorphanol

Partial Mu agonist and kappa agonist

Tramadol

Weak mu agonist Inhibits NE/5HT reuptake

Naloxone

Opioid receptor antagonist Opioid overdose drug

Sumatriptan

Migraine medication 5HT agonist CV issues, coronary artery vasospasm

Location of nerve exit, cervical nerves

Each cervical nerve leaves vertebral canal ABOVE cervical level Ie 2nd cervical nerve leaves between 1st and 2nd vertebrae 8th cervical nerve leaves below C7 (No C8)

Location of nerve exit, thoracic/lumbar nerves

Nerves leave vertebral canal below

LMN Damage: Strength, muscle tone, stretch reflexes, atrophy

Strength: Decrease Tone: Decrease Stretch reflex: Decrease Atrophy: Severe

UMN Damage: Strength, muscle tone, stretch reflexes, atrophy

Strength: Decrease Tone: Increase Stretch reflex: Increase Atrophy: Mild

Anterior corticospinal tract

Do not cross at pyramidal decussation Terminate in medial portion of anterior horn or in intermediate gray matter Most end in cervical and thoracic segments --> neck/shoulder

6th pharyngeal arch

Cricoid cartilage Ductus arteriosus and pulmonary trunk Recurrent laryngeal branch of CN X

Thyroid cartilage

Forms laryngeal prominance

Cricoid cartilage

Inferior to thyroid cartilage, ring like structure

Sternocleidomastoid O and I

O: Sternum and clavicle I: Mastoid process Innervated by CN XI

Left side origin of common carotid artery

Directly from arch of aorta

Right side origin of common carotid

Comes off brachiocephalic trunk

Carotid sinus

Proximal to bifurcation of carotids, swelling that contains stretch receptors Site of BP baroreceptors

Carotid body

Measures pH of blood

Common carotid bifurcation

Internal - brain blood supply External - Neck

External carotid branches in neck

1. Superior thyroid artery 2. Lingual artery - Tongue 3. Facial artery

Subclavian artery branches

1. Vertebral artery - Brain supply | 2. Thryrocervical trunk - Inferior thyroid

Internal jugular vein

Primary venous drainage of brain

External jugular vein

Primary drainage of face and neck Travels on surface of sternocleidomastoid

Superior cervical ganglion

Largest ganglion of sympathetic chain Supplies fibers to entire head, rides blood vessels

Vagus nerve travel and branches

Runs in carotid sheath Gives of laryngeal, pharyngeal and cardiac branches

Accessory nerve travel

Arises in cervical spinal cord and enters foramen magnum Leaves via jugular foramen

Anterior triangle of neck

Anterior sternocleidomastoid Jugular notch of manubrium Median line of neck

Muscles of mastication

1. Temporalis 2. Masseter 3. Medial pterygoid 4. Lateral pterygoid

Temporalis

Fan shaped muscle on side of cranium Strong jaw closure and jaw retraction

Masseter

Origin on zygomatic and insertion on lateral mandibular ramus Jaw closer

Medial pterygoid

Deepest Similar to masseter but more medial

Lateral pterygoid

Two heads Jaw opening

Muscles of mastication innervated by...

V3 of trigeminal

External carotid artery branches in face

1. Superficial temporal 2. Maxillary 3. Facial

Maxillary artery branches

Middle meningeal - Through foramen spinosum --> Dura and cranial borns Inferior alveolar - Exits infratemporal fossa through mandibular foramen. Supplies lower teeth and mandible

Branches of V3

1. Lingual nerve - touch sensory of anterior tongue. Joined by chorda tympani (taste, CN VII) 2. Inferior alveolar nerve - Lower teeth and jaw

Caudal medulla

No 4th ventricle Location of posterior column synapse with second order neurons (nuclei cuneatus and gracilus) Arise in ML --> cross over --> synapse in nuclei

Damage to one side of brainstem will cause what sided damage to long tracts and CN's

Ipsilateral CN damage Contralateral long tract damage

Rostral medulla

4th ventricle visible Inferior olivary nucleus on lateral anterior side. Crosses midline and synapses to inferior cerebellar peduncle

Caudal pons

4th ventricle continues Basal pons visible - contains pontine nuclei which are associated with cerebellum Nerves from cortex --> synapse in pontine nuclei --> Cross midline --> middle cerebellar peduncle Medial lemniscus moving more lateral

Rostral pons

Narrowing of 4th ventricle Superior cerebellar peduncle leaves cerebellum and joins brainstem

Caudal midbrain

4th ventricle gone, aqueduct surrounded by PAG PAG flanked by Inferior colliculus Center = decussation of superior cerebral peduncle Basal pons gone, replaced by cerebral peduncle STT adjacent to ML

Rostral midbrain

Aqueduct with PAG, flanked by superior colliculus Red nucleus bilateral in center Cerebral peduncle (CP and CST) on anterior lateral portion STT and ML form thin strip between RF and substantia nigrans Substantia nigra is lateral to cerebral peduncle

Midbrain Cranial Nerves

CN III CN IV

Pons Cranial nerves

CN V CN VI

Pontomedullary junction Cranial Nerves

CN VII CN VIII

Medulla Cranial Nerves

CN IX CN X CN XII

CN XI arises from

Cervical spinal cord

Midline medulla blood supply

Anterior spinal artery Vertebral arteries

Lateral structures of medulla blood supply

PICA

Midline pons blood supply

Basilar

Lateral pons blood supply

AICA

Midbrain midline blood supply

Posterior cerebral artery

Lateral midbrain blood supply

Superior cerebellar artery

Trigeminal pain/temperature afferents nuclei

Fibers enter sensory nucleus --> Travel caudally to spinal nucleus --> Synapse on second order neuron --> thalamus

Trigeminal touch/position afferents nuclei

Enter sensory nucleus --> Synapse to second order --> cross midline and join ML --> thalamus

Facial taste afferents nuclei

Solitary tract --> solitary tract nucleus --> thalamus --> visceral cortex

Facial skeletal efferents nuclei

Motor nucleus in caudal pons

PS facial nerve nuclei

Superior salivary nucleus

Glossopharyngeal afferent nuclei

Solitary nucleus and solitary tract for taste Carotid body and sinus also enter solitary tract

Glossopharyngeal efferent nuclei

Nucleus ambiguus

Glossopharyngeal PS motor nuclei

Inferior salivary nuclei

Vagus visceral afferent nuclei

Solitary nucleus/tract

Vagus efferent motor nuclei

Nucleus ambiguus

Vagus PS efferent

Dorsal motor nucleus of vagus

Nuclei for somatic sensory of cranial nerves

Spinal trigeminal nucleus

Visceral sensory nucleus for CN VII, IX, X

Solitary nucleus --> thalamus --> visceral cortex --> hypothalamus --> reflex

Nuclei for CN VII glands

Superior salivary nucleus

Nuclei for CN IX glands

Inferior salivary nucleus

Nuclei for CN IX and X branchial motor

Nucleus Ambiguus

Cranial nerve nuclei for motor only nerves

CN III, IV, VI, XII, V/VII (Motor) Nuclei of same name III - Oculomotor nucleus IV - Trochlear nucleus V - Motor trigeminal nucleus VI - Abducens nucleus VII - Facial motor nucleus XII - Hypoglossal nucleus

Trigeminal CN somatic sensory nuclei

Facial sensation Primary sensory Mesencephalic Spinal trigeminal (pain/temperature)

Trigeminal CN exit foramina

V1 - Superior orbital fissure V2 - Foramen rotundum V3 - Foramen ovale

Location of CN III nuclei

Rostral midbrain, midline

Location of CN IV nuclei

Caudal midbrain, midline Nerves are contralateral

Location of CN VI nuclei

Caudal pons

Location of CN XII nuclei

Rostral medulla

Corneal reflex pathway

Primary afferent from cornea (CN V afferent) --> synapse with interneuron in spinal trigeminal nucleus (rostral medulla) --> interneuron synapses @ facial (CN VII) motor nucleus --> blink

Serotonin in brain: Location, associated diseases and treatment

Produced in Raphe nucleus Depression, anxiety, eating disorders = low serotonin High BMI = More serotonin transporters --> decreased serotonin Treatment: SSRI, TCA

Norepinephrine in brain: Location, associated diseases and treatment

Produced in RF and Locus ceruleus Low NE = depression, ADHD High NE = PTSD Depression treatment = SNRI, TCA, Catecholamine reuptake blockers

Dopamine in brain: Location, associated diseases and treatment

Produced in Substantia nigra and ventral tegmental area Associated with reward Increase Dopamine = schizophrenia Decreased Dopamine = Parkinsons

Acetylcholine in brain: Location, associated diseases and treatment

Produced in basal nucleus and RF | Decrease Ach = Dementia

Selectively vulnerable areas of cell death in hypoxic encephalopathy

1. Sommer sector, Hippocampus 2. Cerebral cortex - Deep layers (Laminar necrosis) 3. Purkinje cells in cerebellum

Astrocyte and injury

Astrocytes proliferate and send out processes to form "astrocyte scar"

Gemistocytic astrocytes

Large cytoplasm of astrocytes Response to injury

Progressive multifocal leukoencephalopathy

Caused by activation of JC virus Invades Oligodendrocytes --> demyelination Also causes abnormal astrocytes Progressive Multiple areas Viral inclusions in oligodendrocytes

Leukodystrophy

Demyelinating disease that affects brain diffusely

Necrotizing vasculitis

Inflammation of blood vessel, narrowing of lumen and destruction of vessel wall Causes ischemic changes in nerve

Distal vs segmental demyelination

Distal: Primary destruction of axon and distal axons degenerate. Cell body damage can also be cause Segmental demyelination: One axonal segment degenerates. Caused by Schwann cell damage or damage to myelin sheath

Guillain Barre

Acute inflammatory demyelinating polyradiculopathy Ascending paralysis Preceded by flu like illness --> T cell hypersensitivity Sural nerve biopsy usually negative because disease affects proximal nerve

Chronic inflammatory demyelinating polyradiculopathy (CIDP)

Relapses and remissions Repeated demyelination and remyelination Onion bulb formation

Diabetic neuropathy

Axonal degeneration and reduplication of capillary BM

Occlusive or ischemic cerebrovascular disease types

Atherosclerosis causing stenosis and embolization of thrombi Arteriolosclerosis causing lacunar infarcts Cardiac embolism Vasculitis

Atherosclerosis leading to stenosis and thromboembolus

Occlusion of arteries to due atherosclerosis Most common area at carotid bifurcation

Areriolosclerosis

Small infarct, smaller vessels Basal ganglia and pons because of occlusion of small penetrating arterioles

Cardiac embolism

Embolus would go up through internal carotid and block artery Emboli cause hemorrhagic infarct Embolus might lyse and reperfusion will occur

Events following infarction

6-48hrs - Ischemic neurons and inflammation 2-6 days: Phagocytosis of necrotic debris by macrophages Weeks: Liquefaction, gemistocytic astrocytes and angiogenesis Months to years: Cystic cavity

Hypertensive hemorrhage

HTN causes arteriolosclerosis of perforating arteries Vessels may weaken resulting in microaneurysms --> rupture and HTN hemorrhage forms Pooling of blood

Berry Aneurysm

Small aneurysms that occur at major vessel branch points Rupture can lead to death Hemorrhage in subarachnoid space

Vascular malformation

Arteriovenous malformation Arteries connected to veins without capillaries High pressure blood flow in veins --> venous proliferation and scarring

Subarachnoid hemorrhage/berry aneurysm complications

Rebleeding Vasospasm Fibrosis of subarachnoid space

Cerebral amyloid angiopathy

Amyloid protein deposits in walls of small/med arteries leading to vessel weakening and hemorrhage Lobe hemorrhage Congo red stain

Hypertensive hemorrhage vs cerebral amyloid angiopathy differences

HTN Hemorrhage: Result of penetrating artery bleeding so more central brain. Basal ganglia etc CAA: Results in lobular hemorrhage

CN's that innervate tongue

CN V, VII, IX, X, XII

CN's involved in taste

CN VII, IX, X

Facial nerve taste innervation

Fungiform, anterior foliate papillae, palate papillae Anterior 2/3 tongue

Glossopharyngeal taste innervation

Circumvillate papillae, foliate papillae Posterior 2/3 tongue

Vagus taste innervation

Taste buds on epiglottis and esophagus

NT released for taste

ATP which depolarizes peripheral endings of taste cranial nerves

Taste pathway

First order (CN ganglia) --> solitary nucleus (second order) --> VPM thalamus (third order) --> gustatory cortex of insula

Olfactory depolarization initiation

Odorant molecules in mucus covering olfactory epithelium bind to receptors --> cAMP activation and Ca entry --> Cl exit (depolarization)

Olfactory pathway

Olfactory receptors that are same converge at specific olfactory bulb glomerulus --> olfactory bulb neuron (mitral cell) --> Mitral cells reach cortex near uncus (primary olfactory cortex/piriform cortex) --> olfactory association areas

Damage to olfactory system

Ansomia