Neuro Block A

• sensory behaviors: seeing, hearing, touch, smell, taste
• motor behaviors: reflex or voluntary
• emotional behaviors: anger, fear, joy
• visceral functions: temperature, blood pressure, heart rate, sexual drive
• higher cognitive functions: reasoning, learning/memory, consciousness, speech
• personality: mood, temperament

• CNS: brain & spinal cord
• PNS: all nerves after they exit the CNS
• ANS: SNS & PSNS

• neurons: cell body (soma, perikaryon), dendrites (receptive region), axon (effector region)
• glial cells: structural & functional cells
• synapses: connections between neurons

• dendrites: receptive & integrative
• cell body: soma
• axon: effector/ sends information
• presynaptic terminal & synapse

• double layer of phospholipids
• channels, protein structures, positioned across the membrane
• "selectively" permeable to ions

• unipolar cell: invertebrate neuron
• pseudo-unipolar cell: DRG
• bipolar cell: retinal cells
• multipolar cells: spinal motor neuron, hippocampal pyramidal cell, Purkinje cell of cerebellum, stellate

• sensory
• motor
• preganglionic autonomic
• postganglionic autonomic
• local interneurons
• projection

• surround neurons
• 50X more numerous than neurons
• serve as supporting elements
• form electrical insulation (Schwann cells & oligodendrocytes)
• remove debris after injury
• buffer ions
• guide neuron growth/ nutritive function

• mix of fats, water & protein
• non-conducting
• "white matter"

tubulin structures involved in transport of proteins & for skeletal framework

protein structures for transport & maintaining structure

• receptive regions of the neuron (& integration)
• come off multiple locations of the cell body
• extend from cell body to form dendritic trees
• dendritic spines: protrude off of the dendrite & increase surface area; increase receptive area of neuron
• made of cytoskeleton consisting of microtubules, microfilaments, rER & mitochondria

• input component
• integrative
• conductile
• presynaptic terminal

• ion distribution differs across neuronal membrane (-70mV)
• extracellular: Na+ and Cl-
• intracellular: K+ and P-

• electrostatic force & chemical concentration gradients: produced by membrane bound ion channels which leave more K+ inside, more Na+ outside the cell membrane
• Na/K ATPase pump: pushes Na+ out and K+ into the cell

electrical cellular property than can change quickly (allow quick signaling)

• neurons are electrically charged (voltage difference between inside & outside of cell)
• neurons receive inputs which summate to produce electrical signals sent to the next neuron in the circuit
• signals are propagated down axon by an electrical impulse (an all or none event)
• electrical signaling is usually in one direction

• channel connects cytoplasm of two neurons and/or glial cells
• channels on presynaptic cell line up perfectly with channels on postsynaptic cell
• change in ion concentration in one cell flows quickly into next cell

• synaptic gap junctions
• chemical synapse

• release of NT
• exocytosis: action potential triggers voltage gated Ca2+ channels; Ca2+ signals synaptic vesicles to fuse with the membrane
• release: as the vesicles fuse, they spill their contents into the synapse

• graded potentials which occur at the synapse; summate at trigger zone (axon hillock)
• occur in respons to presynaptic transmitter release
• proportional to number of ion channels activated
• EPSP: excitatory postsynaptic potential (depolarize the cell; ACh & glutamate); usually mediated by Na+ channels (influx)
• IPSP: inhibitory postsynaptic potential (hyperpolarize the cell; gamma aminobutyric acid & glycine); usually mediated by K+ channels (efflux)

• excitatory
• asymmetric binding site
• round vesicles

• inhibitory
• symmetric binding site
• pleomorphic vesicles

• postsynaptic proteins which have an affinity for neurotransmitters (ligand binding site)
• usually consist of transmembrane glycoproteins with one/multiple subunits
• binding of ligand to receptor produces a change in protein conformation
• change results in alteration in membrane polarization either directly or indirectly
• ionotropic: direct & fast; ligand and/or voltage gatedmetabatropic: indirect & slow; ligand gated

• nuclei: groups of functionally related cells usually recognized by a cluster of cell bodies in CNS
• layer (lamina): groups of functionally related cells forming layers
• tract (fasciculus): bundle of axons in CNS
• funiculus ("cable"): groups of tracts
• ganglion: group of nerve cell bodies

• simplest connection between two neurons
• reflexes are involuntary motor responses to sensory stimuli

more complex connections with brainstem; cerebral cortex relay from spinal cord to thalamus to cerebral cortex and back to spinal cord

• topographic localization of function: many areas of cerebral cortex have maps in which the sensory or motor surface is laid out topographically onto the brain
• parallel processing: distinct parallel pathways for many sensory & motor sub-modalities
• input to output processing: information is processed from sensory to unimodal association to multimodal association to motor cortex
• crossed pathways: right side = left brain
• lower motor neurons: spinal motor neuron; directly innervates muscle (alpha motor neuron)
• upper motor neurons: controls activity of LMNs

• spinal cord: receives sensory information from periphery; sends axonal projections from motor neurons to muscle & glands
• brainstem: contains CN nuclei
• basal ganglia: motor related nuclei involved in initiating movement
• thalamus: projection nuclei which send sensory & motor information to cerebral       cortex
• hypothalamus: endocrine function, emotions, feeding-drinking
• cerebral hemispheres: sensory, motor & association areas (higher cognitive functions)

• medulla oblongata: CN nuclei IX, X, XII and parts of V, VIII; inferior olive, pyramids; important in regulating respiration & cardiac function
• pons: CN nuclei VI, VII, parts of V & VIII; reticular formation, pontine nuclei projecting to cerebellum
• midbrain: CN nuclei III, IV, part of V; mediates visual & auditory reflexes

• basal ganglia: knots of nuclei within the base of telencephalon (caudate nucleus, putamen, globus pallidus)
• thalamus: relay, association & diffuse nuclei which project to various regions of cortex

• dorsal thalamus: relay nuclei, association nuclei, diffuse projecting nuclei
• epithalamus: habenula, pineal body
• subthalamus
• metathalmus

• hippocampus proper (Ammon's horn)
• dentate gyrus
• fornix (fibers)

• corpus callosum
• anterior & posterior commissures
• fornix of hippocampus

• frontal lobe: motor, prefrontal
• parietal lobe: somatosensory
• occipital lobe: visual
• temporal lobe: auditory, visual
• limbic lobe: emotions, memory
• insular cortex: isle of Reil buried in lateral cortex

• two lateral ventricles: within the cerebral hemispheres; complex C shaped structures w/ five components
• third ventricle: at midline, adjacent to thalamus & hypothalamus
• fourth ventricle: on dorsal surface of brainstem, below cerebellum; V shaped

• sensory
• motor
• reflexes
• integration

• receives primary sensory input from receptors in skin, muscle, tendons
• somatosensory - GSA (proprioceptive & exteroceptive)
• viscerosensory - GVA (from thoracic, abdominal & pelvic viscera)

• somatic motor (GSE) neurons that project to skeletal muscle
• visceral motor (autonomics) (GVE) neurons that project to smooth, cardiac muscle & glandular epithelium

forms local segmental reflex arcs (spinal reflexes) that convey sensory input to motor neurons, either directly or through an interneuron

integrates information from descending fibers of higher centers, cerebral cortex & brainstem

the portion of the spinal cord that gives rise to a single spinal nerve

• arises as dorsal & ventral roots from a single spinal cord segment
• each nerve exits through its own intervertebral foramen

• C2 & C3: posterior head and neck
• C4 & T2: adjacent to each other in the upper thorax
• C5: anterior shoulder
• C6: thumb
• C7: index & middle fingers
• C7/8: ring finger
• C8: little finger
• T1: inner forearm
• T2: upper inner arm
• T2/3: axilla
• T4 or T5: nipple
• T10: umbilicus
• L1: anterior upper inner thigh; inguinal ligament
• L2: anterior upper thigh
• L3: knee
• L4: medial malleolus
• L5: dorsum of foot; toes 1-3
• S1: toes 4,5; lateral malleolus
• S3/C1: anus

• 8 cervical spinal nerves
• 12 thoracic spinal nerves
• 5 lumbar spinal nerves
• 5 sacral spinal nerves
• 1 coccygeal spinal nerves

• cervical enlargement: C4 through T1 spinal cord segments; innervation of upper limb (brachial plexus)
• lumbosacral enlargement: L2 through S3 spinal cord segments; innervation of lower limb (lumbar & sacral plexus)

• dura mater
• subdural space
• arachnoid mater
• subarachnoid space
• denticulate ligament
• pia mater

• anterior median fissure: anterior spinal artery
• anterior white commissure
• anterolateral sulcus: ventral roots
• dorsolateral fasciculus: Zone of Lissauer
• posterolateral sulcus: dorsal root entry zone
• posterior intermediate septum
• posteror intermediate sulcus
• posterior median septum
• posterior median sulcus

• anterior spinal artery: from vertebral arteries; supplies anterior 2/3 of the spinal cord; 75% of the blood supply to the spinal cord is from the ASA
• posterior spinal artery: from posterior inferior cerebellar arteries; supply posterior 1/3 of the spinal cord
• radicular arteries: from segmental vessels; supplies blood to roots as well as cord
• Artery of Adamkiewicz: arteria radicularis magnus; supplies lower 1/3 of cord
• all of these join to form the arterial vasocorona

• external vertebral venous plexus
• internal vertebral venous plexus: Batson's plexus; located between the dura mater and the vertebral periosteum in the epidural space
• thin walled, incompetent valves or valveless
• dependent upon pressure differential, venous blood can flow between the vertebral plexuses & skull, neck, thorax, abdomen & pelvis
• pathway for metastasis of prostate cancer OR pelvic infections to the vertebral column & cranial cavity

• posterior funiculus: dorsal columns; fasciculus cuneatus & fasciculus gracilis
• lateral funiculus: lateral corticospinal tract
• anterior funiculus: anterolateral system
• intrasegmental fibers & intersegmental tracts
• dorsolateral fasciculus: Lissauer's tract
• fasciculus proprius: propriospinal tract
• anterior white commissure

• cervical: large, oval shape; enlarged ventral horn; most white matter
• thoracic: small, round shape; IMLCC (T1-L2)
• lumbar: round; enlarged ventral horn
• sacral: small, round; least amount of white matter

• nuclear regions in the spinal cord
• named by nuclear groups or by lamina

• lamina I: posteromarginal nucleus
• lamina II: substantia gelatinosa
• laminae III + IV: principal sensory nucleus, nucleus proprius
• laminae V + VI: base of posterior horn
• lamina VII: nucleus dorsalis of Clarke (T1-L2); IMLCC (T1-L2/3); sacral parasympathetic cell column (S2-4)
• lamina VIII: motor neurons & interneurons; receive descending information
• lamina IX: lower motor neurons (medial, lateral, anterior & posterior columns)
• lamina X: region around central canal

• medial motor neurons: axial muscles (proximal)
• lateral motor neurons: extremities (distal)
• anterior motor neurons: extensor muscles
• posterior motor neurons: flexor muscles 

• motor neurons located in the ventral horn of the spinal cord [and in brainstem CN motor nuclei] that innervate muscle fibers
• final common pathway

• motor neurons with cell bodies in the motor region of the cerebral cortex or the brainstem
• carry motor information down to the lower motor neuron to influence it's output
• any motor neurons that are not directly responsible for stimulating the target muscle

• an involuntary, stereotyped response to a sensory input
• requires an afferent fiber, interneurons and/or motor neurons, and a target tissue usually skeletal muscle

• simple reflex; confined to a single spinal cord segment
• involves a receptor structure, an associated afferent neuron in the dorsal root ganglion & an efferent neuron within the CNS

complex reflex, involving multiple spinal cord segments

reflexes are greatly exaggerated

reflexes are diminished

reflexes are absent

• the only reflex that does not involve one or more interneurons
• important for the constant automatic corrections during movements and postures

• biceps brachii: C5 musculocutaneous
• brachioradialis: C6 radial
• triceps brachii: C7 radial
• quadriceps femoris: L4 femoral
• gastrocnemius, soleus: S1 tibial

• monosynaptic myotatic stretch reflex - intersegmental reflex
• tap on patellar tendon stimulate muscle spindles
• quadriceps contracts
• extension of the leg at the knee joint

• one group of muscles is excited & the antagonistic group is inhibited
• reflex activity in a given muscle produces similar activity in its ipsilateral synergists and the opposite activity in its ipsilateral antagonists

• inverse myotatic reflex
• involves Golgi tendon organ - monitors muscle tension
• reflex inhibition of a motor unit in response to excessive tension in the muscle fibers it supplies
• protective mechanism to prevent muscles from exerting more force than the bones & tendons can tolerate

• nociceptive reflex
• more complex intersegmental polysynaptic reflex
• initiated by cutaneous receptors
• withdrawal from a painful or nociceptive stimulus
• involves the whole limb & several spinal cord segments & interneurons
• primary afferents bifurcate on entering the spinal cord & their processes extend one or two segments in both a rostral and a caudal direction

• builds on basic circuits of the flexor reflex
• withdrawal [flexion] in the ipsilateral limb is accompanied by a simultaneous and opposite activity [extension] in the contralateral limb

• motor (descending) pathways: lateral corticospinal tract & corticobulbar (corticonuclear) fibers
• sensory (ascending) pathways: dorsal column/medial lemniscal pathway; anterolateral system [lateral spinothalamic tract]

sensory: vibration, conscious proprioception, two point discrimination (fine touch)

• 1* dorsal root ganglion: T6 & above - fasciculus cuneatus; T7 & below - fasciculus gracilis
• 2* dorsal column nuclei: give off internal arcuate fibers that cross at lower medulla to form contralateral medial lemniscus
• 3* ventral posterolateral nucleus of thalamus: project up to somatosensory cortex

sensory: pain (nociceptive), temperature, crude touch

• 1* dorsal root ganglion: enters Zone of Lissauer and ascends before synapsing
• 2* dorsal horn laminae 1,2,5: sends neurons across midline at anterior white commissure to form contralateral spinothalamic tract
• 3* ventral posterolateral nucleus of thalamus: projects to somatosensory cortex

motor: movement of contralateral limbs

• begins in motor cortex (area 4/precentral gyrus)
• travels through crus cerebri of cerebral peduncle & corticospinal fibers --> form pyramids of medulla
• cross at pyramidal decussation
• fibers terminate on ventral horn cells (Upper Motor Neurons)

• peripheral nerve lesion
• motor & sensory deficits
• peripherally: trauma is most common cause (cervical rib, herniated IV disc)
• peripheral entrapment: carpal tunnel syndrome or pronator teres syndrome

lesion of the dorsal root - sensory deficites only

lesion of the ventral root - motor deficits only

lesion of motor neurons in ventral horn - motor deficits only

• lesions 1 (peripheral nerve), 3 (ventral root), 4 (motor neuron in ventral horn)
• alpha & gamma motor neurons of lamina Ix
• includes axon in spinal or peripheral nerves (ex. brachial plexus lesions, carpal tunnel syndrome)

• descending pathways and cells of origin
• motor cortex lesions (trauma, vascular)
• spinal cord or brainstem lesions that interrupt descending pathways

• areflexia: absent deep tendon reflexes
• flaccid paralysis: complete loss of muscle tone & all voluntary and reflex movements
• muscle wasting: wasting & eventual fibrosis & contracture of affected muscles
• fasciculations: visible spontaneous contraction of motor units
• all signs occur IPSILATERAL and in muscles (myotomes) supplied by the affected motor neurons

• paresis: difficulty in movement or weakness
• paralysis: loss of movement
• spastic paralysis: spasticity, increased muscle tone, increased resistance to passive stretching of muscles due to loss of descending influences on the LMN
• little wasting of muscles
• hyperreflexia: exaggerated deep tendon reflexes due to loss of inhibitory reflexes on gamma motor neurons
• Babinski sign: abnormal superficial plantar reflex
• all signs occur IPSILATERAL and below the level of the spinal cord lesion

ipsilateral loss of vibration, position, two point discrimination & deep touch

ipsilateral paralysis, paresis, spasticity, hyper-reflexia/clonus, Babinski sign (**UMN symptoms)

contralateral loss of pain & thermal sense

ipsilateral paralysis, paresis, hypotonia, hyporeflexia to areflexia, fibrillations, muscle atrophy (LMN symptoms)

ipsilateral miosis, ptosis, anhidrosis, enopthalamus; urinary & bowel incontinence

• results in loss of all sensation & voluntary movement inferior to the lesion
• trauma commonly associated with C spine fracture
• deficits depend on the level of transsection

• consists of respiratory insufficiency
• quadriplegia: paralysis of all four limbs (bilateral paralysis)
• spinal shock: period of areflexia of upper & lower extremity following trauma to spinal cord
• autonomic symptoms
• spasticity below level of lesion
• hyperreflexia: exaggerated DTR below level of lesion (lateral corticospinal tract)
• bilateral anesthesia, loss of pain & temperature (spinothalamic tract)
• loss of proprioception (dorsal column system)

spares respiratory muscles (C3,4,5 keep the diaphragm alive)

paraplegia: paralysis of lower body including both lower extremities

• spinal cord hemisection
• ipsilateral dorsal column signs: loss of the following sensations at & below the level of the hemisection; vibration; conscious proprioception (position sense); two point discriminitive touch
• ipsilateral corticospinal tract signs: lateral corticospinal tract injury; muscle paralysis, spasticity, clonus, hyperreflexia, Babinski sign
• contralateral spinothalamic tract signs: loss of pain & temperature in the contralateral half of the body beginning one or two segments below the hemissection

• lesiosn around central canal
• occurs commonly in ages 25-40; males more than females
• cyst or cavity (syrinx) forms within spinal cord
• lesions in & around the central canal encroach initially on fibers conveying pain & temperature in the anterior white commissure
• causes segmental & bilateral loss of pain & temperature sensations in corresponding dermatomes
• usually affects cervical spinal cord segments

crossing spinothalamic fibers involved

crossing spinothalamic fibers & motor neurons involved

• loss of pain & temperature in the upper limbs on back of both arms & shoulders
• paresis of hands
• weakness & wasting in hands & arms
• fasciculations - visible spontaneous contractions of muscle units
• eventual paralysis of limbs

• anterior cord syndrome: occlusion of the anterior spinal artery (supplies anterior 2/3 of the spinal cord)
• characterized by abrupt onset of symptoms & signs; damage is related to vascular insufficiency
• syndrome is manifested by complete motor paralysis (corticospinal function) & sensory anesthesia (spinothalamic functions)
• posterior columns are spared
• deep pressure & proprioception are only retained sensibility of trunk & lower extremities
• flaccid paralysis below level of the lesion - LMN spinal shock
• patient demonstrates greater motor loss in legs than arms

• conduit functions: ascendign & descending fiber systems
• cranial nerve functions: motor & sensory cranial nerve nuclei
• integrative function: nuclei control respiration, cardiac function, consciousness, pain, balance, equilibrium
• cranial reflexes: mediates cranial reflexes (jaw jerk reflex, corneal reflex, accomodation reflex, vestibulo-ocular reflexes)

• medulla, pons & midbrain
• each division has roof, tegmentum & basilar parts

GSE, GSA, GVE, GVA, SVE, SSA, SVA

• general somatic efferent
• multipolar neuronal cell bodies in the motor nuclei of cranial nerves
• synapse directly on striated muscle via motor end plates
• CN: III, IV, VI, XI and XII

• general somatic afferent
• found in several cranial nerves, but primarily CN V
• supplies skin & mucous membranes of head & neck
• CN: V, VII, IX, and X

• general visceral efferent (parasympathetic)
• primary preganglionic neurons for the parasympathetic nervous system are multipolar neurons in parasympathetic nuclei associated with CN III, VII, IX and X
• sympathetic fibers innervating the head & neck originate from secondary postganglionic neurons located in the superior cervical ganglion

• general visceral afferent
• pain & sensibility of viscera
• CN: VII, IX & X

• special visceral efferent (branchiomotor)
• supply striated muscles embryologically derived from pharyngeal arches
• CN V: supplies muscles derived from 1st pharyngeal arch; muscles of mastication, tensor tympani, tensor veli palatini, anterior belly of the digastric, mylohyoid
• CN VII: supplies muscles derived from 2nd pharyngeal arch; muscles of facial expression, posterior belly of digastric, stapedius, stylohyoid
• CN IX: supplies muscle derived from 3rd pharyngeal arch; stylopharyngeus m
• CN X: supplies muscles derived from the 4th & 6th pharyngeal arches; pharyngeal, palatal & laryngeal musculature

• special somatic afferent (special senses with physical stimulus)
• CN II: responds to light stimuli
• CN VIII: responds to sound stimuli

• special visceral afferent (taste & smell)
• CN I: responds to chemical stimuli that mediate the sense of smell
• CN VII, IX, X: responds to chemical stimuli that mediate the sense of taste

• somatosensory information from face - mediate touch, pain, and temperature
• dorsal trigemino-thalamic tract
• ventral (anterior) trigeminothalamic tract
• from spinal trigeminal nucleus & principal (chief) sensory nucleus of CN V
• to ventral posterior medial nucleus (VPM) of thalamus

• trigeminal motor nucleus: CN V; bilateral
• facial motor nucleus: CN VII; contralateral, bilateral to upper face
• nucleus ambiguus: CN IX, CN X; bilateral, contralateral to CN X to soft palate & uvula
• accessory nucleus: CN XI; ipsilateral
• hypoglossal nucleus: CN XII; bilateral but predominantly contralateral
• corticoreticular & corticopontine fibers

• contralateral lower facial paralysis
• sparing of contralateral upper face because of bilateral corticonuclear projections

Bell's Palsy: ipsilateral facial paralysis (upper and lower face)

• uvula deviates to the side of the lesion
• tongue deviates to the side opposite the lesion

• Hypoglossal Nucleus: CN XII - GSE
• Dorsal Motor Nucleus: CN X - GVE
• Inferior Salivatory Nucleus: CN IX - GVE
• Nucleus Ambiguus: CN IX, X - SVE
• Solitary Nucleus: CN VII, IX, X - SVA, GVA
• Spinal Trigeminal Nucleus: CN V, VII, IX, X - GSA
• Cochlear & Vestibular Nuclei: CN VIII - SSA

• Abducens Nucleus: CN VI - GSE
• Facial motor nucleus: CN VII - SVE
• Superior Salivatory Nucleus: CN VII - GVE
• Trigeminal Motor Nucleus: CN V - SVE
• Principal (Chief) Sensory Nucleus of CN V: CN V - GSA
• Spinal Trigeminal Nucleus: CN V, VII, IX, X - GSA
• Vestibular Nuclei: CN VIII - SSA

• Oculomotor Nucleus: CN III - GSE
• Edinger-Westphal Nucleus: CN III - GVE
• Trochlear Nucleus: CN IV - GSE
• Mesencephalic Nucleus of CN V: CN V - GSA

• AKA PICA syndrome; Wallenberg Syndrome
• lesion of posterior inferior cerebellar artery
• anterolateral system fibers damaged: contralateral loss of pain & thermal sense on body
• spinal trigeminal tract & nucleus damaged: ipsilateral loss of pain & thermal sense on face
• nucleus ambiguus, roots of CN IX & X damaged: dysphagia, soft palate paralysis, hoarseness, diminished gag reflex

• infereior alternating hemiplagia
• lesion of anterior spinal artery
• pyramid (corticospinal  fibers) damaged: contralateral hemiplegia of arm & leg
• medial lemniscus damaged: contralateral loss of position sense, vibratory sense & discriminatory touch
• hypoglossal nerve in medulla or hypoglossal nucleus damaged: deviation of tongue to ipsilateral side; muscle atrophy and fasciculations

• middle alternating hemiplagia
• lesion of paramedian branches of basilar artery
• corticospinal fibers in basilar pons damaged: contralateral hemiplagia of arm & leg
• medial lemniscus damaged: contralateral loss or decrease of position & vibratory sense & discriminitive touch (arm & leg)
• abducens nerve fibers or nucleus damaged: ipsilateral lateral rectus muscle paralysis

• lesion of long circumferential branches of the basilar artery
• facial motor nucleus (caudal levels) damaged: ipsilateral paralysis of facial muscles
• trigeminal motor nucleus damaged: ipsilateral paralysis of masticatory muscles
• spinal trigeminal tract & nucleus damaged: ipsilateral loss of pain & thermal sense from face
• anterolateral system damaged: contralateral loss of pain & thermal sense from body

• superior alternating hemiplagia, Weber syndrome
• lesion of paramedian branches of P1 segement of posterior cerebral artery
• CN III damaged: ipsilateral paralysis of eye movement ("down & out")
• corticospinal fibers in cerebral peduncle (crus cerebri) damaged: contralateral hemiplegia of arm & leg
• red nucleus spared: no contralateral ataxia

• clue: CN III palsy or vertical gaze problem
• Claude's syndrome: central midbrain region (tegmentum, red nucleus, CN III)
• Benedikt's syndrome: lesion of tegmentum, red nucleus, CN III & cerebral peduncle
• Weber's syndrome

• mental status
• cranial nerves
• motor
• coordination
• sensory
• gait

• screening of each of the subsets (mental status, CNs, motor, coordination, sensory & gait)
• allows one to check entire neuroaxis (cortex, subcortical white matter, basal ganglia/thalamus, brainstem, cerebellum, spinal cord, peripheral nerves, NMJ & muscles)
• expand evaluation of a given subset to answer questions generated from the history OR confirm/refute expected or unexpected findings on exam

• is NEVER done given the amount of time & effort it would take
• LONG & REDUNDANT
• take advantage of this to confirm/refute abnormal findings

• level of alertness
• degree of orientation
• concentration
• memory
• language

• subjective view of examiner
• definition of consciousness
• terminology for depressed level of consciousness
• coma
• delerium

• to what? name, place date
• A and O x 4: alert and oriented to person, place, time, etc.

• requires a patient to remain on task during a sustained mental activity
• serial 7s or 3s, WORLD backwards, etc
• try to quantify degree of impairment

• immediate recall: a task of concentration
• short-term memory: 3/3 objects after 5 minutes; function of hippocampus & connection to cortex
• long-term memory: last thing to go

• confined to dominant hemisphere
• aphasia: have difficulty with spoken language AND reading, writing, sign language & gestures (localization of problem area)
• dysarthria: intact language with a motor speech production problem (does not localize to language areas)
• receptive language: command following; function of Wernike's area
• expressive language: fluency & word finding; function of Broca's area
• repetition: screens for receptive, expressive & conductive aphasias

• Gerstmann's Syndrome: difficulty with calculations, R-L confusion, finger agnosia & agraphia (deficiency in writing); dominant parietal lobe lesion
• Hemineglect: non-dominant parietal lobe lesion

• olfactory nerve
• distinguis coffee from cinnamon
• smelling salts irritate nasal mucosa & test V2 trigeminal sense
• disorders of smell result from closed head injuries; loss of tate will also occur

• optic nerve
• tests acuity, field, pupil & fundus
• visual acuity: cover one eye, read line on chart, switch
• visual field: direct confrontational testing of peripheral vision
• pupillary light reflex: afferent portion through CN II, efferent through CN III (papillary constrictor mm)
• fundoscopic exam: looks at nerve

• afferent pupillary defect
• intact consentual pupillary light reflex but neither pupil constricts when light is shined on affected eye

pupils equal, reactive to light and accomodation

• oculomotor nerve
• responsible for most extra-ocular eye muscles (all except lateral rectus & superior oblique)
• Edinger Westphal nucleus: in tegmentum of midbrain; efferent limb of pupillary light reflex
• lesion: lateral strabismus ("down & out"), blown pupil & ptosis

• trochlear nerve
• innervates superior oblique m.
• lesion: extorted eye (patient cannot depress or intort adducted eye; leads to head tilt)

• abducens nerve
• innervates lateral rectus m.
• lesion: adducted eye (cannot abduct)

extraocular movement intact without involuntary movements of the eye

• trigeminal nerve
• opthalmic (V1): primary sensation; afferent input for the corneal blink reflex
• maxillary (V2): primary sensation
• mandibular (V3): sensory & motor component (muscles of mastication)
• test by light touch, cold, pin prick, position & vibration sense, movement of jaw

• facial nerve: motor innervation to facial muscles; efferent output to corneal blink reflex
• UMN deficit: affects contralateral corticobulbar tracts resulting in weakness of the lower part of the face only
• LMN deficit: affects the upper & lower facial muscles ipsilateral to the site of injury
• test by smiling & wrinkling forehead

• vestibulocochlear nerve
• hearing & balance: patients will complain of tinnitis, hearing loss &/or vertigo
• Weber test: tuning fork on vertex of skull, conductive hearing loss detected in loudest ear; sensory neural hearing loss detected in ear opposite of loudest sound
• Renne Test: air conduction should be louder than bone conduction
• Doll's eye maneuver: in comatose patients, when head is moved quickly to one side, eyes should lag but follow
• cold calorics: cold water in right ear; eyes should drift to right side

• glossopharyngeal nerve
• afferent component of gag reflex - not usually tested
• check for palate elevation when patient says AHHH

• vagus nerve
• efferent component of gag reflex - not usually tested
• parasympathetic innervation from neck to midtransverse colon
• check for palate elevation when patient says AHHH

• spinal accessory nerve
• check sternocleidomastoid & trapezius strength

• hypoglossal nerve
• have patient stick out their tongue - look for deviation, atrophy & fasciculations
• UMN lesion: contralateral deviation of tongue
• LMN lesion: ipsilateral deviation of tongue; hemi-atrophy & fasciculations

• strength
• tone
• DTRs
• plantar responses
• involuntary movements

• measure of strength
• 5/5: full strength
• 4/5: weakness with resistance
• 3/5: can overcome gravity only
• 2/5: can move limb without gravity
• 1/5: can activate muscle without moving limb
• 0/5: cannot activate muscle

• decrease strength
• spasticity - increased tone
• brisk DTRs
• upgoing toes on plantar response
• no atrophy/fasciculations
• cause: corticospinal tract lesion, stroke
• symptomes: strong flexors in upper limb, strong extensors in lower limb, Babinski sign

• decreased strength
• hypotonia - decreased tone
• diminished or absent DTRs
• downgoing toes on plantar response
• +/- atrophy/fasciculations
• causes: ALS (anterior horn cell degeneration)

symptoms: distal weakness (hands/feet), spared proximal weakness (shoudler/hip girdle)

• symptoms: proximal weakness (shoulder/hip girdle), spared distal weakness (hands/feet)
• causes: Duchenne's Muscular Dystrophy

• resistance appreciated when moving a limb passively
• central hypotonia: Down's syndrome
• peripheral hypotonia: myopathy, neuropathy
• spasticity: limb must be moved at a certain direction/velocity to produce tone (corticospinal tract)
• rigidity: no direction/velocity component, tone is constant (basal ganglia, Parkinson's Disease)
• dystonia: discoordination of agonist & antagonistic muscles (basal ganglia)

• deep tendon reflexes
• 0/4: absent
• 1-2/4: normal range
• 3/4: pathologically brisk
• 4/4: clonus ("flapping reflex")

• chorea: rapid, quick movements all over body
• athetosis: distal writhing
• tics: repetitive contractions localized to a group of muscles or vocalizations (Tourette Syndrome)
• myoclonus: shock like contraction of a group of muscles

• parkinsonism: tetrad of bradykinesia, rigidity, postural instability & resting tremor
• dystonia: keeping limbs in fixed/twisted uncomfortable position

• bradykinesia: slow movements, decreased facial expressioins
• rigidity: form of increased tone
• postural instability: falls easily
• resting tremor: relieved with voluntary movement

• primary sensory modalities: light touch, pain/temperature sensation, vibration/position sensation
• cortical sensory modalities: stereognosis, graphesthesia, two point discrimination, double simultaneous extinction

• light touch (multiple pathways)
• pain/temperature sensation (spinothalamic tract)
• vibration/position sense (posterior columns)
• reflect input from sensory receptors, sensory nerves, spinal cord, brainstem, through to the level of the thalamus

• stereognosis: test by placing coin into contralateral hand & ID by touch
• graphesthesia: ID letter "drawn" on hand
• two point discrimination: ability to sense one or both points of stimulation
• double simultaneous extinction: can identify stimuli individually on R & L side, but only one side when stimulated bilaterally
• reflects processing by the somatosensory cortex (post-central gyrus)

• small unmyelinated fibers provide pain & temperature input
• travels through DRG
• Lissauer's tract up/down a few segments
• synapse in lamina II (substantia gelatinosa)
• 2* neurons cross midline at anterior white commissure
• travel up lateral spinothalamic tract
• synapse on VPL nucleus of thalamus

• large myelinated fibers bring sensory information concerning vibration & joint position sense
• fasciculus gracilis (legs) & fasciculus cuneatus (arms)
• synapse on ipsilateral dorsal column nuclei
• 2* neurons corss at medial lemniscus
• synapse on VPL nucleus of thalamus

• tests cerebellum inputs/outputs
• hemisphere dysfunction
• midline dysfunction

• ipsilateral hemiataxia
• dysmetria on finger-nose-finger testing
• irregularly irregular tapping rhythm
• dysdiadochokinesis
• impaired check
• hypotonia
• impaired heel-knee-shin
• falls to side of lesion
• variable directions of nystagmus

• lesion to Vermis of cerebellum
• truncal ataxia
• titubation
• ataxic speech
• gait ataxia (acute or chronic)

• normal: requires multiple levels of the neuroaxis to be intact (vision, strength, balance/coordination, joint position)
• observe arm swing, base of gait, heel strike, time spent on each leg, posture of trunk, toe walking, heel walking, tandem walking

• parkinsonism gait: shuffling, magnetic gait
• hemiparetic gait: circumduction of leg with flexion & adduction of arm
• spastic diplegia gait: "knock kneed"
• acute ataxia gait: drunken gait
• chronic ataxia gait: wide base
• waddling gait: hip girdle weakness (Gower's sign)
• high stepping gait: due to foot drop (LMN) or loss of proprioception of feet

• dorsal thalamus: relay, association & diffuse projecting nuclei to cortex
• hypothalamus: controls endocrine function and autonomic behaviors
• ventral/ subthalamus: subthalamic nucleus and zona incerta (an extension of midbrain reticular formation)
• epithalamus: pineal body, habenular nucleus, stria medullaris- receives fibers from the globus pallidus & limbic system; enables basal ganglia & limbic system to modulate the reticular system in brainstem; helps control circadian rhythms

• anterior division
• medial division
• lateral division - dorsal & ventral tiers

• anterior division: anterior nuclei
• medial division: dorsomedial nucleus
• lateral division - dorsal tier: laterodorsal & lateroposterior nuclei
• lateral division - ventral tier: ventral anterior, ventolateral, ventral posterolateral, & ventral posteromedial nuclei
• metathalamus: lateral & medial geniculate nuclei
• lamiar tracts: intralaminar nuclei
• surrounding the thalamus: reticular nucleus
• pulvinar nucleus: posterior thalamus

• specific (or relay) nuclei
• association nuclei
• non-specific nuclei

• mostly comprise the ventral tier and the geniculate bodies (nuclei & inputs)
• the result is a somatosensory thalamus that is the first place to bring the whole body map together

• ventral anterior nucleus: from globus pallidus and sustantia nigra
• ventrolateral nucleus: from cerebellus & globus pallidus
• ventral posterolateral nucleus: somatosensory from body to primary somatosensory cortex
• ventral posteromedial: somatosensory from head to primary somatosensory
• lateral geniculate nucleus: from retina to primary visual cortex
• medial geniculate nucleus: from auditory pathway to primary auditory cortex
• lateral dorsal nucleus: from hippocampus to cingulate cortex

• extensive thalamocortical efferents that merge and become part of the internal capsule
• 4: anterior, inferior, posterior, superior

• reciprocally connected to the association areas of the cortex
• dorsomedial nucleus: inputs from olfactory & limbic systems; reciprocal connections with entire prefrontal cortex
• lateral posterior & pulvinar nuclei: receive afferents from parietal, occipital & temporal lobes; each has reciprocal efferents back to the same lobes

• reciprocally connected to the association areas of the cortex
• intralaminar/ centromedian/ parafascicular: afferents from the basal ganglia & limbic system; efferents to the cerebral cortex, basal ganglia & limbic system
• reticular nucleus: afferents from the dorsal thalamus and cortex; efferents from the dorsal thalamus; almost exclusively GABA neurons inhibiting/modulating specific (or relay) nuclei
• enables increased detection of novel or deviant stimuli, enabling attention

• blood pressure & electrolyte composition: thirst, salt appetite, drinking, vasomotor tone
• energy metabolism: hunger, feeding, digestion, regulates GH & TSH
• reproductive behavior: sexual & parental; autonomic control of reproductive organs, endocrine regulation of gonads
• body temperature: thermoregulation behavior, metabolic rate
• defense behavior: regulates stress response (fight or flight)
• sleep wake cycle: circadian clock via suprachiasmatic nucleus

• contextual information: cerebral cortex, amygdala, hippocampal formation
• sensory inputs: visceral & somatic sensory pathways, chemosensory & humoral signals
• hypothalamus - compares input to biological set points
• effect: visceral motor, somatic motor, neuroendocrine, behavioral responses

• chiasmatic zone: lies above the optic chiasm, includes nuclei related to anterior pituitary
• tuberal zone: several nuclei in this zone are related to feeding & drinking behaviors; others to pituitary function
• mammillary zone: includes mammillary bodies which are involved in memory
• medial-lateral zones: hypothalamic areas involved in food & water intake; lateral zone contains medial forebrain bundle

• rostral: preoptic, supraoptic, paraventricular, &  suprachiasmatic nuclei
• middle: ventromedial hypothalamic & lateral hypothalamic nuclei
• caudal: mammillary nuclei

• rostral nuclei: magnocellular neurons produce vasopressin (antiduretic - neural control of BP & water balance), oxytocin (uterine control) & GnRH (gonal control) project to pituitary
• stimulation of ventromedial hypothalamic nucleus: refusal to eat
• stimulation of lateral hypothalamic nucleus: increase food/water intake (destruction --> refusal to eat)
• damage to mammillary nuclei: impaired ability to learn specific location within a cognitive map

• fornix: from the hippocampus to the mammillary bodies; related to emotional components of behavior & memory
• medial forebrain bundle: brainstem inputs related to states of consciousness & autonomic afferents (bidirectional)
• mammillothalamic tract: ascending pathway that projects from mammillary bodies to anterior nucleus of thalamus (which projects to cingulate cortex

• posterior cerebral artery
• thalamogeniculate arterial branches
• thalamoperforator arterial branches

• neocortex: thin layer of cell bodies covering the cerebrum
• subcortical nuclei: basal ganglia, hippocampus & amygdala (and all fiber tracts between them)

• dorsal: cerebral cortex & hippocampus
• ventral: basal ganglia

• frontal
• parietal
• occipital
• temporal
• limbic (cingulate gyrus)

• rostral to the central sulcus
• contains primary motor, premotor (including Broca's area for speech production)
• critical to planning response to stimuli
• attention
• much executive function

• caudal to the central sulcus
• contains primary & secondary somatosensory; multimodal association areas; part of Wernicke's area
• critical to mediating endogenous (self generated) attention

• posterior lobe bounded by the parieto-occipital sulcus & preoccipital notch
• contains much of the visual processing in the cortex (some multimodal processing too)

• inferior to the lateral fissure
• largely consists of Heschl's gyrus (auditory), part of Wernicke's area (association for speech processing) & multimodal sensory processing (including recognizing audio & visual stimuli)

• part of the cortex on the medial aspect of cerebral hemispheres
• forms rim (limbus) around the corpus callosum & diencephalon
• largely consists of cingulate gyrus, parahippocampal gyrus, olfactory bulb & cortex
• cortical control of emotional expression

• the number & size of the layers (created by cell bodies at different depths) varies for different types of cortex
• archicortex: hippocampus; 3-4 layers
• paleocortex: pyriform cortex; 3 layers
• neocortex: motor & visual cortex: 6 layers

• supragranular: layers above layer IV; densely packed; pyramidal neurons; cortico-cortical connections
• internal granular: layer IV; densely packed stellate cells; receives input from thalamus
• infragranular: layers below layer IV; develops first; primary descending projections (efferent mechanisms); layers V & VI - pyramidal neurons the thalamus, brainstem & spinal cord

• commissural fiber systems: corpus callosum; cortico-cortical connections
• projection fiber systems: internal capsule
• association fiber systems: within a lobe (NOT across)

Brodmann's areas: regional difference in cell morphology (different cell type suggests different functions)

• visual: areas 17,18,19 (occipital, temporal lobes)
• auditory: areas 41,42 (superior temporal lobe; parts of Heschel's gyrus)
• somatosensory: areas 1,2,3,5-7 (postcentral gyrus, parietal lobe)
• motor: areas 4,6,8 (precentral gyrus, frontal)
• frontal association cortex: areas 9,10
• Broca's speech area: areas 44,45 (frontal)
• Wernicke's speech areas: areas 22,39,40 (parietal & temporal lobes)

• areas of primary sensory input: subcortical or non-cortico-cortical source
• peripheral organization: sensitivity & output is maintains in areas of cortex
• cortical magnification: more complex processing requires relatively more cortical (and subcortical) space than the relative amount of body area occupied by the sensory receptors
• columns: the primary sensory cortices (& subcortical stations) are organized into repeating patterns of neurons with similar functional properties
• association areas: multisensory integration (LOTS of cortico-cortical)
• areas of primary motor output: neurons that go directly to other brain regions
• premotor: neurons coordinating sequences of motor output

• primary visual cortex: area 17 (occipital lobe)
• primary auditory cortex: areas 41,42 (superior temporal lobe)
• primary somatosensory cortex: areas 1,2,3 (postcentral gyrus of parietal lobe)
• primary olfactory cortex: medial temporal lobe (pyriform cortex near first nerve entrance)
• primary gustatory cortex: located in part in the insula of the frontal lobe

• "sensorotopic" mapping
• the organization of stimulus processing in the sensory receptor cells is maintained in areas of the cortex

• primary motor cortex: rostral of central sulcus; contains neurons that go directly to other brain regions outside the cortex
• premotor cortex: neurons activate prior to the initiation, coordination & timing of movements (connection to LMNs)

• parieto-temporal association cortex (non dominant hemisphere): mediates spatial relationships, attention, object recognition
• prefrontal association cortex: planning, judgement, intellect
• parieto-frontal association cortex: dominant hemisphere; mediates language comprehension (Wernicke's area) and expression (Broca area); initiates attention instructions

• common brain lesion that results in striking attentional deficits
• arises from strokes, tumors, or traumatic injury to right inferior parietal lobe

• caudate nucleus
• putamen
• globus pallidus
• substantia nigra
• subthalamic nucleus
• do NOT project to local circuit or LMNs: influence movement by regulating activity of UMNs

caudate + putamen

globus pallidus

neostriatum (caudate + putamen) & paleostriatum (globus pallidus)

putamen + globus pallidus

• anterior cerebral artery: frontal lobe back to parietal
• middle cerebral artery: parietal lobe
• posterior cerebral artery: occipital lobe, some parietal & temporal lobe

results in deficits in stimulus detection & discrimination

results in deficits of paralysis

• inattention or contralateral neglect
• defect or affect (humorless, lack of concern, lack of speech prosody)

• deficits in recognizing stimulus
• agnosia - detection or no recognition
• face blindness

• speech
• writing
• lexical & syntactic language
• analysis of right visual field
• mathematical skills

• rudimentary speech
• spatial abilities
• prosodic aspects of language
• analysis of left visual field
• music & artistic skills