Neurotanatomy Final- Sup AMY

UMN Syndrome Signs

-paresis/paralysis
-impaired motor control (voluntary)
-decrease muscle tone
-spasticity
-rigidity
-abnormal reflexes
-compensatory co-contraction
-muscle hyperreflexia

LMN Lesions Symptoms

-prevent muscle contract
-loss of reflex
-atrophy
-flaccid paralysis
-fibrillations

Hemi section (Brown-Sequard syndrome)

-At level: ipsi loss DCML & motor loss, and bilateral loss of SpTh
-Below: ipsi paralysis (hyperreflexia), ipsi loss of DCML, and contra loss of SpTh

Anterior Horn Cell Disease (Polio)

-inflammed gray matter of SC
-DCL and SpTh intact at and below level
-lateral corticospinal intact below
-atrophy at level of lesion due to loss of apples

Release of bowel and bladder trajectory

-frontal lobe (urination center)
-pons (urination center - PUC)
-sacral segments (urination center): S2-S4

What level of SC are bowel and bladder responsible for?

T11-L2 (sensory afferents) and S2-S4 (motor efferents)

Lesion at S2-S4

flaccid bladder due to loss of motor efferents and alphas are busted

Lesion above S2

hypertonic/reflexive bladder due to loss of ascending and descending control - alphas firing with no control

What level of SC is responsible for sexual functioning/ejactulation?

L1-L2/S2-S4

Psychogenic process of sex

-thoughts, frontal lob influences spinal region activity (motor)
-L1-L2 sends signal from frontal lobe
-S2-S4 motor control to organ

Reflexive process of sex

-direct sensory stimulation causing spinal activity (motor)
-afferent and efferent branches are S2-S4

Sex: lesion above T12

-reflexive process can happen, no psychogenic
-think about quick stretch reflex

Sex: lesion at L3-S1

-might have psychogenic process
-reflexive process will be most used because S2-S4 is intact

Sex: Lesion at S2-S4

-have flaccid organ
-no enlargement or lubrication
-impotence

Visual system provides:

-sight
-processing of visual info: recognize and locate objects
-eye movement control
-info used in postural and limb movement control

Retinogeniculocalcarine pathway components

-retina
-CNII (optic)
-lateral geniculate of thalamus
-primary visual cortex

Right visual field

activates left side retina of both eyes

Left visual field

activates right side retina of both eyes

Nasal visual field

activates right side of right eye and left side of left eye retinas

Temporal visual field

activates right side of left eye and left side of right eye retinas

Tunnel vision

only seeing middle (left side of left eye loss and right side of right eye loss)

Homonymous hemianopsia

loss of visual info from same side in each eye

Cortical blindness

no awareness of visual info

blindsight

ability of a cortically blind people to orient to, point to, or detect movement of visual objects, or even distinguish facial expression, despite inability of consciously see objects

Gaze stabilization

Keeping the position of the yes stable during head movements, so the environment does not bounce

Direction of gaze

directing graze at visual targets

Auditory system functions

-consciousness awareness & recognition of sounds
-orients head and eyes towards sounds
-increases arousal level in response to auditory input

Receptor of auditory system and its function

Cochlea: snail shaped, fluid filled, spiral tube that transmits info related to hearing

Organ for hearing

Corti: found inside the cochlea

Process for hearing

-sound enters eardrum
-vibrations go in and open chamber of cochlea
-movement of fluid in chamber
-vibration in basilar membrane and hair cells
-hair cells bend and cause depolarization (contract)
-cochlear nerve endings are activated

Relay centers of auditory system

-reticular formation
-inferior colliculus
-medial geniculate

What CN is responsible in auditory system?

CN 8

Cortical areas for sounds transmissions

-primary auditory cortex (awareness of sound)
-auditory association cortex (categorize sounds thru memory)
-werkincke's area (comprehension of spoken language)

Sensory functions of vestibular system

-detects head position relative to gravity
-rotary head movement

Efferent outputs of vestibular system

-gaze stabilization
-postural adjustments
-autonomic functions, arousal, and consciousness

Appartai in vestibular system

-semicircular canals (3)
-otolithic organs (utricle and saccule)

Ampulle

swelling of the end of SCC

Endolymph fluid

flows through SCC in a circle and hair cells

Utricle

horizontal macula
-detects head change when picking something off floor

Saccule

vertical macula
-detect head change when going from side laying to upright

Macula

hair cells embedded in gelatinous mass

Otoliths

calcium carbonate crystals on top of the macula

Crista

-inside the ampullae
-contains supporting cells and hair cells

Cupula

sits on top of hair cells and bends when fluid is moved over it

Rotary movement receptors

-posterior, horizontal, and superior SCCs

linear deceleration of head receptors

utricle and saccule (otolithic organs)

change in head position relative to gravity receptors

utricle and saccule (otolithic organs)

Symptoms of vestibular dysfunction

-vertigo
-pathologic nystagmus
-disequilibrium/unsteadiness
-ataxia
-nausea and vomitting

Post rotary nystagmus

-eyes move back and forth after rotation
-fluid inside canals move and causes cupola and hair cells to bend
-action potential sent down vestibular nerve to let know head is moving

CN 3 nuclei location & symptoms

high midbrain
Diplopia, lateral strabismus, ptosis, loss of pupillary reflex

CN 4 nuclei location & symptoms

low midbrain
Diplopia, challenges with reading and stairs

CN 5 nuclei location & symptoms

high pons
Loss of sensation from the face and TMJ; jaw deviation toward lesion side; loss of blink reflex

CN 6 nuclei location & symptoms

low pons
Diplopia; medial strabismus

CN 7 nuclei location & symptoms

pons
Facial droop; inability to close eye (Bell's Palsy)

CN 8 nuclei location & symptoms

pons
Deafness - cochlear branch

Four D's

-Dysphagia: difficulty swallowing (CN V, VII, IX, X, XII)
-Dysarthria: difficulty speaking (CN V, VII, IX, X, XII)
-Diplopia: double vision (CN III, IV, VI)
-Dysmetria: difficulty controlling distance of movement

Corticobulbar UMN lesion

-hypertonia and hyperreflexia
-symptoms are contralateral is before the crossing

Corticobulbar LMN lesion

-muscle flaccidity because alphas busted
-symptoms are ipsilateral if after crossing

Corticobulbar CN 7 lesion (UMN)

-eyes able to close (intact)
-lower face has contralateral hypertonicity

Corticobulbar CN 7 lesion (LMN)

ipsilateral flaccidity of face

reticular formation

a nerve network in the brainstem that conregulatestrols motor, autonomic, pain, and consciousness

Ventral Tegmental Area & neurotransmitter

in the brainstem that releases dopamine for decisions, pleasure, and rewards

Pedunculopontine nuclei (PPN) & neurotransmitter

in brainstem that releases Ach for role in movement and emotion

Raphe nuclei & neurotransmitter

in brainstem and releases serotonin to improve mood

Medial Reticular zone & neurotransmitter

norepinephrine and epinephrine for autonomic functions

Locus Cerulus

release most epinephrine in the body for attention, pain, and movement

Ascending reticular activating system (ARAS)

conscious awareness, sleep, alertness, and attention

Four connective tissue sheaths

-Endoneurium
-Perineurium
-Epineurium
-Mesoneurium

Endoneurium

separate individual neurons, covers the myelin sheath is present

Perineurium

surrounds bundles of axons; surrounds fascicles (small groups of nerve fibers)

Epineurium

encloses the entire nerve trunk; dense connective tissue; bundles together groups of fascicles

Mesoneurium

layer of connective tissue around the epineurium that protects axons and glia and mechanical forces that are changing length of nerve

Neuromuscular junction

at muscle between motor axon and synapse with motor fiber

Role of Ach in neuromuscular activity

-AP of motor neuron releases Ach into the cleft and Ach binds to receptors and causes depolarization (contraction) or muscle fiber's membrane
-Always an excitatory (contract) response from Ach

Classifications of mononeuropathies

-Class I: Traumatic Myelinopathy
-Class II: Traumatic Axonopathy
-Class III: Severance

Class I: Traumatic Myelinopathy

-focal compression due to pressure on nerve where myelin is lesioned
-decreased/loss of large axons
-motor, touch, proprioception, stretch reflex, sensory changes

Class II: Traumatic Axonopathy

-crushing of nerve, affects all sizes of axons, reflexes are reduced, wallerian degeneration distal to lesion, atrophy

Class III: Severance

-cut of nerve, laceration, stretched, connective tissue damage, immediate loss of sensation or muscle paralysis
-wallerian degeneration

mononeuropathy

affecting a single nerve

Multiple mononeuropathy

several nerves, multifocal, asymmetrical involvement of individual nerves

polyneuropathy

many nerves together, presents symmetrical in distribution (distal to proximal symptoms)

Peripheral nerve lesions

-interruption of sympathetic innervation causes tropic changes in skin
-loss of vascular control
-poor healing of cuts and wounds
-edema

Diabetic neuropathy symptoms

autonomic changes, Charcot's foot, yellowness, edema

Guillian Barre symptoms

-motor affected more than sensory
-paresis will worsen
-rapid onset
-will regain function

Charcot Marie Tooth disease symptoms

-paresis of muscle distal to knee
-foot drop
-tripping, muscle atrophy, step-page gait
-onset in young adults

Muscular dystrophy symptoms

-random muscle fiber degenerate
-less motor units available in muscle fiber to be active
-weak contractions

Carpal Tunnel Myelinopathy symptoms

-Median nerve is lesions in space with carpal ones and myelin degenerates
-decreased sensation
-numbness at night

Sympathetic NS

-Optimal blood supply
-Fight or flight
-Cell bodies in T1-L2
-Preganglionic neurons: secrete Ach
-Postganglionic neurons: secrete norepinephrine

Parasympathetic NS

-homeostasis
-cell bodies in brainstem and sacral SC
-Preganglionic and postganglionic secrete Ach

SCI above T6

-Autonomic dysreflexia
-Orthostatic hypotension
-Inability to regulate temperature

Horner's Syndrome

-interruption of sympathetic activity to head
-ispi symtoms
-drooping upper eyelid
-constriction of pupil
-vasodilation of arteries in skin
-absent sweat on face/neck

Cholinergic neurons and receptors

Neurons: secrete acetylcholine
-2 types of receipts: nicotinic & Adrenergic neurons and receptors

Adrenergic neurons and receptors

Neurons: secrete norepinephrine and epinephrine
-2 types of receptors: alpha (1 and 2) and beta (1 and 2)

Left hemisphere brain functions

-comprehend spoken language
-understand what letters/symbols mean
-reading
-vision
-writing - control of hand

Right hemisphere brain functions

-nonverbal communication
-gestures
-facial expression
-tone of voice

Goal-directed behavior loop

-caudate
-decision making for goals
-planning, choosing actions
-active in learning and interacting

Social behavior loop

-caudate
-recognize social cues
-regulates self control
-relevant from irrelevant info

Emotion/Motivation loop

-ventral striatum
-emotion, cognitive, and motor
-perception of emotions
-seeking rewards (addiction)

Oculomotor loop

-caudate
-makes decisions about spatial attention and eye movements

Motor loop/basal ganglia loop

-regulate motor output
-tone, contract, sequence