neurology exam two

frontal, parietal, temporal, occipital, insular

five lobes of the brain

gyrus

a convoluted ridge between anatomical grooves

sulcus

narrow groove

central sulcus

divides parietal and frontal lobes

lateral sulcus (sylvian fissure)

separates temporal lobe from frontal and parietal lobes

superior longitudinal fissure

divides left and right hemispheres

broadmann's areas

numbered brain regions based on types of neurons and the function of that region

main divisions of the frontal lobe

prefrontal cortex, premotor area, supplemental area, primary motor area

motor areas of the frontal lobe

primary motor cortex, premotor cortex, supplementary motor area

precentral gyrus

- also known as the primary motor cortex; is responsible for the control of simple motor movement

- brodmann area 4

voluntary motor activation

the origin of the corticospinal and corticobulbar tracts

the pre-central gyrus is responsible for

primary motor strip (aka the precentral gyrus)

narrow strip that goes from near the top of the head right down along where your ear is located

responsible for producing the contractions of all the muscles needed for the chosen movement with the brainstem and the spinal cord

determines how much force each muscle group must exert and then sends this information to the spinal motor neurons and interneurons that generate the movement itself, as well as the postural adjustments that accompany it

premotor region

motor planning

involved in sensory-guided movement (rather than internally generated movement)

for complex movements

mirror neurons in premotor regions

helps us internalize the actions of others

the premotor region is strongly connected with

the parietal lobe, motor strip/precentral gyrus, SMA, and prefrontal cortex

the pathology of the premotor region is

ideomotor apraxia

ideomotor apraxia

inability to imitate gestures or mimic using tools (i.e., "use a hammer")

from disorder in left parietal lobe and premotor cortex

great example:

https://www.youtube.com/watch?v=EvOYeqM-6CE

supplementary motor area (SMA)

portion of area six and eight, including medial surface

involved in internally-generated movement (i.e., making a decision to move, rather than responding to an external stimulus)

planning and rehearsal of the motor act

decision-making about movement

what area controls sequential movements

the supplementary motor areas

cerebellum

the supplementary motor area works with the _____________ to specify the precise sequence of contractions of the various muscles that will be required to carry out the selected motor action

the tissue makeup of an association cortex determines

what kind of neural information can be processed by cells in different areas of the brain

motor association areas are sites where

motor plans, programs, and commands are formulated with input from auditory and somatosensory processing, particularly touch, as well as other modalities

motor associations are very important for

the articulation of clear speech

the front of the frontal lobe

prefrontal area

prefrontal area

responsible for the ability to concentrate and attend, elaboration of thought

executive functioning

personality and emotional traits

planning

reigns in the impulsive aspects of our behavior

highly connected to the limbic system, which is primarily responsible for our emotional life

damage to the prefrontal area results in

-impairment of recent memory, inattentiveness, inability to concentrate, behavior disorders, difficulty in learning new information

-inappropriate social and/or sexual behavior

-emotional lability (especially when both hemispheres are damaged)

the prefrontal cortex is

the single largest brain region in human beings

estimated to constitute 29% of the total cortex

the prefrontal cortex is the only area of the brain that is

connect with all of the senses

cognitive processes

attention, memory, visuospatial processes, and linguistic processes

executive functions used for cognition to "execute" or complete tasks

inhibition of responses

accessing memory

organization of stimuli and memories

planning and sequencing: motor planning of a response

judgement

etc.

middle frontal gyrus

aka dorsolateral cortex

9, 10, 46, and 8 cognitive association areas

- implementing memory strategies

- working memory

- organization of material for encoding

- memory verification and evaluation

highest-level executive functions of the middle frontal gyrus

decision making

controlling executive functions

inferior frontal gyrus

consists of 44, 45, and 47 areas

responsible for risk aversion (area 47)

- addiction resistance (people with addiction tend to have lower activation in this area)

-implications in autism

-implications in tourette syndrome

inferior frontal gyrus: pars opercularis

area 44

-overlies insula

-people with autism may have smaller bilaterally

damage to the prefrontal cortex results in

disorders of categorizing, a decrease in voluntary motor behavior, decreased will and energy, a tendency to engage in repetitive or preservative behavior, difficulty in shifting response set, and abnormalities of affect and emotion, particularly apathy, indifference, and shallowness also occur

lobotomy

a psychosurgical procedure once used to calm uncontrollably emotional or violent patients

-the procedure cut the nerves connecting the frontal lobes to the emotion-controlling centers of the inner brain

walter freeman

doctor who streamlined lobotomies and made them extremely common

he shocked patients into unconsciousness instead of anesthesia and used an ice pick through the eye to get to the brain

orbitofrontal cortex

a region of the brain in which impulses involving reward processing, body response gnosis and interpretation, fear knowledge, drive and emotional regulation, mood

superior frontal gyrus

responsible for memory and memory strategies, memory verification, conjugate eye movement

oculomotor apraxia is a result of damage in this area

broca's area

controls language expression - an area of the frontal lobe, usually in the left hemisphere, that directs the muscle movements involved in speech

inferior frontal gyrus: pars triangularis

area 45

expressive language function

pars opercularis (44) and pars triangularis (45) make up broca's area

critical for motor planning for speech

expressive language function In dominant hemisphere

broca's aphasia (nonfluent aphasia)

area 44 and 45 make up

broca's area

expressive language impairment

ability to produce language is impaired

brain lateralization

the two hemispheres of the brain - the left and the right - are specialized for different functions

even though they work together, each area has plays a bigger role in some functions

left hemisphere (for most right-handed people) is known for

language (speech, reading, and writing)

logic, math, and analytical thinking

broca's and wernicke's areas (speech production and comprehension)

the right hemisphere, for many individuals, includes the

inferior frontal gyrus (right homologue of broca's area)

-located in the frontal lobe of the right hemisphere

-while broca's area on the left controls speech production, the right inferior frontal gyrus helps control

prosody (emotional tone and intonation in speech)

understanding and expressing emotional content through voice

turn-taking and social aspects of speech

both broca's aphasia and acquired apraxia of speech (AOS) are linked to damage in

the left frontal lobe, especially in areas around broca's area

broca's area is located in

the left hemisphere, specifically the left inferior frontal gyrus (brodmann areas 44 and 45)

suppelementary motor areas (sma) and the premotor cortex are involved in

planning and programming the movements needed for speech

broca's aphasia

condition resulting from damage to broca's area, causing the affected person to be unable to speak fluently, to mispronounce words, and to speak haltingly

comprehension is often better than expression

apraxia of speech (AOS)

an impairment of motor programming and planning of speech movements

phineas gage

railroad worker who survived a severe brain injury to his prefrontal cortex that dramatically changed his personality and behavior; the case played a role in the development of the understanding of the localization of brain function

afferent neurons

otherwise known as sensory or receptor neurons--carry nerve impulses from receptors or sense organs toward the central nervous system

primary sensory cortex

occupies broadmans 1, 2, and 3

processes somatosensory information such as:

vibration

propioception

touch

astereognosis (stereognosis)

somatosensory association cortex

occupies broadman’s 5 and 7

interprets sensory experience during motor movements

sensory movements used to refine motor action

involved in the fine movements associated with speech

plays role in writing sensory and motor experience

angular gyrus

- occupies broadman's area 39

-primarily involved in semantic processing, particularly in the left hemisphere

-plays a key role in reading, especially when making semantic associations, and is important for understanding speech and written language

-involved in arithmetic fact retrieval, shifting attention toward salient stimuli related to motion, emotion, value, or meaning

-helps in the ability to discriminate left from right and is associated with verbal working memory

-may play a role in understanding metaphors and self-recognition, as well as in theory of mind

damage to the angular gyrus results in

angular gyrus syndrome:

agraphia, alexia, gerstmann's syndrome, poor memory, behavioral manifestations such as depression, frustration, and irritability

gerstmann's syndrome

a cognitive impairment caused by damage to the left parietal lobe, specifically the angular gyrus

-may result from a stroke or other damage to the parietal lobe

-characterized by four main symptoms: writing disability (agraphia or dysgraphia), difficulty with arithmetic (acalculia or dyscalculia), inability to distinguish right from left, and inability to identify fingers (finger agnosia)

-some adults with the syndrome may also experience aphasia

parietal lobe: supramarginal gyrus

-occupies BA 40

- closely rated to the angular gyrus (BA 39)

- involved in phonological system; stores auditory representations of phonemes (auditory images)

- helps us sound out words

- damage can result in phonological dyslexia, difficulty reading new and nonwords

supramarginal gyrus

spatiomotor tasks - identifying functional orientation of object

phonological processing of language - phonological processing of speech and written language

the right hemisphere of the supramarginal gyrus is

involved in learning phonological sequences

the left hemisphere of the supramarginal gyrus is

more active in well-learned sequences

Some Say Marry Money But My Brother Says Big Brains Matter More

sensory, motor, or both in cranial nerves

upper motor neurons originate in the

motor cortex

most cranial nerve nuclei have _________ innervation

bilateral

CN I - olfactory nerve

function: smell

location: telencephalon

clinical sign of damage: anosmia (loss of smell)

CN II - optic nerve

function: vision

location: diencephalon

clinical sign of damage: vision loss, visual field defects

CN III - oculomotor nerve

•eye movement, eyelid elevation, pupil constriction

•damage: ptosis, eye deviates down/out, diplopia

CN IV - trochlear nerve

•superior oblique muscle (eye down & in)

•damage: vertical diplopia

CN VI - abducens nerve

•lateral rectus muscle (eye out)

•damage: medial strabismus, diplopia

CN V - trigeminal nerve

sensory: Face, scalp, cornea, oral & nasal cavities

motor: muscles of mastication (chewing)

nuclei: pons (chief sensory, spinal trigeminal, mesencephalic)

corticobulbar tract: bilateral innervation

damage:

LMN lesion: ipsilateral jaw weakness, jaw deviates to weak side, loss of corneal reflex (afferent limb)

UMN lesion: minimal effect due to bilateral innervation

branches:

ophthalmic: sensory

maxillary: sensory

mandibular: mixed

functions:

sensory: tactile facial sensation

motor: mastication (masseter, temporalis, medial & lateral pterygoid), tensor veli palatini, mylohyoid, anterior digastric, tensor tympani

muscles of mastication:

masseter, temporalis, medial pterygoid, lateral pterygoid

CN VII - Facial Nerve

Motor: Muscles of facial expression (like smiling, frowning)

Sensory: Taste from the front 2/3 of the tongue

Parasympathetic: Controls lacrimal (tear) and salivary glands

Nuclei: Located in the pons

Corticobulbar tract:

Upper face: Bilateral control (both sides of brain)

Lower face: Contralateral control (opposite side of brain)

Damage:

LMN lesion: Complete facial paralysis (like Bell's palsy) on one side of the face

UMN lesion: Weakness in the lower part of the face (forehead stays unaffected)

Motor Functions:

Controls muscles of facial expression, posterior belly of digastric (raises hyoid), stylohyoid, and stapedius (ear muscle)

Sends impulses to tear and salivary glands

Sensory Functions:

Taste: Anterior 2/3 of the tongue

General sensation: Skin on the ear and small area behind the ear

Damage Effects:

Motor Damage: Paralysis of one side of the face, including emotional movements (like smiling). The face may look asymmetrical, with wrinkles smoothing out on the affected side.

CN VIII - Vestibulocochlear

Vestibular: Balance, equilibrium

•Cochlear: Hearing

•Nuclei: Pons/Medulla junction

Damage:

•Vestibular: Vertigo, imbalance

•Cochlear: Sensorineural hearing loss

Has been known as the Auditory Nerve

The nerve originates in the ear and carries sensory info.

There are 2 branches: the cochlear which is responsible for hearing and the vestibular branch which is responsible for balance

CN IX - Glossopharyngeal

Sensory: Taste posterior 1/3 tongue, carotid body

Motor: Stylopharyngeus (swallowing)

Parasympathetic: Parotid gland

Nuclei: Medulla

Damage:

Loss of gag reflex (afferent limb)

Dysphagia

The motor component of this nerve

supplies the stylopharyngeus muscle

Carries visceral sensory information from the carotid sinus (of the carotid artery) and body.

Provides general sensory information from the skin of the external ear, the internal surface of the tympanic membrane, the upper pharynx, and the posterior one-third of the tongue.

Provides taste sensation from the posterior one-third of the tongue

Damage to CNIX

Lesions to CNIX also typically involve CNX Reduced pharyngeal sensation

Decreased gag Reduced pharyngeal elevation Sometimes glossopharyngeal neuralgia is reported (radiating throat pain)

stylopharyngeus muscle

elevates and opens pharynx, elevates the larynx

neuralgia

a stabbing, burning, and often severe pain due to an irritated or damaged nerve

CN XII - Hypoglossal

Motor: Intrinsic & extrinsic tongue muscles

Nuclei: Medulla

Corticobulbar: Contralateral innervation (mostly)

Damage:

LMN lesion: Ipsilateral tongue weakness, atrophy, fasciculations, tongue deviates toward lesion

UMN lesion: Contralateral tongue weakness, deviates away from lesion

Oh Oh Oh To Touch And Feel Very Good Velvet AH

olfactory, optic, oculomotor, trochlear, trigeminal, abducens, facial, vestibulocochlear, glossopharyngeal, vagus, accessory, hypoglossal

trigeminal neuralgia

characterized by severe lightning-like pain due to an inflammation of the fifth cranial nerve

severe facial pain due to trigeminal nerve dysfunction

90% of trigeminal neuraligia is due to

compression by the Superior Cerebellar Artery (SCA)

treatment options for trigeminal neuraligia

Medical Management

Carbamazepine (anti-convulsant)

Gabapentin (mechanism unclear, but effective)

2. Surgical Interventions

Microvascular decompression

Radiofrequency ablation

Gamma Knife surgery

afferent

sensory

efferent

motor

somatic

body wall and skeletal muscle

controls voluntary muscles and relays conscious sensory input

visceral

organs and glands

controls involuntary functions & unconscious sensory input

general

widespread functions

special

unique functions of cranial nerves

CN X - Vagus

Motor Functions:

Controls muscles for phonation (voice), swallowing, and the soft palate

Supplies muscles of the pharynx, most of the larynx, and one muscle of the tongue

Parasympathetic: Controls heart, lungs, and GI tract

Sensory Functions:

Sensation from the thoracic & abdominal organs, larynx, esophagus, and trachea

Provides taste from the epiglottis and sensory from the ear and pharynx

Branches Important for Speech/Swallowing:

Pharyngeal, Superior Laryngeal, Recurrent Laryngeal

Unique Feature:

The only nerve that extends from the medulla and travels all the way to the abdomen

It's called "Vagus" because it "wanders" from the brainstem to the colon

Damage Effects:

LMN lesion: Affects voice, swallowing, and gag reflex

Unilateral: Weakness in the soft palate and voice

Bilateral: Significant issues with resonance, voice, phonation, and clarity of speech

motor association areas are extremely important for

highly coordinated and specific functions like, clearly articulated speech, chewing gum, and chewing gum and speaking clearly at the same time!

the prefrontal area doesn’t fully develop until

twenty-five

the frontal lobe is highly connected to the

limbic system

result of lobotomy on brain

more white matter damage than gray

some of the tracts could not recover over time

priming

repeating words

grammarian

leaving out connecting words like is, the, etc.

theory of mind

not everyone shares the same thoughts

all cranial nerve nuclei have bilateral innervation besides

the lower face (CN VII) and the tongue (CN XII)

CN I, II, III, and IV are located in the

midbrain

CN V, VI, VII, VIII, and are located in the

pons

the largest cranial nerve is

CN V: Trigeminal

Bell's Palsy

A condition that causes sudden, temporary weakness or paralysis of the muscles on one side of the face due to facial nerve inflammation - IPSILATERAL

IX, X, XI, and XII are located in the

medulla