Neuroanatomy Exam 2 USAHS

Central cord lesion (large)

"sacral sparing" has bowel control or sexual function still. Injury to C1-C6

Anterior cord lesion

- caused by flexion injuries - occurs when 2/3 of the anterior cord is lost - *motor function, pain, and temperature sensation lost bilaterally below the lesion* (*flaccidity* below the lesion)

Common symptoms and signs of elevated intracranial pressure

Headache Altered mental status (irritability and low level of attention) Nausea and vomiting Papilledema (bulging of the eyes) Visual loss Diplopia (double vision) Cushing's triad (Hypertension, bradycardia, irregular respirations).

Lateral corticospinal tract (LCST)

Origin: Primary Motor Cortex (BA4) UMN (1st order neuron) descends Decussates:Pyramidal decussation at the cervicomedullary junction Travels: Entire spinal cord and out the anterior horn. UMN synapses with LMN (2nd order neuron) at anterior horn. Function: Movement of contralateral limbs, voluntary and fine skilled movements of the extremities

Anterior Corticospinal Tract (ACST)

Origin: Primary motor cortex NO DECUSSATION: Ipsilateral; remaining 10-15% fibers from LCST and goes out the anterior horn to muscles Travels: Only in cervical and upper thoracic levels. Function: Voluntary movements axillary and trunk proximal muscles.

Posterior column-medial lemniscus AKA DCML

Origin: Receptor Decussates: Caudal medulla 2nd order neurons crosses at internal arcuate fibers at nucleus gracilis or nucleus cuneatus Travels: Ascends 1st order neuron: enters the dorsal root ganglion, goes through the ipsilateral posterior column at either the fasciculus gracilis (below T6) or fasciculus cuneatus (above T6) 2nd order neuron: crosses contralateral via internal arcuate fibers at nucleus gracilis or nucleus cuneatus travels up midbrain and synapses with 3rd order neuron: @ VPL nucleus of the Thalamus to reach primary sensory cortex at opposite side of the stimulus Function:proprioception, vibration, fine touch Ex. phone vibrating in back pocket

Anterolateral (spinothalamic) tract

Origin: Skin Receptor Decussates: At every level @Anterior Commissure Travels: 1st order neuron: enters the dorsal root ganglion, synapses immediately in the spinal cord's gray matter with the 2nd order neuron. 2nd order neuron: starts in dorsal horn and crosses contralateral via anterior commissure. travels in the anterolateral spinothalamic tract and synapses in the thalamus VPL nucleus with 3rd order neuron 3rd order neuron: from VPL nucleus of thalamus to primary sensory cortex Function: pain, temperature, crude touch

Tectospinal tract

Origin: Superior colliculus of the tectum (Mickey mouse midbrain) Decussates: Immediately at the dorsal tegmental decussation Travels: descends contralateral, then enters anterior horn and ends in cervical level Function: Coordination of head and eye movement Ex. movements in response to visual/ auditory stimuli. Peripheral vision when someone walks by class

Rubrospinal tract (Mickey mouse)

Origin: red nucleus (midbrain aka mesencephalon) Decussates: immediately at the tegmentum (front of the midbrain) Travels: Only to the cervical cord Function: uncertain but OT figured it out

Medullary reticulospinal tract

Origin: reticular formation of the medulla NO DECUSSATION: Ipsilateral Travels: Entire spinal cord to enter anterior horn to synapse on medial LMN's Function: automatic posture and gait related movements Ex for both: When feeling sleepy we respond by stretching our body into extension to wake up.

Pontine reticulospinal tract

Origin: reticular formation of the pons NO DECUSSATION: Ipsilateral Travels: Entire spinal cord to enter anterior horn to synapse on medial LMN'S Function: automatic posture and gait related movements

What is perseveration?

Persistent repeating of verbal or motor response

What are the ascending sensory spinal tracts

Posterior column medial lemniscus AKA DCML Anterolateral Spinothalamic tract

Autonomic Dysreflexia (SCI)

Potentially life threatening Spinal Shock Occurs at level of T6 and above Poikilothermia- inability to control body temperature Orthostatic hypotension- BP drops after change in posture

Pinprick test

Primary sensation: Anterolateral spinothalamic tract (pain)

Temperature sensation test

Primary sensation: Anterolateral spinothalamic tract (temperature)

Vibration sense test

Primary sensation: Posterior column/ DCML

Joint position sense test

Primary sensation: Proprioception

Anterior Cerebral Artery (ACA) stroke we see reemergence of what?

Primitive reflexes such as the grasp reflex

Cortical stroke territories: Right MCA inferior division

Profound L hemineglect L visual field and somatosensory deficits

Medial motor systems control?

Proximal muscles, trunk, extensors, and postural balance

Circle of Willis: The vertebral arteries branch off of what artery?

Subclavian Artery

Trauma to the back of the brain can cause?

Swelling and issues with the flow of CSF

The superior colliculus is the origin of which tract?

Tectospinal tract

Which medial descending motor tract has a decussation?

Tectospinal tract

The spinal cord tract carrying pain, temperature, and crude touch is called

The anterolateral pathway

Within the cavernous sinus along with the internal carotid artery, what cranial nerves pass through here?

CN III Oculomotor CN IV Trochlear CN VI Abducens (Ophthalmic part of V Trigeminal)

Automatic (subconscious) posture and gait related movements are a function of

The reticulospinal tract

Circle of Willis: Posterior Inferior Cerebellar Artery (PICA) branches off from what artery?

Vertebral Artery

Signs of upper motor neuron lesion

Weakness without fasciculations Hyperreflexia

Coronal radiata and internal capsule

White matter fibers that when you have a deep MCA stroke causes pure motor impairment

Meissner's corpuscles

light touch and texture

Central cord lesion small

loss of function in upper extremities caused by injury to C5-C7

What is homonymous hemianopia?

loss of half of the field of view contralaterally on the same side in both eyes

Arachnoid Mater

middle layer of the meninges

Right homonymous hemianopia would cause

not being able to see out of the left field of view in both eyes

Left homonymous hemianopia would cause

not being able to see out of the right field of view in both eyes

anterior spinothalamic pathway

pathway for crude touch and pressure

lateral spinothalamic pathway

pathway for pain and temperature

Dura mater 2 layers

periosteal layer and meningeal layer

Free nerve endings

respond to pain and temperature

Meninges

secondary line of defense Dura Arachnoid Pia

Subdural space

space between dura mater and arachnoid mater

What are frontal release signs?

reemergence of primitive reflexes

Embolism

the sudden blockage of a blood vessel by an embolus that has been brought to its site by the blood current

Pia Mater

thin, delicate inner membrane of the meninges

Signs of lower motor neuron lesion

weakness, atrophy, fasciculations, decreased reflexes, decreased tone

Motor pathway descending tracts: How many neurons involved?

2 to go from the cortex to the muscles

Sensory pathway ascending tracts: How many neurons involved?

3

Brainstem stroke characterized by the

4 D's Diplopia Dysphagia Dysarthria Dizziness

Amyotrophic lateral sclerosis (ALS) onset and result

50-60 years old Leads to respiratory failure and death within 5 years of diagnosis

Epidural hematoma

A hematoma located on top of the dura Can be due to temporal bone fracture Ex. Banging your head

What are the medial motor system tracts? (Descending)

Anterior Corticospinal tract Vestibulospinal tract Reticulospinal tract Tectospinal tract

Which descending motor tract is responsible for the 10-15% of volitional motor control and does not decussate?

Anterior corticospinal tract

Circle of Willis anterior blood supply

Aorta > Common carotid > Internal Carotid (MCA & ACA in brain)

Circle of Willis posterior blood supply

Aorta > Subclavian > Vertebral > Basilar (PCA in brain)

Infarct

Area of dead tissue after a lack of blood supply In the brain can lead to CVA (stroke)

Infection in tooth can lead to what

Bacterial meningitis (trigeminal nerve)

Circle of Willis: Posterior Cerebral Artery (PCA) branches off from what artery

Basilar artery

Circle of Willis: Primary provider for Anterior Inferior Cerebellar Artery (AICA)?

Basilar artery

Circle of Willis: Superior Cerebellar Artery (SCA) comes off of what artery

Basilar artery

Hematoma and how to alleviate pressure

Bleed, tumor, or bruise of the brain Craniotomy

Subarachnoid hemorrhage

Bleeding into the subarachnoid space, where the CSF circulates. Symptom: severe headache

OT clinical implications of VP shunt

Caution when putting child on tummy No tight fitted clothing

Cortical stroke territories: Left MCA stem

Combination of above R hemiplegia R hemianesthesia R homonymous hemianopia Global aphasia

Cortical stroke territories: Right MCA stem

Combination of the above L hemiplegia L hemianesthesia L homonymous hemianopia Profound L hemineglect

Circle of Willis: Internal Carotid Artery (ICA) main artery provider is?

Common Carotid Artery

LCST lesions above the pyramidal decussation contralateral or ipsilateral?

Contralateral

Brown-Sequard Lesion/ Hemi cord lesion

Contralateral loss of pain, temperature and crude touch Ipsilateral motor loss and loss of proprioception, vibration, and fine touch **Ipsilateral loss of Dorsal columns **Anterior commissure of ALST cannot cross info over **Ipsilateral loss of Lateral corticospinal tract **Contralateral loss of (Antero)Lateral spinothalamic tract (pain and temp)

Spinomesencephalic tract

Controls pain and moves eyes and head towards stimulus Location: Midbrain periaqueductal area

Two point discrimination test

Cortical sensation: Posterior column/ DCML

Stereognosis test

Cortical sensation: ability to recognize objects by feeling their form, size, and weight while the eyes are closed

Graphesthesia test

Cortical sensation: processed in primary somatosensory cortex Ability to recognize writing on hand

ASIA exam

Dermatome exam for all 28. Figures out what level lesion is likely at, and what is deficit. T6 ASIA A would be complete loss of sensory and motor function below T6. A: both sensory and motor B: sensory intact, motor function below NLI and sacral segments C: motor function preserved, with more than 1/2 key muscles below NLI < 3/5 strength (most are on the threshold of walking) D: motor function preserved, more than 1/2 of key muscles >= 3/5 (most can walk) E: Normal

The midbrain is supplied by the cortical blood vessels. (T/F)

False, not supplied by any

The rubrospinal tract has a decussation at the tegmentum of the pons

False; it decussates at the tegmentum of the midbrain at the cervical level

ACA vascular territory in the brain

Frontal lobe Parietal lobes medially

MCA vascular territory in the brain

Frontal lobe laterally Parietal lobe laterally

Posterior cord syndrome

Loss of dorsal columns bilaterally, bilateral loss of proprioception, vibration, pressure, stereognosis, 2 point discrimination; preservation of motor function, pain, temperature, and light touch; very rare!

Epidural Space

Space between the skull and the dura mater Contains Middle meningeal artery

Non cortical stroke

ICA

Result of Hydrocephalus

Increased weakness

PCA vascular territory. in the brain

Inferior and medial temporal lobe Occipital lobe

Dura venous sinuses

Spaces in between the dura mater layers that's important for drainage

Circle of Willis: Anterior Cerebral Artery (ACA) main provider is?

Internal Carotid Artery

Circle of Willis: Middle Cerebral Artery (MCA) main provider is?

Internal Carotid Artery

Circle of Willis: Posterior Communicating Artery (PComm) connects with?

Internal Carotid Artery

The spinal cord tract carrying proprioception, vibration, and fine touch decussates at the

Internal arcuate fibers

The anterior blood supply of the circle of willis enters through which vessel?

Internal carotid artery

LCST lesions below the pyramidal decussation contralateral or ipsilateral

Ipsilateral

Cortical stroke territories: Right MCA superior division

L face and arm weakness L hemineglect Some cases: L face and arm cortical type sensory loss

Cortical stroke territories: Right PCA

L homonymous hemianopia

Cortical stroke territories: Right ACA

L leg weakness L cortical type sensory loss Grasp Reflex reemergence

LCST: What happens at the pyramidal decussation of the cervicomedullary junction?

LCST: 85-90% fibers cross over to the other side ACST: 10-15% stays ipsilateral and goes to the anterior corticospinal tract (medial tract)

Blood brain barrier lower uptake into brain of dopamine

Lack of dopamine can lead to Parkinson's Levodopa prescribed

Vestibulospinal tract: Lateral division

Lateral VST Origin: Lateral vestibular nucleus of the pons NO DECUSSATION: Ipsilateral Travels: Entire spinal cord Function: Balance of whole body Ex. walking on a tightrope with arms extended away from body

What are the Lateral motor system tracts? (Descending)

Lateral corticospinal tract (LCST) Rubrospinal tract

Flow of CSF through ventricles

Lateral ventricles -> Interventricular foramen -> Third ventricle -> Cerebral aqueduct -> Fourth ventricle -> Foramen of Magende-> Cervical medullary junction -> Central canal of spinal cord

Which of the vestibulospinal tracts continue through the entire spinal cord and is responsible for balance?

Lateral vestibulospinal tract

Cortical stroke territories: Right MCA deep territory

Left pure motor hemiparesis

transverse cord lesion

all sensory and motor pathways are either partially or completely interrupted. Arms sometimes affected

Vestibulospinal tract: Medial division

Medial VST Origin: Medial and inferior vestibular nuclei in the rostral medulla NO DECUSSATION: Ipsilateral Travels: Bilaterally; cervical and upper thoracic levels Function: Maintenance of head/ neck muscle to Ex. driving car and head stays in place when moving forward

Transient Ischemic Attack (TIA)

Minor stroke; where neurological function is regained quickly with time complete recovery in most cases

Cortical stroke syndromes

Most common type of stroke Occlusion to MCA ACA PCA

Middle Cerebral Artery (MCA) lesion

Motor and sensory Areas of Face and UE opposite side to the lesion in the brain (contralateral)

Anterior Cerebral Artery (ACA) lesion

Motor and sensory Contralateral LE opposite side to the lesion in the brain

Cortical stroke territories: Left MCA superior division

R face and arm weakness Broca's aphasia Some cases: R face and arm cortical type sensory loss. Graphesthesia and Stereognosis ^

Cortical stroke territories: Left PCA

R homonymous hemianopia

Cortical stroke territories: Left ACA

R leg weakness R leg cortical type sensory loss Grasp Reflex reemergence

Cortical stroke territories: Left MCA deep territory

R pure motor hemiparesis

Cortical stroke territories: Left MCA inferior division

R visual field deficit Wernicke's aphasia Some cases: R face and arm cortical type sensory loss

Spinoreticular tract

Responsible for increasing our level of arousal/ alertness in response to pain/ temperature Location: brainstem reticular formation

Subdural hematoma

Rupture in bridging veins Common in elderly

Posterior Cerebral Artery (PCA) lesion

Sensory Visual problems such as diplopia, homonymous hemianopia, inability to see half the field of view opposite side to the lesion in the brain (contralateral)

Anterior spinal cord injuries typically result in loss of pain and temperature as well as motor loss

True

The red nucleus is located at the midbrain and serves as the origin for the rubrospinal tract (t/f)

True

15% of pt with TIA will have CVA (stroke) in the future. (T/F)

True, TIA is a warning sign for CVA (stroke)

If a person sustains a transverse cord injury to the spinal cord at T4, they would likely be able to:

Use arms and trunk muscles

VP shunt

Used to treat swelling of the brain due to excess buildup of cerebrospinal fluid (hydrocephalus)

Thrombus

a blood clot attached to the interior wall of an artery or vein

Amyotrophic lateral sclerosis (ALS) definition

a degenerative disease of the central nervous system causing loss of muscle control involving both UMN & LMN

Subarachnoid space

a space between the arachnoid and pia that contains the CSF and major arteries of the brain. MCA, PCA, ACA

Ischemic stroke

a type of stroke that occurs when the flow of blood to the brain is blocked

Hydrocephalus and 3 main causes

accumulation of fluid in the spaces of the brain 1. Tumor, swelling can block CSF circulation 2. Problem with Arachnoid Villa CSF reabsorption 3. Too much production of CSF

Spinal Muscular Atrophy (SMA)

affects only LMN's, lesion in this area fatigue, cranial nerves affected

Primary Lateral Sclerosis (PLS)

affects only UMNs, lesion in this area

Watershed areas or zones

areas of overlapping blood supply person can have symptoms of both due to stroke area

Lateral motor system controls?

arm, flexor, and distal muscles; more skilled movements contralateral

Reticular formation responsible for

arousal and alertness

Anterior Communicating Artery

connects right and left anterior cerebral arteries (ACA's)

Dura folds within the 2 layers

falx cerebri, falx cerebelli, tentorium cerebelli

Cisterns

pockets of CSF filled cavities reabsorbed from arachnoid villa

Pacinian corpuscles

pressure and vibration, deep touch

Choroid plexus

produces CSF hydration is key to production

Arachnoid villi

reabsorbs CSF into venous system that leads to cisterns

What's intracranial pressure?

swelling

spinal shock s/s

temporary if cord not seriously injured. flaccid paralysis, loss of feeling below level of injury, loss of bowel and bladder control, temp affected