Unit 7: Tutoring

Question 1

Primary Motor Cortex

Answer 1

Efferent

-Cause contralateral motor deficits & facial anomalies

Question 2

Motor Association Cortex

Answer 2

• Made up of premotor cortex and supplementary motor area

- Cause deficit in motor: Apraxia

Question 3

Sensory Cortex

Answer 3

Afferent (parietal lobe)

-Sensory deficit on contralateral side of body and face pain/temp loss, neglect

Question 4

Somatosensory Association Cortex

Answer 4

Lesions here would cause high-order sensory analysis

Question 5

Homunculus

Answer 5

• Legs medial in brain (affected by ACA)

- Hand, face, & tongue lateral (affected by MCA)

Question 6

Anatomy of SC

Answer 6

• Cervical &. Lumbrosacral Enlargements
• Gray matter on inside (butterfly shape)
• Ex, of GTO (Sensory receptor for stretch)
• Somatotopic SC organization

Question 7

Cervical and Lumbosacral Englargemtents (Anatomy of SC)

Answer 7

• Much more motor neurons in anterior horn

- Most white. matter in cervical segments> makes it the biggest of all

Question 8

Example of GTO (anatomy of SC)

Answer 8

• Sensory receptor for stretch
• GTO sends info to dorsal root ganglion, sends signal through dorsal rootlets, enter SC through dorsal horn, and synapses w/ ascending tract or direct w/ alpha motor neuron (which control muscles), AMN then sends signal back to muscle to contract (bc GTO senses stretch)
• Alpha motor neuron sends signal out through Rexed laminae IX (motor nuclei for innervation of skeletal muscle)

Question 9

Somatotopic SC Organization (anatomy of SC)

Answer 9

-Descending motor pathways are divided into lateral and medial system based on location in the SC
-Lateral Motor System: for distal limb movements and
favoring flexors
-Medial Motor System: for proximal limb/ trunk
movements, favoring extensors
-Flexors tend to be more superior/ dorsal, and extensors tend to be more inferior/ ventral

Question 10

ACA and PCA’s (SC Blood Supply)

Answer 10

ASA (SC Blood Supply)
-Causes motor problems if cut off  
-Ventral ⅔ of SC 
-Branches off of Vertebral Artery
PSA's (SC Blood Supply)
-Syphilis> Sensory loss> Posterior cord syndrome
-Dorsal 1/3 of SC
-Braches off the vertebral or PICA
Both. combine to form artery plexus around spinal cor

Question 11

Radicular Arteries

Answer 11

Great Radicular Artery of Adamkiewics
-Lumbar and Sacral region (T9-12)
Vulnerable Zone
-Mid-thoracic area (T4-8) there are no radicular arteries> sole supply from either ASA or PSA
-Area is susceptibe to infarct (especially of ASA) during surgery
-Blood cut off> ASA cut off> motor loss

Question 12

Lateral Motor System

Answer 12

• Lateral Corticospinal Tract
• Rubrospinal tract
• Flexor and distal masculature to a skilled movement

Question 13

Medial Motor System (AVTR)

Answer 13

• Anterior Corticospinal Tract
• Vestibulospinal Tract (2)
• Reticulospinal Tract (2)
• Tectospinal Tract: Posture, balance

Question 14

Lateral Corticospinal Tract

Answer 14

Most important descending motor pathway in SNA

Question 15

LCST & ACST have neurons referred to as…

Answer 15

Corticospinal fibers as they originate in the brain

• Synapse at the Ventral Horn (SC)
• Have Corticobulbar fibers that directly control the CN in the brainstem (bulb) to move face, jaws, tongue, and eyelid
• These fibers can influence the brainstem tracts, but NOT directly control them

Question 16

Rubro, tecto, vestibulo, and reticulospinal tracts all originate in the…

Answer 16

Brain stem

• Descend to the ventral horn of the spinal cord.
• The brain itself does send corticobulbar fibers onto these tracts but does not fully control them nor considered the origination of these tracts.

Question 17

ANS Review

Answer 17

ANS neurons have additional synapses before terminating on target
-Motor nerves have direct pathway to skeletal muscle

Question 18

Sympathetic (ANS Review)

Answer 18

• Short PREganglionic fibers that originate at Rexed Lamina VII
• Terminate onto either: Paravertebral Ganglia or Prevertebral Ganglia
• Paravertebral Ganglia (outside vertebrae) running from C4-S4 (AKA: Sympathetic Trunk) ~or~
• Prevertebral Ganglia of celiac ganglia (liver, stomach, pancreas) or at inferior mesenteric ganglia

Question 19

Parasympathetic (ANS Review)

Answer 19

Long preganglionic fibers that terminate close or near the target end organ
-No thoracic involvement

Question 20

Preganglionic Neurons (Pharmacology)

Answer 20

-In BOTH SYMPATHETIC & PARASYMPATHETIC → release acetylcholine to activate Nicotinic cholinergic receptors

Question 21

POSTganglionic Neurons -

Answer 21

-SYMPATHETIC → release epinephrine/ norepinephrine onto target end organ w/ adrenergic/Noradrenergic receptors
-PARASYMPATHETIC → release mostly acetylcholine on to Muscarinic receptors of end organs
-End organ control is done through these rules w/ the exception of sweat glands,
actually receiving sympathetic postganglionic releasing UMN vs. L

Question 22

Fasciculations

Answer 22

Rapid twitching motion

• Indicative of a muscle dying when the alpha motot neurons (ex. LMN) to the muscle that is lesioned
• Appears as a twitching of the muscle at rest and/or with movements, can occur w/ injury or overuse of a muscle as well
• Spasticity
• Weakness patterns and localization

Question 23

Spacicity (Fasciculations)

Answer 23

Velocity dependent & assesses resistance (rididity) to PROM. Often the modified ashworth scale is used

Question 24

Weakness Patterns & Localization

Answer 24

• Can result from lesion to anywhere
• Lesion to BA 4 = severe deficits
• While association cortices like 3, 1, 2, 5, & 7 and Limbic Structures can lead to apraxia and other forms of ‘weakness’ with movements.
• Association cortices lead to Apraxia & weakness with movements
• Although weakness occurs at LMN & UMN, it can also occur anywhere else such as Thalamus, Cerebellum, Basal Ganglia —> anywhere. Not just the motor neurons

Question 25

Unilateral Face (droop), arm, and leg weakness or paralysis (hemiparesis) with sensory deficits

Answer 25

• Rule out: likely not medulla/SC or muscles since the face is involved
• (CN VII facial N. above pons so it’s probably not lesion in medulla/SC)
• We are left with everything above the medulla
• Entire B4, internal capsule (IC), cerebral peduncle or basis pontis (corticospinals of LCST, and corticobulbars to face)
• Lesion will be contralateral to the deficits as any of these structures are above pyramidal decussation
• Common causes: CVA, hemorrhage, tumor, trauma, or brain herniation results in an infarct (dead brain tissue) in addition it can appear briefly in a postictal state (post seizure state) but generally resolves.

Question 26

Multiple Sclerosis

Answer 26

-Autoimmune of CNS Myelin
-No known cause
-Onset 20-40 y/o
Diagnosis:
-Symptoms: Spasticity, pain, impaired
B&B, sexual dysfunction, dysphagia, and
psychiatric findings
-MRI→ can see plaques where myelin has
been destroyed
-Lumbar puncture of CSF
-Evoked potentials (slow conduction
velocity)
Characteristics: MS affects people in one of
these ways, and may progress from RRMS-SPMS:
-Relapsing remitting MS: Multiple symptoms, Remitting phase to complete recovery
-Secondary progressive MS: Progressive symptoms, Never remit to normal over time
-Primary progressive MS: Onset digress- no remitting
-Relapse: exacerbation, attack, flare-up