BIOM 3000 Lecture 7: Lecture 7 -Descending tracts & cranial nerves I

82 views40 pages

byzantiumcod740

20 Oct 2017

School

Department

Course

Professor

For unlimited access to Class Notes, a Class+ subscription is required.

Document Summary

Travel up through anterolateral part of white matter. Syanpse with thalamus on contra-lateral side and syanpse into somatosensory cortex. By the end of today"s lecture, students will be able to: Explain the consequences of a given spinal cord injury. Explain the function of the sensory and motor cranial nerves. Final common pathway of the motor system re ex tracts - sensory coming in can synapse onto lower motor neurons: involves both somatic (voluntary) and autonomic (involuntary) control depends on level of spinal cord you are in. Corticospinal tract point which many bres tract - pyramidal decussation: control of conscious, voluntary movement, aka. Other descending pathways: reticulospinal tract from reticular formation within the brainstem. Upper motor neurons from contralateral motor cortex, voluntary movement. Pain & temperature information from the contralateral half of the body. Figure 10-9 because the decussation happens within the level of the spinal cord (where info comes in)

Related Questions

#1 Visceral sensory information enters the CNS on afferent fibers within

A) dorsal roots S_2 to S_4.

B) dorsal roots T_1 to L_2.

C) cranial nerves V, VII, IX, and X.

D) both B and C

E) A, B, and C

#2 Which of the following is not a function of the neuroglia?

A) support

B) memory

C) phagocytosis

D) secretion of cerebrospinal fluid

E) maintenance of blood-brain barrier

#3 Mary is in an automobile accident and suffers a spinal cord injury. She has lost feeling in her lower

body. Her doctor tells her that swelling is compressing a portion of her spinal cord. Which part of

her cord is likely to be compressed?

A) the anterior gray commissures

B) the anterior white commissures

C) the anterior gray horns

D) ascending tracts

E) descending tracts

#4 The efferent division of the peripheral nervous system innervates:

A) skeletal muscle cells

B) glandular cells

C) smoothmusdecells

D) heart muscle cells

E) all of the above

#5 Cerebrospinal fluid flows within the

A) pia mater.

B) dura mater.

C) filum terminale.

D) arachnoid mater.

E) subarachnoid space.

#6 A patient develops a tumor of a cranial nerve that leads to difficulty in speaking from a loss of

tongue movement.which cranial nerve is affected?

A) glossopharyngeal

B) vagus

C) spinal accessory

D) hypoglossal

E) trigeminal

#7 Parkinson disease is the result of

A) inadequate production of dopamine by substantia nigra neurons.

B) inadequate production of GABA by neurons in the basal nuclei.

C) weak response of the red nuclei of the mesencephalon.

D) decreased levels of acetylcholine from neurons in the substantia nigra.

E) hyperactivity of the limbic system.

#8 Based on the motor homunculus, which of the followingbody regions has the largest motor units?

A) larynx B) hands C) tongue D) face E) back

#9 If the corpus callosum is surgically cu!

A) conscious decisions are made without regard to sensations from the left side.

B) objects toudred by the left hand can be recognized but not verbally identified.

C) symptoms of the "disconnection syndrome" appear.

D) the two cerebral hemispheres operate independently.

E) all of the above

#10 The flexor reflex

A) moves a limb away from a painful stimulus.

B) is an example of a monosynaptic reflex.

C) prevents a musde from generating damaging tension.

D) usually depends on cranial neurons.

E) prevents a muscle from overstretching.

#11 The subdural space lies between

A) the dura mater and the arachnoid mater.

B) the arachnoid mater and the pia mater.

C) the endosteum and the periosteum.

D) the pia mater and the dura mater.

E) the pia mater and the subarachnoid space.

#12 _____ is a condition resulting from an inflammation of a facial nerve.

A) Cerebral palsy

B) Addison disease

C) Bell palsy

D) any of the

#12 Clusters of RER and free ribosomes in neurons are called

A) microglia.

B) neurofilaments.

C) neurofibrils.

D) Nisslbodies.

E) perikaryon.

#1 Visceral sensory information enters the CNIS on afferent fibers within

A) dorsal roots 52 to 54.

B) dorsal roots T1 to L2.

C) cranial nerves V VIL DC and X.

D) bothB and C

E) a, n, and C

#2 Which of the following is not a function of the neuroglia?

A) support

B) memory

C) phagocytosis

D) secretion of cerebrospinal fluid

E) maintenance of blood-brain barrier

#3 Mary is in an automobile accident and suffers a spinal cord injury. She has lost feeling in her lower

body. Her doctor tells her that swelling is compressing a portion of her spinal cord. Which part of

her cord is likely to be compressed?

A) the anterior gray commissures

B) the anterior white commissures

C) the anterior gray horns

D) ascending tracts

E) descending tracts

#4 The efferent division of the peripheral nervous system innervates:

A) skeletal muscle cells

B) glandular cells

C) smoothmusdecells

D) heart muscle cells

E) all of the above

#5 Cerebrospinal fluid flows within the

A) pia mater.

B) dura mater.

C) filum terminale.

D) arachnoid mater.

E) subarachnoid space.

#6 A patient develops a tumor of a cranial nerve that leads to difficulty in speaking from a loss of

tongue movement. IA/hich cranial nerve is affected?

A) glossopharyngeal

B) vagus

C) spinai accessory

D) hypoglossal

#7 Parkinson disease is the result of

A) inadequate production of dopamine by substantia nigra neurons.

B) inadequate production of GABA by neurons in the basal nuclei.

C) weak response of the red nuclei of the mesencephalon.

D) decreased levels of acetylcholine from neurons in the substantia nigra.

E) hyperactivity of the limbic system.

#8 Based on the motor homunculus, which of the followingbody regions has the largest motor units?

A) larynx B) hands C) tongue D) face E) back

#9 If the corpus callosum is surgically cu!

A) conscious decisions are made without regard to sensations from the left side.

B) objects toudred by the left hand can be recognized but not verbally identified.

C) symptoms of the "disconnection syndrome" appear.

D) the two cerebral hemispheres operate independently.

E) all of the above

#10 The flexor reflex

A) moves a limb away from a painful stimulus.

B) is an example of a monosynaptic reflex.

C) prevents a musde from generating damaging tension.

D) usually depends on cranial neurons.

E) prevents a muscle from overstretching.

#11 The subdural space lies between

A) the dura mater and the arachnoid mater.

B) the arachnoid mater and the pia mater.

C) the endosteum and the periosteum.

D) the pia mater and the dura mater.

E) the pia mater and the subarachnoid space.

#12 _____ is a condition resulting from an inflammation of a facial nerve.

A) Cerebral palsy

B) Addison disease

C) Bell palsy

D) any of the

#12 Clusters of RER and free ribosomes in neurons are called

A) microglia.

B) neurofilaments.

C) neurofibrils.

D) Nisslbodies.

E) perikaryon.

To investigate Neilâs symptoms further, doctors referred him to a neurologist, Dr. Bonasera, that specialized in motor disorders. Dr. Bonasera noted that Neil exhibited diminished right dorsalis pedis and posterior tibial pulses. His cognitive tests were normal. Tests of the cranial nerves were normal, with the exception of occasional slurred speech. His motor tests revealed generally slowed movements. Neil was experiencing pain and stiffness in the shoulder joints, which could explain his restricted range motion. Dr. Bonasera tested the motor strength of his finger extensors (4+/5), hip flexors (4/5), and various muscle groups in his arms and legs (5/5). There were tests for dysmetria (i.e., lack of coordination) and dexterity, which were normal yet slowed. Neil did have difficulty lifting his legs for some of the examinations, and he walked with a shuffling gate, often keeping both feet close together for a narrow base of support. He took very small steps and often stooped over while walking. When placing one foot in front of the other in a tandem walking stance, he would fall to either side and was unable to regain his balance. Sensory examination was normal, deep tendon reflexes were normal, and the Babinski sign was absent bilaterally. There were no Parkinsons-like symptoms, increased motor tone, or muscle fasciculations observed in testing.

Just one day later, another neurologist noted brisk reflexes and bilateral Babinski signs. Doctors performed magnetic resonance imaging (MRI) of the brain to reveal an infarct in the right caudate nucleus and an infarct in the right cerebellum. Doctors prescribed intense physical therapy. Neil saw some improvements for articulation, but he continued to struggle with the speed of speech and began to experience weakness of the tongue on his left side. CT angiograms revealed an aneurysm of the infrarenal aorta extending into the right common iliac artery. A spinal MRI revealed degenerative disease of the cervical spine (C4-C5) with a mild central canal stenosis. No such degeneration was present in the thoracic or lumbar spine. However, Neil did have mild impingement of the right L3-L5 nerve roots. A lumbar puncture revealed normal CSF pressures, cell counts, and composition. Neil continued physical therapy and experienced significant improvements in speech, walking, and balance. He also commented that his muscle soreness and fatigue had improved.

Neil continued his physical therapy while recovering at home. However, his symptoms worsened over the following weeks. Neil grew progressively weaker, occasionally falling. He required assistance for walking, and he was experiencing some numbness in both hands. He was admitted to a hospital, where he underwent a neurological examination. Cognitive and cranial nerve tests were normal. There were no fasciculations of the neck or tongue muscles. He was able to rotate and extend the neck with normal strength, however neck flexion seemed to be compromised. Neil exhibited widespread fasciculations in his arms and legs, and the muscles of these limbs had mildly atrophied. Motor tests were conducted for the arms and legs (4/5), and wrist extensors and intrinsic muscles of the hand (3+/ 5). Neil exhibited hyperactive deep-tendon reflexes and positive Babinski signs bilaterally. Sensory examinations were unchanged.

Based on the compounding symptoms and rapid progression of the disease, doctors suspected that Neil was suffering from amyotrophic lateral sclerosis (ALS), a disease that results in the destruction of upper and lower motor neurons. To confirm this diagnosis, neurologists conducted a series of tests., including nerve conduction tests and needle EMG. Nerve conduction tests of the motor and sensory nerves revealed normal conduction velocities with low amplitude compound motor action potentials, and normal sensory nerve potentials. There were abundant fasciculations and characteristics that suggested remodeling of motor units following denervation. Furthermore, EMG suggested net motor unit loss. There was no evidence of demyelination. Based on these results, doctors confirmed the diagnosis of ALS. For the following weeks, Neil experienced physical therapy aimed to help him preserve his strength and energy. He soon began to experience difficulty swallowing, and his cough progressed. Soon thereafter he developed pneumonia, was placed on a feeding tube, and ultimately died just 15 weeks after his initial hospitalization.

7. Based on the etiology of the disease, justify the finding of hyperactive deep-tendon reflexes and positive Babinski signs bilaterally in a patient suffering from ALS. Be sure to describe a typical reflex, and describe how descending inhibition may modulate a reflex response.

BIOM 3000 Lecture 7: Lecture 7 -Descending tracts & cranial nerves I

Document Summary

Get access

Related Documents

BIOM 3000 Lecture 3: Lecture 3 -NS Development

BIOM 3000- Final Exam Guide - Comprehensive Notes for the exam ( 272 pages long!)

BIOM 3000 Lecture Notes - Lecture 8: Spinal Trigeminal Nucleus, Cranial Nerve Nucleus, Facial Motor Nucleus

Related Questions