iT/F The muscle supplied by the posterior rami are rich in neuromuscular spindles.
T. The erecotr spinae and other postural muscle are very rich in neuromuscular spindles. Nueromuscular
spindles are abundant in antigravity muscles of the vertebral column, femur and tibia, and the muscles of the neck and in the hand intrinsic.
Neurologic test suggest the pt. has attenuation of sensory feedback concerning
changes in position from the neuromuscular spindles in his hand. What
type of nerve is primarily involved?
A. Type Ia sensory afferent nerves. TypeIa (120m/s) are connected to the nuclear bags and chains. Type Ia involved with the chain would be responsible for sensing gross amount of stretch. Type Ia are the primary afferent fibers. Type II (70m/s) sensory afferent nerves are the nerves that are found in the intrafusal tissues of the muscle spindles just outside of the bags and chains. Theyare also sensitize to length changes, but are secondary fibers. Alpha efferent (120m/s are the motor sensory for extrafusal fibers. Gamma (40m/s) efferent are the motor for intrafusal fibers.
Pt. is performing isometric contractions. During the contractions, which sensory receptors will be the most active?
D. The nuclear bags will be the most active because they are phasic and detect rate of movement while the nuclear chains mostly detect gross changes in position.
During DTR, reciprocal inhibition affects the
A. The antagonist is affected by reciprocal inhabition. The neuromuscular spindle will be pulled by the movement of the tendon. When the muscle spindle detects movement in the intrafusal fibers, it will cause inhibition of the antagonist and contraction of the agonist.
T/F The neuromuscular spindle makes small movements in the intrafusal fibers which then elicit much larger movements in the extrafusal fibers. This is an example of a servomechanism
True. A servo mechanism is a type of feedback system were minute changes will be translated into large actions. Such being the case in that a muscle spindle can barely move and ellicit a large motor movement in extrafusal fibers.
Positive feedback of the muscle spindle fibers means that
C. Positive feedback means when one the happens it will cause another action. One stimulation facilitates another stimulation
This specialized nerve ending is found interdigitation with collagenous fibers at muscle-tendon joints.
T/F Rashante is lifting a really heavy box. She is straining so much that the GTO shuts her down.
False. The GTO does not shut anything down in that sense. The GTO detects tension in the tendons. When there is too much tension it will send and inhibitory signal to the agonist involved in that movement. If necessary it may also send a reciprocal excitatory signal to the antagonist. It is considered negetive feedback since it primarily cause inhibition, or calms and relaxes the muscle.
Rashante is writing a snail mail. She has note done so in many years. While writing she grips the pencil so hard that she has bruising in her fingers. This is most likely due to failure in
A. GTO. The golgi tendon organ calms and relaxes the muscles. In this case sensory feedback from the GTO should have told her that she was contracting her writing muscles more than she needed to (or rather that there was excessive tension being created in the muscle). Had the GTO functioned properly, she would have eased up on her grip and prevented bruising. The GTO sense tense while the muscle spindles sense position and movement.
T/F Function of the GTO is an example of positive feedback.
F. GTO is considered a negetive feeback system. Although it does also perform reciprocal excitation of the antagonist.
Lashinwa touches a hot burner. Which mechanoreptors are most involved in this situation?
C. Free nerve endings are responsible for nociception and thermoception.
Follicular nerve endings: rapidly adapting and found in the follicles.
Merkel disks: slow adapting and have small areas of representation so the can
detect small details. They discharge continuously in response to sustained pressure
Meissner’s corpuscles: are most numerous in finger pads. They are rapidly adapting
and have fine discriminative touch, very sensitive
Ruffini endings: respond to shear stress (tension in skin) and are slow adapting
Pacinian corpuscles: About the size of a grain of rice. They are rapidly adapting and sensitive to vibration and mechanical distortion. They are also found in periosteum.
In elementary school you gave your friend an indian burn. This would most likely be associated with
A. Ruffini endings.
Merkel disks: slow adapting and have small areas of representation so the can detect small details. They discharge continuously in response to sustained pressure
Meissner’scorpuscles: are most numerous in finger pads. They are rapidly adapting and have fine discriminative touch, very sensitive
Ruffini endings: respond to shear stress (tension in skin) and are slow adapting
Paciniancorpuscles: About the size of a grain of rice. They are rapidly adapting and sensitive to vibration and mechanical distortion. They are also found in periosteum.
Tuning forks are used to test for stress fractures. This nerve ending may facilitate that
C. Pacinian corpuscles detect vibration and mechanical distortion
Your blind friend uses these nerve endings to discrimininate minute differences in brail
A. Meissener's corpuscles
These two encapsulated nerve endings have the larger receptor feilds
This type of cell is more diverse in structure, function, and metabolic characteristics than all other cells in the body combined.
B. Nerve cells. Each is genetically programmed to have its particular structure and critical metabolic pathways.
T/F All nerve cells produce the same amount of pigment.
T/F All nerve cells are responsible to all types of stimuli
T/F Nerve cells may produce excitatory transmitters, inhibitory transmitters, or both
F. F. T.
Different pathogens will attack different neurons. Which most accurate explains why?
C. The primary reason a cell is vulnerable to one pathogen and not another is because of the metabolic pathways of the neuron and the mechanism of attack of a pathogen.
T/F An example of selective vulnerability would be the brain cells high vulnerability to hypoxia.
T/F Motor neurons are more vulnerable to poliomyelitis than are sensory neurons. While herpes zoosters seems to be more detrimental to sensory neurons
Parkinson’s causes systematized degeneration of related neuronal populations. What is a good explanation for this?
A. Selective vulnerability of neurons may lead to systematized degeneration of related neuronal populations. Neurons are like families, if you kill one it will affect others.
The death of a soma will result in
A. If the soma dies, there will be no regeneration of any kind. Interruption of metabolic machinery in the perikaryon can result in cell death. In the CNS the death of one cell may also cause death in other cells if they do not have sufficient afferent connections. Mature neurons cannot regenerate themselves, the have to ability to regenerate axon and dendrite in some situations.
What happens to the muscle cells if the motor neuron that innervated it dies?
D. atrophy will occur until the cell experiences reinnervation. The response is similar in glands
When a nerve is damaged
A. When the damage is not too severe, the nerve may regenerate the axon and the dendrite. The soma will not be degenerated if destroyed.
Wallerian degeneration occurs
A. This is true, but remember degeneration does occur in the proximal direction. It is called retrograde degeneration and usually is only a 1cm in length.
If there is sufficient axon left, it will begin to regrow from the stump to
Which leukocyte will enter the site of a damaged axon to clean up the debris?
D. They also have a mitogenic effect (causing to seperate and grow) on schwann
cells and help schwann cells in providing trophic and tropic factors. The schwann cells, effector organs, and monocytes release these chemicals that signal to the neuron where to go and help nourish it to
get there. The is in the PNS. In the CNS, microglial cells also help with the debridement.
T/F An intact endoneurium will make it easier for the regrowth to reach the correct destination.
T/F When axonal degeneration occurs, it may degenerate proximally about 1cm stopping at the next proximal collateral axon or the nearest node.
What do you call it when a cell is damaged, swells, and becomes pale because it is yielding its production of neurotransmitters?
Relative to the axon that was damaged, where does the nucleus end up during regeneration?
C. This occurs so that there is room for lines of mircotubules and neurofillaments to be transported in the regenerating axon. The neurofibrils move at about 5-10 mm/day normally, but the growth of the new axon is about 1-2 mm/day.
Affected axons are demyelinated but still intact
Remyelination and conduction can resume following removal of compression, nerve conduction is usually normal except in cases of severe compression where loss of feeling can occur.
When the axon of a nerve is crushed it is which class of injury?
Wallerian degeneration occurs in this class of nerve injury
A nerve is severely crush, but the endoneurial tube is still intact. Which Class?
A. This is very helpful for allowing the nerve to reach the correct effect organ synapse location.
All of the neural and connective tissue components are severed. Which class?
Skilled surgery is required to give hope of functional recovery. Which class?
Regeneration of axons may enter inappropriate endoneurial tubes. Which class?
What is this called?
B. aberrant regeneration
Chanaquish injures her radial nerve. There is a clean cut. When can she expect the nerve to begin sprouting?
D. If there is a clean cutting sprouting begins quickly. When the nerve is crush or torn, it may takes up to a week for retrograde degeneration to cease and for sprouting to occur. We know that monocytes will go in and can help clean up the area and that they, combined with schwann cells and the effector organ will release trophic and tropic factors to help stimulate and direct the growth.
A nerve regrows 30 cm! But is fails to reach the effector organ. Was this successful regeneration?
C. The best answer is no, it was a failure because it didn’t reach the fibers of the effector organ to establish a synapse. When there is no connection a neuroma often results.
T/F Growth cones are from the axon while filopodia are from the schwann cells
T/F Growth cones have a similar affect on schwann cells as monocytes do.
T. T. Growth cones are mitogenic to schwann cells which means the cause the schwann cell to divide and grow.
Denishwa injuries her posterior interosseous nerve. She is have difficulty in
extending her wrist. What percent of her muscle has atrophied after 2
A. After 2 months on average 50-60% of the muscle has atrohpied and the muscle is undergoing fibrosis. 30% is the 1 month range. 60-80% is the 4 month range. After a year, if the axon has not reach the motor end plate the muscle will be extremely atrophied and functional reinnervation diminishes.
In the CNS distal degeneration occurs in a similar manner to that of the PNS; however,
C. Debris is cleared at a a much slower rate by both glialcells and monocytes. Debris can often be found upto six months later.
T/F Following damage to a neuron in the central nervous system the neuron will turn white and cease production of neurotransmitters, the karyon will move to the opposite side of the axon hillock of the injured axon and swelling of the soma will occur.
F. This process discribed is chromatolysis and it does not occur in the CNS neurons. There is little change that can be observed in the neuron since there is minimal repair.
What is it called when large scale death occurs in a region where CNS neurons were injured?
C. Transneuronal atrophy. This occurs because the neurons of the CNS have a trophic affect on each other. If a neuron losses sufficient synapse it will atrophy and die.
Assuming there has been death of many neurons in the CNS a small lesion usually forms, what is this called?
C. Gliosis is the name given for the glial scar tissues that forms in place of neuronal debris, primarily astrocytes. Sclerotic plaque occurs in MS when old plaques of scar tissue, usually around the ventricles become hard. Glioma is a tumor usually composed of astrocytes. A tombstone is used to describe the nuerofibrillary tangles that mark the death of CNS neurons in Alzheimer’s disease.
T/F Large lesions form a cavity walled off by scar tissues and filled with CSF, blood and uric acid.
F. No Uric acid
CNS is ineffective at regenerating axons. At most
A. The axon my grow up to a few mm, but it does not re-establish the synaptic connections with the effectors. Glial scar tissue and growth inhibition factors from broken down oligodendrocytes inhibit the ability of the axon to re-establish a connection.
A condition in which one experiences severe muscle weakness is called
C. Myasthenia gravis. It is an autoimmune disease where the immune system
produces ACH receptor antagonists which interfere with the normal action
What muscles are most affected by myasthenia gravis?
D. The muscles of the cranial nerves, face, mouth, eyes and limbs, especially proximal, and most often affected. swallowing and resipratory weakness may be life threatening.
Which is not a treatment for myasthenia gravis?
B. Themectomy can help i nabout 50% of cases. Neoestigmine is and anti ACHestarase drug. They work by slowing the break down of ACH so there is more ACH in the junction for a longer time.
What is the cause of leprosy?
What is the mechanism of destruction by Leprosy bacillus?
A. This killing of schwann cells causes segmental demyelinattion along the nerve and then an inflammatory response that compromises all the axon.
Which of the following is not a symptom of Leprosy?
A. Hyperhydrosis is excessive sweating of the hands that may be treated by a sypathectomy, usually just below the stellate ganglion.
Lebizma has a HNP, what area is most like to be damaged and what type of damage is most common?
D. lumbar neurapraxia. Neurapraxia, or compression is most common in the mobile areas of the spine. HNP and spondylosis are common causes.
Jeishwa has weird sensations at her right thenar emminence. What may be the cause?
Pt. first noticed leg weakness 3 weeks ago. She is now experiencing motor neuropathy and some sensory dysfunction. What are these symptoms indicative of?
D. Guillain Barre Syndrom. If that is what she has, she should begin to recover in about 5 weeks since nadir will most likely be in one week.
T/F 1/4 of people who have had Guillain Barre Syndrome, be still struggle after 2 years.
T/F The visceral organs, smooth muscle, and secretory glans are controlled by the Somatic nervous system.
F. 1/3 will
F. The somatic nervous system controls skeletal muscle and voluntary movements.
Which is not a function of the autonomic nervous system?
B. Mastigation is a voluntary action and would be controlled by the somatic nervous system
T/F ANS fibers mainly leave the CNS through the cranial nerves.
T/F The ANS has no volitional control.
False. Both cranial and spinal nerves are important for the route of the nerves.
False. There is a small amount of volitional control. This may function through the ascending connections in the spinal cord that connect the ANS with conscious awareness.
The first of the two efferent ANS neurons, preganglionic, begins in the
B. The second, postganglionic, originates in the autonomic ganglia. There are sympathetic and parasympathetic ganglia. The sympathetic are connect and run along the sides of the vertebral column. The parasympathetic are closer to their effector organs.
What does it mean when we say that the sympathetic neurons take the long route?
At a given level, when a neuron leaves the spinal nerve they run with the ventral ramus. At this point they passup entering the grey ramus communicans and enter the distal white ramus communicns. Then they enter the sympathetic gaglion where the preganglionic neuron synapses with the post ganglionic neuron. Now the post ganglionic neuron exits the sypathetic ganglion through the grey ramus communicans and proceeds to the effecto organ.
Which is the most superior of the sympathetic ganglia outside of the sympathetic trunk?
T/F When the Sympathetic NS is hyperactive, they parasympathetic shuts down.
F. It dampens its affects, but does not shut off.
Sympathetic NS is catabolic in nature. This means
a. it is involved in energy expending
b. it is involved in energy conservation
a. It increase BP and HR. It caused bronchial and vaso dilation. It increase blood glucose. It causes sweating, pupil dilation and ejaculation in men.
The is the primary parasympathetic nerve
The parasympathetic nervous system does not
A. The sympathetic increases sweat.
Visceral afferents do not
B. The bladder is the best example of precise sensory innervation in the vesceral organs. Otherwise they do not have very exact sensory.
Where does referred usually pain present?
A. It is sometime referred to the dermatome corresponding to the segments of SNS that innervate the diseased viscera.
T/F The Convergence-projection theory suggests that visceral and somatic nociceptors share sime projection neurons and so the brain often has to guess which nerve is sending the signal and it assumes the somatic since that makes the most sense.
Pt. has complex regional pain syndrom (CRPS). The Dr. wants to inject buprenorphine and/or lidocain. Where is the most likely site of injection?
A. The stellate is most common site for sympathetic blocks when dealing with the UE. For the LE they are given at the L2 spinal cord ganglion.
Which is not and indication for a sympathectomy?
D. Horner’s is actually the a side effect of a sympathectomy. It can cause Ptosis, Miosis, and anhidrosis. A sympathectomy should be done at the level of the 2nd rib. Raynaur's sydrome is extreme sympathetic overactivity causing vasoconstriction in the fingers. It can lead to severe pain and blanching of fingers. It is usually triggered by cold or emotional stress. It is what Andrew has.
T/F There are two main mechanism of erection in males and of arousal and
lubrication in females, psychogenic (T11-L2) and reflexogenic (S2-S4)
What are the chances of getting and erection after a complete cervical lesion?
What are the chances of getting an erection after an incomplete cervical lesion?
What are the chances of getting and erection after a complete lesion above the sacral segments?
What are the chances of getting and erection after a complete lesion at the sacral segments?
Which is not true of ejacualtion after a SCI
A. Orgasms are reported in 50% of SCI, but ejaculation in a complete lesion occurs in 4% of cases. It will depending on which descending pathway were affected.
T/F An intact sacral reflex arc is necessary for orgasm through direct genital stimulation.