Just everything... Flashcards
Holy eft…just get us through this exam!
List somatosensory sensations carried EXCLUSIVELY by the DC/ML
Vibration (fine touch), proprioception, texture
List somatosensory sensations carried EXCLUSIVELY by the ALS
Temperature, slow pain, visceral pain
List somatosensory sensations carried EXCLUSIVELY by both the DC/ML and ALS
Pressure touch, hair associated touch, fast pain
Special skin receptor sensing texture (discriminatory touch)
Meissner corpuscles
Special skin receptor sensing vibration
Deep = Pacinian corpuscles. Superficial = Meissner corpuscles
Special skin receptor sensing pressure
Deep = Pacinian corpuscles. Superficial = Merkel’s disks
Where are the cell bodies in the DC/ML pathway?
DRG - Caudal Medulla (Gracile and Cuneate Nuclei) - Ventral Posterior Lateral Nucleus of the Thalamus - Precentral Gyrus
Where do the tracts of the DC/ML pathway terminate?
Pre central gyrus of the cerebral cortex
Do the fibers of the DC/ML pathway decussate? If so, where?
Yes, in the caudal medulla’s pyramidal decussation
Do any branches come off the DC/ML pathway? If so, what function do they serve?
Yes, but they are going to the cerebellum and serve to provide proprioceptive feedback of what the body is doing
Where do the corticobulbar fibers decussate?
In the middle Pons
What fibers make up the bulk of the INCOMING middle cerebellar peduncle fibers?
The corticobulbar fibers from the basilar pontine nuclei
Once in the cerebellum, what happens to the corticobulbar fibers?
They split with some going to the deep cerebellar nuclei and others going to the cerebellar cortex
Proprioceptive loss if the dorsal column at C4 was destroyed?
Loss of proprioception on the same side
Proprioceptive loss if the DRG at C4 was destroyed?
Loss of proprioception on the same side
Proprioceptive loss if the ALS at C4 was destroyed?
No loss of proprioception. ALS is NOT proprioception
Proprioceptive loss if the lateral portions of the primary somatosensory cortex was destroyed?
Loss of proprioception of the face and upper extremities on the opposite side
Proprioceptive loss if the medial portions of the primary somatosensory cortex was destroyed?
Lower limb proprioceptive loss on the opposite side
What sensation is unique in that it does not reach the cerebral cortex by going through relay nuclei?
Olfaction
When does sensation enter conscious awareness?
When the signal reaches the cerebral cortex
T/F DC/ML neurons are larger and more heavily myelinated than ALS neurons
TRUE
Where does DC/ML pathway information decussate?
In the caudal medulla
Where does the ALS pathway decussate?
In the spinal cord
T/F Many more ALS axons reach the cerebrum
FALSE. Many more DC/ML fibers do…which contributes to such fine perception and localization of sensation
When cell damage occurs, probradykinin is converted to ____ which minds to pain receptors on the free nerve endings of axons causing them to fire.
Bradykinin
NSAIDs inhibit the formation of ____ which in turn prevent bradykinin from causing free nerve endings to fire.
Prostaglandins (COX 1 and COX 2)
In a life or death situation, human beings can reduce the amount of pain perceived. This occurs because the cerebrum can send a signal to the _____ of the midbrain where opioid containing ____ become excited. These ____ then activate neurons that project down to serotonergic nuclei located within the ____ medulla which then project down to lamina ____ of the ____ horn gray matter of the spinal cord. Here, these serotonergic nuclei activate ____ containing interneurons which pre-synaptically inhibit pain in afferent nerve endings. This in effect…”turns off” the ____ synapse in the pain pathway
Periaqueductal gray nucleus, interneurons, opioid containing interneurons, ventral, 2, dorsal, opioid, first
Where do opioid drugs act?
On the periaqueductal grey nucleus of the midbrain as well as directly on the dorsal horn grey matter
What type of receptors the target cells of opioids express?
Mu
The sensations of fullness and ischemia are considered…
Visceral pain
Of the four main types of special mechanoreceptors, which is the most sensitive to vibration?
Merkel
How does proprioceptive feedback from the body enter the cerebellum?
Via the inferior cerebellar peduncle
T/F The feedback through the inferior cerebellar peduncles is specific to the corticospinal system
FALSE. It contains non specific input from both the corticospinal and bulbospinal systems
Proprioceptive feedback comes from the ____
DC/ML somatosensory system
T/F There is a branch from the DC/ML system that doesn’t go directly to the brain, but branches off and goes into the cerebellum. It’s called the ____
TRUE. This is called dorsal spinocerebellar tract
A proprioceptive sensation reporting on what was intended to be a conscious and voluntary movement that originated from the motor cortex is sent via the DC/ML which branched up the dorsal spinocerebellar tract to a deep motor neuron in the cerebellum. From there, where will the signal be sent?
Back to the motor cortex via a relay in the thalamus to report on the success or failure of the movement.
A proprioceptive sensation reporting on what was intended to be an unconscious movement that originated from the vestibular nuclei is sent via the DC/ML which branched up the dorsal spinocerebellar tract to a deep motor neuron in the cerebellum. From there, where will the signal be sent?
The vestibular nuclei to report on the success or failure of the movement
T/F Efferent axons from the cerebellum go the same region of the brain that initiated the intended movement in the first place.
TRUE
What two places within the cerebellum does information about intended movement go to?
Deep cerebellar nuclei, cerebellar cortex
A block in the cerebral aqueduct would cause what form of hydrocephalus? Communicating or non-communicating? What ventricles would be affected?
Non-communicating. The lateral and 3rd ventricles.
A “brain” bleed that prevents CSF from exiting the arachnoid villa would cause what form of hydrocephalus? Communicating or non-communicating?
Communicating. All ventricles.
Complete: Afferents to the cerebellum that are either _____ command or _____ sensory information enter the cerebellum through their respective _____. They then split. One short branch goes to the _____ and one long branch to the _____. The short branch reaches its target first and causes these _____ to fire a bunch of action potentials toward the ____ (think morse code). The long branch excites _____ neurons in the _____ which in turn send their axons to excite _____ in the molecular layer. These cells then send their axons through the _____ to synapse with the _____ to inhibit them and stop them from firing.
Motor, proprioceptive, peduncle, deep cerebellar nuclei, cerebellar cortex, deep cerebellar nuclei, brain, granule, cerebellar cortex, purkinje neurons, cerebellar white matter, deep cerebellar nuclei
If both the intended action and actual action of a conscious or unconscious movement is perceived by the cerebellum…and the “code” is the same, this means what?
What you want to do or what your brain intends to do and what is actually happening are the same. Conversely, if they “codes” are NOT the same, then corrections must be made because what is supposed to happen and what is actually happening are different.
Consciously, what part of the motor cortex generally “plans” a movement? What part of the motor cortex generally “controls or executes” a movement?
Pre-motor cortex plans, primary motor cortex executes.
Where do corticospinal fibers cross the midline?
Pyramidal decussation
When do corticobulbar fibers cross the midline and where does this occur?
Right after they synapse in the pons and before they enter the cerebellum…it occurs in the Pons
What comes in the inferior cerebellar peduncle?
Proprioceptive feedback from the body
What come in the middle cerebellar peduncle?
Motor input from the brain
What leaves the superior peduncle?
Information “code” about intended and actual movement headed toward the brain
If you have damage to the right side of your cerebellum, you will see ramifications in the ____ side of the body.
Right, same, ipsilateral
If you have damage to the right side of your cerebrum, you will see ramifications in the ____ side of your body.
Left, opposite, contralateral
Where are Mu receptors located?
In the periaqueductal grey and the dorsal horn grey matter
Where are the vestibular nuclei and how many are there?
They are in the brainstem, 4 on each side, 2 for sensory and 2 for motor.
If you were to trip, and the sensation of falling to the side were sensed by the sensory vestibular nuclei in the brainstem, what would happen?
These sensory nuclei would signal the motor vestibular nuclei to send a signal down the vestibulospinal tract of the spine to LMN’s initiating involuntary movement of the “anti-gravity muscles”…and hopefully you don’t fall on your face. At the same time, a copy of what is intended is sent to the cerebellum along with the proprioceptive data that arrives via the dorsal spinocerebellar tract to tell the cerebellum what is actually happening. The deep cerebellar nuclei then send the signals back to the vestibular nuclei so corrections can be made.
Damage to the cerebellum generally causes ____ because it prevents the brain from making ____
Incoordination, mid-course corrections
The inability to carry out mid-course corrections or “measure” movements is known as ____
Dysmetria
If you display limb and hand/foot incoordination, you might have a problem with the ____ portion of the ____
Lateral, cerebellum
Medial damage to the cerebellum causes problems with ____ musculature
Medial
I can’t do the finger-to-nose test very smoothly at all with my left arm and hand.
Left lateral cerebellar damage
