Week 8 HW Flashcards
Most lower motor neurons (LMNs) with somas in the cranial nerve motor nuclei receive bilateral upper motor neuron (UMN) innervation via the corticobrainstem tracts. This results in sparing of voluntary motor control if one corticobrainstem tract is damaged. One exception to this is?
LMNs to the muscle of facial expression of the lower half of the face
LMNs to the muscle of facial expression of the lower half of the face
Tegmentum
In the brainstem, the descending motor tracts run predominately:
Anterior to the sensory tracts
The [1] is the most ventral part of the midbrain and is situated anterior to the substantia nigra. Within this region are the [2], [3], and [4] tracts. Your textbook also indicates the corticoreticular tracts are in this area, however the literature is inconsistent on this location.
1) Cerebral peduncle
2) Corticospinal
3) Corticobrainstem
4) Corticopontine
A patient has a stroke resulting in lateral medullary syndrome (Wallenberg syndrome). Which of the following will this patient likely experience (check all that apply)?
A) Impaired nociception and temperature sense on the contralateral limbs and trunk
B) Impaired unconscious proprioception in the ipsilateral limbs and trunk
C) Sensory ataxia ipsilaterally
A: The four cranial nerves that exit from the medulla are (Note the main component of one of the 4 originates in the cervical spinal cord, but has a small component that originates in the medulla.):
B: The four cranial nerves that exit from the pons (three at the pontomedullary junction) are:
C: The two cranial nerves that exit from the midbrain are:
A: Cranial Nerve IX Glossopharyngeal Cranial Nerve X Vagus Cranial Nerve XI Accessory Cranial Nerve XII Hypoglossal
B: Cranial Nerve V Trigeminal Cranial Nerve VI Abducens Cranial Nerve VII Facial Cranial Nerve VIII Vestibulocochlear
C:
Cranial Nerve III Oculomotor
Cranial Nerve IV Trochlear
The system of neurons that originates in the reticular formation of the brainstem and helps to modulate attention, alertness and induces sleep is the ___.
Ascending reticular activating system
Name one cranial nerve that originates at the level of the medulla medial to the olive [1] and one cranial nerve that originates lateral to the olive [2].
Specified Answer for: 1
CorrectCranial Nerve XII Hypoglossal
Specified Answer for: 2
CorrectCranial Nerve IX Glossopharyngeal
According to your textbook, the basis pedunculi consists of the [1] plus the [2].
Specified Answer for: 1
Correctcerebral peduncles
Specified Answer for: 2
Correctsubstantia nigra
There are two bumps making up the most dorsal aspect of the midbrain tectum on each side. The bump located more rostrally is the [1] and the bump located more caudally is the [2].
Specified Answer for: 1
superior colliculus
Specified Answer for: 2
inferior colliculus
Motor system tracts are found predominantly in the ___ region of the brainstem and sensory system tracts are found predominantly in the ___ region of the brainstem.
Basilar, Tegmental
The postsynaptic neuron in the parasympathetic nervous system uses [1] as its neurotransmitter which binds to [2] (adrenergic/cholinergic) receptors. The postsynaptic neuron in the sympathetic nervous system uses [3] as its primary neurotransmitter which binds to [4] (adrenergic/cholinergic) receptors.
1) Correctacetylcholine
2) Correctcholinergic
3) Correctnorepinephrine
4) Correctadrenergic
To prevent syncope when standing, vasoconstriction of capacitance vessels occurs prior to standing by:
Sympathetic nervous system release of norepinepherine to bind with alpha-adrenergic receptors on veins and venules
Indicate if True or False: A spinal cord injury in the cervical or upper thoracic region can result in Horner’s syndrome.
True
The descending sympathetic tract descends from the hypothalamus to the sympathetic nervous system (SNS) presynaptic neurons in the spinal cord. A spinal cord injury with disruption to this tract in the cervical or upper thoracic spinal cord or damage to the presynaptic SNS neurons in the upper thoracic spinal cord can lead to Horner’s syndrome.
In the discussion of Horner’s syndrome on p. 180 of Lundy-Ekman there is an error in the book regarding possible sites of injury. What is this error?
Damage within the brachial plexus does not cause Horner’s syndrome. The pathway to the head/face does not travel in the brachial plexus on its way to its target.
Overstretching of the brachial plexus and the nerve tissues proximal to it can result in injury to these more proximal structures. These types of injuries may result in avulsion of the spinal nerves or ventral roots, or tearing of the ventral rami proximal enough to damage the presynaptic neurons as they head into the sympathetic trunk (or create an injury to the trunk itself if sufficient force). Because these traction injuries are likely to injure the brachial plexus and the more proximal neural tissues it originates from, many authors will say that brachial plexus injuries can lead to Horner’s syndrome. But an injury limited to the plexus itself (such as from a gunshot or knife wound) would not produce Horner’s syndrome. Even the part of the T1 ventral ramus making up one of the roots of the plexus is distal to the white ramus communicans. Thus no part of the pathway to the face/head travels in the brachial plexus. This is not saying that there won’t be injury to the more proximal structures simultaneously with injury to the brachial plexus with forced traction injuries. But if someone were to have a type of injury that would damage the brachial plexus in isolation from the more proximal structures, this individual would not develop Horner’s syndrome. This should be clarified in the text, as her wording gives the appearance that the pathway includes the brachial plexus as it ascends.
