Rotation: Spinal Cord Flashcards
The axons now forming the lateral corticospinal tract will continue their caudal descent in the spinal cord until they reach their synaptic targets- a second neuron in the ______ of the spinal cord, called an alpha motorneuron.
ventral grey matter
In the caudal medulla, approximately ___% of the fibers decussate.
80
The nucleus gracilis’ axon immediately crosses the midline to ascend within the brainstem as part of a bundle called the _______.
medial lemniscus
What happens when the anterior/ventral corticospinal tract reach their intended segment of the spinal cord?
they innervate not only the ipsilateral alpha motor neuron, but they also send a branch of their axon across the midline in a white matter band called the ventral white commisure to innervate some contralateral alpha motor neurons
What is the corona radiata?
a bundle of white matter fibers extending from the cortex to the spinal cord
This is a small band of white matter near the dorsal rootlet where pain and temperature afferents travel the spinal cord.
Lissauer’s fasciculus
Alpha motor neurons located medially in the grey matter innervate _____ important for _____ and are innervated by the anterior corticiospinal pathways.
core muscles; posture
What is the connection btw the caudate and the putamen called?
the ventral striatum
The _____ splits into a medial caudate and a lateral putamen and globus pallidus- here they are part of white matter called the internal capsule.
corona radiata
How does a dissociated sensory loss, in which one side of the body below the injury lacks pain and temperature sensation, and the other lacks dorsal column sensation, occur?
a hemisection injury of the spinal cord (Brown-Sequard syndrome)
On the lateral surface of the brain, the primary motor cortex is found along the pre-central gyrus, just anterior to ______.
the central sulcus
Alpha motor neurons located laterally in the ventral grey matter innervate muscles important for _____, like the ________. These neurons are innervated by the lateral corticospinal tract.
dexterity; fingers or thumb musculature
What is upper motor neuron (UMN) syndrome?
- muscles innervated by these lower motor neurons are weak.
- There is an initial loss of reflex activity and muscle tone for a period between a few days and weeks.
- After this time, the muscle tone and reflex activity returns in an exaggerated fashion (spasticity and hyperreflexia)
On the lateral surface of the brain, the primary motor cortex is found along the ______, just anterior to the central sulcus.
pre-central gyrus
The white matter fibers traverse the diencephalon laterally and then enter the midbrain, where they form a stalk-like white matter bundle called the ______- a part of the midbrain referred to as the cerebral peduncle.
crus cerebri
The medial lemniscus will terminate on a third neuron in the pathway, located in a nucleus of the _____, called the ventral posteriolateral nucleus, or VPL.
thalamus
What is the nucleus cuneatus?
a second order neuron in a nucleus lateral to the nucleus gracilis where axons about T6 synapse
This is a second order neuron in a nucleus lateral to the nucleus gracilis where axons about T6 synapse.
the nucleus cuneatus
The white matter fibers traverse the ______ laterally and then enter the ______, where they form a stalk-like white matter bundle called the crus cerebri- referred to as the cerebral peduncle.
diencephalon; midbrain
The axons continue through the ____ then reemerge as part of a structure visible on the ventral surface of the medulla known as the pyramid.
pons
What happens to the pt with a hemisection injury of the spinal cord (Brown-Sequard syndrome)?
a dissociated sensory loss, in which one side of the body below the injury lacks pain and temperature sensation, and the other lacks dorsal column sensation
The axons now forming the lateral corticospinal tract will continue their caudal descent in the spinal cord until they reach their synaptic targets- a ______ in the ventral grey matter of the spinal cord, called ______.
second neuron; an alpha motorneuron
What does the corticospinal tract divide into?
- the anterior/ventral corticospinal tract
- the lateral corticospinal tract
Above ______, axons still enter the spinal cord at their respective segments, but then ascend in a white matter column that is just lateral to the fasciculus gracilis called the fasciculus cuneatus.
the T6 dermatome
Dx?:
- muscles innervated by these alpha motor neurons would fail to respond to commands from the UMNs, producing weakness
- in those muscles, reflexes mediated by those segments would be attenuated
- muscle tone would be decreased, producing hypotonia or flaccidity
lower motor neuron (LMN) syndrome
The principal efferent pathway from the brain to the spinal cord is the _______.
corticospinal tract
What is the column of white matter in the spinal cord called?
the lateral corticospinal tract
_______ located medially in the grey matter innervate core muscles important for posture and are innervated by the anterior corticiospinal pathways.
Alpha motor neurons
Alpha motor neurons located laterally in the ______ innervate muscles important for dexterity, like the fingers or thumb musculature. These neurons are innervated by the lateral corticospinal tract.
ventral grey matter
The Babinski reflex is a hallmark of ____ syndrome.
UMN
