Help with Spinal Physiology
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Anatomy › Help with Spinal Physiology
Where do the nuclei of the parasympathetic nervous system originate?
Craniosacral region (cranial nerves and S2-S4)
Thoracolumbar (T1-L3) and S2-S4
S2-S4 only
Thoracolumbar region (T1-L3)
Explanation
Preganglionic neurons of the parasympathetic nervous system originate in the nuclei of the craniosacral region (cranial nerves and in the spinal cord segments of S2-S4). Those of the sympathetic nervous system originate in the thoracolumbar region (spinal cord segments of T1-L3).
The thoracic spine gives rise to how many segments?
Explanation
The spinal cord consists of 31 segments/pairs. The cervical contains 8, thoracic contains 12, lumbar contains 5, sacral contains 5, and coccygeal contains 1.
What passes through the anterior roots of the spinal cord?
Outgoing instructions
Incoming sensory information
Cell bodies of neurons
Axons of the neurons
Explanation
The anterior roots are where outgoing instructions leave the spinal cord. The posterior roots are where incoming sensory information enter the spinal cord. Grey matter contains the cell bodies of neurons, while the white matter contains the axons of nerves.
The dorsal column tracts ascend in the fasciculus gracilis and fasiculus cuneatus and cross over in the __________.
medulla
spinal cord
midbrain
thalamus
hypothalamus
Explanation
The dorsal column track is an ascending system conveying somatic sensory information to the brain. The dorsal column tracts ascend in the fasiculus gracilis and fasiculus cuneatus. They synapse in the medulla so that signals from the left side of the body are transmitted to the right side, and vice versa.
Cerebrospinal fluid (CSF) is made by the choroid plexus in the lateral ventricals of the telencephalon. The CSF is then reabsorbed in the arachnoid villi in the superior sagittal sinus.
Before cerebrospinal fluid (CSF) travels from the third ventricle into the fourth ventricle, what does it flow through?
Cerebral aqueduct of Sylvius
Foramen of Magendie
Foramen of Lushka
Foramen of Monro
Central canal
Explanation
The correct order of CSF flow is as follows:
Lateral ventricals, foramen of Monro, third ventricle, cerebrel aqueduct of Sylvius, fourth ventricle, foramen of Magendie (medial) and foramen of Lushka (lateral), central canal and subarachnoid space, superior sagittal sinus
Where do A delta fibers terminate in the Rexed laminae?
I and II
II, III, and V
V only
II and III
II only
Explanation
A delta fibers are responsible for signaling "new" sharp pain. The body sends this sensory information to Rexed Laminae I and II. *I and II are called the substantia gelatinosa.
Which of these is a feature of the somatic motor nervous system?
Muscle contraction ceases when neural stimulation ceases
Somatic motor outflow from the CNS is limited to the spinal cord from T1 through L1 or L2
Some axons in peripheral nerves carry signals that prevent or weaken the contraction of skeletal muscle fibers
The somatic motor nervous system includes a limited number of fibers from the sympathetic and parasympathetic nervous systems
Explanation
The somatic nervous system is the voluntary nervous system and part of the peripheral nervous system. It is associated with voluntary skeletal muscle control over body movements and is associated with involuntary reflex arcs. The somatic nervous system consists of afferent (relay sensations to central nervous system) and efferent (relays commands from central nervous system to the body) nerves stimulating muscle contractions. Thus muscle contraction ceases when neural stimulation ceases.
At which vertebra is the conus medullaris found?
L2
S2
T2
C1
T12
Explanation
The conus medullaris is the cone-shaped ending of the spinal cord and it is found at the level of the second lumbar vertebrae (L2). It is located superior to the cauda equina.
Fasciculus gracilus carries primarily __________ information.
proprioception/touch
pain and temperature
motor
gustatory
taste
Explanation
Fasciculus gracilus is one of the component to the dorsal columns. Remember that anything that is dorsal of the spinal cord is associated with sensation. In addition, the dorsal columns control touch while the spinothalamic tract carries pain and temperature information.
The cauda equina falls within which area?
conus medullaris to C0
S5 to C0
T12 to L5
T12 to C0
L5 to S5
Explanation
The cauda equina is the bottom of the conus medullaris. It extends from the conus medullaris and terminates at C0 vertebrae.