Nervous System - Chapter 17 Flashcards
What are the general characteristics of nervous system pathways? (3)
- CNS communicates with peripheral body structures through pathways
- Process and Integrate information continuously along the pathways
- Pathways travel through the white matter of the brainstem or spinal cord
What does a pathway consist of?
a tract and a nucleus
The ascending pathways consist of what type of neuron axon?
sensory
The descending pathways consist of what type of neuron axon?
motor
Sensory pathways are composed of which neurons?
primary, secondary, and sometimes tertiary neurons
Motor pathways are composed of which neurons?
upper motor and lower motor neurons
This pathway (part of the sensory pathway) conducts information about limb position, sensations or touch, pressure, temperature, and pain to the brain
somatosensory pathways
What is the function of visceral pathways?
process stimuli from the viscera
What are the 3 somatosensory pathways?
- posterior funiculus (medial lemniscus pathway)
- anterolateral pathway
- spinocerebellar pathway
The posterior funiculus obtains sensory information regarding what? (3)
proprioception discriminative touch, precise pressure, and vibration
Tracts in the spinal cord are called what?
posterior funiculus
the posterior funiculus is composed of what 2 portions?
Fasciculus cuneatus and the fasciculus gracilis
Neurons from the upper limbs, superior trunk, neck, and posterior regions of the head are from which portion of the posterior funiculus?
fasciculus cuneatus
Neurons from the lower limbs and inferior trunk are from which portion of the posterior funiculus?
fasciculus gracilis
What are tracts in the brainstem called?
medial lemniscus
Where is the anterolateral pathway located?
in the anterior and lateral white funiculi of the spinal cord
The anterolateral pathway is composed of which 2 tracts?
Anterior spinothalamic and lateral spinothalamic tract
Axons that enter the anterolateral pathway conduct stimuli related to what?
touch and pressure, as well as pain and temperature
What is the function of the spinocerebellar pathway?
conduct proprioceptive information to cerebellum for processing to coordinate body movement
Which 2 tracts make up the spinocerebellar pathway?
anterior spinocerebellar and posterior spinocerebellar tracts
Sensory Pathways of the spinocerebellar pathway use integrate and act upon information on what level?
subconscious level
What is the function of the motor pathways of the spinocerebellar pathway?
regulate skeletal muscle activity
What are the 2 motor neurons in somatic motor pathways?
upper motor and lower motor neurons
Where is the upper motor neuron located?
within the cerebral cortex or a nucleus within the brainstem
What is the function of the upper motor neuron?
excite or inhibit the activity of lower motor neuron
Where is the lower motor neuron located?
within the anterior horn of the spinal cord or within brainstem cranial nerve nucleus
What is the function of the lower motor neuron?
always excitatory toward skeletal muscle fibers
What is the function of direct pathways?
conscious control of skeletal muscle activity
What is another name for the direct pathway?
pyramidal pathway
The 3 descending motor tracts of the direct pathway are what?
- corticobulbar tract
- lateral corticospinal tract
- anterior corticospinal tract
Where does the corticobulbar tract originate?
from the facial region within the motor homunculus of the primary motor tract
Axons of upper and lower motor neurons synapse on lower motor neurons where in the spinal cord?
anterior horn
What are the 2 components of the anterior horn?
lateral corticospinal tract and the anterior corticospinal tract
innervating the skeletal muscles that control skilled movements in the limbs is the function of which tract?
lateral corticospinal tract
innervating the axial skeleton muscles is the function of which tract?
anterior corticospinal tract
The lateral corticospinal tract and the anterior corticospinal tract make up which tract?
Corticospinal tract
Indirect pathways control what type of skeletal muscle activity?
unconscious
What is the function of indirect pathways?
modify and help control the pattern of somatic motor activity by:
- alter motor neuron sensitivity to incoming impulses to control muscles individually or in groups
- activate feedback loops to project into primary motor cortex
What are the 2 tracts of the indirect pathways?
Medial pathway and lateral pathway
What is the function of the lateral pathway?
regulate and control precise, discrete movements, and tone in the flexor muscles
What is the function of the medial pathway?
regulate muscle tone and gross movements of the muscles of the head, neck, proximal limbs, and trunk
The medial pathway consists of what 3 tracts?
reticulospinal tracts, tectospinal tracts, and vestibulospinal tracts
Helping to control more unskilled autonomic movements related to posture and maintaining balance is the function of which tract?
reticulospinal tracts
Helping to regulate positional changes of the arms, eyes, head, and neck as a consequence of visual and auditory stimuli is the function of which tract?
tectospinal tracts
