Neuroanatomy Ascending Tracts

what kind of information is carried by the fasiculus gracillis

fine touch, pressure, conscious sensation, and proprioception from the lower body

what kind of information are carried through ascending tracts

sensory

Ascending/Descending: fasciculus gracilis and fasciculus cuneatus

ascending

what kind of information is carried by the fasiculus cuneatus

fine touch, pressure, conscious sensation, and proprioception from the upper body

these neurons are entirely within the CNS and control the lower motor neurons

upper motor neurons

the cell bodies of these neurons are in the anterior horn of the spinal cord or the nuclei of the cranial nerves

lower motor neurons

these neurons initiate and regulate voluntary movements

upper motor neurons

these neurons target skeletal, cardiac muscles, and glands

lower motor neuron

Lesions of UMN leads to what kind of effects

spasticity (tense)

Lesions of the LMU leads to what kind of effects

flaccid (weak)

where does the fasciculus gracilis originate

dorsal root ganglia below T6

where does the fasciculus cuneatus originate

dorsal root ganglia T6 and above

the location of the spinal cord is the medial part of the dorsal colum n

fasciculus gracilis

the location of the spinal cord is the lateral part of the dorsal column

fasciculus cuneatus

which neurons are primarily located in the primary motor cortex

UMN

these tracts mediate voluntary and involuntary movements

descending tracts

this tracts regulate muscle tone and visceral functions

descending tracts

somatic functions:

voluntary control of skeletal muscles

visceral functions:

involuntary functions of internal organs

what are the pyramidal tracts responsible for

voluntary, precise movement of the skeletal muscles

where do pyramidal tracts originate in the brain

primary motor cortex

what are the two main pyramidal tracts

corticospinal and corticobulbar

pyramidal tracts are also called

direct

what is the function of the anterior limb

ascending sensory information and communication fibers

what does the Genu carry

corticobulbar fibers

what is the function of Genu

motor control of cranial nerves; sends UMN signals to brainstem for face, jaw, tongue, pharynx, and larynx movements

what does the posterior limb carry

corticospinal fibers (descending)

what is the somatotopy of the corticospinal tract within the internal capsule

Arms - Trunk - Leg (from anterior to posterior limbs)

lesions in the lateral corticospinal tract will involve in

difficulty with voluntary fine motor movements of limbs

lesions in the anterior corticospinal tract will involve in

difficulty with movements of the head and trunk

lesions in the anterior corticobulbar tract will involve in

difficulty with cranial nerve-related movements; puffing cheeks, moving eyes, smiling

all of the cranial nerves innervate the neurons bilaterally except

CN VII (facial), CN XI (accessory), and XII (hypoglassal)

ascending/descending: spinothalamic tract

acending

ascending/descending: spinobulbar

ascending

ascending/descending: spinoreticular tract

ascending

ascending/descending: spinomesencephalic tract

ascending

ascending/descending: spinohypothalamic tract

ascending

ascending/descending: dorsal and ventral spinocerebellar tract

ascending

ascending/descending: cuneocerebellar tract

ascending

ascending/descending: rostal spinocerebellar tract

ascending

all of the cerebellar tracts are

ascending

ascending/descending: lateral and medial vestibulospinal tracts

descending

ascending/descending: lateral and medial reticulospinal tracts

descending

ascending/descending: tectospinal

descending

ascending/descending: rubrospinal tract

descending

what kind of information does the spinothalamic tracts carry

pain, temp, and crude touch

list the 5 tracts that are in the spinothalamic tract:

-spinothalamic

-spinobulbar

-spinoreticular

-spinomesencephallic

-spinalhypothalamic

list the 4 tracts that are in the spinocerebellar trcts

-dorsal spinocerebellar

-ventral spinocerebellar

-cuneocerebellar

-rostral spinocerebellar

where do the fasciculus gracilis and cuneatus decussate

medulla

where does the spinothalamic tracts decussate

anterior white commissure of spinal cord

lesion is the spinothalamic and spinobulbar tract leads that what impariment

pain and temperature, crude touch problems

lesion in the spinoreticular, spinomescenohallic, and spinohypothalamic tracts leads to what impariment

disrupt pain processing, alertness/arousal, and autonomic control — leading to heightened pain, poor modulation of pain, and autonomic dysfunction (like unstable blood pressure or heart rate).

what kind of sensory information is superficial or cutaneous sensations

touch, pain, temperature

what kind of sensory information comes from the musculoskeletal system

proprioception (sense of body position and movement) and pain

chemoreceptors detect:

gases, dissolved chemicals

photoreceptors detect:

light

thermoreceptors detect:

temperature

mechanoreceptors detect:

touch

nociceptors detect:

pain

sensory receptors become less sensitive to a stimulus over time is

receptor adaptation

examples of slow adapting receptors are

pain and pressure

examples of fast adapting receptors are

smell and vibration

what are the two types of proprioception receptors

muscle spindles and golgi tendeon organs

these proprioception receptors detect muscle length

muscle spindles

these proprioception receptors detect muscle strength/tension

golgi tendon

this contracts or tightens to prevent muscles from overstretching

muscle spindles

this causes the muscle to relax to prevent the tendon from rupturing

golgi tendon organs

what are the groups of nerve cells in the anterior grey column

medial

central

lateral

what are the groups of nerve cells in the posterior grey column

substantia gelatinosa

nucleus proprius

nucleus dorsalis

visceral afferent group

receives afferents for pain and temperature

substantia gelatinosa

receives afferents for touch

nucleus proprius

all ascending tracts are composed of how many neurons that synapse on each other as they ascend

three

what are the 2 posterior/dorsal column-medial lemniscus pathways

fasciculus gracilis and cuneatus

both of the posterior/dorsal column-medial lemniscus pathways cross over where

in the medulla

is the posterior/dorsal column-medial lemniscus pathways ipsilateral or contralateral

contralateral

anterior spinothalamic tract carrys information of

crude touch and pressure

lateral spinothalamic tract carries information on

pain and temperature

localize the site, timing, and intensity of tissue damage or potential tissue damage

discriminative component

Effects of the pain experience on emotions and behavior

motivational-affective aspect

the meaning that the person ascribes to the pain

cognitive-evaluative aspect

what are the arteries that supply the anterolateral (spinothalamic) system

anterior spinal artery

what are the arteries that supply the posterior/dorsal column-medial lemniscus system

posterior spinal arteries

what kind of information does the posterior/dorsal spinocerebellar tract carry

unconscious proprioception, lower body, individual muscles and joints

what kind of information does the anterior/ventral spinocerebellar tract carry

lower body: whole limb movements and postural adjustments

what kind of information does the cuneocerebellar tract carry

upper extremity and upper trunk: unconscious proprioception

what kind of information does the rostral spinocerebellar tract carry

upper body movement: whole limb movements and postural adjustments

what is the only spinocerebellar tract that decussates

anterior/ventral spinocerebellar tract

where does the anterior/ventral spinocerebellar tract cross

1st crossing: in the spinal cord at the anterior horn

2nd crossing: in the cerebellum

**double crossing means ends up ipsilateral to input**

hyperreflexia of the reflexes is related to which neurons

UMN

hyporeflexia of the reflexes is related to which neurons

LMN

direct communication between sensory and motor neurons is which reflex

monosynaptic reflex (stretch)

interneuron facilitates sensory-motor communication, is which reflex

polysynaptic reflex (withdrawal)

what is the primary receptor for stretch reflex

muscle spindle and golgi tendon organ