White matter tracts Flashcards
There are _ pairs of spinal nerves;
_ cervical
_ thoracic
_ lumbar
_ sacral
_ coccygeal
There are 31 pairs of spinal nerves;
8 cervical
12 thoracic
5 lumbar
5 sacral
1 coccygeal
The _ root contains axons of somatic motor nerves
The ventral root contains axons of somatic motor nerves
* These innervate skeletal muscles
The _ root contains axons of somatic sensory nerves
The dorsal root contains axons of somatic sensory nerves
* These convey sensation (pain, touch, temperature)
The spinal nerve carries _ type of information
The spinal nerve carries somatic and visceral motor & sensory information
* The ventral and dorsal roots unite to form a spinal nerve
The cell bodies of somatic motor nerves are found in the [location of spinal nerve]
The cell bodies of somatic motor nerves are found in the ventral horn
The cell bodies of somatic sensory nerves are found in the [location of spinal nerve]
The cell bodies of somatic sensory nerves are found in the dorsal root ganglion
Sympathetic nerves originate in the [gray matter location]
Sympathetic nerves originate in the lateral horns of the gray matter
* Only between T1-L2
The lateral horn of gray matter is found in [spinal cord regions]
The lateral horn of gray matter is found in T1-L2
Sympathetic nerves exit the spinal cord via _ before entering _
Sympathetic nerves exit the spinal cord via ventral root before entering sympathetic chain
* These are visceral motor nerves
The cell body of visceral motor nerves is in the [spinal nerve region]
The cell body of visceral motor nerves is in the lateral horn
The cell body of visceral sensory nerves is found in the [region]
The cell body of visceral sensory nerves is found in the dorsal root ganglion
Most spinal nerves contain 4 distinct types of nerves:
Most spinal nerves contain 4 distinct types of nerves:
1. Somatic motor
2. Somatic sensory
3. Visceral motor
4. Visceral sensory
The _ rami of spinal nerves combine to form nerve plexuses
The ventral rami of spinal nerves combine to form nerve plexuses
* Cervical, brachial, lumbar, and sacral plexuses
* Intercostal nerves don’t form a plexus
Cervical plexus forms from [spinal cord rami] and innervates structures within the neck (and diaphragm)
Cervical plexus forms from C1-C4 and innervates structures within the neck (and diaphragm)
Brachial plexus forms from [spinal cord rami] and innervates the upper limb/shoulder girdle
Brachial plexus forms from C5-T1 and innervates the upper limb/shoulder girdle
Lumbar plexus forms from [spinal cord rami] and combines with the sacral plexus
Lumbar plexus forms from T12-L4 and combines with the sacral plexus
Sacral plexus forms from [spinal cord rami] and combines with the lumbar plexus to innervate the lower limb and perineum
Sacral plexus forms from L4-S4 and combines with the lumbar plexus to innervate the lower limb and perineum
Sensory information from the thumb and lateral arm returns to the spinal cord via the _ spinal nerve and enters the respective spinal cord segment
Sensory information from the thumb and lateral arm returns to the spinal cord via the C6 spinal nerve and enters the respective spinal cord segment
Neck/shoulder dermatome:
Neck/shoulder dermatome: C3,4,5
Thumb/lateral arm dermatome:
Thumb/lateral arm dermatome: C6
Middle finger dermatome:
Middle finger dermatome: C7
Little finger/medial arm dermatome:
Little finger/medial arm dermatome: C8
Nipple dermatome:
Nipple dermatome: T4
Umbilicus dermatome:
Umbilicus dermatome: T10
Perineum/Perianal dermatome:
Perineum/Perianal dermatome: S2,3,4
Anterior knee/big toe dermatome:
Anterior knee/big toe dermatome: L4
Middle toes dermatome:
Middle toes dermatome: L5
Little toe/lateral foot dermatome:
Little toe/lateral foot dermatome: S1
[Spinal cord segment] : abduction of the shoulder
C5 : abduction of the shoulder
[Spinal cord segment] : flexion of elbow
C6 : flexion of elbow
[Spinal cord segment] : extension of elbow
C7 : extension of elbow
[Spinal cord segment] : extension of wrist/fingers
C7 : extension of wrist/fingers
[Spinal cord segment] : flexion of wrist/fingers
C8 : flexion of wrist/fingers
[Spinal cord segment] : hip flexion
L2 : hip flexion
[Spinal cord segment] : hip adduction
L3 : hip adduction
[Spinal cord segment] : knee extension
L4 : knee extension
[Spinal cord segment] : ankle dorsiflexion
L5 : ankle dorsiflexion
[Spinal cord segment] : ankle plantarflexion
S1 : ankle plantarflexion
The spinal cord ends at [vertebral levels]
The spinal cord ends at L1 or L2
Cervical nerves C1-C7 traverse through their corresponding intervertebral foramen _ to the vertebra
Cervical nerves C1-C7 traverse through their corresponding intervertebral foramen superior to the vertebra
All spinal nerves below _ traverse inferior to the vertebra
All spinal nerves below C8 traverse inferior to the vertebra
* C8 and below will go below
The lateral horn is the location of _ cell bodies
The lateral horn is the location of preganglionic sympathetic nerve cell bodies
The white matter is divided into (3) columns:
The white matter is divided into (3) columns:
1. Dorsal columns (posterior)
2. Ventral columns (anterior)
3. Lateral columns
The _ is a central region of the spinal cord where axons that convey pain and temperature can cross over to the other side of the cord
The anterior commissure is a central region of the spinal cord where axons that convey pain and temperature can cross over to the other side of the cord
Dorsal columns convey [type information]
Dorsal columns convey ascending sensory nerves
* Convey touch, pressure, vibration, proprioception
* “Be sensative and stay P.C.” = posterior column
Anterior columns convey [type information]
Anterior columns convey descending motor nerves to control voluntary movements
* Anterior corticospinal tract
Lateral columns convey [type information]
Lateral columns convey descending motor nerves to control voluntary movements
* Lateral corticospinal tract
Lateral columns convey [type information]
Lateral columns convey ascending sensory nerves
* Spinothalamic tracts
[Tract] detects mechanical-like stimuli (pressure, vibration, fine touch, proprioception)
Dorsal column medial lemniscus detects mechanical-like stimuli (pressure, vibration, fine touch, proprioception)
[Tract] detects pain and temperature
Spinothalamic detects pain and temperature
* Our nervous system separates mechanical stimuli from pain/temperature
Pain and temperature information crosses over in the _
Pain and temperature information crosses over in the spinal cord
Mechanical sensations cross over in the _
Mechanical sensations cross over in the caudal medulla
Dorsal column medial lemniscus tract conveys mechanical information to the [brain region]
Dorsal column medial lemniscus tract conveys mechanical information to the primary somatosensory cortex
* Fine touch, vibration, pressure, proprioception
The DCML involves [#] neurons
The DCML involves 3 neurons
DCML tract:
Neuron 1 cell body: [location]
Neuron 2 cell body: [location]
Neuron 3 cell body: [location]
DCML tract:
Neuron 1 cell body: dorsal root ganglion
Neuron 2 cell body: caudal medulla
Neuron 3 cell body: thalamus
Neuron 1 in the DCML pathway senses mechanical sensation in our lower body and enters the spinal cord via the _ and ascends to the _
Neuron 1 in the DCML pathway senses mechanical sensation in our lower body and enters the spinal cord via the dorsal column (gracile tract) and ascends to the medulla
In the [medullary nucleus] neuron 1 synapses on neuron 2 (DCML)
In the gracile/cuneate nucleus neuron 1 synapses on neuron 2 (DCML)
Which neuron of the DCML decussates?
Neuron 2 of DCML decussates in the medulla
Neuron 2 (DCML) begins in the _ and ascends to the _
Neuron 2 (DCML) begins in the gracile/cuneate nucleus and ascends to the VPL nucleus of the thalamus
* Decussates in medulla and ascends via medial lemniscus
The second synapse of the DCML occurs in the _
The second synapse of the DCML occurs in the VPL of the thalamus
Neuron 3 (DCML) begins in the _ and travels to the _
Neuron 3 (DCML) begins in the VPL and travels to the primary sensory cortex
* Traversing the internal capsule
Neuron 1 in the DCML pathway senses mechanical sensation in our upper body and enters the spinal cord via the _ and ascends to the _
Neuron 1 in the DCML pathway senses mechanical sensation in our upper body and enters the spinal cord via the dorsal column and ascends to the cuneate nucleus
Spinothalamic pathway carries [information] to the [brain region]
Spinothalamic pathway carries pain and temperature to the primary somatosensory cortex
Spinothalamic pathway:
Neuron 1 cell body: [location]
Neuron 2 cell body: [location]
Neuron 3 cell body: [location]
Spinothalamic pathway:
Neuron 1 cell body: DRG
Neuron 2 cell body: dorsal horn
Neuron 3 cell body: thalamus
The site of the spinal cord where spinothalamic tracts decussate is the _
The site of the spinal cord where spinothalamic tracts decussate is the anterior commissure
Lower motor neurons originate in the _ and project directly onto the muscle
Lower motor neurons originate in the ventral horn of spinal cord and project directly onto the muscle
* Some lower motor neurons will actually be in the brainstem (cranial nerve nuclei) and innervate head/neck
UMN descend through the [portion] of the internal capsule
UMN descend through the posterior limb of the internal capsule
90% of UMN will decussate in the _ and form the _ tracts
90% of UMN will decussate in the caudal medulla and form the lateral corticospinal tracts
10% of UMN cross over in the _ and form the _ tracts
10% of UMN cross over in the anterior commissure and form the ventral (anterior) corticospinal tracts
LMNs of the lateral corticospinal tracts innervate [muscles]
LMNs of the lateral corticospinal tracts innervate limb muscles
* For complex motor activities
LMNs of the ventral corticospinal tracts innervate [muscles]
LMNs of the ventral corticospinal tracts innervate truncal muscles
* Core body muscles for postural control
UMNs of the corticobulbar tracts traverse through the [portion] of the internal capsule
UMNs of the corticobulbar tracts traverse through the genu of the internal capsule
Corticobulbar tracts synapse on _
Corticobulbar tracts synapse on cranial nerve motor nuclei
Why are many cranial nerve motor functions preserved in stroke patients?
Many cranial nerve motor nuclei receive UMN input from both cortices
* CN XII only receives UMN from the contralateral motor cortex
[3 CNs] do not receive corticobulbar tracts; they are controlled by the frontal eye fields
CN III, IV, VI do not receive corticobulbar tracts; they are controlled by the frontal eye fields
The upper half of the face is controlled by the [CN nucleus] and receives UMN from _
The upper half of the face is controlled by the upper facial motor nucleus and receives UMN from both motor cortices
The lower half of the face is controlled by the [CN nucleus] and receives UMN from _
The lower half of the face is controlled by the lower facial motor nucleus and receives UMN from contralateral motor cortex
When a patient suffers from UMN damage to the facial nerve the [nucleus] remains functional
When a patient suffers from UMN damage to the facial nerve the upper facial nucleus remains functional
* Therefore the upper facial muscles continue to function, while lower muscles are paralyzed
Rubrospinal tract: [function]
Rubrospinal tract: facilitates arm movements
* Augments the lateral corticospinal tracts
* E.g. flexor muscles of the upper limb
The rubrospinal tract runs from the _ to the _
The rubrospinal tract runs from the red nucleus (midbrain) to the cervical spinal cord
The tectospinal tract: [function]
The tectospinal tract: influences reflex head movements in response to visual and auditory systems
The tectospinal tract runs from the _ to the _
The tectospinal tract runs from the colliculi (midbrain) to the cervical spinal cord
* Also called the colliculospinal
Reticulospinal tract: [function]
Reticulospinal tract: helps activate muscles involved in posture/balance/equilibrium
The reticulospinal tract runs from the _ to the _
The reticulospinal tract runs from the reticular formation to the lower spinal cord
Vestibulospinal tract: [function]
Vestibulospinal tract: controls muscles which respond to changes in gravity and balance
The lateral and medial vestibular nuclei receive input from the _
The lateral and medial vestibular nuclei receive input from the semicircular canals
* Information about head and body position
Inputs to the lateral vestibular nuclei are relayed (ipsilaterally/contralaterally)
Inputs to the lateral vestibular nuclei are relayed ipsilaterally
* Via the lateral vestibulospinal tracts
Inputs to the _ vestibular nuclei are relayed bilaterally into the cervical spinal cord
Inputs to the medial vestibular nuclei are relayed bilaterally into the cervical spinal cord
* Via the medial vestibulospinal tracts
The lateral vestibulospinal tracts function to _
The lateral vestibulospinal tracts function to activate antigravity muscles to maintain balance
* E.g. activating extensor muscles
* We call this vestibulospinal reflex
The medial vestibulospinal tracts function to _
The medial vestibulospinal tracts function to stabilize head movements
* Vestibulocervical reflex
The trigeminothalamic tract involves [#] neurons
The trigeminothalamic tract involves 3 neurons
Touch, pressure, and vibration from the face/head is carried by the first neuron of the trigeminothalamic tract and synapses at the [nucleus]
Touch, pressure, and vibration from the face/head is carried by the first neuron of the trigeminothalamic tract and synapses at the main/principle nucleus of the trigeminal
The trigeminothalamic pathway decussates at the _
The trigeminothalamic pathway decussates at the pons
* The second neuron crosses over in the pons and ascends up the trigeminothalamic tract
The second neuron of the trigeminothalamic tract travels up and synapses in the _
The second neuron of the trigeminothalamic tract travels up and synapses in the VPM of the thalamus
The third neuron of the trigeminothalamic tract ascends through the internal capsule to the _
The third neuron of the trigeminothalamic tract ascends through the internal capsule to the primary sensory cortex
Mechanical receptors are [structure] axons that are specialized to detect touch, pressure, vibration
Mechanical receptors are large encapsulated receptors with myelinated axons that are specialized to detect touch, pressure, vibration
(3) types of proprioceptors
(3) types of proprioceptors:
1. Muscle spindles (sense muscle length)
2. Golgi tendon organs (muscle tension)
3. Joint receptors (joint position)
The mechanical receptors are all associated with [afferent axon type]
The mechanical receptors are all associated with AB axons
* These are large and myelinated
* Very quick
Free nerve endings are associated with [afferent axon type]
Free nerve endings are associated with Adelta axons or C axons
* Adelta are small, lightly myelinated, slow while C axons are unmyelinated
The proprioceptors are associated with [afferent axon type]
The proprioceptors are associated with Ia and II axons
* These are very large and myelinated
* Fastest action potentials
Aalpha axons carry [information]
Aalpha axons carry proprioception
Abeta axons carry [information]
Abeta axons carry touch, vibration
Adelta axons carry [information]
Adelta axons carry pain, temperature
* These are fast and myelinated
C axons carry [information]
C axons carry pain, temperature
* These are slow, unmyelinated
