Download MBBS (Bachelor of Medicine, Bachelor of Surgery) Human Anatomy ppt lectures Topic 75 Spinal Cord Tracts Notes. - anatomy ppt free download human anatomy ppt lectures, medicine notes ppt, anatomy handwritten notes pdf, mbbs 1st year anatomy notes pdf download, best anatomy notes pdf, human anatomy notes pdf, anatomy easy notes pdf, anatomy notes online, anatomy short notes, Anatomy ppt, Powerpoint Presentations and lecture notes.
White Matter- classification
Tracts
Ascending Tracts
Descending Tracts
Clinical Correlates
Mixture of:
1. Nerve fibers,
2. Neuroglia,
3. Blood vessels.
surrounds the grey matter
white colour
myelinated nerve fibres.
Sensory
Motor
Association
Anterior white column
(or funiculus)
Lateral white column
(or funiculi)
Posterior white
column (or funiculus)
Anterior white
commissure.
Collection of nerve fibres
with same
Origin,
Course,
Termination
Spinotectal tract
Spinoreticular tract
Descending autonomic tract
Spino-olivary tract
Lateral Spinothalamic Tract
Pain,
Thermal sensation
Anterior Spinothalamic Tract
Crude (Light) touch, (non-discriminative touch)
Pressure
Tickle, Itch
Dorsal Column
Fine touch (discriminative touch)
Fasciculus gracilis
Two point discrimination
Fasciculus cuneatus
Vibration
Conscious Proprioception
Anterior Spinocerebellar Tract
Unconscious Proprioception
Gross movements
Posterior Spinocerebellar Tract
Unconscious Proprioception
Fine movements
Spinotectal tract
Spinoreticular tract
Descending autonomic tract
Spino-olivary tract
Lateral spinothalamic tract
Destination
Posterior central gyrus
3rd Order Neuron
Ventral posterolateral
nucleus of Thalamus
Pathways
Lateral spinothalamic,
Spinal lemniscus? Spinotectal
2nd Order Neuron
? Substantia
gelatinosa/
Rexed III-VII
1st Order Neuron
Posterior root ganglion
Decussation
Receptor
Free nerve endings
Anterior spinothalamic tract
Destination
Posterior central gyrus
3rd Order Neuron Ventral posterolateral
nucleus of Thalamus
Pathways
Anterior spinothalamic,
Medial lemniscus
2nd Order
? Substantia gelatinosa/
Neuron
Rexed III-VII
1st Order Neuron
Posterior root ganglion
Decussation
Receptors
Pacinian Corpuscle
Posterolateral tract of Lissauer
1st order neuron enters posterior horn & divides into ascending and
descending branches that travel for 1-2 segments, then terminate
synapsing with 2nd order neurons in substantia gelatinosa.
Antero-
Spinotectal tract
Spinoreticular tract
Descending autonomic tract
Spino-olivary tract
Dorsal Column
Destination
Posterior central gyrus
3rd Order Neuron
Ventral posterolateral
nucleus of Thalamus
2nd Order Neuron
Nuclei gracilis and cuneatus in
medulla oblagata
Few IV-VI
FC
FG
Pathways
Ipsilateral Fasciculi gracilis & cuneatus
Medial lemniscus
T 1-6, C
1st Order Neuron
Posterior root ganglion
Receptors
Meissner's corpuscles, Pacinian corpuscles,
muscle spindles & tendon organs
T 7-12, L, S
Axons of the second-order neurons
Called Internal arcuate fibres cross the
median plane.
Decussate with the corresponding fibres of
the opposite side in the medulla as sensory
FC
FG
Decussation
Fibres ascend as a single compact bundle
T 1-6, C
called medial lemniscus through the
brainstem.
T 7-12, L, S
Spinotectal tract
Spinoreticular tract
Descending autonomic tract
Spino-olivary tract
Spinocerebellar Tracts
Destination
Cerebellar Cortex
Through Superior & Inferior Cerebellar peduncles
Pathways
Anterior Spinocerebellar tracts (Superior)
Posterior Spinocerebellar tracts (Inferior)
2nd Order Neuron
Nucleus Dorsalis/ Clarke's column C8-L3/4
V-VII
1st Order Neuron
Collateral branches of Ascending tracts of Dorsal Column
from dorsal root ganglion
Receptors
muscle spindles & tendon organs, joint receptors
Spinotectal tract
Spinovisual reflexes
Movements of the eyes & head in response to
the source of the stimulation
Spinoreticular tract
Reticular formation,
Levels of consciousness
Pain perception
Spino-olivary tract
Conveys cutaneous and proprioceptive
information to cerebellum
Spino-cervicothalamic
Hair movement, pinch, pressure,
pathway
thermal stimuli, noxious stimuli
Origin
Primary motor cortex (area 4),
secondary motor cortex (area 6),
parietal lobe (areas 3, 1, and 2)
Pass through
Corona radiata,
posterior limb of Internal Capsule
middle 3/5 of basis pedunculi of midbrain
Site of crossover
pyramids of medulla
Pathway
Corticospinal tracts
Termination
98% on contralateral alpha and gamma motor neurons
in grey matter or interneurons.
also known as pyramidal tracts.
Controls rapid, skilled, non-postural, voluntary movements,
especially distal ends of limbs
gives branches to cerebral cortex,
? basal nuclei,
? red nucleus,
? olivary nuclei,
? reticular formation.
These branches keep the subcortical regions aware about the
cortical motor activity.
Origin
Red nucleus of midbrain
Site of
Immediately in midbrain
crossover
Pathway
Rubrospinal tract
Destination
Motor neurons in grey matter
Function
Facilitates activity of flexor muscles and
inhibits activity of extensor muscles in
the upper limb
? Red nucleus receive afferent impulses through connections with the :
? 1. cerebral cortex
? 2. cerebellum.
? 3. Globus Pallidus
? Extends as far as corticospinal tract
? Cortico-rubral connections from ipsilateral red nucleus
? indirect pathway by which the cerebral cortex and the cerebellum
can influence the activity of motor neurons of the spinal cord.
Extrapyramidal Tracts
Reticulospinal tract
Inhibit or facilitate voluntary movement, reflex activity,
assist hypothalamus controls sympathetic,
parasympathetic outflows.
Tectospinal tract
Reflex postural movements of head concerning visual
stimuli
Vestibulospinal tract
Unconscious maintenance of posture and balance; acts
on extensors
mediates head & neck movements in response to
vestibular sensory input
Descending autonomic Control sympathetic and parasympathetic
fibers
systems
Anterior Spinothalamic Tract
contralateral loss of light touch sensations below the level of the
lesion
contralateral loss of pressure sensations below the level of the lesion
The patient will
not feel the light touch of a piece of cotton placed against the skin
and cant feel pressure from a blunt object placed against the skin.
is caused by syphilis.
a selective destruction of nerve fibres at the
point of entrance of the posterior root into the
spinal cord,
specially in the lower thoracic and lumbosacral
regions.
Results in loss of some sensation &
hypersensitivity of others.
Upper Motor Neuron (UMN) Lesions:
Lesions of corticospinal tracts (Pyramidal Tracts)
Lesions of Extrapyramidal Tracts
Lesions of corticospinal tracts (Pyramidal Tracts)
Babinski sign is present.
superficial abdominal reflexes are absent.
cremasteric reflex is absent.
There is loss of performance of fine-skilled,
voluntary movements, especially at the distal
end, of the limbs.
Lesions of Extrapyramidal Tracts lesions:
Spastic paralysis, (lower limb extended, and the upper limb flexed),
Exaggerated deep muscle reflexes in some flexors,
Clasp-knife reaction -the muscles, after resistance on stretching,
suddenly give way.
By any lesion ( ex. Poliomyelitis) destroying neurons in the anterior grey
column or its axon in the anterior root or spinal nerve.
Clinical signs:
1.
Flaccid paralysis
2.
Muscular Atrophy
3.
Loss of muscular reflexes
4. Muscular fasciculation
5. Muscular contracture and degeneration .
Following a spinal cord injury there will be :
a short term loss of all neurological activity below the level of injury.
loss of motor, sensory reflex & autonomic function.
due to temporary physiologic disorganisation of spinal cord function,
may last 30-60 minutes or up to 6 weeks.
It can be caused by fracture dislocation of the vertebral column,
Clinical features :
1. Bilateral LMN paralysis
2. Bilateral spastic paralysis below the level of the lesion
3. Bilateral loss of all sensations below the level of the lesion.
4. Bladder and bowel functions are no longer under voluntary control
1. Bilateral LMN paralysis in the segment of lesion,
2. Bilateral spastic paralysis below level of the lesion,
3. Bilateral loss of pain, temprature & light touch
below the level of the lesion,
4. Two point discrimination & vibratory and
proprioception sensations are preserved.
1. Bilateral LMN paralysis in the segment of lesion,
2. Bilateral spastic paralysis below the level of the
lesion with characteristic sacral sparing,
3. Bilateral loss of pain, temperature & light touch and
pressure sensations below the level of the lesion with
characteristic sacral sparing.
A 36 year old male is observed to have difficulty in walking during a clinic visit.
Testing indicates that his joint position sense is intact. However, his reflexes in his
lower limbs are diminished. Based on the findings in this patient, which of the
following pathways most likely have been damaged?
A.
Lateral spinothalamic
B.
Ventral spinothalamic
C.
Dorsal spinocerebellar
D.
Cuneocerebellar
A 19 year old gang member presented in the ER with a stab wound of the neck.
Neurological examination revealed left hemiparesis with complete loss of vibratory
and joint position sense below C6 on the same side as the weakness. Loss of pain
and temperature sensation was elicited on the left at C6 only and on the right
below C6. An MRI of the cervical spinal cord will reveal which of these findings?
A.
Hemisection of the left spinal cord
B.
Complete transection of the spinal cord
C. Lesion of the left anterolateral white mater only of the spinal cord
D. Damage to the cervical dorsal roots at C6 on the left side only
A patient has an injury that results in damage to the lower motor neurons. Which of
the following would you expect to see in the patient?
A.
Spastic paralysis
B.
Hyperreflexia
C.
Increased muscle tone
D.
Flaccid paralysis
A pain researcher wants to make a lesion to the Spinothalamic tract so that his
subjects feel no pain and temperature sensation from the right leg, but leaves pain
and temperature sensation rostral to the arm. Where would you advise this
researcher to make his lesion?
A.
Lesion the most lateral aspect of the left spinothalamic tract
B.
Lesion the most medial aspect of the left spinothalamic tract
C.
Lesion the most lateral aspect of the right spinothalamic tract
D.
Lesion the most medial aspect of the right spinothalamic tract
During a play-off game, a college hockey player is struck hard on the back of his
neck with a hockey stick. A CT scan reveals a bone fragment lodged into the
medial aspect of his dorsal columns in the cervical spinal cord. Which of the
following functions will most likely be affected given this patient's presentation?
A.
Touch, pressure, vibratory sense from ipsilateral leg
B.
Pain and temperature sense from contralateral leg
C.
Pain from ipsilateral face
D.
Pain and temperature sense from contralateral arm
This post was last modified on 05 April 2022