Download MBBS Anatomy PPT 50 Spinal Cord Tracts Notes

--- Content provided by‍ FirstRanker.com ---

Tracts

Ascending Tracts

Descending Tracts

--- Content provided by⁠ FirstRanker.com ---

Clinical Correlates

Mixture of:

--- Content provided by⁠ FirstRanker.com ---

1. Nerve fibers,

2. Neuroglia,

3. Blood vessels.

--- Content provided by​ FirstRanker.com ---

surrounds the grey matter

white colour

--- Content provided by​ FirstRanker.com ---

myelinated nerve fibres.

Sensory

Motor

--- Content provided by​ FirstRanker.com ---

Association


Anterior white column

--- Content provided by⁠ FirstRanker.com ---

(or funiculus)

Lateral white column
(or funiculi)

--- Content provided by‌ FirstRanker.com ---

Posterior white
column (or funiculus)

Anterior white
commissure.

--- Content provided by‌ FirstRanker.com ---

Collection of nerve fibres

with same

--- Content provided by FirstRanker.com ---

Origin,

Course,

Termination

--- Content provided by​ FirstRanker.com ---

Spinotectal tract

Spinoreticular tract

--- Content provided by‍ FirstRanker.com ---

Descending autonomic tract

Spino-olivary tract

--- Content provided by‍ FirstRanker.com ---

Lateral Spinothalamic Tract

Pain,

--- Content provided by‌ FirstRanker.com ---

Thermal sensation

Anterior Spinothalamic Tract

Crude (Light) touch, (non-discriminative touch)

--- Content provided by‍ FirstRanker.com ---

Pressure
Tickle, Itch

Dorsal Column

--- Content provided by⁠ FirstRanker.com ---

Fine touch (discriminative touch)

Fasciculus gracilis

Two point discrimination

--- Content provided by​ FirstRanker.com ---

Fasciculus cuneatus

Vibration
Conscious Proprioception

--- Content provided by⁠ FirstRanker.com ---

Anterior Spinocerebellar Tract

Unconscious Proprioception
Gross movements

--- Content provided by‌ FirstRanker.com ---

Posterior Spinocerebellar Tract

Unconscious Proprioception
Fine movements

--- Content provided by FirstRanker.com ---

Spinotectal tract

Spinoreticular tract

--- Content provided by FirstRanker.com ---

Descending autonomic tract

Spino-olivary tract

Lateral spinothalamic tract

--- Content provided by FirstRanker.com ---

Destination

Posterior central gyrus

--- Content provided by‍ FirstRanker.com ---

3rd Order Neuron

Ventral posterolateral
nucleus of Thalamus

--- Content provided by FirstRanker.com ---

Pathways

Lateral spinothalamic,
Spinal lemniscus? Spinotectal

--- Content provided by​ FirstRanker.com ---

2nd Order Neuron

? Substantia

gelatinosa/

--- Content provided by FirstRanker.com ---

Rexed III-VII

1st Order Neuron

Posterior root ganglion

--- Content provided by‍ FirstRanker.com ---

Decussation

Receptor

--- Content provided by‌ FirstRanker.com ---

Free nerve endings

Anterior spinothalamic tract

Destination

--- Content provided by‍ FirstRanker.com ---

Posterior central gyrus

3rd Order Neuron Ventral posterolateral

--- Content provided by‌ FirstRanker.com ---

nucleus of Thalamus

Pathways

Anterior spinothalamic,

--- Content provided by‍ FirstRanker.com ---

Medial lemniscus

2nd Order

? Substantia gelatinosa/

--- Content provided by⁠ FirstRanker.com ---

Neuron

Rexed III-VII

--- Content provided by⁠ FirstRanker.com ---

1st Order Neuron

Posterior root ganglion

Decussation

--- Content provided by FirstRanker.com ---

Receptors

Pacinian Corpuscle

--- Content provided by​ FirstRanker.com ---

Posterolateral tract of Lissauer

--- Content provided by‍ FirstRanker.com ---

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.

--- Content provided by FirstRanker.com ---

Antero-

Spinotectal tract

--- Content provided by⁠ FirstRanker.com ---

Spinoreticular tract

Descending autonomic tract

Spino-olivary tract

--- Content provided by‍ FirstRanker.com ---

Dorsal Column

Destination

--- Content provided by FirstRanker.com ---

Posterior central gyrus

3rd Order Neuron

Ventral posterolateral

--- Content provided by⁠ FirstRanker.com ---

nucleus of Thalamus

2nd Order Neuron

Nuclei gracilis and cuneatus in

--- Content provided by​ FirstRanker.com ---

medulla oblagata
Few IV-VI

FC

--- Content provided by FirstRanker.com ---

FG

Pathways

Ipsilateral Fasciculi gracilis & cuneatus

--- Content provided by​ FirstRanker.com ---

Medial lemniscus

T 1-6, C

1st Order Neuron

--- Content provided by⁠ FirstRanker.com ---

Posterior root ganglion

Receptors

--- Content provided by‍ FirstRanker.com ---

Meissner's corpuscles, Pacinian corpuscles,
muscle spindles & tendon organs

T 7-12, L, S

--- Content provided by FirstRanker.com ---

Axons of the second-order neurons

Called Internal arcuate fibres cross the

median plane.

--- Content provided by​ FirstRanker.com ---

Decussate with the corresponding fibres of

the opposite side in the medulla as sensory

--- Content provided by FirstRanker.com ---

FC

FG

Decussation

--- Content provided by‍ FirstRanker.com ---

Fibres ascend as a single compact bundle

T 1-6, C

--- Content provided by‍ FirstRanker.com ---

called medial lemniscus through the

brainstem.

T 7-12, L, S

--- Content provided by​ FirstRanker.com ---

Spinotectal tract

Spinoreticular tract

--- Content provided by​ FirstRanker.com ---

Descending autonomic tract

Spino-olivary tract

--- Content provided by‌ FirstRanker.com ---

Spinocerebellar Tracts

Destination

Cerebellar Cortex

--- Content provided by‍ FirstRanker.com ---

Through Superior & Inferior Cerebellar peduncles

Pathways

--- Content provided by‍ FirstRanker.com ---

Anterior Spinocerebellar tracts (Superior)
Posterior Spinocerebellar tracts (Inferior)

2nd Order Neuron

--- Content provided by‌ FirstRanker.com ---

Nucleus Dorsalis/ Clarke's column C8-L3/4
V-VII

1st Order Neuron

--- Content provided by‌ FirstRanker.com ---

Collateral branches of Ascending tracts of Dorsal Column
from dorsal root ganglion

Receptors

--- Content provided by​ FirstRanker.com ---

muscle spindles & tendon organs, joint receptors

Spinotectal tract

Spinovisual reflexes

--- Content provided by FirstRanker.com ---

Movements of the eyes & head in response to
the source of the stimulation

Spinoreticular tract

--- Content provided by FirstRanker.com ---

Reticular formation,
Levels of consciousness
Pain perception

Spino-olivary tract

--- Content provided by‍ FirstRanker.com ---

Conveys cutaneous and proprioceptive
information to cerebellum

Spino-cervicothalamic

--- Content provided by‌ FirstRanker.com ---

Hair movement, pinch, pressure,

pathway

--- Content provided by‌ FirstRanker.com ---

thermal stimuli, noxious stimuli


Origin

--- Content provided by​ FirstRanker.com ---

Primary motor cortex (area 4),
secondary motor cortex (area 6),
parietal lobe (areas 3, 1, and 2)

Pass through

--- Content provided by‌ FirstRanker.com ---

Corona radiata,
posterior limb of Internal Capsule
middle 3/5 of basis pedunculi of midbrain

--- Content provided by​ FirstRanker.com ---

Site of crossover

pyramids of medulla

Pathway

--- Content provided by​ FirstRanker.com ---

Corticospinal tracts

Termination

--- Content provided by​ FirstRanker.com ---

98% on contralateral alpha and gamma motor neurons
in grey matter or interneurons.

also known as pyramidal tracts.

--- Content provided by‌ FirstRanker.com ---

Controls rapid, skilled, non-postural, voluntary movements,

especially distal ends of limbs

gives branches to cerebral cortex,

--- Content provided by⁠ FirstRanker.com ---

? basal nuclei,
? red nucleus,
? olivary nuclei,
? reticular formation.

--- Content provided by⁠ FirstRanker.com ---

These branches keep the subcortical regions aware about the

cortical motor activity.

--- Content provided by‌ FirstRanker.com ---

Origin

Red nucleus of midbrain

--- Content provided by​ FirstRanker.com ---

Site of

Immediately in midbrain

crossover

--- Content provided by FirstRanker.com ---

Pathway

Rubrospinal tract

--- Content provided by‍ FirstRanker.com ---

Destination

Motor neurons in grey matter

Function

--- Content provided by⁠ FirstRanker.com ---

Facilitates activity of flexor muscles and
inhibits activity of extensor muscles in
the upper limb

--- Content provided by⁠ FirstRanker.com ---

? Red nucleus receive afferent impulses through connections with the :
? 1. cerebral cortex
? 2. cerebellum.
? 3. Globus Pallidus
? Extends as far as corticospinal tract

--- Content provided by‍ FirstRanker.com ---

? 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.

--- Content provided by​ FirstRanker.com ---

Extrapyramidal Tracts

Reticulospinal tract

Inhibit or facilitate voluntary movement, reflex activity,

--- Content provided by​ FirstRanker.com ---

assist hypothalamus controls sympathetic,
parasympathetic outflows.

Tectospinal tract

--- Content provided by⁠ FirstRanker.com ---

Reflex postural movements of head concerning visual
stimuli

Vestibulospinal tract

--- Content provided by FirstRanker.com ---

Unconscious maintenance of posture and balance; acts
on extensors
mediates head & neck movements in response to
vestibular sensory input

--- Content provided by‌ FirstRanker.com ---

Descending autonomic Control sympathetic and parasympathetic
fibers

systems

--- Content provided by‌ FirstRanker.com ---

Anterior Spinothalamic Tract

contralateral loss of light touch sensations below the level of the

--- Content provided by FirstRanker.com ---

lesion

contralateral loss of pressure sensations below the level of the lesion

The patient will

--- Content provided by‌ FirstRanker.com ---

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.

--- Content provided by‌ FirstRanker.com ---

is caused by syphilis.

a selective destruction of nerve fibres at the

point of entrance of the posterior root into the

--- Content provided by⁠ FirstRanker.com ---

spinal cord,

specially in the lower thoracic and lumbosacral

--- Content provided by‍ FirstRanker.com ---

regions.

Results in loss of some sensation &

hypersensitivity of others.

--- Content provided by⁠ FirstRanker.com ---

Upper Motor Neuron (UMN) Lesions:

Lesions of corticospinal tracts (Pyramidal Tracts)

--- Content provided by‍ FirstRanker.com ---

Lesions of Extrapyramidal Tracts

Lesions of corticospinal tracts (Pyramidal Tracts)

--- Content provided by‌ FirstRanker.com ---

Babinski sign is present.

superficial abdominal reflexes are absent.

cremasteric reflex is absent.

--- Content provided by FirstRanker.com ---

There is loss of performance of fine-skilled,

voluntary movements, especially at the distal

--- Content provided by‌ FirstRanker.com ---

end, of the limbs.

Lesions of Extrapyramidal Tracts lesions:

Spastic paralysis, (lower limb extended, and the upper limb flexed),

--- Content provided by‌ FirstRanker.com ---

Exaggerated deep muscle reflexes in some flexors,

Clasp-knife reaction -the muscles, after resistance on stretching,

--- Content provided by FirstRanker.com ---

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.

--- Content provided by​ FirstRanker.com ---

Clinical signs:

1.

--- Content provided by FirstRanker.com ---

Flaccid paralysis

2.

Muscular Atrophy

--- Content provided by⁠ FirstRanker.com ---

3.

Loss of muscular reflexes

--- Content provided by FirstRanker.com ---

4. Muscular fasciculation

5. Muscular contracture and degeneration .

--- Content provided by‌ FirstRanker.com ---

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.

--- Content provided by⁠ FirstRanker.com ---

due to temporary physiologic disorganisation of spinal cord function,

may last 30-60 minutes or up to 6 weeks.

--- Content provided by‍ FirstRanker.com ---

It can be caused by fracture dislocation of the vertebral column,

Clinical features :

1. Bilateral LMN paralysis

--- Content provided by​ FirstRanker.com ---

2. Bilateral spastic paralysis below the level of the lesion

3. Bilateral loss of all sensations below the level of the lesion.

--- Content provided by FirstRanker.com ---

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,

--- Content provided by‌ FirstRanker.com ---

3. Bilateral loss of pain, temprature & light touch

below the level of the lesion,

--- Content provided by‍ FirstRanker.com ---

4. Two point discrimination & vibratory and

proprioception sensations are preserved.

1. Bilateral LMN paralysis in the segment of lesion,

--- Content provided by⁠ FirstRanker.com ---

2. Bilateral spastic paralysis below the level of the

lesion with characteristic sacral sparing,

--- Content provided by FirstRanker.com ---

3. Bilateral loss of pain, temperature & light touch and

pressure sensations below the level of the lesion with

characteristic sacral sparing.

--- Content provided by​ FirstRanker.com ---

A 36 year old male is observed to have difficulty in walking during a clinic visit.

--- Content provided by‍ FirstRanker.com ---

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

--- Content provided by​ FirstRanker.com ---

following pathways most likely have been damaged?

A.

Lateral spinothalamic

--- Content provided by FirstRanker.com ---

B.

Ventral spinothalamic

--- Content provided by‌ FirstRanker.com ---

C.

Dorsal spinocerebellar

D.

--- Content provided by⁠ FirstRanker.com ---

Cuneocerebellar

A 19 year old gang member presented in the ER with a stab wound of the neck.

--- Content provided by‍ FirstRanker.com ---

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

--- Content provided by‍ FirstRanker.com ---

below C6. An MRI of the cervical spinal cord will reveal which of these findings?

A.

--- Content provided by FirstRanker.com ---

Hemisection of the left spinal cord

B.

Complete transection of the spinal cord

--- Content provided by‌ FirstRanker.com ---

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

--- Content provided by‌ FirstRanker.com ---

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.

--- Content provided by​ FirstRanker.com ---

Spastic paralysis

B.

--- Content provided by‍ FirstRanker.com ---

Hyperreflexia

C.

Increased muscle tone

--- Content provided by‌ FirstRanker.com ---

D.

Flaccid paralysis
A pain researcher wants to make a lesion to the Spinothalamic tract so that his

--- Content provided by​ FirstRanker.com ---

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

--- Content provided by⁠ FirstRanker.com ---

researcher to make his lesion?

A.

Lesion the most lateral aspect of the left spinothalamic tract

--- Content provided by‍ FirstRanker.com ---

B.

Lesion the most medial aspect of the left spinothalamic tract

--- Content provided by​ FirstRanker.com ---

C.

Lesion the most lateral aspect of the right spinothalamic tract

D.

--- Content provided by⁠ FirstRanker.com ---

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

--- Content provided by​ FirstRanker.com ---

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?

--- Content provided by‍ FirstRanker.com ---

A.

Touch, pressure, vibratory sense from ipsilateral leg

--- Content provided by FirstRanker.com ---

B.

Pain and temperature sense from contralateral leg

C.

--- Content provided by⁠ FirstRanker.com ---

Pain from ipsilateral face

D.

--- Content provided by‍ FirstRanker.com ---

Pain and temperature sense from contralateral arm

5 year painter was rushed to the ER after he fell from a high building and fractured

his cervical vertebra and damaged his spinal cord. During examination of his

--- Content provided by FirstRanker.com ---

reflexes immediately after the accident, which of the following are most likely to be

seen?

--- Content provided by‌ FirstRanker.com ---

A.

Increased reflexes

B.

--- Content provided by‌ FirstRanker.com ---

Decreased reflexes

C.

--- Content provided by FirstRanker.com ---

Rigidity

D.

Fasiculations

--- Content provided by FirstRanker.com ---