Transection of Spinal cord

Effects of complete transection of spinal cord

• Spinal cord injury can occur during accidents
• Injury leading to complete transection of spinal cord shows features such as
• Immediate and permanent loss of all voluntary movements below the level of injury
• Immediate loss of all reflexes below the level of injury
• Permanent loss of all sensations below the level of injury

There are three stages of spinal injury with complete transection

1. Stage of spinal shock
2. Stage of reflex activity
3. Stage of reflex failure

Stage of spinal shock

• Loss of reflexes due to the removal of supraspinal influences.
• Loss of voluntary muscle power.
• All sensations below the level of leasion are lost.
• Sharp fall in blood pressure due to vasomotor paralysis and circulation becomes sluggish
• Overling skin and subcutaneous tissue suffer lack of nutrition and are prone to  develop bedsores.
• Urinary bladder muscles become hypotonic or atonic
• Bowel becomes hypotonic.

Stage of reflex activity

• After a lapse of 2 weeks, the tone of flexor muscle returns, give rise to paraplegia in flexion.
• Babinski’s sign becomes positive.
• Tendon jerk begins to appear.
• Mass reflex may appear.
• Bladder becomes automatic.

Stage of reflex failure

• Degeneration of spinal cord and intercurrent infections cause failure to reflex activities.
• Once again the muscle become hypotonic, mass reflexes disappear and the patient dies.

Effects of Hemisection of Spinal cord (Brown Sequard Syndrome)

Above the level of lesion

• The zone of hyperesthesia limited to one segment.

At the level of lesion on the same side

Sensory changes

• Loss of all sensations (fine touch, pressure, pain, temperature, vibration)

Motor changes

• Lower motor neuron type of paralysis.

Below the level of lesion

Sensory changes

• Pain and temperature sensations lost on the opposite site.
• Position sense, fine touch and vibration sense lost on the same side.

Motor chages

• The upper motor neuron type of p aralysis on the same side because of damage to the corticospinal tract.
• On the opposite side, there is minimal motor paralysis following damage to the anterior corticospinal tract.

Applied Aspects

Poliomyelitis

• It is an acute infectious disease characterized by local or widespread muscular paralysis.
• It is produced by a virus causing destruction of anterior horn cells of the spinal cord or the corresponding cell in the medulla.

Facial palsy

• It is produced due to the damage of faceial nerve
• There are three types of facial palsy
• Supranuclear
• Nuclear
• Infranuclear

In the supranuclear type, one side of the face is affected (unilateral), but the upper part of the face is spared due to bilateral innervation

Voluntary movements of facial muscles are affected by emotional expressions are intact

Innucear and infranuclear types, one half of the face is affected.

It may be unilateral or bilateral

There is no impairment of taste sensation

Features of nuclear and infracuclear types of facial palsy

• Facial muscles are paralysed on one side.
• The eye cannot be closed completely and palperbral fissure is widened. Tears collect in the eye and tend to overflow which is called Epiphora.
• Whenever the individual tries to close the eye, the eyball rolls upward under a partly covered eyelid. This is known as Bells’ phenomenon.
• The angle of the mouth is drooping on the affected side and the other agle gets deviated to the normal side.
• Nasolabial fold is lost on the affected side.

Motor System - Pyramidal & Extrapyramidal tracts

Descending pathways from the motor tracts

It is divided as 

1. Pyramidal tracts
2. Extrapyramidal tracts

Pyramidal tracts or Corticospinal tracts

Origin

• Arise from the pyramidal cells in the motor area (4), premotor area (6) and frontal eye field (8).
• It also gets fibers from the sensory area (3,1,2)

Course

Termination

• End on the anterior horn cell of the spinal cord.
• Some fibers give collateral to cranial nerve nucleus which are called corticonuclear fibers

Upper Motor Neuron

• From cerebral cortex to anterior horn cells of spinal cord.

Lower Motor Neuron

• From anterior horn cell to the effector organ.

Dorsal or Posterior column medial lemniscus pathway (Tract of Goll and Burdach)

It is consists of two tracts

1. Tract of Goll (Fasciculus gracilis)
2. Tract of Burdach (Fasciculus cuneatus)

Hence it is also called Tract of Goll and Burdach

They carry sensations of

• Fine touch
• Proprioception (Joint and position sense)
• Vibration
• Pressure

Pathway of Tract of Goll and Burdach

Three orders of neurons are present in this pathway - First, Second and Third order.

First order neuron

• It arises from the respective sensory receptors and enters the spinal cord through the dorsal or posterior root.
• They ascend on the same side of spinal cord in Fasciculus grasalis and Fasciculus cuneatus and relay in the Nucleus gracilis and Nucleus cuneatus present in the medulla.
• Fasciculus gracilis which lies medially in the spinal cord, contains fibers from the lower parts of the body.
• Fasciculus cuneatus which lies laterally in the spinal cord, contains fibers from the upper part of the body.

Second order neurons 

• They cross to the opposite side and relay in the Ventral Posterolateral Nucleus (VPN) of Thalamus.
• The crossing fibers are called Internal Arcuate Fibers.
• The crossings of fibers occur at the level of medulla and not at the level of spinal cord.

Third order neurons 

• They arise from the Ventral Posterolateral Nucleus of Thalamus and project on to the Sensory cortex, area number 3, 2, 1. 

Dorsal column medial lemniscus pathway

Sensory system - Ascending tracts, Synthetic sense

Sensory Tracts

They are group of neurons present in the spinal cord which carry the sensory information to the brain.

They are also called as ascending tracts.

The sensory information is first relayed in the thalamus and finally projected to the sensory cortex, area number 3, 2, 1.

The crude form of sensation and pain which are called protopathic sensation are appreciated at the thalamus.

The finer details of sensations which are called epicritic sensation is perceived by the cerebral cortex.

The important sensory tracts are

1. Dorsal or Posterior column pathway
2. Anterior or ventral column pathway
3. Lateral column pathway Pathway

Dorsal or Posterior column pathway

It is consists of two tracts

1. Tract of Goll (Fasciculus gracilis)
2. Tract of Burdach (Fasciculus cuneatus)

Hence it is also called Tract of Goll and Burdach

They carry sensations of

• Fine touch
• Proprioception (Joint and position sense)
• Vibration
• Pressure

Pathway of Tract of Goll and Burdach

Three orders of neurons are present in this pathway - First, Second and Third order.

First order neuron

• It arises from the respective sensory receptors and enters the spinal cord through the dorsal or posterior root.
• They ascend on the same side of spinal cord in Fasciculus grasalis and Fasciculus cuneatus and relay in the Nucleus gracilis and Nucleus cuneatus present in the medulla.
• Fasciculus gracilis which lies medially in the spinal cord, contains fibers from the lower parts of the body.
• Fasciculus cuneatus which lies laterally in the spinal cord, contains fibers from the upper part of the body.

Second order neurons 

• They cross to the opposite side and relay in the Ventral Posterolateral Nucleus (VPN) of Thalamus.
• The crossing fibers are called Internal Arcuate Fibers.
• The crossings of fibers occur at the level of medulla and not at the level of spinal cord.

Third order neurons 

• They arise from the Ventral Posterolateral Nucleus of Thalamus and project on to the Sensory cortex, area number 3, 2, 1. 

Dorsal column pathway

Lateral column pathways consists of 

• Lateral spinothalamic tracts
• Dorsal spinocerebellar tract
• Ventral spinocerebellar tract
• Spinotectal tract
• Spino-oivary tract
• Spino-vestibular tract
• Spino-pontine tract
• Spinoreticular tract

Anterior and lateral column pathway are together called Anterolateral Spinothalamic pathway

They carry sensatons of

• Pain and temperature by the lateral tract
• Curde touch by the ventral tract

Pathway of Anteriolateral Spinothalamic tract (also known as Pain Pathway)

First order neurons arising from the receptors enter the spinal cord through the dorsal horn and end there. 

Second order neurons arise from the dorsal horn and cross to the opposite side at the same level of spinal card. 

The second order neurons of lower part of the body are present laterally and upper part of the body are present medially.

This arragement is seen oppostite in Tract of Goll and Burdach (Dorsal column pathway)

The fibers ascend in the anterior and lateral part of spinal cord, passes through medulla, pons and midbrain to end in Ventral Posterolateral Nucleus of Thalamus.

Third order neurons arise from the Vertral Posterolateral Nucleus of Thalamus and finally project on to the Sensory cortex, area number 3, 2, 1. 

Anterolateral spinothalamic tract

The other ascending tracts apart from Dorsal column and Anterolateral Spinothalamic tracts do not relay in Thalamus, instead relay in different nucleus of the brain stem and cerebellum.

They are:

• Dorsal spinocerebellar tract
• Ventral spinocerebellar tract
• Spinotectal tract
• Spino-oivary tract
• Spino-vestibular tract
• Spino-pontine tract
• Spinoreticular tract

Important of them are Dorsal and Ventral Spinocereballar Tracts

Dorsal spinocerebeallar tract

It is also called as Flechsig's tract.

The sensations carried by this tract are:

• Unconciuous kinesthetic impusles to cerebellum

Pathway of Dorsal spinocerebellar tract

First order neurons arise from muscle spindle, joints and skin and enter the spiral cord through dorsal root.

They terminate at the Clarke's column situated at the base of the dorsal horn of spinal cord.

Second order neurons arise from Clarke's column and ascend on the same side of the spinal cord till the medulla.

In the medullay it turns posteriorly to enter the cerebellum through the Inferior Cerebellar Peduncle.

Ventral spinocerebellar tract

It is also called as Gower's tract.

The senstions carried by Ventral spinocerebeallar tract are:

• Uncondious kinestehtic impulses to the cerebellum

First order neurons arise from muscle spindle, joints and skin and enter the spiral cord through dorsal root.

They terminate at the Rexed lamina situated in the lateral horn of spinal cord.

Second order neurons cross to the opposite side at the same level and ascend till medulla, pons and midbrain.

In the midbrain it turns posteriorly to enter cerebellum through Supeiror Cerebellar Pedunce.

Dorsal and Ventral Spinocerebellar tracts

Synthetic sense

It is produced by combination of two types of basic sensations.

Examples of Synthetic sensations are:

1. Stereognosis
2. Vibration sense

Stereognosis

It is the ability of a person to appreciate the size, shape, texture and weight of the objects without actually looking at them. This is possible by the past experience of the objects by the person.

Stereognosis is a combination of two sensations - Touch and Pressure.

Any damage to the Parietal lobe posterior to the post central gyrus will lead to impaired Stereognosis.

The inability of a person to identify the commonly used objects by touching them is called as Tactile agnosia.

Vibration sense

It is also a type of synthetic sesantion produced by combination of touch and pressure sensation

It is lost under the following conditions

• Damage to dorsal column tracts
• Uncontrolled/poorly controlled diabetes mellitus
• Vitamin B12 deficiency
• Pernicious anemia
• Tabes dorsalis

Sensory System - Receptors, Homunculus, Dermatomes

Sensory system carries the sensations from all parts of the body to the brain.

Any sensation is first detected by the receptors in the form of its stimulation.

Receptors transmit the information in the form of impulse to the spinal cord.

The ascending tracts present in the spinal cord carry the information to the brain relaying in the thalamus

From the thalamus the information is projected to the sensory cortex, area number 3, 2, 1

Understanding the meaning of sensation is called perception.

Perception is the function of neural processing of sensory information by the brain.

Sensory unit

A single afferent neuron with all its receptors is known as sensory unit. 

Sensory unit

Sensory receptors

They are modified nerve endings capable of converting different forms of energy into nerve impulse.

The sensory receptors are classified as

1. Exteroceptors
2. Interoceptros
3. Telereceptors
4. Proprioceptors

1) Exteroceptors

• They are capable of detecting any change in the external environment. Eg: Touch receptors, Pain receptors.

2) Interoceptors

• They are capable of detecting any change in the internal environment. Eg: Baroreceptors, Chemoreceptors.

3) Telereceptors

• They are capable of detecting any change in the environment from a distance. Eg: Receptors for Vision, Hearing.

4) Proprioceptors

• They are capable of detecting any change in the position of different parts of the body in space. Eg: Muscle spindle, Glogi apparatus 

The sensory receptors can also be classified according to the type of sensations they subserve as 

1. Receptors for General sensations
2. Receptors for Special sensation

1) Receptors for General sensations

• For touch and pressure
• Rapidly adapting: Meissner’s corpuscles and Pacinian corpuscles
• Slow adapting: Merkel’s disc
• For Pain
• Free nerve endings
• For Temperature: Rufini’s end organ
• For Joint sense
• Muscle length: Muscle spindle
• Muscle tension: Golgi tendon organ

Receptors for Special sensations

• For vision: Rods & Cones
• For Hearing: Hairs cells of organ of corti
• For Taste: Taste receptor cells of taste buds
• For smell: Olfactory neurons
• For Linear and rotational acceleration: Hair cells of vestibular apparatus

Sensory Homunculus

The representation of the body in the sensory cortex is called sensory homunculus

The body is represented upside down in the sensory cortex

Sensory homunculus

The representation is contralateral that means the right hemisphere of the cerebral cortex receive sensory information from left side of the body and the left hemisphere of the cerebral cortex receive sensory information from the right side of the body

However the face is represented bilaterally

The parts which are involved in fine movements such as hand and finger have larger area of representation.

Dec 2023 (RS-3), RGUHS 2nd Year BSc. Neuro Science Technology Question Paper, QP 3309

 

II Year B.Sc. Neuro Science Technology Degree Examination

Dec-2023, Time: 3 Hours, Max. Marks: 80

Applied Anatomy and Physiology Related to Neuroscience Technology (RS-3)

LONG ESSAYS (Second Question Choice) 2 x 10 = 20 Marks

1. What is meant by dementia? What are the common causes of dementia?

2. Describe Autonomic Nervous system and symptoms of Autonomic Nervous system.

OR

Hypoxic ischemic encephalopathy – pathophysiology clinical features and EEG findings.

SHORT ESSAYS (Question No 5 & 10 choice) 10 x 5 = 50 Marks

3. Neuro cysticercosis.

4. Narcolepsy.

5. Facial palsy.

OR

CSF circulation.

6. Duchenne muscular dystrophy.

7. Cerebellar ataxia.

8. Arterial blood supply of Brain

9. Stages of sleep.

10. Neuro myelitis optica.

OR

Neuro transmitters.

11. Oculomotor palsy.

12. Symptoms and sinus of meningitis.

SHORT ANSWER 10 x 3 = 30 Marks

13. Sub dural hematoma.

14. Pain Pathway

15. Myasthenia Gravis

16. Pachy meningitis.

17. Essential tremor.

18. Mild congnitive impairment.

19. Membrane potentials

20. Clinical features of Parkinsons disease.

21. Neuromuscular junction.

22. Gag reflex.

May 2023 (RS-3), RGUHS 2nd Year BSc. Neuro Science Technology Question Paper, QP 3309

 

II Year B.Sc. Neuro Science Technology Degree Examination

May-2023, Time: 3 Hours, Max. Marks: 80

Applied Anatomy and Physiology Related to Neuroscience Technology (RS-3)

LONG ESSAYS (Second Question Choice) 2 x 10 = 20 Marks

1. Essay on ANS and its applied physiology.

2. Describe the sulci, gyri, main functional areas and blood supply of cerebrum.

OR

Write an essay on corpus callosum with its applied anatomy and functions.

SHORT ESSAYS (Question No 5 & 10 choice) 10 x 5 = 50 Marks

3. CSF (Cerebrospinal Fluid).

4. Classification of receptors.

5. Circle of Willis

OR

Basal ganglia.

6. Blood supply of the spinal cord.

7. Facial nerve.

8. Brief note on Occipital lobe with diagram.

9. Visual pathway.

10. Fourth ventricle.

OR

Lumbar puncture.

11. Action potential.

12. Functions of thalamus.

SHORT ANSWER 10 x 3 = 30 Marks

13. Meninges.

14. Broca’s area.

15. Glaucoma.

16. Thalamic syndrome.

17. Hemiplegia.

18. Functions of limbic system.

19. BBB.

20. Name any four neurotransmitters.

21. Internal capsule.

22. Kyphosis.