Unit 10 Lecture 3 the spinal cord nerves

Описание: Unit 10 – Lecture 3: The Spinal Cord

Introduction

Spinal cord central nervous system (CNS) ka ek mahatvapurn hissa hai. Yeh brain aur body ke beech sensory aur motor impulses ko transmit karta hai aur reflex actions ka control center hota hai.

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Location & Extent
• Spinal cord foramen magnum se shuru hoti hai
• Adult mein L1–L2 vertebra tak hoti hai
• Newborn mein L3 vertebra tak hoti hai
• Length: approx. 45 cm (adult)

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Coverings of Spinal Cord (Meninges)
1. Dura mater – outer protective layer
2. Arachnoid mater – middle layer
3. Pia mater – inner layer, spinal cord se chipki hoti hai

👉 Subarachnoid space mein cerebrospinal fluid (CSF) hota hai.

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Structure of Spinal Cord

External Features:
• Cervical enlargement
• Lumbar enlargement
• Anterior median fissure
• Posterior median sulcus

Internal Structure:
• Gray matter (H-shaped):
• Anterior horn – motor neurons
• Posterior horn – sensory neurons
• Lateral horn – autonomic neurons
• White matter:
• Ascending tracts (sensory)
• Descending tracts (motor)

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Spinal Nerves
• Total 31 pairs:
• 8 Cervical
• 12 Thoracic
• 5 Lumbar
• 5 Sacral
• 1 Coccygeal

Each spinal nerve has:
• Dorsal root – sensory
• Ventral root – motor

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Functions of Spinal Cord
1. Conduction of nerve impulses
2. Control of reflex actions
3. Coordination between brain and body
4. Autonomic nervous system regulation

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Reflex Action
• Rapid, automatic response
• Controlled by spinal cord
• Example: withdrawal reflex, knee jerk reflex

Reflex arc includes:
Receptor → Sensory neuron → Interneuron → Motor neuron → Effector

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Clinical Importance
• Spinal cord injury → paralysis
• Lumbar puncture for CSF examination
• Herniated disc, poliomyelitis, meningitis

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Conclusion

Spinal cord body ke movements, sensations aur reflexes ke liye essential hai. Iski proper functioning human survival ke liye bahut zaroori hai.