2. The cord is composed of: The cord is composed of: Inner core of Gray matter. Inner core of Gray matter. On cross section On cross section It is H- shaped Pillar or Butter Fly. It is H- shaped Pillar or Butter Fly. Outer core of White matter. Outer core of White matter.

3. It is correlated to: Amount of Muscle Innervated. It is correlated to: Amount of Muscle Innervated. Greatest in: Greatest in: Cervical and Lumbosacral Segments. Cervical and Lumbosacral Segments. They innervate the muscles of the Upper and Lower limbs. They innervate the muscles of the Upper and Lower limbs.

4. Anterior and Posterior Gray Columns or Horns. Anterior and Posterior Gray Columns or Horns. They are united by: They are united by: A thin Gray Commissure. A thin Gray Commissure. It contains the small Central Canal. It contains the small Central Canal.

5. It Receives It Receives Most of the Termination of the Dorsal Nerve Roots entering the spinal cord. Most of the Termination of the Dorsal Nerve Roots entering the spinal cord.

6. Contains: Contains: Lower Motor Neurons. Lower Motor Neurons. Their axons exit through Ventral Nerve Roots to innervate the skeletal muscles. Their axons exit through Ventral Nerve Roots to innervate the skeletal muscles. The Neurons The Neurons receive Input from: Descending pathways for the motor control. receive Input from: Descending pathways for the motor control. Some dorsal root afferents. Some dorsal root afferents.

7. A small Intermediolateral Horn is present in: A small Intermediolateral Horn is present in: Thoracic and Upper Lumbar Segments. Thoracic and Upper Lumbar Segments. It contains the cell bodies of Preganglionic Sympathetic Neurons. It contains the cell bodies of Preganglionic Sympathetic Neurons.

8. A similar place is found in: A similar place is found in: 2 nd 3 rd and 4 th Sacral Segments. 2 nd 3 rd and 4 th Sacral Segments. It gives rise to Preganglionic Parasympathetic Neurons. It gives rise to Preganglionic Parasympathetic Neurons.

9. The Gay Matter can be divided into (10) Zones. The Gay Matter can be divided into (10) Zones. They are Numbered Sequentially from Dorsal to Ventral. They are Numbered Sequentially from Dorsal to Ventral.

10. Superficial Laminae Receive: Superficial Laminae Receive: Cutaneous Afferents. Cutaneous Afferents. Deeper Laminae Receive: Deeper Laminae Receive: Proprioceptive and Muscle Afferents. Proprioceptive and Muscle Afferents.

11. At the Tip of the Dorsal Horn (Laminae 1-111) At the Tip of the Dorsal Horn (Laminae 1-111) It Extends: It Extends: Throughout the Length of the spinal cord. Throughout the Length of the spinal cord. It receives: It receives: 1. Nerve Fibers associated with Nociception Temperature and Touch. 1. Nerve Fibers associated with Nociception Temperature and Touch. 2. Input from Supraspinal Levels. 2. Input from Supraspinal Levels.

12. Large Nerve Cells. Large Nerve Cells. Position: Position: Anterior to Substantia Gelatinosa. Anterior to Substantia Gelatinosa. Extension: Extension: Throughout the spinal cord. Throughout the spinal cord. It receives: It receives: Fibers from the Posterior White Column associated with the senses of Position and Movement. Fibers from the Posterior White Column associated with the senses of Position and Movement.

13. Composed of: Composed of: Thoracic Nucleus. Thoracic Nucleus. Nucleus Dorsalis. Nucleus Dorsalis. Occupies: Occupies: Base of the Dorsal Horn (Lamina V11): Segments C8- L3 Base of the Dorsal Horn (Lamina V11): Segments C8- L3 It receives afferents from: It receives afferents from: Muscle Spindle. Muscle Spindle. Golgi Tendon Organs. Golgi Tendon Organs. Tactile and Pressure Receptors. Tactile and Pressure Receptors. These form the ascending fibers of the Dorsal Spinocerebellar Tract. These form the ascending fibers of the Dorsal Spinocerebellar Tract.

14. (1) Alpha Neurons : (1) Alpha Neurons : Innervate Extrafusal muscle fibers. Innervate Extrafusal muscle fibers. (2) Gamma Neurons: (2) Gamma Neurons: Innervate Intrafusal muscle fibers within the muscle. Innervate Intrafusal muscle fibers within the muscle.

15. Neurons innervating Muscles of the Neck and Trunk : Neurons innervating Muscles of the Neck and Trunk : Medial. Medial. Neurons innervating Muscles of the Limbs : Neurons innervating Muscles of the Limbs : Lateral. Lateral.

16. Phrenic Nucleus Phrenic Nucleus Centrally Located (C3- C5). Centrally Located (C3- C5). Gives rise to: Phrenic Nerve. Gives rise to: Phrenic Nerve. Essential for Breathing. Essential for Breathing. Acessory Nucleus Acessory Nucleus Located in the Upper Cervical Segments. Located in the Upper Cervical Segments. Its Axons form the Spinal Part of the Acessory Nerve. Its Axons form the Spinal Part of the Acessory Nerve.

17. Completely Surrounds the Gray Matter. Completely Surrounds the Gray Matter. More Abundant in the Upper Levels of the cord The Ascending Tracts gain More Fibers at each successive level. More Abundant in the Upper Levels of the cord The Ascending Tracts gain More Fibers at each successive level. The Descending fibers have the opposite. The Descending fibers have the opposite.

18. Dorsal. Dorsal. Lateral. Lateral. Ventral Ventral

19. It is Dorsolateral Fasciculus. It is Dorsolateral Fasciculus.Located Superficial to the Tip of the Dorsal Horn. Formed of Ascending and Descending branches of the Dorsal Roots which Don’t Terminate at their Point of Entry. Fibers within the Tract Run Varying Distances in Either Direction

20. Fasciculus Proprius Fasciculus Proprius Occupies: Occupies: A Narrow band immediately Peripheral to the Gray Matter. A Narrow band immediately Peripheral to the Gray Matter. Functions: Functions: Interconnects Adjacent or Distant Cord Segments. Interconnects Adjacent or Distant Cord Segments. Permit Intersegmental Coordination. Permit Intersegmental Coordination.

21. Between the Posterior Median Sulcus and the Posterior Horn. Between the Posterior Median Sulcus and the Posterior Horn. Composed of: Composed of: Fasciculus Gracilis : Fasciculus Gracilis : Medial throughout the Length of the Spinal Cord. Medial throughout the Length of the Spinal Cord. Contains Contains Ascending fibers from Ascending fibers from Sacral, Lumbar and Lower Thoracic. Sacral, Lumbar and Lower Thoracic.

22. Fasciculus Cuneatus Fasciculus Cuneatus Lateral. Lateral. Receives fibers from: Receives fibers from: Upper Thoracic and Cervical regions. Upper Thoracic and Cervical regions. The Fasciculi (Gracilis & Cuneatus)are concerned with The Fasciculi (Gracilis & Cuneatus)are concerned with Proprioceptive Information (Awareness of Posture and Discriminitive Touch). Proprioceptive Information (Awareness of Posture and Discriminitive Touch).

23. CONTAIN: CONTAIN: (1) Ascending Tracts (1) Ascending Tracts Dorsal Spinocerebellar: Dorsal Spinocerebellar: Carries information from: Muscles, joints and ligaments. Carries information from: Muscles, joints and ligaments. For the Control of Posture and Coordination of Movement. For the Control of Posture and Coordination of Movement. Lateral Spinothalamic : Carries impulses of Carries impulses of Pain, Temperature, Pressure and Coarse Touch (Extroceptive). Pain, Temperature, Pressure and Coarse Touch (Extroceptive).

24. (2) Descending Tracts: (2) Descending Tracts: Lateral Corticospinal: Lateral Corticospinal: Controls Controls Voluntary, Discrete and Skilled Movements. Voluntary, Discrete and Skilled Movements. Rubrospinal: Rubrospinal: Has a control over the Tone of Limb Flexor Muscles. Has a control over the Tone of Limb Flexor Muscles.

25. CONTAIN: CONTAIN: (1) Descending Tracts (1) Descending Tracts 1. Ventral Corticospinal 1. Ventral Corticospinal 2.Tectospinal. 2.Tectospinal. Mediates reflex movements in response to Visual Stimuli. Mediates reflex movements in response to Visual Stimuli.

26. 3.Vestibulospinal 3.Vestibulospinal Has an Influence upon Extensor Motor neurons. Has an Influence upon Extensor Motor neurons. 4. Reticulospinal 4. Reticulospinal It influences Voluntary movement, Reflex activity and Muscle Tone. It influences Voluntary movement, Reflex activity and Muscle Tone.

27. (2) Ascending Tracts (2) Ascending Tracts 1. Ventral Spinocerebellar. 1. Ventral Spinocerebellar. 2. Ventral Spinothalamic. 2. Ventral Spinothalamic. 3. Medial Longitudinal Fasciculus. 3. Medial Longitudinal Fasciculus.

28. (1) Poliomyelitis (1) Poliomyelitis Acute Viral Infection of the Lower Motor neurons. Acute Viral Infection of the Lower Motor neurons. Rapid Paralysis and Wasting of the Limb. Rapid Paralysis and Wasting of the Limb. Can Affect the Diaphragm. Can Affect the Diaphragm. Recovery is Incomplete. Recovery is Incomplete.

29. Chronic Degenerative Disease. Chronic Degenerative Disease. A Progressive Muscular Atrophy with Hypotonia and Wasting of the limb muscles. A Progressive Muscular Atrophy with Hypotonia and Wasting of the limb muscles. Affect both the Lower Motor Neurons and the Descending Tracts. Affect both the Lower Motor Neurons and the Descending Tracts. Degeneration of the Descending Tracts cause Spasticity and Weakness of the muscles. Degeneration of the Descending Tracts cause Spasticity and Weakness of the muscles.

30. SPINAL REFLEXS Involuntary stereotyped response that is initiated by a sensory stimulus. Involuntary stereotyped response that is initiated by a sensory stimulus. The pathway is formed of afferent neurones conveying impulses from sensory receptors in the CNS ( spinal cord or brain stem) and efferent neurones coming out from the CNS to the effector organ (muscle or gland). The pathway is formed of afferent neurones conveying impulses from sensory receptors in the CNS ( spinal cord or brain stem) and efferent neurones coming out from the CNS to the effector organ (muscle or gland).

31. SPINAL REFLEXS Interneurons within the CNS exist between the afferent and efferent components. Interneurons within the CNS exist between the afferent and efferent components. Reflexes are qualitatively the same but quantitatively they differ. Reflexes are qualitatively the same but quantitatively they differ.

32. FUNCTIONS OF STRETCH REFLEXES (1) control of muscle tone which in turn determine the proportion of motor units that are active at any one time. (1) control of muscle tone which in turn determine the proportion of motor units that are active at any one time. (2) control of posture by keeping the anti gravity muscles at a constant length in opposition to imposed stretch. (2) control of posture by keeping the anti gravity muscles at a constant length in opposition to imposed stretch.

33. STRETCH RECEPTORS Neuromuscular spindles (muscular spindles) are most numerous in the central non contractile part toward the tendinous attachment of skeletal muscles.They provide sensory information that is used by the CNS in the control of muscle activity. Each spindle has a fusiform capsule and contains slender intrafusal muscle fibers. Neuromuscular spindles (muscular spindles) are most numerous in the central non contractile part toward the tendinous attachment of skeletal muscles.They provide sensory information that is used by the CNS in the control of muscle activity. Each spindle has a fusiform capsule and contains slender intrafusal muscle fibers.

34. STRETCH RECEPTORS The nuclear bag fibers are concerned with dynamic responses and are associated more with velocity and position of contraction.the nuclear chain fibers are associated with slow static contractions. The nuclear bag fibers are concerned with dynamic responses and are associated more with velocity and position of contraction.the nuclear chain fibers are associated with slow static contractions.

35. STRETCH RECEPTORS The intrafusal fibers are of two types : the nuclear bag and the nuclear chain. The intrafusal fibers are of two types : the nuclear bag and the nuclear chain. There are two types of sensory ending of muscle spindles : the (primary) annulospiral and the (secondary) flower spray. There are two types of sensory ending of muscle spindles : the (primary) annulospiral and the (secondary) flower spray. The ordinary muscle fibers outside the spindles are the extrafusal fibers. The ordinary muscle fibers outside the spindles are the extrafusal fibers.

36. STRETCH RECEPTORS There are two types of sensory ending of muscle spindles : the (primary) annulospiral and the (secondary) flower spray. There are two types of sensory ending of muscle spindles : the (primary) annulospiral and the (secondary) flower spray. The ordinary muscle fibers outside the spindles are the extrafusal fibers. The ordinary muscle fibers outside the spindles are the extrafusal fibers.

37. STRETCH (MONOSYNAPTIC ) REFLEX Stretching(elongationo f the intrafusal fibers results in stimulation of the annulospiral and flower spray endings. Stretching(elongationo f the intrafusal fibers results in stimulation of the annulospiral and flower spray endings. Nerve impulses pass to the spinal cord in the afferent neurons.In the spinal cord, they stimulate the large alpha motor neurons.the efferent motor neurons stimulate the extrafusal fibers and the muscle contracts. Nerve impulses pass to the spinal cord in the afferent neurons.In the spinal cord, they stimulate the large alpha motor neurons.the efferent motor neurons stimulate the extrafusal fibers and the muscle contracts.

38. STRETCH (MONOSYNAPTIC ) REFLEX The muscle spindle afferent neurons inhibit the alpha motor neurons supplying the antagonist muscles (reciprocal inhibition ). The muscle spindle afferent neurons inhibit the alpha motor neurons supplying the antagonist muscles (reciprocal inhibition ).

39. GAMMA REFLEX LOOP Centers in the brain and spinal cord( reticular formation, basal ganglia and cerebellum)give rise to tracts that synapse with the gamma motor neurons. Centers in the brain and spinal cord( reticular formation, basal ganglia and cerebellum)give rise to tracts that synapse with the gamma motor neurons. Gamma efferent motor fibers cause shortening of the intrafusal fibers and stimulate the sensory nerve endings and lowers the threshold to externall applied stretch.this in turn initiates the reflex contraction of the extrafusal fibers. Gamma efferent motor fibers cause shortening of the intrafusal fibers and stimulate the sensory nerve endings and lowers the threshold to externall applied stretch.this in turn initiates the reflex contraction of the extrafusal fibers.

40. FLEXOR REFLEX It is a polysynaptic reflex in which one or more interneurons are interposed between afferent and efferent neurons. Cutaneous stimulation of the limbs causes withdrawal from the stimulus. It is a polysynaptic reflex in which one or more interneurons are interposed between afferent and efferent neurons. Cutaneous stimulation of the limbs causes withdrawal from the stimulus. All forms of cutaneous stimulation can initiate flexor reflex but normally they are inhibited by descending tracts from the brain unless the stimulus is painful. All forms of cutaneous stimulation can initiate flexor reflex but normally they are inhibited by descending tracts from the brain unless the stimulus is painful.

41. CROSSED EXTENSOR REFLEX Activation of the flexor reflex in a weight bearing limb simultaneously causes reflex extension of the contralateral limb so as to carry the weight of the body. Activation of the flexor reflex in a weight bearing limb simultaneously causes reflex extension of the contralateral limb so as to carry the weight of the body.