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Joint Receptors

Golgi End Organs: In ligaments of joints, respond to position of joint

End Organ of Ruffini: In the capsule responds to movements of joints.

Pacinian Corpuscle: In the ligaments very sensitive to quick movements & vibrations
  • Rapidly adapting receptors sense vibration;
  • Slowly adapting receptors sense pressure.
  • Rapidly adapting receptors are encapsulated nerve endings.
  • Slowly adapting receptors are expanded nerve endings.
  • Itch is carried by C-mechanoreceptors.


Function of spinocerebellar tract (AIIMS May 09)?

A. Planning & programming of movement
B. Coordination & smoothing of movement
C. Equilibrium
D. Vibration


B. Coordination & smoothing of movement

Sensory Pathways

  • Anterolateral system: crossed tract
  • Dorsal (or posterior) column system: uncrossed
  • SPINOCEREBELLAR TRACT : Unconscious proprioception
  • (Anterior or Ventral & Posterior or Dorsal)

Anterolateral system

This includes:

1.  Anterior (or ventral)

    Spinothalamic tract: This carries crude touch

2.  Lateral Spinothalamic tract: This carries pain and temperature


Due to a central cord lesion, dissociative sensory loss seen due to. (AIIMS Nov 09).

  1. Decussating branches of lateral spinothalamic tract
  2. Dorsal column
  3. Anterior spinothalamic tract
  4. Cilioretinal pathway



A- Decussating branches of lateral spinothalamic tract


Pain innervation of the viscera

Pain innervation of the viscera. Pain afferents from structures between the pain lines reach the CNS via sympathetic pathways, whereas, they traverse parasympathetic pathways from structures above the thoracic pain line and below the pelvic pain line. 

Gate Control Theory & Lateral inhibition

  1. Gate Control Theory & Lateral inhibition                                                                   
  2. Stimulation of skin at the site of pain also gives some pain relief. The relief may result from inhibition of pain pathways in the dorsal horn gate by stimulation of large-diameter touch-pressure afferents.
  3. Collaterals from these myelinated afferent fibers synapse in the dorsal horn. These collaterals inhibit the input from nociceptive afferent fibres that also synapse in the dorsal horn. This is called the gate-control hypothesis.
  4. The same mechanism is probably responsible for the efficacy of counterirritants, Hot water bags etc . Stimulation of the skin over an area of visceral inflammation produces some relief of the pain due to the visceral disease by inhibiting C unmyelinated Adrenergic fibres from GIT carrying visceral pain.
  5. Afferent fibers from visceral structures reach the CNS via sympathetic and parasympathetic nerves. Their cell bodies are located in the dorsal roots and the homologous cranial nerve ganglia.
  6. Specifically, there are visceral afferents in the facial, glossopharyngeal, and vagus nerves; in the thoracic and upper lumbar dorsal roots; and in the sacral roots .
  7. Vagal connections provide a massive sensory link for "physiological information", while sympathetic unmyelinated C fibres provide sensations of visceral pain.

Dorsal column

This carries the rest of the sensations e.g. proprioception, vibration, fine touch, etc.

Spinocerebellar Tract

  1. The kinesthetic & proprioceptive information from the body relayed via spinocerebellar tracts are used for coordination.
  2. The copy of motor plan relayed from motor cortex via pontocerebellar tract is matched with the actual muscle movements information relayed via spinocerebellar tract (Comparator Servo Mechanism).Then prompt correction are made to coordinate and smoothen the ongoing activity.
  3. Dorsal spinocerebellar is uncrossed and reaches cerebellum via inferior peduncle.
  4. Ventral spinocerebellar is mostly crossed and reaches cerebellum via superior peduncle.

Diagram Showing the Dorsal Col. Pathway


Fig. Ascending tracts carrying sensory information from peripheral receptors to the cerebral cortex.
(a) Dorsal-column pathway mediating touch, vibratory sense, and proprioception.
(b) Ventrolateral spinothalamic tract mediating pain and temperature.

Law of reciprocal innervation of agonist antagonist muscles/ (AIIMS May 08)
  1. Hering's law
  2. Sherrington's law
  3. Laplace’s law
  4. Hick’s law
B. Sherrington's law

This is hemi-section of the spinal cord.

Brown Sequard Syndrome

Opposite side:

  • Loss of pain and temperature sensation

Same side:

  • Other sensations lost (except touch)
  • LMN type of paralysis or the level of lesion
  • UMN type of paralysis below the level of lesion

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