Difference between general sensation and special sensation

 

Difference between general sensation and special sensation

General and Special Sensations in the Nervous System

The nervous system processes different types of sensations through the somatic and special sensory pathways. These sensations help us interact with our environment and maintain body functions.

1. General Sensation

🔹 Definition: General sensation refers to the sensations perceived from the skin, muscles, joints, and internal organs.
🔹 Pathway: Carried by the somatic sensory system via the spinal cord and brainstem.
🔹 Types:

• Exteroception (External Sensation) → From the skin

  • Touch (Fine & Crude)
  • Pressure
  • Temperature (Hot & Cold)
  • Pain (Nociception)

• Proprioception (Position Sense) → From muscles, tendons, and joints

  • Joint Position Sense
  • Vibration Sense
  • Kinesthesia (Movement Awareness)

• Visceral Sensation → From internal organs

  • Distension of organs (e.g., stomach, bladder)
  • Pain from ischemia or inflammation

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2. Special Sensation

🔹 Definition: Special sensations are those that require specialized sensory organs and are processed by cranial nerves.
🔹 Types:

• Vision → Processed by the optic nerve (CN II)
• Hearing → Processed by the vestibulocochlear nerve (CN VIII)
• Balance (Equilibrium) → Controlled by the vestibular system (CN VIII)
• Taste → Carried by CN VII (Facial), CN IX (Glossopharyngeal), and CN X (Vagus)
• Smell (Olfaction) → Transmitted via the olfactory nerve (CN I)

Clinical Relevance

1. Neuropathy → Damage to general sensory nerves can cause numbness, tingling, or loss of sensation.
2. Hearing Loss / Balance Disorders → Dysfunction in CN VIII can lead to vertigo, tinnitus, or deafness.
3. Anosmia (Loss of Smell) → Damage to the olfactory nerve (CN I) due to head trauma or infection.
4. Stroke or Brain Lesions → Can selectively affect general or special sensory pathways, leading to sensory deficits.

General sensation	Special sensation
•      Touch •      Temperature •      Pain •      Pressure •      Proprioception from muscles & joint  •      Vibration  •      Itching ( is a subthreshold sensation of pain; both itch &  pain sensations share common nerve pathways) •      Visceral sensation •      Chemical	•      Olfaction •      Taste •      Vision •      Balance •      Hearing
Functional component of general sensation General somatic afferent General visceral afferent	Functional component of special  sensation Special  somatic afferent Special visceral afferent
General somatic afferent : collect information from external world   General visceral afferent: collect information about internal organs of body	Special  somatic afferent : vision, balance , hearing Special visceral afferent: olfaction , taste
Simple neural pathway	complex neural pathway
Scarred throughout the body	Anatomically distinct structure