General Sensation: Definition and Classification (Physiology)

Definition

General sensations (also called somatic senses) are the sensory information collected from receptors distributed throughout the body — skin, muscles, joints, tendons, and internal organs — as opposed to the special senses (vision, hearing, smell, taste, and equilibrium), which arise from specialized sense organs confined to particular locations in the head.

According to Guyton and Hall's Textbook of Medical Physiology: "The somatic senses are the nervous mechanisms that collect sensory information from all over the body." - Guyton and Hall Textbook of Medical Physiology, p. 621 (block 6)

Classification of Somatic (General) Senses

1. Physiological classification (by receptor/stimulus type)

The somatic senses are classified into three physiological types:

Mechanoreceptive somatic senses - stimulated by mechanical displacement of tissue. This category includes:
- Tactile sensations: touch, pressure, vibration, and tickle
- Position sensations: static position sense and rate-of-movement (kinesthetic) sense
Thermoreceptive senses - detect heat and cold
Pain sense - activated by factors that damage tissue (noxious/tissue-damaging stimuli)

2. Other classification (by anatomical origin)

Somatic sensations are also grouped by where they arise from:

Exteroceptive sensations - arise from the surface of the body (e.g., touch, pressure, temperature, pain on the skin)
Proprioceptive sensations - relate to the physical state of the body, including:
- Position sensations
- Tendon and muscle sensations
- Pressure sensations from the soles of the feet
- Sensation of equilibrium (often classified as a "special" sensation rather than somatic)
Visceral sensations - arise from the internal organs (viscera)
Deep sensations - arise from deep tissues such as fascia, muscle, and bone; these include mainly deep pressure, deep pain, and vibration
Guyton and Hall Textbook of Medical Physiology, p. 621

Summary Table

Classification basis	Types
By receptor/stimulus	Mechanoreceptive (touch, pressure, vibration, tickle, position) · Thermoreceptive (heat, cold) · Pain
By anatomical source	Exteroceptive (skin surface) · Proprioceptive (muscle, tendon, joint, equilibrium) · Visceral (internal organs) · Deep (fascia, muscle, bone)

This dual classification framework (physiological type + anatomical origin) is the standard approach used in medical physiology to organize the sensory modalities carried by the somatosensory system before they ascend via pathways such as the dorsal column-medial lemniscal system and anterolateral (spinothalamic) system to the thalamus and cortex.

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