Glossary
Somatosensory
What does somatosensory mean?
Somatosensory refers to the systems that carry and process information about the body. These include touch, body position and movement, temperature, and potentially damaging stimulation.
Different sensations, different routes
Feeling an object against your skin differs from sensing where your arm is without looking. The second ability is proprioception. Different receptors and neural pathways contribute to these functions.
Somatosensory receptors
Mechanoreceptors in and beneath the skin respond to features such as touch, pressure, and vibration. Proprioceptors in muscles, joints, and other deep structures provide information about body position and movement. Other sensory pathways concern temperature and potentially harmful stimulation.
The system includes peripheral nerves, spinal or brainstem circuits, and brain regions. Information from the body and face does not all follow one route through the spinal cord. The somatosensory cortex is part of the system, not the whole of it.
The somatosensory cortex
The primary somatosensory cortex lies in the postcentral gyrus of the parietal lobe. Its organization maps different body regions, often illustrated by the sensory homunculus. The map is not proportional to body size: areas such as the hands and face have relatively large representations.
A pathway example
The dorsal column–medial lemniscus pathway carries much of the information used for fine tactile discrimination and limb-position sense. The neuroscience textbook describes how damage limited to the spinal dorsal columns can impair judging a moving touch’s direction or sensing a limb’s position, while having a more modest effect on simple touch tasks. Other pathways also carry some information about skin contact.
This shows why “can feel touch” and “can accurately sense where a limb is” are different questions. It also explains why sensory assessment tests several functions. A report of tingling, numbness, or clumsiness alone does not identify which pathway, if any, is damaged.
Why it matters
A change in one sensory function does not mean every part of the system is affected in the same way. The term covers several functions that need to be distinguished.