Ruffini's end organs are best described as which?

• A. Free nerve endings
• B. Merkel's Disks
• C. Slow Adapting Sensors for Broad Deformation of Skin
• D. Hair Follicle Receptors

Answer: (C)

Ruffini endings are mechanoreceptors in the deeper layers of the skin that fire steadily when the skin is stretched or under sustained pressure. They have large receptive fields and support the sense of finger position and movement by encoding ongoing deformation, not quick changes. That makes the description of “slowly adapting sensors for broad deformation of skin” the best fit, since it captures both the slow response and the broad, stretching/deforming nature of these receptors.

Other receptor types describe different functions: free nerve endings cover pain and temperature, Merkel’s discs provide high-resolution, static touch and texture with small fields, hair follicle receptors respond to hair movement, and Pacinian corpuscles are rapidly adapting and detect high-frequency vibrations and quick pressure changes.