Ruffini ending
Corpusculum bulboideum (Ruffini)
Also known as: Ruffini corpuscle, bulbous corpuscle, SA2 receptor
Ruffini endings are spindle-shaped, slowly adapting encapsulated mechanoreceptors in the deep dermis and joint capsules that respond to skin stretch and sustained deformation.
Overview
A Ruffini ending is an elongated, spindle-shaped capsule (≈0.5–2 mm long) in which the branched terminals of an Aβ axon intertwine with collagen fibres that are continuous with the surrounding dermis or capsule. Stretching the tissue pulls on these collagen fibres and compresses the nerve endings — much like a Golgi tendon organ, to which it is structurally similar.
They are slowly adapting type II (SA2) receptors with large receptive fields and a marked directional sensitivity. They signal sustained skin stretch, for example around the nails and over the knuckles as the fingers move, and so contribute to the perception of hand shape and finger position (proprioception) and to the direction of forces acting on an object. Classic SA2 corpuscles are surprisingly sparse in human fingertip skin; they are more abundant in hairy skin and especially in joint capsules and ligaments.
- Location
Deep (reticular) dermis and hypodermis, especially of hairy skin and around nail beds; joint capsules and ligaments.
Anatomy
- Innervation
Aβ myelinated afferents; dorsal column–medial lemniscus pathway.
Function
- Detection of skin stretch and sustained deformation
- Proprioceptive contribution to finger and hand position
- Signalling direction of tangential force (e.g. object slipping)
- Physiology
Slowly adapting, large receptive field with directional sensitivity to stretch.
Compiled from standard anatomy and physiology references — see the Integumentary System sources. For education only; not medical advice.