I | Globular or ovoid corpuscles. Fine capsule. Arborizing nerve terminal, linked in clusters of 3–6 corpuscles | 100 × 40 | Superficial joint capsule | 5–8 | Mechanoreceptor (low threshold, slowly adapting) |
II | Cylindrical or conical corpuscles. Thick laminated capsule (up to 10–12 layers). Single nerve terminal: may be bifid or trifid. Linked in clusters of 2–3 corpuscles | 280 × 120 | Fibrous capsule (deep layers), fat pads | 8–12 | Mechanoreceptor (low threshold, rapidly adapting) |
III | Fusiform corpuscles. Thin capsule (1–3 layers). Densely arborizing nerve terminal. Usually single, occasionally linked in clusters of up to 3 corpuscles | 600 × 100 | Ligament, tendon | 13–17 | Mechanoreceptor (high threshold, slowly adapting) |
IV | (a) Unmyelinated plexuses | < l.5 | Fibrous capsule, ligament, fat pad, blood vessel, subsynovial | 2–5 (thinly myelinated) | Nociceptor (non-adapting) |
Unmyelinated free nerve endings | 0.5–1.5 | Ligments, tendons | < 2 (unmyelinated) | Nociceptor (non-adapting) |
(b) Unmyelinated nerve terminals | < 1.0 | Walls of small arteries and arterioles | < 2 | Vasomotor, efferent |