A mechanoreceptor is a sensory receptor that responds to mechanical pressure or distortion. Normally there are four main types in glabrous, or hairless, mammalian skin: lamellar corpuscles, tactile corpuscles, Merkel nerve endings, and bulbous corpuscles.
1993; Gronenberg 1996) work, in particular, makes a strong case based on histology and morphology of the hairs that they are mechanoreceptors attached to large neurons capable of rapid transmission of signals to the muscles controlling jaw-closure.
Merkel nerve endings are mechanoreceptors, a type of sensory receptor, that are found in the basal epidermis and hair follicles. They are nerve endings and provide information on mechanical pressure, position, and deep static touch features, such as shapes and edges.
The muscle spindle is a proprioceptor located deep within the muscle parallel to the extrafusal muscle fibers. It is encapsulated in connective tissue and located directly inside the muscle interwoven between the intrafusal fibers.
Lamellar corpuscles, or Pacinian corpuscles, are pressure receptors located in the skin and also in various internal organs. Each is connected to a sensory neuron. Because of its relatively large size, a single lamellar corpuscle can be isolated and its properties studied.
Phasic mechanoreceptors are useful in sensing such things as texture or vibrations, whereas tonic receptors are useful for temperature and proprioception among others. Slowly adapting: Slowly adapting mechanoreceptors include Merkel and Ruffini corpuscle end-organs, and some free nerve endings.