Name That Receptor
Which receptor detects vibration?
Pacinian corpuscle
Pacinian corpuscles respond to vibration of the skin
Do afferent neurons carry sensory information toward or away from the CNS?
Toward the CNS
Somatosensory neurons are afferent neurons
What sensory organ detects muscle stretch?
Muscle spindle
Muscle spindles respond to changes in muscle length and the velocity of those changes
A patient has a painful unilateral rash following a band-like area of the trunk. What condition might this suggest?
Shingles (herpes zoster)
Shingles commonly produces a painful rash following a dermatome
Which receptor continues firing while a stimulus remains present?
Tonic
Tonic receptors respond throughout a sustained stimulus
Which receptor detects skin stretch?
Ruffini corpuscle
Ruffini corpuscles respond to stretching of the skin
Where are receptive fields generally smaller: fingertips or trunk?
Fingertips
Distal regions have smaller receptive fields and higher receptor density
What sensory organ detects tension in a tendon?
Golgi tendon organ
GTOs respond to tendon tension during active contraction or strong passive stretch
A patient has better balance with eyes open but becomes unsteady with eyes closed. What type of ataxia might this suggest?
Sensory ataxia
Patients with sensory ataxia rely heavily on vision for balance
Which receptor type responds strongly to a change in a stimulus?
Phasic
Phasic receptors emphasize changes and adapt to constant stimulation
Which receptor detects movement across the skin or slippage?
Meissner's corpuscle
Meissner's corpuscles detect dynamic movement across the skin
What is the area of skin supplied by a single spinal nerve root called?
Dermatome
Dermatomes help identify sensory changes associated with nerve root injuries
Which motor neurons contract intrafusal muscle fibers?
Gamma motor neurons
Gamma activation maintains spindle sensitivity as the muscle changes length
A patient is unsteady with eyes open AND closed. Which type of ataxia might this suggest?
Cerebellar ataxia
Cerebellar ataxia affects coordination even when visual information is available
A receptor stops responding to a constant stimulus after initially firing. Tonic or phasic?
Phasic
Phasic receptors adapt to an unchanged stimulus
Which receptor detects light pressure, curvature, and edges?
Merkel cells
Merkel cells help distinguish light pressure and the edges of objects
Which clinical test measures the ability to distinguish two closely applied stimuli?
Two-point discrimination
Smaller receptive fields allow better spatial discrimination
What is the simultaneous activation of alpha and gamma motor neurons called?
Alpha-gamma coactivation
It helps keep muscle spindles sensitive during voluntary contraction
Which test measures peripheral nerve conduction velocity, distal latency, and response amplitude?
Nerve conduction study (NCS)
NCS evaluates peripheral nerve function, including fast, large-diameter sensory axons
Which muscle spindle afferent is phasic and responds most strongly to quick stretch?
Type Ia
Type Ia primary endings respond maximally during quick muscle stretch