Dr Gawad Physiology Course Online Exams – Mechanoreceptors, Thermoreceptors

The sense of joint movement is not an unconscious kinesthetic sensation because it is a conscious sensation. It refers to the ability to perceive the movement and position of our joints, which requires conscious awareness and attention. In contrast, the other options - sense of muscle tone, momentary state of muscle contraction, and muscle length - are all examples of unconscious kinesthetic sensations, as they are related to the perception of our muscles and their activity without conscious effort.

Stereogenesis is the ability to perceive and interpret depth and spatial relationships. It relies on various sensory inputs, including touch and pressure sensations. The spinocerebellar tract is responsible for transmitting proprioceptive information from the body to the cerebellum, but it does not play a direct role in stereogenesis. Therefore, the spinocerebellar tract, specifically the uncrossed ventral one, is not involved in stereogenesis. The integration of central sensory areas, on the other hand, is crucial for processing and interpreting sensory information, including that required for stereogenesis.

The gracile pathway is responsible for transmitting subconscious kinesthetic sensation. It is characterized by thin, slow afferents. This pathway runs in the spinal cord medially to the cuneate tract. The transmission of sensation through this pathway is perceived by the thalamus.

The cuneate pathway is a sensory pathway that transmits information related to fine touch, vibration, and proprioception from the upper body to the brain. It is responsible for transmitting vibration sense, which is the ability to perceive vibrations. This pathway does not transmit impulses from the inner aspect of the thigh, as that is the role of the gracile pathway. The crossing of the pathway fibers occurs mainly in the second order neuron, not the third order neuron. Therefore, the correct answer is that the cuneate pathway transmits vibration sense.

The ventral spinothalamic tract is responsible for transmitting pain and temperature sensations. It is composed of type A-delta fibers, not type C fibers. The crossing of the tract to the midline occurs mainly in the first order neuron, not the second order neuron. It transmits crude touch, not pain and temperature sensations. The thalamus is not the main center for this tract; instead, the main center is the somatosensory cortex in the brain.

The statement "It controls function of the ipsilateral group of muscles" is true for the spinocerebellar pathway. This pathway is responsible for transmitting sensory information from the muscle spindles and Golgi tendon organs to the cerebellum. It primarily controls and coordinates the movement and function of the muscles on the same side of the body (ipsilateral). This allows for precise and coordinated movement of the limbs and trunk.

The dorsal column lemniscal pathway is responsible for transmitting fine touch, proprioception, and vibration sensations, not thermal sensations. Thermal sensations are transmitted through the spinothalamic tract. Therefore, the statement "Transmitted by dorsal column lemniscal pathway" is incorrect.