Which of the following somatic sensations is not carried by the posterior columns?
a. Tactile senses
b. Temperature
c. Proprioception
d. Stretch

Verified step by step guidance

1. Understand the function of the posterior columns: The posterior columns (also known as the dorsal columns) are responsible for transmitting specific types of somatic sensory information to the brain, including fine touch (tactile senses), vibration, and proprioception (sense of body position).
2. Review the types of somatic sensations listed in the question: Tactile senses, temperature, proprioception, and stretch. Determine which of these sensations aligns with the functions of the posterior columns.
3. Recall that temperature sensation is carried by the spinothalamic tract, not the posterior columns. The spinothalamic tract is responsible for transmitting pain, temperature, and crude touch sensations.
4. Analyze the other options: Tactile senses, proprioception, and stretch are all associated with the posterior columns or related pathways. Stretch sensation is closely tied to proprioception, which is carried by the posterior columns.
5. Conclude that temperature is the somatic sensation not carried by the posterior columns, as it is transmitted via the spinothalamic tract instead.

Key Concepts

Posterior Columns

The posterior columns, also known as the dorsal columns, are pathways in the spinal cord that carry sensory information related to fine touch, vibration, and proprioception. They are crucial for transmitting detailed sensory information to the brain, allowing for precise perception of body position and movement.

Somatic Sensations

Somatic sensations refer to the sensory modalities that arise from the skin, muscles, and joints, including touch, temperature, pain, and proprioception. These sensations are essential for interacting with the environment and maintaining body awareness, and they are processed by different neural pathways in the nervous system.

Temperature Sensation

Temperature sensation is the ability to perceive thermal changes in the environment, which is primarily carried by the spinothalamic tract rather than the posterior columns. This pathway transmits information about temperature and pain, distinguishing it from the modalities of touch and proprioception that the posterior columns handle.