Anatomy & Physiology: The Unity of Form and Function, 7th Edition

Published by McGraw-Hill Education
ISBN 10: 0073403717
ISBN 13: 978-0-07340-371-7

Chapter 13 - Section 13.1 - Study Guide - Assess Your Learning Outcomes - Page 504: 11

Answer

Ascending tracts in the spinal cord are neural pathways that carry sensory information from the periphery (such as the skin, muscles, and joints) to the brain for processing and perception. These tracts are responsible for transmitting various sensory modalities, including touch, pain, temperature, proprioception (body position awareness), and vibration. Here are some of the key ascending tracts of the spinal cord, along with their names and functions: 1. **Dorsal Column-Medial Lemniscus Pathway (DCML)**: - **Function**: This pathway carries fine touch, vibration, proprioception, and two-point discrimination sensations from the body to the brain. - **Pathway**: Sensory information is first received by the dorsal root ganglia neurons and then ascends ipsilaterally (on the same side) in the dorsal columns of the spinal cord. It crosses over to the opposite side (decussates) in the medulla oblongata, forming the medial lemniscus, which continues to the thalamus and finally to the primary somatosensory cortex in the cerebral cortex. 2. **Spinothalamic Tracts**: - **Function**: These tracts carry pain, temperature, and crude touch sensations from the body to the brain. - **Pathway**: Sensory input is received by the dorsal root ganglia neurons and then travels up the spinal cord. The spinothalamic tracts cross over to the opposite side (decussate) in the spinal cord itself, typically at the same spinal level, before ascending to the thalamus. From the thalamus, the information is relayed to the somatosensory cortex for perception. 3. **Spinocerebellar Tracts**: - **Function**: These tracts carry proprioceptive information about limb and joint position to the cerebellum for coordination of voluntary movements. - **Pathway**: Unlike most other sensory pathways, spinocerebellar tracts do not decussate. They ascend ipsilaterally and provide the cerebellum with sensory input that is used for coordination and fine-tuning of motor movements. 4. **Spinoreticular Tract**: - **Function**: This tract is involved in pain modulation and carries pain signals to the reticular formation in the brainstem. - **Pathway**: Sensory input from pain receptors is transmitted via this tract to the reticular formation in the brainstem, which can then modulate the perception of pain. These ascending tracts serve essential roles in sensory perception, allowing the brain to receive and process information about the external environment and the body's internal state. They enable us to perceive and respond to various sensory stimuli, including touch, temperature, pain, and proprioception, which are critical for maintaining balance, coordination, and overall sensory awareness.

Work Step by Step

Ascending tracts in the spinal cord are neural pathways that carry sensory information from the periphery (such as the skin, muscles, and joints) to the brain for processing and perception. These tracts are responsible for transmitting various sensory modalities, including touch, pain, temperature, proprioception (body position awareness), and vibration. Here are some of the key ascending tracts of the spinal cord, along with their names and functions: 1. **Dorsal Column-Medial Lemniscus Pathway (DCML)**: - **Function**: This pathway carries fine touch, vibration, proprioception, and two-point discrimination sensations from the body to the brain. - **Pathway**: Sensory information is first received by the dorsal root ganglia neurons and then ascends ipsilaterally (on the same side) in the dorsal columns of the spinal cord. It crosses over to the opposite side (decussates) in the medulla oblongata, forming the medial lemniscus, which continues to the thalamus and finally to the primary somatosensory cortex in the cerebral cortex. 2. **Spinothalamic Tracts**: - **Function**: These tracts carry pain, temperature, and crude touch sensations from the body to the brain. - **Pathway**: Sensory input is received by the dorsal root ganglia neurons and then travels up the spinal cord. The spinothalamic tracts cross over to the opposite side (decussate) in the spinal cord itself, typically at the same spinal level, before ascending to the thalamus. From the thalamus, the information is relayed to the somatosensory cortex for perception. 3. **Spinocerebellar Tracts**: - **Function**: These tracts carry proprioceptive information about limb and joint position to the cerebellum for coordination of voluntary movements. - **Pathway**: Unlike most other sensory pathways, spinocerebellar tracts do not decussate. They ascend ipsilaterally and provide the cerebellum with sensory input that is used for coordination and fine-tuning of motor movements. 4. **Spinoreticular Tract**: - **Function**: This tract is involved in pain modulation and carries pain signals to the reticular formation in the brainstem. - **Pathway**: Sensory input from pain receptors is transmitted via this tract to the reticular formation in the brainstem, which can then modulate the perception of pain. These ascending tracts serve essential roles in sensory perception, allowing the brain to receive and process information about the external environment and the body's internal state. They enable us to perceive and respond to various sensory stimuli, including touch, temperature, pain, and proprioception, which are critical for maintaining balance, coordination, and overall sensory awareness.
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