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Ch. 12 The Central Nervous System
Amerman - Human Anatomy & Physiology 2nd Edition
Amerman2nd EditionHuman Anatomy & PhysiologyISBN: 9780136873822Not the one you use?Change textbook
All textbooksAmerman 2nd EditionCh. 12 The Central Nervous SystemProblem L3.3
Chapter 12, Problem L3.3

In a diving accident, Arlene damages the left side of her upper thoracic spinal cord. On which side of the body will she lose: muscle control, tactile sensation, and pain sensation? Explain.

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Understand the anatomy of the spinal cord: The spinal cord is organized into tracts that carry sensory and motor information. Motor control is carried by descending tracts, while tactile sensation and pain sensation are carried by ascending tracts. These tracts cross over (decussate) at different points in the nervous system.
Analyze muscle control: Motor control is carried by the corticospinal tract, which decussates (crosses over) in the medulla oblongata. Damage to the left side of the upper thoracic spinal cord will affect motor control on the same side (ipsilateral) of the body below the injury.
Analyze tactile sensation: Tactile sensation is carried by the dorsal column-medial lemniscus pathway, which decussates in the medulla oblongata. Damage to the left side of the spinal cord will result in loss of tactile sensation on the same side (ipsilateral) of the body below the injury.
Analyze pain sensation: Pain and temperature sensation are carried by the spinothalamic tract, which decussates immediately upon entering the spinal cord. Damage to the left side of the spinal cord will result in loss of pain sensation on the opposite side (contralateral) of the body below the injury.
Summarize the findings: Muscle control and tactile sensation will be lost on the left side of the body (ipsilateral to the injury), while pain sensation will be lost on the right side of the body (contralateral to the injury). This is due to the specific decussation points of the respective neural pathways.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Spinal Cord Anatomy

The spinal cord is divided into segments that correspond to different regions of the body. Each segment controls specific functions and sensations. Damage to the upper thoracic spinal cord affects the pathways that transmit signals to and from the brain, leading to loss of function and sensation on the body side opposite to the injury.
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Contralateral Effects

In the context of spinal cord injuries, contralateral effects refer to the phenomenon where damage to one side of the spinal cord results in loss of function or sensation on the opposite side of the body. This occurs because motor and sensory pathways cross over at various points in the nervous system, leading to this cross-hemispheric impact.
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Types of Sensation

Different types of sensory information are processed through distinct pathways in the nervous system. Tactile sensation (touch) and pain sensation are transmitted via different neural pathways, with tactile information typically traveling through the dorsal columns and pain sensation through the spinothalamic tract. Damage to the spinal cord can selectively affect these pathways, leading to specific sensory deficits.
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