The neural machinery of the spinal cord is at the
(a) precommand level
(b) projection level
(c) segmental level

Name: Marieb Human Anatomy & Physiology
Author: Hoehn, Haynes, Abbott
ISBN: 9780138242732

Verified step by step guidance

Understand the hierarchical organization of motor control in the nervous system, which includes the precommand level, projection level, and segmental level.

Recognize that the precommand level involves higher brain areas like the cerebellum and basal nuclei that plan and coordinate complex movements.

Know that the projection level consists of motor cortex and brainstem nuclei that send commands to the spinal cord.

Identify that the segmental level refers to the neural circuits within the spinal cord itself, which directly control reflexes and simple motor patterns.

Conclude that since the question asks about the neural machinery of the spinal cord, it corresponds to the segmental level, where local circuits generate reflexes and basic motor outputs.

Key Concepts

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

Precommand Level

The precommand level involves higher brain centers such as the cerebellum and basal ganglia that plan and coordinate complex motor activities before sending instructions to lower levels. It is responsible for initiating voluntary movements and ensuring smooth execution.

Projection Level

The projection level consists of motor cortex and brainstem neurons that send commands to the spinal cord. This level translates motor plans into specific instructions for muscle activation, acting as a relay between higher brain centers and the spinal cord.

Segmental Level

The segmental level refers to the neural circuits within the spinal cord that directly control reflexes and simple motor patterns. It processes sensory input and generates motor output at the level of individual spinal segments, enabling basic movements and reflex actions.

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Textbook Question

The large onion-shaped receptors that are found deep in the dermis and in subcutaneous tissue and that respond to deep pressure are

a. Epithelial tactile complexes

b. Lamellar corpuscles

c. Free nerve endings

d. Muscle spindles

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