Table of contents

1. Introduction to Anatomy & Physiology5h 43m
2. Cell Chemistry & Cell Components12h 36m
3. Energy & Cell Processes10h 6m
4. Tissues & Histology10h 3m
5. Integumentary System2h 20m
6. Bones & Skeletal Tissue2h 16m
7. The Skeletal System2h 35m
8. Joints2h 17m
9. Muscle Tissue2h 33m
10. Muscles1h 11m
11. Nervous Tissue and Nervous System1h 35m
12. The Central Nervous System1h 6m
- Introduction to the Central Nervous System
  18m
- The Cerebrum
  48m
13. The Peripheral Nervous System1h 26m
14. The Autonomic Nervous System1h 38m
15. The Special Senses2h 41m
16. The Endocrine System2h 48m
17. The Blood3h 22m
18. The Heart3h 42m
19. The Blood Vessels3h 35m
20. The Lymphatic System3h 16m
21. The Immune System14h 37m
22. The Respiratory System3h 20m
23. The Digestive System2h 5m
24. Metabolism and Nutrition4h 0m
25. The Urinary System2h 39m
26. Fluid and Electrolyte Balance, Acid Base Balance37m
27. The Reproductive System2h 5m
28. Human Development1h 21m
29. Heredity3h 32m

13. The Peripheral Nervous System

Sensory Receptor Classification by Modality

Anatomy & Physiology

13. The Peripheral Nervous System

Sensory Receptor Classification by Modality

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1:42 minutes

Problem 14

Textbook Question

All of the following descriptions refer to dorsal column–medial lemniscal ascending pathways except one:
a. They include the fasciculus gracilis and fasciculus cuneatus.
b. They include a chain of three neurons.
c. Their connections are diffuse and poorly localized.
d. They are concerned with precise transmission of one or a few related types of sensory input.

Verified step by step guidance

Step 1: Understand the dorsal column–medial lemniscal pathway. This pathway is responsible for transmitting precise sensory information such as fine touch, vibration, and proprioception (sense of body position). It is highly organized and localized.

Step 2: Review the components of the pathway. The fasciculus gracilis carries sensory information from the lower body, while the fasciculus cuneatus carries sensory information from the upper body. These are part of the dorsal column–medial lemniscal system.

Step 3: Recall the structure of the pathway. It involves a chain of three neurons: the first-order neuron (from the sensory receptor to the medulla), the second-order neuron (from the medulla to the thalamus), and the third-order neuron (from the thalamus to the sensory cortex).

Step 4: Evaluate the descriptions provided in the question. The pathway is known for precise transmission of sensory input, not diffuse or poorly localized connections. This characteristic is key to identifying the incorrect description.

Step 5: Identify the exception. Based on the characteristics of the dorsal column–medial lemniscal pathway, the description stating 'their connections are diffuse and poorly localized' does not align with the pathway's function and organization.

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Key Concepts

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

Dorsal Column-Medial Lemniscal Pathway

The dorsal column-medial lemniscal pathway is a sensory pathway in the central nervous system that transmits fine touch, vibration, and proprioceptive information. It consists of a series of neurons that relay sensory information from the periphery to the brain, specifically through the fasciculus gracilis and fasciculus cuneatus, which are responsible for lower and upper body sensations, respectively.

Neuronal Chain

This pathway typically involves a chain of three neurons: the first-order neuron, which carries sensory information from the body to the spinal cord; the second-order neuron, which transmits the signal to the thalamus; and the third-order neuron, which relays the information from the thalamus to the sensory cortex. Understanding this chain is crucial for grasping how sensory information is processed and perceived.

Sensory Localization

The dorsal column-medial lemniscal pathway is characterized by its ability to provide precise localization of sensory input, distinguishing it from other pathways that may transmit more diffuse or generalized sensory information. This precision is essential for tasks requiring fine motor skills and detailed sensory feedback, such as reading Braille or playing a musical instrument.