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

12. The Central Nervous System

Introduction to the Central Nervous System

Anatomy & Physiology

12. The Central Nervous System

Introduction to the Central Nervous System

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1:52 minutes

Problem 27

Textbook Question

Describe the spinal cord, depicting its extent, its composition of gray and white matter, and its spinal roots.

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The spinal cord is a cylindrical structure that extends from the foramen magnum at the base of the skull to the level of the first or second lumbar vertebra (L1-L2) in adults. It is protected by the vertebral column, meninges, and cerebrospinal fluid.

The spinal cord is composed of two types of tissue: gray matter and white matter. The gray matter is located in the center of the spinal cord and has a butterfly or H-shaped appearance in cross-section. It contains neuron cell bodies, dendrites, and unmyelinated axons, and is organized into regions called horns (anterior, posterior, and lateral horns).

The white matter surrounds the gray matter and consists of myelinated axons that form ascending and descending tracts. These tracts are responsible for transmitting sensory information to the brain (ascending tracts) and motor commands from the brain to the body (descending tracts).

The spinal cord gives rise to 31 pairs of spinal nerves, which are part of the peripheral nervous system. Each spinal nerve is formed by the union of two roots: the dorsal (posterior) root and the ventral (anterior) root. The dorsal root contains sensory neurons that transmit information from the body to the spinal cord, while the ventral root contains motor neurons that transmit commands from the spinal cord to the body.

The spinal cord is segmented into regions corresponding to the vertebrae: cervical, thoracic, lumbar, sacral, and coccygeal. Each segment gives rise to a pair of spinal nerves, which exit the vertebral column through intervertebral foramina to innervate specific regions of the body.

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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 a cylindrical structure that extends from the base of the brain (medulla oblongata) down to the lower back, typically ending around the first or second lumbar vertebra. It is encased in the vertebral column and serves as a major conduit for information traveling between the brain and the rest of the body.

Gray and White Matter

The spinal cord is composed of gray matter and white matter. Gray matter, which contains neuronal cell bodies, is organized into horns (dorsal, ventral, and lateral) and is primarily involved in processing information. White matter surrounds the gray matter and consists of myelinated axons that form ascending and descending pathways, facilitating communication between different regions of the nervous system.

Spinal Roots

Spinal roots are the structures that connect the spinal cord to the peripheral nervous system. Each spinal nerve emerges from the spinal cord as two roots: the dorsal (sensory) root, which carries sensory information to the spinal cord, and the ventral (motor) root, which transmits motor commands from the spinal cord to muscles. Together, these roots form the spinal nerves that innervate various body regions.

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