Chapter 13, Problem 1TYR

Below L2. the vertebral canal is occupied by a bundle of spinal nerve roots called

1. a. the terminal filum.
2. b. the descending tracts.
3. c. the gracile fasciculus
4. d. the medullary cone.
5. e. the cauda equina.

Summary Introduction

Introduction:

Spinal cord is a collection of nerve tissue that arises from the brain stem.

Answer to Problem 1TYR

Correct answer:

Below L2, the vertebral canal is occupied by a bundle of spinal nerve roots called the cauda equina. Therefore, option e is correct.

Explanation of Solution

Justify reasons for the correct statement:

Cauda equina is a collection of spinal nerves at the first lumbar vertebra and medullary cone. It occupies the vertebral canal from L2 to S5.

Option (e) is given as “the cauda equina”.

Cauda equina has approximately 10 fiber pairs that consist of 3 to 5 lumber fibers, 5 sacral fiber pairs, and 1 one coccygeal nerve. The cauda equina functions as to send and receive messages from the pelvic and the lower limbs.

Hence, option (e) is correct.

Justify reasons for the incorrect statements:

Option (a) is given as “the terminal filum”.

It is a delicate fibrous tissue or terminal thread that precedes downward from the apex of the conus medullaris. Hence, it is a wrong answer.

Option (b) is given as “the descending tracts”.

The descending tracts are motor signals that carry the signals from the brain to lower motor neurons. Hence, it is a wrong answer.

Option (c) is given as, “the gracile fasciculus”.

It carries signals from the mid-thoracic and lower parts of the body. Hence, it is a wrong answer.

Option (d) is given as “the medullary cone”.

The medullary cone or the conus medullaris occurs at the lumbar vertebral level 1 and level 2. Hence, it is a wrong answer.

Hence, options (a), (b), (c), and (d) are incorrect.

Conclusion

In conclusion, the cauda equina is a collection of spinal nerve that occurs below the lumbar vertebral level 2 and occupies from L2 to S5.