Тест: Spinal Cord Pathways and Reflexes — 18 въпроса

1. What do the dorsal, lateral, and ventral funiculi of the spinal cord represent?

A. White-matter columns divided into dorsal, lateral, and ventral regions

B. Gray-matter horns that contain sensory nuclei

C. Clusters of motor neurons in the ventral horn

D. Peripheral nerve bundles outside the spinal cord

Answer: (A)

Обяснение

Funiculi are the spinal cord white-matter columns arranged into dorsal, lateral, and ventral regions. The other options describe gray matter, peripheral nerves, or motor neuron groups rather than funiculi.

2. Which statement best describes the general function of descending spinal pathways?

A. They carry sensory information from receptors toward the brain

B. They convey motor commands from the brain to spinal cord neurons

C. They transmit only autonomic signals to the periphery

D. They connect one spinal segment to another within gray matter

Answer: (B)

Обяснение

Descending pathways convey motor commands from the brain to spinal cord neurons. Sensory information traveling upward is the role of ascending pathways.

3. Which spinal cord column contains specific ascending sensory tracts in the dorsal white matter?

A. Central canal

B. Lateral funiculus

C. Dorsal funiculus

D. Ventral funiculus

Answer: (C)

Обяснение

The dorsal funiculus contains specific ascending sensory tracts in the dorsal part of the white matter. The ventral and lateral funiculi are different columns.

4. Which tract is identified as carrying pain information upward?

A. Spinothalamic tract

B. Rubrospinal tract

C. Corticospinal tract

D. Vestibulospinal tract

Answer: (A)

Обяснение

The spinothalamic tract is an ascending sensory pathway that carries pain information. The corticospinal and rubrospinal tracts are motor pathways.

5. What is the main role of the spinothalamic pathway?

A. It carries pain and temperature signals to the thalamus and then to the cerebral cortex

B. It carries voluntary motor commands from cortex to spinal cord

C. It relays tactile information through the medulla only

D. It carries proprioceptive signals directly to the cerebellum

Answer: (A)

Обяснение

The spinothalamic pathway carries pain and temperature information to the thalamus and then to the cerebral cortex. It is a sensory pathway, not a descending motor pathway.

6. Axons terminating in the lateral thalamus are most associated with which component of pain?

A. Motivational-affective aspects of pain

B. Reflex withdrawal of the limb

C. Discriminative aspects of pain

D. Motor planning for skilled movement

Answer: (C)

Обяснение

Lateral thalamic projections mediate the discriminative aspects of pain. Motivational-affective aspects are linked to the medial thalamus.

7. What does the spinocervicothalamic pathway represent?

A. A descending motor pathway from the cortex to the spinal cord

B. A cerebellar pathway for unconscious coordination

C. A reflex circuit that bypasses the thalamus

D. A conscious ascending pathway that relays sensory information through the cervical region to the thalamus

Answer: (D)

Обяснение

The spinocervicothalamic pathway is a conscious ascending pathway that carries sensory information via the cervical region and then to the thalamus. It is not a descending motor tract.

8. What structure serves as the relay before sensory information proceeds toward cortical processing in this pathway?

A. Ventral horn

B. Cerebellar cortex

C. Thalamus

D. Red nucleus

Answer: (C)

Обяснение

The thalamus functions as the relay for sensory signals on their way to cortical processing. The red nucleus and ventral horn are not the relay structures described here.

9. Which descending motor pathway is mainly responsible for voluntary skilled movements requiring conscious thought and concentration?

A. Corticospinal tract

B. Spinocervicothalamic pathway

C. Spinothalamic tract

D. Panniculus reflex arc

Answer: (A)

Обяснение

The corticospinal tract is mainly responsible for voluntary skilled movements. The other options are sensory pathways or reflex circuitry.

10. Why is the corticospinal pathway called part of the pyramidal system?

A. It crosses only within the dorsal horn

B. It originates in the pituitary gland

C. Its axons pass through the pyramid region of the ventral medulla oblongata

D. It consists exclusively of interneurons

Answer: (C)

Обяснение

The corticospinal axons pass through the ventral medulla in the pyramid region, which gives the pyramidal system its name. The other options do not match the pathway's anatomy.

11. How do descending extrapyramidal motor tracts primarily influence movement?

A. By transmitting sensory input to the cerebellum

B. By modulating lower motor neuron activity

C. By carrying pain signals to the thalamus

D. By directly innervating skeletal muscle fibers

Answer: (B)

Обяснение

Extrapyramidal motor tracts influence movement by modulating lower motor neuron activity. They do not directly act on muscle fibers.

12. Which statement best describes lower motor neurons?

A. They send axons from the spinal ventral horn or somatic cranial motor nuclei to skeletal muscle

B. They carry ascending sensory signals to the brain

C. They are limited to the thalamus and basal nuclei

D. They remain entirely in the cerebral cortex

Answer: (A)

Обяснение

Lower motor neurons are located in the spinal ventral horn or somatic cranial motor nuclei and send axons to skeletal muscle. The other options describe upper motor neurons or sensory pathways.

13. Where are upper motor neuron cell bodies located?

A. In skeletal muscle fibers

B. In the neuromuscular junction

C. In peripheral ganglia outside the CNS

D. Within the central nervous system

Answer: (D)

Обяснение

Upper motor neurons are neurons in the brain that remain within the central nervous system. Peripheral ganglia and muscle fibers are not their cell-body location.

14. What feature distinguishes upper motor disease signs from lower motor disease signs?

A. The lesion level changes the pattern of downstream motor effects

B. Upper motor disease signs are caused only by muscle damage

C. Both produce identical clinical signs

D. Lower motor disease signs involve sensory cortex lesions

Answer: (A)

Обяснение

Upper versus lower motor disease signs differ because the lesion is at different levels of the motor system, producing different downstream effects. They do not produce identical findings.

15. What is a reflex arc?

A. A sensory pathway that ends only in the thalamus

B. A voluntary pathway from cortex to muscle

C. A bundle of axons linking two spinal nerves

D. The pathway that carries a reflex stimulus from sensory input through the spinal cord to motor output

Answer: (D)

Обяснение

A reflex arc carries a reflex stimulus from sensory input through the spinal cord to motor output. It is not a voluntary corticospinal pathway.

16. Which sequence best matches the basic components of a reflex pathway?

A. CNS synapse, receptor, motor neuron, sensory neuron, target organ

B. Motor neuron, sensory neuron, target organ, CNS synapse, receptor

C. Target organ, receptor, motor neuron, sensory neuron, CNS synapse

D. Sensory receptor, sensory neuron, CNS synapse, motor neuron, target organ

Answer: (D)

Обяснение

A reflex pathway includes a sensory receptor, sensory neuron, CNS synapse, motor neuron, and target organ. The other sequences place the elements in the wrong order.

17. Which reflex is elicited by tapping the patellar tendon and is used to assess pelvic limb reflex function?

A. Withdrawal reflex

B. Perineal reflex

C. Patellar reflex

D. Panniculus reflex

Answer: (C)

Обяснение

The patellar reflex is the myotatic reflex elicited by tapping the patellar tendon and is used to assess pelvic limb reflex function. The other reflexes test different stimuli and segments.

18. What response is expected in the perineal reflex?

A. Bilateral contraction of the cutaneous trunci muscles

B. Quadriceps contraction with reciprocal inhibition

C. Withdrawal of the limb from a noxious stimulus

D. Anal sphincter contraction and tail flexion

Answer: (D)

Обяснение

The perineal reflex causes anal sphincter contraction and tail flexion when the perineal or anal skin is mildly compressed. The other options describe different reflexes.