Exam 3 Spinal cord SG (pt3)

Question 1

Name the two main routes along which sensory impulses travel in the spinal cord.

Answer 1

• Posterior columns

- Spinothalamic tracts

Question 2

What are the names of the two components of the posterior column?

Answer 2

• Gracile fasciculus (nearest the midline on each side)

- Cuneate fasciculus

Question 3

Where is each of the tracts located (of the posterior column)?

Answer 3

• Gracile fasciculus (nearest the midline on each side)

- Cuneate fasciculus (further from midline)

Question 4

State the type of sensation(s) carried by the posterior columns of the spinal cord.

Answer 4

Convey nerve impulses for conscious proprioception discriminative touch, two-point discrimination, light pressure, and vibration sensations

Question 5

State the two types of descending pathways in the spinal cord.

Answer 5

• Direct

- Indirect

Question 6

Which tracts are part of direct pathways?

Answer 6

• Lateral corticospinal tract
• Anterior corticospinal tract
• Corticobular tract

Question 7

Which tracts are part of indirect pathways?

Answer 7

• Rubrospinal tract
• Tectospinal tract
• Vestibulospinal tract
• Lateral reticulospinal tract
• Medial reticulospinal tract

Question 8

What does the lateral corticospinal tract innervate?

Answer 8

Distal parts of the limbs

Question 9

What does the anterior corticospinal tract innervate?

Answer 9

The trunk and proximal parts of limbs

Question 10

What does the corticobulbar tract innervate?

Answer 10

conveys impulses from the motor cortex to skeletal muscles of the head and neck

All cranial nerves, except for I and II (they are strictly sensory)

Question 11

Describe the overall functions of indirect pathways in general.

Answer 11

• help coordinate body movements with visual stimuli,
• maintain skeletal muscle tone and contraction of postural muscles,
• regulate muscle tone in response to movements of the head

Question 12

Where do indirect pathway impulses originate, in general?

Answer 12

impulses originate in the brain stem or other parts of the brain that govern automatic movements

Question 13

What are the two types of reflexes based on site of integration of stimuli?

Answer 13

• Spinal reflex, when integration takes place in spinal cord gray matter
• Cranial reflex, when integration occurs in the brain stem

Question 14

Discuss the clinical value of somatic reflex arcs.

Answer 14

The predictability of reflexes makes them useful in the diagnosis of disease, usually tested by tapping or stroking the body surface

(Autonomic reflexes are NOT practical for this)

Question 15

State the components of a somatic reflex arc.

Answer 15

• Sensory receptor
• Sensory neuron
• Integrating center
• Motor neuron
• Effector

Question 16

What is the only autonomic reflex that is of routine diagnostic value?

Answer 16

the pupillary light reflex; pupils of both eyes decrease in diameter when either is exposed to light