Ch. 14.4

Question 1

Conduction Pathway

Answer 1

Refers to all the series of nerves and their associated structures that relay signals between the brain and the body.

Question 2

Characteristics of conduction pathways

Answer 2

Paired tracts
Composed of two or more neurons
Common location of neuron cells bodies- located in the posterior root ganglion, one of the horns, or the nuclei in the brain.
Common location of axons
Decussation- where the nerves cross over from one side to the other
Limited ipsilateral pathways- pathways the don’t cross over.

Question 3

Fascicules

Answer 3

A structural subdivision of a funiculus that shares common features

Question 4

Funiculus

Answer 4

Specific location of the white matter int the spinal cord.

Question 5

Tract

Answer 5

Myelinated axons that relay signals from a common origin to a common destination.

Question 6

General sense receptors: two division

Answer 6

Sensory receptors located throughout the body.
Somatic sensory receptors- tactile and proprioreceptors
Autonomic sensory- like chemo and baro receptors

Question 7

Tactile receptor locations

Answer 7

Skin and mucous membranes the line body cavities

Question 8

Proprioreceptros location

Answer 8

Located in joints, muscles, and tendons

Question 9

Location of Visceral receptors

Answer 9

In the visceral walls and blood vessels

Question 10

What are the sensory pathways made of?

Answer 10

Two or three neurons
Primary- First in the chain. Extend from the sensory receptor to the CNS. Where it synapses with the secondary neurons.
Secondary- Interneuron that extends from the primary neuron to the tertiary neuron or the cerebellum. If it goes to the cerebellum, no tertiary pathway is present.
Tertiary- Interneuron that extends from the secondary neuron to the cerebrum- specifically the primary somatosensory cortex of the parietal lobe.

Question 11

Posterior Funiculus-Medial Lemniscal Pathway

1) What type of receptors are involved
2) Location of each sensory neuron within the chain of neurons
3) What region of the brain receives and processes this information

Answer 11

1) This originates with either tactile or proprioreceptros.
These will provide information to the cerebral cortex about discriminative touch, precise pressure, vibration, and body position. This decussates just prior to the medial lemiscus in the medulla oblongata.
2) Primary neuron- extends from the receptor to the the spinal cord and ascends within the posterior funiculus. Synapses with the secondary neuron in the medulla oblongata.
Secondary neuron- extends from the medulla oblongata and extends within the medial lemniscus to the thalamus.
Tertiary neuron- extends from the thalamus to the cerebrum. (specifically a location within the primary somatosensory cortex which is in the post central gyrus of the parietal lobe.

Question 12

Anterolateral pathway

1) What type of receptors are involved
2) Location of each sensory neuron within the chain of neurons
3) What region of the brain receives and processes this information

Answer 12

1) Tactile somatosensory receptors within the skin and mucous membranes. Provides info to the cerebral cortex.
Cured touch and pressure as well as pain and temperature. Info that requires a response usually comes though this pathway.
2) Primary neuron- goes from receptor to the gray matter of the posterior horn of the spinal cord.
Secondary neuron- extends from the spinal cord to the thalamus. Projects upward within the spinothalmic tract in the anterior or lateral funiculus. Decussation occurs as the axon extends into the spinaothalmic tract.
Tertiary neuron- extends from the thalamus to the primary somatosensory cortex within the postcentral gyrus. Conscious perception of the tactile and proprioreceptor info happens in the parietal lobe.
This extends through the anterior funiculus and the lateral funiculus

Question 13

Spinocerebellar Pathway

1) What type of receptors are involved
2) Location of each sensory neuron within the chain of neurons
3) What region of the brain receives and processes this information

Answer 13

Only two neurons use this pathway.
1) Originates at proprioreceptors within joints, muscles, and tendons. This info comes through the anterior and posterior spinal-cerebral tracts.
2) Primary neuron extends from the receptor to the posterior horn where it synapses with the secondary neuron.
Secondary neuron extends from posterior horn to the cerebellum within the spinocerebellar tract. This moves in the anterior or posterior portion of the lateral funiuculus.

Question 14

Motor Pathway

Answer 14

Descending pathways that originate in the brain. Originate from the cerebral cortex, cerebral nuclei, or the brainstem. Made up from at least two neurons.

Question 15

What do upper motor neurons do?

Answer 15

The either excite or inhibit lower neurons.

Question 16

What do lower neurons do?

Answer 16

Housed in the anterior cord of the spinal cord. These always excite skeletal muscle fibers.

Question 17

Direct pathways (whats it’s other name?)

Answer 17

Pyramidal pathway- derived form the pyramid like shape of the cell bodies that are in the upper motor cortex.
Motor pathway that uses only two motor neurons.
Originates in the primary motor cortex of the cerebral frontal lobe.

Question 18

Lateral corticospinal tracts.

Answer 18

One of the two direct pathways.
This innervates skeletal muscle that controls skilled movements like playing the guitar, dribbling a soccer ball, or typing on a keyboard.
Decussates at the opposite side of the brain at the medulla oblongata.

Question 19

Anterior cortiocspinal tracts

Answer 19

On of two direct pathways.
Innervates axial skeletal muscle.
Decussates through the anterior gray commissure at the level of the spinal cord.

Question 20

Indirect pathways

Answer 20

Named because they take un indirect route through the brain and use multiple neurons to do so.
These help modify or control somatic motor pathways thought the way they affect lower neurons.

Question 21

Lateral pathwyas

Answer 21

Regulate or control precise discrete movements and tone in flexor muscles of the limbs.

Question 22

Medial pathways

What are the three groups?

Answer 22

Reflexive muscle tone and reflexive movements of the head, neck, and proximal parts of limbs and trunk.
Reticulospinal
Tectospinal
Vestibulospinal

Question 23

Reticulospinal

Answer 23

Originate in the reticular formation of the midbrain

Control reflexive movements relating ot poster and balance.

Question 24

Tectospinal

Answer 24

Extend from the superior and inferior colliculi in the tectum of the midbrain.
Reflexive changes of upper limbs, eyes, head, and neck responding to visual and auditory changes.

Question 25

Vestibulospinal

Answer 25

Originates within vestibular nuclei of the brainstem.

Reflexive muscle activity that helps maintain balance during sitting, standing, and walking.