Motor Cortex and Corticospinal tracts

Question 1

Both the premotorcomplex and the Supplementary motor complex can be found in which Broadmans section?

Answer 1

Broadmens section 6 - Frontal Lobe

In control of planning out a movement before sending it to the primary motor complex.

Question 2

The Frontal Eye Field cortex is located within what Broadmans area and has what function?

Answer 2

Located within the Frontal lobe; Broadmens section 8

In control of the positioning of the eyes and visual tracking.

Question 3

The posteiror parietal cortex can be found within which broadmans section and has what function?

Answer 3

Located within the parietal lobe; Broadmens section 7

responsible for controlling sight guided movement.

Question 4

Where can the primary motor complex be found, what function does it have, and which side of the body does it control?

Answer 4

The PMC is found within the precentral gyrus of the frontal lobe broadmens area 4..
It has the control of executing movements by synapsing into the brain stem,
The Primary motor complex innervates the contralateral side.

Question 5

The primary somatosensory cortex is located where and has what function?

Answer 5

Located within the post central gyrus of the parietal lobe Broadmens area 1,2,3.

Influences movement by modulating/filtering sensory input that enters the spinal cord.

Question 6

The somatosensory cortex relays information to which nuclei?

Answer 6

Nucleus gracillis
Nucleus cuneatus - Both within the brainstem.
and the dorsal horn nuclei within the spinal cord.

Question 7

This structure is very prominent in the motor complex and contains the cell bodies of the upper motor neurons whos axons form the descending motor pathways to the brainstem and spinal cord….

Answer 7

Layer 5 AKA the internal pyramidal layer of the cerebral cortex.

Question 8

Where are the cell bodies of the upper motor neurons found?

Answer 8

Found within the motor cortex or the brainstem. Function by modulating the Lower motor neurons.

Question 9

Where are the cell bodies of the lower motor neurons found?

Answer 9

The cell bodies of the lower motor neurons are found within the ventral horn of the spinal cord.

Question 10

Which side of the body does the corticospinal tract control?

Answer 10

Controls the contralateral side of the body with motor supply.

Question 11

Where is the origin of the corticospinal tract?

Answer 11

Found within the cortex of the frontal and parietal lobes divided into thirds between broadmen areas 1,2,3,4,5,6,7
(1/3 4 and 1/3 6 with the rest being other numbers)

Question 12

Within the medulla, the cortical spinal tracts funnel through what structure?

Answer 12

Flow together to descend within the pyramid.

Question 13

After the cortical spinal tracts enter the pyramid they split, what is the splitting pattern?

Answer 13

85-90% will decussate in the pyramidal decussation to the opposite side.

10-15% will not decussate at all and will descend down the same side of origin.

Question 14

The decussated cortical spinal tracts run within the spinal cord in which area?

Answer 14

The lateral corticospinal tract terminating at all spinal cord levels but concentrated at the cervical and LS levels.

Question 15

The corticospinal tract provides what special sensation?

Answer 15

Provides the distinct, skilled, well-defined manipulative and independent voluntary movements of the fingers.

Question 16

What is the pathway for the uncrossed spinothelamic tract nerves?

Answer 16

the 10-15% uncrossed fibers descend in the anterior corticospinal tract where they will eventually cross near termination and control the axiial muscles of the neck, shoulder and track.

Question 17

Loss of the Lateral corticospinal tract would show what deficiencies?

Answer 17

Loss of distinct, skilled, well defined, manipulative and independently voluntary movements of the hand.

Question 18

Loss of the anterior corticospinal tract would show what deficiencies?

Answer 18

Loss of axial muscles in the neck, shoulder, and trunk.

Question 19

Which tract is the ONLY UMN tract that decussates within the sponal cord?

Answer 19

The Anterior corticospinal tract controlling axial muscles.

Question 20

Following an UMN lesion, which nerve fibers become overactive resulting in hypertonia?

Answer 20

The gamma motor neurons from the LMN intermingling with the UMN become damaged and result in hypertonia.

Question 21

What is Spasticity following an umn/lmn lesion?

Answer 21

Develops within the fine movements of the distal limb musceles displaying as an exaggeration of the stretch reflex causing resistance to passive motion.