L11 Motor Cortex

Question 1

Motor cortex site

Answer 1

(posterior 1/3 of frontal lobes):
– Anterior to central cortical sulcus

Question 2

– Motor cortex is divided into three subareas

Answer 2

(1) primary motor cortex
(2) premotor area
(3) supplementary motor area

Question 3

-primary motor cortex site

Answer 3

anterior to central sulcus ( pre central gyrus )

Question 4

-area 4 in Brodmann’s classification?

Answer 4

PRIMARY MOTOR CORTEX

Question 5

-Body representation in PRIMARY MOTOR CORTEX

Answer 5

Upside down
crossed, inverted, with head in correct position

• Face and mouth → near the sylvian fissure
• Arm and hand → midportion of the primary motor cortex
• Trunk → near the apex of the brain
• Leg and foot → in the part of that dips into the longitudinal fissure.

Question 6

……………….……… have wide area of representation in area 4

Answer 6

Muscles of Hand , Muscles of mouth ( speech )

Question 7

-Most of the body muscles represented ………………….in area 4

Answer 7

Unilateral

Question 8

-Respiratory muscle represented …………in area 4

Answer 8

bilaterally

Question 9

-Excitation of a single motor cortex neuron usually excites a ……,,,,,,,,,,

Answer 9

specific movement ( group of muscles ) rather than one specific muscle

Question 10

PREMOTOR AREA site

Answer 10

anterior to the primary motor cortex.

Question 11

Topographical representation of pre motor area ( responsible for ) ?

Answer 11

More complex “PATTERNS” of movement

**Example:
the pattern may be to position the shoulders and arms so that the
hands are properly oriented to perform specific tasks ( writing )

Question 12

-Anterior part of the premotor area first develops a …………………….

Answer 12

“ MOTOR IMAGE” of the (total) muscle movement that is to be performed.
الحركة كلها بشكل عام

Question 13

-posterior premotor cortex function?

Answer 13

image that have taken in the Ant. Part, excites each successive pattern of muscle activity required to achieve the image.
تحدد صورة للعضلات انه من يتحرك اول وترسله ل 4

Question 14

posterior part of the premotor cortex sends its signals either :

Answer 14

1-directly to the primary motor cortex to excite specific muscles
2-by way of the basal ganglia and thalamus back to the primary motor cortex.

Question 15

-SUPPLEMENTARY MOTOR AREA site

Answer 15

in the longitudinal fissure and ( superior frontal cortex)

Question 16

-SUPPLEMENTARY MOTOR AREA properties?

Answer 16

1-Contractions elicited by stimulating this area BILATERAL rather than unilateral.
2-functions in concert with the premotor area to provide
A.attitudinal movements
B. fixation movements of the different segments of the body
C. positional movements of the head and eyes
D. background for the finer motor control of the arms and hands by the premotor area and primary motor cortex.

E.g bilateral grasping movements of both hands simultaneously ( hand functions required for climbing)

Question 17

SPECIALIZED AREAS IN MOTOR CORTEX

Answer 17

-Broca’s area 44, 45

-Voluntary eye movement 8

-Head rotation area

-Area for hand skills

Question 18

-Broca’s area 44, 45 ?

Answer 18

Word formation (Motor Speech Area)

Damage to it (does not prevent a person from vocalizing)
but makes it impossible to speak whole words

closely associated area also causes appropriate activation of vocal cord simultaneously with movements of mouth and tongue during speech

Question 19

-Voluntary eye movement 8 damage

Answer 19

*prevents a person from voluntarily moving the eyes toward different objects

Loss of blinking

Question 20

-Head rotation area?

Answer 20

It directs the head toward different objects (head rotation )

It is closely associated with the eye movement field

Question 21

-Area for Hand Skills Destruction ?

Answer 21

hand movements become uncoordinated and non-purposeful, a condition called motor ((apraxia))

Question 22

-MIRROR NEURONS

Answer 22

performs a specific motor task or when the person observes the same task performed by others

transform SENSORY representations of acts that are heard or seen into MOTOR representations of these acts ( connection )

LEARNING new skills by imitation.

Question 23

-Motor signals are transmitted from the cortex to the spinal cord through :

Answer 23

Direct via:
1- corticospinal (Pyramidal) tract This pathway is mono-neuronal
2- cortico-bulbar or nuclear

(concerned more with discrete and detailed movements, distal segments of the limbs, hands and fingers)

Indirectly via:
the extrapyarmidal tracts
accessory pathways that involve the basal
ganglia, cerebellum, and various nuclei of the brain stem

Not fine skilled movement as ( hand hanging during walking )

Question 24

PYRAMIDAL TRACT
Origin:

Answer 24

– 30 % from the primary motor cortex
– 30 % from the premotor and supplementary motor areas
– 40 % from the somatosensory areas posterior to the central sulcus

Question 25

PYRAMIDAL TRACT

Course:

Answer 25

Cortex > posterior limb of the internal capsule > brain stem ( pyramid ) > majority cross in the lower medulla to the opposite side descend into the LATERAL CORTICOSPINAL tracts

few of the fibers pass ipsilaterally down the cord in
VENTRAL CORTICOSPINAL tracts (Most of these fibers eventually cross to the opposite side of the cord either in the neck or in the upper thoracic region)

Question 26

PYRAMIDAL TRACT
Termination:

Answer 26

– Principally on the (interneurons) in intermediate regions of the cord gray matter
– Few terminate on (sensory) relay neurons in the dorsal horn
– Very few terminate (directly on the anterior motor neurons)

Question 27

-all motor nuclei of cranial nerves supplied bilaterally fro motor cortex EXCEPT:

Answer 27

1) Lower part of facial nucleus (Lower VII)
2) Hypoglossal nucleus (XII)

Question 28

-Damage of internal capsule led to ?

Answer 28

Hyper-reflexia -> paralysis

Question 29

Damage of motor cortex 4 led to ?

Answer 29

Hypo-reflexia

Question 30

UMNL as unilateral lesion of internal capsule ?

Answer 30

Paralysis
Clonus
babinski sign +
sparing of respiratory muscles

but, lower facial muscles and tongue are affected, there is deviated tongue on protrusion and patient is unable to whistle nor to show teeth.