Chapter 40: Motor Cortex Flashcards
The frontal lobe of the cerebrum is separated from the temporal lobe by the _____.
- Lateral fissure
One can see that three sulci demarcate 2 vertical gyri at the interface of the _____ and _____ lobes.
- Frontal
- Parietal
From anterior to posterior, the sulci are the precentral sulcus, the _____, and the postcentral sulcus.
- Central sulcus
The central sulcus separates the _____ from the _____.
- Frontal lobe
- Parietal lobe
The precentral gyrus is between the _____ and the _____.
- Precentral sulcus
- Central sulcus
The primary motor cortex (Brodmann area 4) occupies the precentral gyrus which is the only vertical gyrus of the _____.
- Frontal lobe
The primary motor cortex (Brodmann area 4) contains the _____ neurons for voluntary motor activity.
- Upper motor
The giant motor neurons of the primary motor cortex (Brodmann area 4) are the same size as Purkinje cells (100 um across), but they are pyramidal instead of _____.
- Oval (ellipsoidal)
Giant pyramidal neurons (Betz cells) are found only in the _____.
- Primary motor cortex
Brodmann defined area _____ as the area of the cerebral cortex containing giant pyramidal neurons.
- 4
The axons of the giant pyramidal neurons descend in the lateral and anterior _____ tracts and synapse on lower motor neurons.
- Corticospinal
The only axons in the corticospinal tracts that synapse on the dendrites and bodies of lower motor neurons are the axons of _____.
- Giant pyramidal
The axons of the large (not giant) pyramidal neurons of the primary motor cortex also descend in the _____, but they synapse on internuncial neurons that synapse on lower motor neurons.
- Corticospinal tracts
The giant pyramidal neurons (100 um across) of Brodmann area _____ are almost twice as large as the large pyramidal neurons (60 um across).
- 4
The axons of giant pyramidal neurons synapse on _____, but the axons of the more numerous large pyramidal neurons synapse on _____.
- Lower motor neurons
- Internuncial neurons
Both kinds of _____ are somatotopically arranged with neurons controlling the larynx at the inferior end of the precentral gyrus.
- Upper motor neurons
The upper motor neurons controlling the tongue are superior to neurons controlling the larynx in the _____ gyrus.
- Precentral
Upper motor neurons controlling the facial muscles are superior to neurons controlling the tongue in the _____.
- Precentral gyrus
_____ controlling fingers are arranged in an ascending 1-5 sequence from the _____ for the facial muscles.
- Upper motor neurons
- Upper motor neurons
Upper motor neurons for the arm are _____ to the upper motor neurons for the fingers and _____ to upper motor neurons for the trunk. which occupy the peak of the precentral gyrus.
- Superior
- Inferior
Upper motor neurons for the _____ are in a descending thigh-calf-foot sequence on the part of the precentral gyrus inside the longitudinal fissure.
- Lower extremity
On the motor homunculus below, each body part of the homunculus is positioned next to the region of the precentral gyrus containing the _____ neurons controlling that part.
- Upper motor
The motor homunculus for a precentral gyrus has only half of a body because the left motor cortex controls only the _____ side of the body.
- Right
The disproportionate amount of space in the _____ devoted to the upper motor neurons for the _____ reflects number of neurons necessary to achieve fine motor control of the _____.
- Precentral gyrus
- Fingers
- Fingers
The motor homunculus is drawn next to a tilted coronal section of the cerebrum because the _____ gyrus is not perfectly vertical.
- Precentral gyrus
A _____ is a convenient mnemonic for the positions of the upper motor neurons controlling each body part.
- Motor humunculus
Upper motor neuron lesions cause _____.
- Spastic paralysis of the hands
The axons of the upper motor neurons pass between the thalamus and the lenticular nucleus to form the posterior limb of the _____.
- Internal capsule
The inferior to superior arrangement of the upper motor neurons becomes an anterior to posterior arrangement of the axons in the _____ limb of the _____.
- Posterior limb
- Internal capsule
The posterior limb of the internal capsule slants from _____ to _____ as it slants from anterior to posterior.
- Medial
- Lateral
The medial to lateral arrangement of the corticobulbar and corticospinal tracts is exaggerated as the axons pass from the posterior limb of the internal capsule to the _____ of the midbrain.
- Crus cerebri
The corticobulbar fibers that control the facial and laryngeal muscles part company with the _____ fibers in the pons and medulla.
- Corticospinal
The medial to lateral order of the corticospinal fibers is maintained through the base of the pons and the _____ of the medulla.
- Pyramid
When the corticospinal fibers cross in the _____, the most lateral fibers cross furthest.
- Pyramidal decussation
The axons of the upper motor neurons for the muscles of the _____ do not cross.
- Trunk (back)
Because the most lateral fibers cross furthest, the fibers that were most lateral in the pyramids of the medulla remain the most lateral in the _____ of the spinal cord.
- Lateral corticospinal tract
The premotor cortex (Brodmann area 6) is just anterior to the primary motor cortex in the _____ lobe.
- Frontal
Brodmann area 6 abuts the anterior edge of area _____ because Brodmann numbers are based on cytoarchitecture rather than position.
- 4
The somatotopic arrangement of area 6 follows the _____ of area 4.
- Somatotopic arrangement
Because the premotor cortex instructs the primary motor cortex in the performance of skilled tasks, the premotor area for the _____ is larger than the other premotor areas.
- Hand
Damage to the premotor cortex causes apraxia, loss of a _____ one once had.
- Skill
The premotor cortex receives _____ input from the _____ nucleus of the _____.
- Stimulatory
- Ventral anterior
- Thalamus
Projections of the _____ of the thalamus assist the premotor cortex in the initiation and rapid execution of _____.
- Ventral anterior nucleus
- Skilled tasks
The primary motor cortex is assisted by direct input from the premotor cortex and the _____ of the _____.
- Ventrolateral nucleus
- Thalamus
The cerebellum influences the primary motor cortex through its projections to the _____ of the _____.
- Ventrolateral nucleus
- Thalamus
Damage to the pontocerebellum or the pontine part of the superior cerebellar peduncle causes _____ in the _____ extremities.
- Clumsiness (apraxia)
- Ipsilateral
Damage to or the ventrolateral nucleus of the thalamus causes _____ in the _____ extremities.
- Clumsiness (apraxia)
- Contralateral
Damage to the primary motor cortex causes _____ of the muscles whose upper motor neurons are damaged.
- Spastic paralysis
The lower motor neurons for the extraocular muscles are in the _____, _____, and _____ nuclei.
- Oculomotor
- Throchlear
- Abducens
The _____ for the extraocular muscles are in the frontal eye field (Brodmann area 8), a triangular region anterior to the arm and trunk regions of the premotor cortex.
- Upper motor neurons
Brodmann area 8 is anterior to the superior part of area _____.
- 6
The _____ are responsible for conscious tracking movements of the eyes.
- Frontal eye fields
The _____ are responsible for unconscious tracking movements of the eyes.
- Superior colliculi
Both the frontal eye fields and the superior colliculus depend on feedback from the _____ cortex in order to track a moving object accurately.
- Parietal association
The primary motor cortex depends on feedback from the _____ when working in the dark or out of the line of sight.
- Parietal association cortex
The intensity of muscular effort depends mostly on feedback through the _____, but the location of muscular effort depends mostly on feedback from the visual cortex and _____.
- Cerebellum
- Parietal association cortex
The frontal lobe is separated from the parietal lobe by the _____.
- Central sulcus
The inferior frontal gyrus is the gyrus of the _____ lobe just superior to the _____.
- Frontal
- Lateral fissure (temporal lobe)
Most of the _____ above the left lateral fissure is occupied by Broca’s motor speech area.
- Inferior frontal gyrus
The left Broca’s area in the left _____ is completely dominant in male speakers of Indo-European languages.
- Inferior frontal gyrus
A stroke in a man’s left Broca’s area causes mute aphasia, the complete _____ to _____.
- Inability
- Speak
A stroke in a woman’s left _____ causes severe loss of speaking ability because her left _____ is partially dominant.
- Broca’s area
- Broca’s area
Recovery from a stroke in the left Broca’s area requires teaching the right _____ to take over the task of programming spoken language.
- Broca’s area
Teaching a man’s _____ to control speech requires about 2 years; a woman’s _____ can learn in a year.
- Right Broca’s area
- Right Broca’s area
Brodmann area 8 is the _____, area 6 is the _____,
and area 4 is the _____.
- Frontal eye field
- Premotor cortex (area)
- Primary motor cortex
The primary motor cortex occupies the _____ gyrus.
- Precentral
The primary motor cortex gets instructions for skilled tasks directly from the _____ and indirectly from the _____ via the _____ of the _____.
- Premotor cortex
- Cerebellum
- Ventrolateral nucleus
- Thalamus
Upper motor neurons are somatotopically arranged in the precentral gyrus from medial to lateral for muscles of the _____ through the _____.
- Leg (or foot)
- Larynx
The upper motor neuron axons are somatotopically arranged from anterior to posterior in the posterior limb of the internal capsule for muscles of the _____ through the _____.
- Face
- Leg
