CH 8: Motor Pathways Flashcards
Brodmann areas:
based on differences in cytoarchitecture in the cerebral cortex
52 anatomic areas
what area is the primary motor area?
Brodmann’s area 4
lies in the precentreal gyrus and paracentral lobule of the frontal lob
the left motor strip of the primary motor area controls the ..?
right side of the body
the right motor strip of the primary motor area controls the …?
left side of the body
neurons in the lowest lateral part of the primary motor area influence the:
followed in:
larynx and tongue
followed in upward sequence by neurons affecting the face, thumb, hand, forearm, upper arm, thorax, abdomen, thight, leg, foot and perineal muscles
the neurons controlling the leg, foot and perineal muscles are in the :
paracentral lobula
areas for the hand, tongue and larynx are :
disproportionally large and conform to the development of elaborate motor control of these muscle groups
what is a homunculus?
the functional map of the motor cortex
resembles a distorted image of the body turned upside down and reversed left for right
immediately rostral to the primary motor area lies the:
premotor cortex (Brodmann’s area 6) on the lateral surface of the hemispheres
contains a homunculus similar to the one in area 4
what is the supplementary motor area?
the most medial aspect of area 6 can be observed on a midsagittal section of the brain just rostral to the paracentral lobule
also contains a functional map of body movements
what are additional regions of cerebral cortex that can influence movement?
Brodmann’s areas 3,1,2 on the postcentral gyrus
and the secondary motor area
where is the secondary motor area?
where the pre and post central gyri are continuous at the base of the central sulcus
overlaps the secondary somatosensory cortex
what is brodmann’s area 8 called?
frontal eye fields
contains neurons that specifically influence eye movements
the brainstem and the SC contain pattern generators for:
complex movements such as locomotion and other rhythmic activities
the descending pathways of the NS have the important task of:
interacting with and controlling lower-level neuronal patterns of discharge in a hierachical manner
at the level of the cerebral cortex, individual neurons can:
control the contractions of individual muscles and can determine the force of these contractions
populations of motor cortical neurons act together to:
specify the direction of movements and the force of movements
these functions pertain not only to neurons in the primary motor cortex but also to those in the premotor, supplementary, and postcentral regions
the premotor and supplementary motor areas are important in:
planning movements
the supplementary motor area appears to have a special role in:
integrating movements performed simultaneously on both sides of the body
skeletal muscle activity results from the:
net influence of higher nervous system structures on motoneurons of the SC and cranial nerve nuclei
what are lower motor neurons?
collectively SC and brain stem neurons provide the final direct link with muscles through neuromuscular junctions (motor end plates)
their cell bodies reside within the CNS and their axons make synaptic contact with extrafusal and intrafusal muscle fibers of somatic and branchiomeric origin
somatic muscle fibers derive from the:
myotomes of true somites in the developing embryo
branchiomeric muscles develop from:
the branchial arches of the embryo
are not true somites but muscles develop from them
like somatic muscle they are striated and under voluntary control
includes muscles of mastication and facial expression, and muscles of the pharynx and larynx
what are upper motoneurons?
regulate lower motoneuron activity
the cerebral cortex, cerebellum and basal ganglia control these descending pathways either directly or indirectly
synapse directly or through interneurons on alpha, beta and gamma motoneurons in the SC and cranial nerve nuclei
contained completely within the CNS
refers to the corticospinal tract and the corticobulbar tract