Date post: | 22-Jan-2018 |
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Health & Medicine |
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Premotor cortex includes anterior portion of precentral gyrus and posterior parts of superior, middle and inferior frontal gyri.
Premotor cortex gives rise to descending projections to lower motor neurons.
It is a mosaic of areas with modular organisation.
Premotor cortex
Medial division of the premotor cortex corresponds
as supplementary motor area (SMA).
There is a part of medial premotor cortex that is
involved in the expression of emotional behavior.
There is also a part of medial premotor cortex
concerned with organising bimanual activites.
There is a division concerned with governing
voluntary saccadic eye movements (frontal eye
field).
Premotor cortex, medial part
In the lateral premotor cortex are present areas that are concerned with organising movements guided by sensory information, including social interactions.
Inferior lateral part is concerned with social communication.
Broca´s area is located in the posterior inferior lateral part of the premotor cortex: this area organizes the vocal motor apparatus for production of speech.
Premotor cortex, lateral part
Near the Broca´s area are parts of premotor cortex concerned with production of speech in written form.
Premotor cortex, lateral part
There is activation of mirror motor neurons when we do some movement and when we observe
another person doing the same movement.
Mirror motor neurons are located in lateral premotor cortex.
These neurons are important in understanding the intention of some motor act.
Mirror motor neurons
Reticular formation extends throughout the entire brainstem.
Lateral and medial vestibulospinal tract: adjustment of posture.
Lateral vestibulospinal tract from lateral vestibular nuclei goes ipsilaterally and terminates in the spinal
cord cell group concerned with extensor muscles tone (primarily in the lower extremities).
Vestibulospinal tracts
Medial vestibulospinal tract is bilateral and terminates among medial lower motor neuronal columns, mainly found in the cervical region of the spinal cord: vestibulocervical reflexes.
Vestibulospinal tracts
Visceral and somatic motor control.
Mesencephalic and rostral pontine reticular formation modulates forebrain activity.
Caudal pontine and medullary reticular formation is concerned with premotor coordination of lower somatic and visceral motor neuronal pools.
Reticulospinal system is concerned primarily with making anticipatory adjustments of posture.
Reticulospinal tract
It is a motor structure that integrates sensory information from vision, audition, pain and temperature sensation.
Superior colliculus
Volitional movement: descending pyramidal and
extrapyramidal projections from motor cortex and
brainstem
Lateral: fine control of
distal muscles of
extremities
Medial: posture and
proximal muscles of
extremities
Brainstem reticular
formation
Motor neuron poolsMotor neurons of cranial nerve nuclei
and ventral horn of the spinal cord
Autonomic preganglionic
neurons
Muscle contraction and
movement
Activation of smooth
muscles and glands
Emotional expression: descending extrapyramidal
projections from limbic centers of ventro-medial
forebrain and hypothalamus
Medial: gain setting,
rhythmical reflexes
Lateral: specific
emotional
behaviors
Pyramidal
pathway
Corticobulbar pathway