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Stack #4565792
motor pathways
| Term | Definition |
|---|---|
| Each type of sensation is first integrated in the | unimodal sensory association corticles |
| UMNs activate LMNs that | innervate and cause contraction of individual muscle fibers. |
| The anterior portion of the frontal lobe is called the | prefrontal cortex -goal directed behavior |
| information from the prefrontal cortex is then relayed to.. | motor planning areas,and the premotor and supplementory motor corticles |
| This function resides in the UMNs in the primary motor cortex, which is located in the | precentral gyrus |
| automatic movements do not involve the circuitry of | the cerebral cortex and occur in three contexts: (1) activation of muscles used to maintain posture and facilitate gait; (2) coordination of muscle contraction across multiple muscle groups to produce smooth, fluid movements; and (3) |
| basal nuclear circuits balance activity in | trunk and limb muscles to influence posture and gait |
| Input into the basal nuclei comes from the | cerebral cortex and from a midbrain nucleus, the substantia nigra. |
| Issues with the cerebellar circuitry leads to uncoordinated movement, known clinically as | ataxia |
| Automatic contraction of muscles of the face occurs through direct activation of motor neurons in the | cranial nerves |
| LAS tracts innvervate | LMN that do limb muscles |
| The medial activating systems tracts activate LMNs for | neck, trunk, and proximal limb muscles to mediate muscle contractions supporting posture and gross limb movements during ambulation. |
| LAS facilitaes | voluntary limb movements |
| Three tracts make up the LAS: | lateral corticospinal tract, the corticobulbar tract, and the rubrospinal tract |
| The lateral corticospinal tract provides | for conscious control of trunk and limb muscles |
| the lateral coricospinal tract makes up 90 percent of | all coricospinal fibers |
| The corticobulbar tract are the UMNs that innervate cranial nerve nuclei in the brainstem that house LMNs innervating the muscles | muscles in the face |
| the axons in the corticobulbar tract are | bilateral |
| e rubrospinal UMNs are located in the | midbrain red nuclues |
| the function of the rubrospinal tract is | arm flexation |
| Only one tract starts in the cerebral cortex | , the anterior corticospinal tract, which is also known as the medial corticospinal tract |
| The anterior corticospinal tract is for conscious turning | of the head |
| Descending though the brainstem, the first medial activating system tract is the one that originates in the midbrain tectum, the dorsal-most midbrain nucleus. These UMNs make up the | tectospinal tract |
| the axons of the tectospinal tract are | ipsilateral |
| Reticulospinal tract UMNs activate | proximal limb extensors and inhibit proximal limb flexors to facilitate gait and posture control. |
| The lateral vestibulospinal tract originates in the lateral | vestibular nucleus in the medulla |
| The medial vestibulospinal tract has UMNs in the | medullary medial vestibular nucleus that project bilaterally to the cervical spinal cord |
| Voluntary contraction of facial muscles is mediated by LMNs that are somatic efferents | somatic effereants that are located in the nuclei with cranial nerve 2, 4,6,9,and 12. |
| LMNs that innervate the muscles of the body are located in the | ventral horns of the spinal cord |
| α motor neurons innervate extrafusal muscle fibers, the... | muscle fibers that make up the bulk of the muscle and are responsible for shortening the muscle and moving associated joints |
| The γ motor neurons innervate intrafusal muscle fibers | the muscle fibers that make up the muscle spindle |
| When LMNs signal extrafusal muscle fibers to contract, | the γ LMNs innervating the same muscle also contract. |
| each extrafusal muscle fiber is innervated by | only ONE motor nueron |
| motor unit consists of an α | motor neuron and all the muscle fibers innervated by that α motor neuron |
| spinal reflexs are | automatic and involuntary |
| The autogenic inhibition reflex occurs when | there is stretch on a muscle that is strong enough to transfer the tension to the attached tendon |
| In the limbs, activation of nociceptors incites the | withdraw reflex |
| when a withdrawl reflex happens, what else happens to maintain balance? | a crossed extension reflex |
| H-wave testing, | records electrophysiological impulses from peripheral nerves to assess the efficacy of the reflex activity. |
| uring development of extrafusal muscle fibers, muscle cell precursors called myoblasts, fuse together to | end to end to create long continuous myocytes, or muscle fibers. |
| All extrafusal muscle fibers are innervated by an LMN at a specialized synapse, the | nueromuscular junction |
| he postsynaptic membrane of a neuromuscular junction on the muscle fiber is arranged in folds and the ligand-gated receptors for | acetycholine |
| icotinic ACh receptors are | ligand sodium ion channels |
| Ca2+ can bind to and activate a protein called | troponin |
| When a muscle fiber is at rest, tropomyosin blocks the active sites on actin filaments, preventing | myosin heads from binding to actin filaments |
| upper motor neurons are | cell bodies located in the cortex |
| lower motor nuerons are activated by | UMNS |
| Premotor cortex | arranging and coordinating sequences of movements |
| Supplementary Motor Cortex | coordinating bimanual movements that involve both hands |
| Primary Motor Cortex | exicuting individual movements |
| Lateral activating system (LAS) | lateral corticospinal tract - corticobulbar tract - rubrospinal tract |
| Medial activation systems MAS | Anterior corticospinal tract - Tectospinal tract - Reticulospinal (lateral and medial) tract - Vestibulospinal (lateral and medial) tract |
| Anterior corticospinal tract | LMNs innervate head and neck muscles |
| Tectospinal – crosses midline at cervical spinal cord level | LMNs respond to visual/auditory stimuli to control neck muscles |
| Reticulospinal trac | Medial – LMNs innervate trunk and proximal limb extensors • Lateral – inhibits LMNs of proximal limb extensors |
| Vestibulospinal | Medial – LMNs innervate muscles for head movements to maintain equilibrium • Lateral – LMNs activate ‘antigravity’ muscles all along spinal cord |
Created by:
ecoesfeldd