Cerebral Cortex and Corticospinal Tract PDF

Presentation by Cerebral Cortex and Cortico-spinal Tract Lois Stevens Senior Lecturer  Cerebral Cortex Vast collection of cell bodies, axons and dendrites coving surface of cerebral hemispheres Gross Anatomy Coronal Section of Brain ...

Presentation by Cerebral Cortex and Cortico-spinal Tract Lois Stevens Senior Lecturer  Cerebral Cortex Vast collection of cell bodies, axons and dendrites coving surface of cerebral hemispheres Gross Anatomy Coronal Section of Brain  Communication Commissural fibres - connect cortices of right and left cerebral hemispheres. The largest bundle forms the corpus callosum. Projection Fibres - efferent and afferent fibres uniting the cortex with the lower parts of the brain and with the spinal cord. Association Fibres - connect regions of the cortex within one hemisphere Inputs/Outputs  Localized Function of Cerebral Cortex Primary sensory cortex – discriminates intensity and quality of sensory information Sensory association cortex – performs complex analysis of sensation Primary motor cortex – descending control motor output Motor planning areas: Broca’s, pre-motor and supplementary motor areas Frontal association cortex – controls behaviour, processes emotions, memory i.e. executive functions  Primary Motor Cortex (PMC) Located within precentral gyrus anterior to the central sulcus Controls contralateral voluntary movement (particularly fine movements of hand and face) Hand, foot and lower face entirely contralateral Muscles that tend to be active bi-laterally simultaneously are controlled by PMC of both sides Homunculus Sagital Section of Brain  Motor Planning Areas Located anterior to PMC Supplementary MC – involved in initiation of internally generated movement, planning bimanual and sequential movements i.e. a sequence of multiple movements performed in a particular order Pre MC – controls trunk and girdle muscles - involved in the sensory guidance of externally generated movement e.g. orientate the body before reaching for the glass of water. Planning. Broca’s – planning movements of the mouth during speech  Pre-frontal Area Prefrontal cortex has access to and can direct the output of several motor centres. Decision to move. Activity 1 : which areas of the frontal lobe are active and what exactly are they up to? Lateral CST  Corticospinal Tract PMC internal capsule (via the corona radiata) Midbrain Pons Medulla 90% fibres decussate to form the lateral corticospinal tract. Fibres that do not decussate descend as the anterior corticospinal tract. Most corticospinal neurones synapse with interneurones which then connect with the motor neurones which innervate muscles Lateral CST Lateral CST Anterior CST The anterior corticospinal tract sends fibres mainly to the trunk or axial muscles. The control is both ipsilateral and contralateral. Therefore, trunk muscles are generally bilaterally cortically innervated Anterior CST Motor Unit Questions please?