Motor system
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MOTOR SYSTEM. MOTOR. THE WORD MOTOR MEANS M O V E M E N T. MOTOR SYSTEM INCLUDES. MOTOR CORTEX PYRAMIDAL TRACTS CORTICO SPINAL CORTICO BULBAR EXTRA PYRAMIDAL TRACTS BASAL GANGLIA CEREBELLUM. Primary (Somatic) Motor Cortex.

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MOTOR SYSTEM

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Motor system

MOTOR SYSTEM


Motor

MOTOR

THE WORD MOTOR MEANS

M O V E M E N T


Motor system includes

MOTOR SYSTEM INCLUDES

  • MOTOR CORTEX

  • PYRAMIDAL TRACTS

    CORTICO SPINAL

    CORTICO BULBAR

  • EXTRA PYRAMIDAL TRACTS

  • BASAL GANGLIA

  • CEREBELLUM


Primary somatic motor cortex

Primary (Somatic) Motor Cortex

  • Located in the precentralgyrus of each cerebral hemisphere.

  • Contains large neurons (pyramidal cells) which synapse on skeletal muscles

    • Allowing for voluntary motor control.

    • These pathways are known as the corticospinal tracts or pyramidal tracts.


Primary motor cortex

PRIMARY MOTOR CORTEX

  • Primary motor cortex (M1) lies in the frontal lobe in precentralgyrus, also called Broadmanns area 4

    Important points regarding primary motor area:

  • Feet are at the top of the gyrus and face at the bottom

  • Arms and the hand area in the mid portion

  • Facial area is represented bilaterally, but rest of the representation is generally unilateral


Primary motor cortex1

PRIMARY MOTOR CORTEX

  • Cortical motor area controls the musculature on the opposite side of the body

  • Cortical representation of each body part is proportionate in size to the skill of that part being used for fine voluntary movement

  • Therefore the area involved in hand movement and in speech have large representation in the cortex (more than half of primary motor cortex)

  • Both individual muscles and movements are represented in M1 area

  • Cells in cortical motor area are arranged in columns


Motor system

CORTICOSPINAL TRACTS OR PYRAMIDAL TRACTS

  • 80 % cross in the medulla Lateral corticospinal tract

  • 20 % do not cross in medulla Ventral or anterior (They cross in spinal cord)Corticospinal tract


Functions of corticospinal tract

FUNCTIONS OF CORTICOSPINAL TRACT

  • LATERAL CORTICOSPINAL TRACT:

    • Fine movements of fingers that is skilled voluntary movement

  • VENTRAL CORTICOSPINAL TRACT:

    • It may be concerned with control of bilateral postural movements


  • Extra pyramidal system

    EXTRA PYRAMIDAL SYSTEM

    DR FAWZIA AL-ROUQ


    Extra pyramidal system1

    EXTRA PYRAMIDAL SYSTEM

    DEFINATION

    • Tracts other than corticospinal tracts are known as EXTRA PYRAMIDAL TRACTS.


    Components of extrapyramidal system

    COMPONENTS OF EXTRAPYRAMIDAL SYSTEM

    • BASAL GANGLIA

    • BRAINSTEM Giving rise to following tracts:

      • Rubrospinal tract

      • Vestibulospinal tract

      • Reticulospinal tract

      • Tectospinal tract


    Functions of extra pyramidal system or multineuronal system

    FUNCTIONS OF EXTRA PYRAMIDAL SYSTEMORMULTINEURONAL SYSTEM

    • REGULATION OF BODY POSTURE, INVOLVING INVOLUNTARY MOVEMENTS OF LARGE MUSCLE GROUPS OF TRUNK AND LIMBS


    Important

    IMPORTANT

    • Complex and overlapping function exist between Pyramidal and extra pyramidal systems for example while doing fine work like needle work (Pyramidal system) one has to subconsciously assume a particular posture of arms( extra pyramidal system) that enables to do your work


    Motor system

    Performance of normal voluntary movement,

    the integrity of two sets of neurons is important

    • Upper motor neurones

      • Neurons originating in the cerebral cortex and the brain stem

      • Synapse directly or indirectly with the anterior horn cells or with the motor neurones of the cranial nerves

      • Grouped into pyramidal and extrapyramidal systems

    • Lower motor neurones

      • Motor cranial nuclei and their axons, i.e. motor fibres of the cranial nerves (3rd, 4th, 5th, 6th, 7th, 9th, 10th, 11th and 12th)

      • In the spinal cord they include the anterior horn motor neurones and their axons, i.e. the motor nerves to skeletal muscles


    Motor system

    UMN lesions

    and

    LMN lesions


    Motor system

    • LMN lesions

    • weakness, paralysis

    • flaccidity, hypotonia

    • Hypo- /no tendon

    • reflex

    • - Babinski sign

    • muscle atrophy

    • fasiculationof

    • involved muscle

    • UMN lesions

    • weakness, paralysis

    • spasticity

    • tendon reflexes

    • + Babinski sign

    • little,if any,muscle atrophy

    • no fasiculation


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