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MOTORTHE WORD MOTOR MEANS
M O V E M E N T
MOTOR SYSTEM INCLUDESMOTOR CORTEXPYRAMIDAL TRACTS
CORTICO SPINAL CORTICO BULBAR
EXTRA PYRAMIDAL TRACTS BASAL GANGLIACEREBELLUM
Primary (Somatic) Motor CortexLocated in the
precentral gyrus 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 (M1)
lies in the frontal lobe in precentral gyrus, 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
•Cortical motor area controls the musculature on Cortical motor area controls the musculature on the opposite side of the bodythe opposite side of the body•Cortical representation of each body part is Cortical representation of each body part is proportionate in size to the proportionate in size to the skillskill of that part being of that part being used for fine voluntary movement used for fine voluntary movement •Therefore the area involved in hand movement and Therefore the area involved in hand movement and in speech have large representation in the cortex in speech have large representation in the cortex (more than half of primary motor cortex)(more than half of primary motor cortex)•Both individual muscles and movements are Both individual muscles and movements are represented in M1 arearepresented in M1 area•Cells in cortical motor area are arranged in Cells in cortical motor area are arranged in columns columns
PRIMARY MOTOR CORTEX
CORTICOSPINAL( PYRAMIDAL TRACT )
Motor signals are transmitted directly from the motor cortex to the spinal cord through corticospinal tracts
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 TRACTLATERAL CORTICOSPINAL TRACT:
Fine movements of fingers that is skilled voluntary movement
VENTRAL CORTICOSPINAL TRACT: It may be concerned with control of bilateral postural movements
DR FAWZIA AL-ROUQ
EXTRA PYRAMIDAL SYSTEMDEFINATION Tracts other than corticospinal tracts are known as EXTRA PYRAMIDAL TRACTS.
COMPONENTS OF EXTRAPYRAMIDAL SYSTEM
BASAL GANGLIABRAINSTEM Giving rise to following tracts:
o Rubrospinal tracto Vestibulospinal tracto Reticulospinal tracto Tectospinal tract
FUNCTIONS OF EXTRA PYRAMIDAL SYSTEMORMULTINEURONAL SYSTEM
REGULATION OF BODY POSTURE, INVOLVING INVOLUNTARY MOVEMENTS OF LARGE MUSCLE GROUPS OF TRUNK AND LIMBS
IMPORTANTComplex 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
Performance of normal voluntary movement, Performance of normal voluntary movement, the integrity of two sets of neurons is importantthe integrity of two sets of neurons is important
Upper motor neuronesUpper motor neuronesNeurons originating in the cerebral cortex and the Neurons originating in the cerebral cortex and the brain stembrain stemSynapse directly or indirectly with the anterior horn Synapse directly or indirectly with the anterior horn cells or with the motor neurones of the cranial nervescells or with the motor neurones of the cranial nervesGrouped into pyramidal and extrapyramidal systemsGrouped into pyramidal and extrapyramidal systems
Lower motor neuronesLower motor neuronesMotor cranial nuclei and their axons, i.e. motor fibres Motor cranial nuclei and their axons, i.e. motor fibres of the cranial nerves (3of the cranial nerves (3rdrd, 4, 4thth, 5, 5thth, 6, 6thth, 7, 7thth, 9, 9thth, 10, 10thth, 11, 11thth and 12and 12thth))In the spinal cord they include the anterior horn In the spinal cord they include the anterior horn motor neurones and their axons, i.e. the motor motor neurones and their axons, i.e. the motor nerves to skeletal musclesnerves to skeletal muscles
UMN lesions and
LMN lesions
UMN lesions
• weakness, paralysis
•spasticity
• tendon reflexes
• + Babinski sign
• little,if any,muscle atro
phy
•no fasiculation
LMN lesions
• weakness, paralysis
• flaccidity, hypotonia
•Hypo- /no tendon
reflex
• - Babinski sign
• muscle atrophy
•fasiculation of
involved muscle