MOTOR THE WORD MOTOR MEANS M O V E M E N T MOTOR SYSTEM INCLUDES MOTOR CORTEX PYRAMIDAL TRACTS...

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