Transcript MOTOR ph226 2015

MOTOR
THE WORD MOTOR MEANS
MOVEMENT
MOTOR SYSTEM INCLUDES
 MOTOR CORTEX
 PYRAMIDAL TRACTS
CORTICO SPINAL
CORTICO BULBAR
 EXTRA PYRAMIDAL TRACTS
 BASAL GANGLIA
 CEREBELLUM
Primary (Somatic) Motor Cortex
 Located 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
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
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 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
DR FAWZIA AL-ROUQ
EXTRA PYRAMIDAL SYSTEM
DEFINATION
 Tracts other than corticospinal tracts
are known as EXTRA PYRAMIDAL
TRACTS.
COMPONENTS OF
EXTRAPYRAMIDAL SYSTEM
 BASAL GANGLIA
 BRAINSTEM Giving rise to following
tracts:
Rubrospinal tract
o Vestibulospinal tract
o Reticulospinal tract
o Tectospinal tract
o
FUNCTIONS OF EXTRA PYRAMIDAL SYSTEM
OR
MULTINEURONAL SYSTEM
 REGULATION OF BODY POSTURE,
INVOLVING INVOLUNTARY MOVEMENTS OF
LARGE MUSCLE GROUPS OF TRUNK AND
LIMBS
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
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
UMN lesions
and
LMN lesions
UMN lesions
LMN lesions
•weakness, paralysis
•weakness, paralysis
•spasticity
•flaccidity, hypotonia
• tendon reflexes
•Hypo- /no tendon
•+ Babinski sign
reflex
•little,if any,muscle
• - Babinski sign
atrophy
•muscle atrophy
•no fasiculation
•fasiculation of
involved muscle