It's good to know where u are body position is now, when u walking there must be to get a balance for moving.

1. Proprioreceptor,
Posture, Equilibrium
15-12 -2019

2. • Proprioceptors or (kinesthetic receptors): are the
receptors, which detect and give response to movement
and change in position of different parts of the body.
• Proprioceptors are situated in:
1. Labyrinth.
2. Muscles, tendon of the muscles, joints, ligaments and
fascia.

3. Locations of proprioceptors
Muscles
Spindle
Joint
Free
Nerve
Ending
Pacinian
Corpuscle

4. MUSCLE SPINDLE:
• Modified skeletal muscle fibers called intrafusal muscle
fibers - 1. Nuclear bag fiber and 2. Nuclear chain fiber.
• Muscle spindle is innervated by both sensory and motor
nerves.
• Each muscle spindle receives two types of sensory nerve
fibers:
1. Primary sensory nerve fiber: type Iα (Aα).
2. Secondary sensory nerve fiber: type II (Aβ).
• Motor (efferent) nerve fiber supplying the muscle spindle
belongs to gamma motor neuron (Aγ) type.
• Muscle spindle has two functions:
1. It forms the receptor organ for stretch reflex.
2. It plays an important role in maintaining muscle tone.

6. (Aα)
(Aβ)

7. GOLGI TENDON ORGAN:
• situated in the tendon of skeletal muscle
• Near the attachment of extrafusal fibers.
• Sensory nerve fiber supplying the Golgi tendon
organ belongs to Ib type.
• Golgi tendon organ gives response to the change
in the force or tension developed in the skeletal
muscle during contraction.
• Prevents damage of muscle due to
overstretching.

8. Ib type

9. Function of Golgi tendon organ in the
inhibition of overstretching:
1- in Forceful Contraction:
• Activation of interneuron in the spinal cord leads to
development of “inhibitory postsynaptic potential”
in motor neuron causes inhibition of muscle
contraction.
2- in Inverse Stretch Reflex:
• inhibition of contraction due to excessive stretching
or by “activating the antagonistic muscle”.
3- in Lengthening Reaction (pathological):
• Increased tension activates golgi tendon then
development of spinal reaction then activation of
gamma motor then facilitation of stretch reflex

11. PACINIAN CORPUSCLE:
• Pacinian corpuscle is a mechanoreceptor that senses
pressure and vibration.
• It is situated in the deeper layers of skin.
• It is also situated in the tissues surrounding the joints such
as fascia over the muscle, tendons and joint capsule.
• Pacinian corpuscles situated in these tissues are
responsible for determining the position of joints.
• Since pacinian corpuscle is a rapidly adapting receptor
(phasic receptor) changes in the position of joints. it is
very sensitive to quick
• So it is believed to send information about joint
movement to CNS.

13. FREE NERVE ENDING:
• Free nerve ending is the receptor for pain
sensation situated in skin, muscles, tendon,
fascia and joints.
• As it is a slow adapting receptor (tonic
receptor) it is maximally stimulated at specific
joint positions.
• So it is believed to send information about
joint position to CNS.

15. Posture:

16. • Significance of posture is to make the movement smooth
and accurate and to maintain the line of gravity constant
or to keep the body in equilibrium with line of gravity.
• Posture is not an active movement.
• Basic phenomena for maintenance of posture are muscle
tone and stretch reflex.
• Muscle tone is defined as the state of continuous and
passive partial contraction of muscle with certain vigor
and tension.
• Gamma motor neurons and muscle spindle are
responsible for the development and maintenance of
muscle tone.
• Tone is more in antigravity muscles such as extensors of
lower limb, trunk muscles and neck muscles.

19. Development And Maintenance Of Muscle Tone.

20. Regulation of Muscle Tone:
• Supraspinal facilitatory centers:
• Supraspinal centers, which increase the muscle tone:
1. Motor area 4 in cerebral cortex.
2. Cerebellum.
3. Descending facilitatory reticular system.
4. Red nucleus.
5. Vestibular nucleus.
• Supraspinal inhibitory centers:
• Supraspinal centers, which decrease the muscle tone:
1. Suppressor areas of cerebral cortex.
2. Basal ganglia.
3. Descending inhibitory reticular system.

21. POSTURAL REFLEXES:
• Postural reflexes are the reflexes which are responsible for
maintenance of posture.
• Afferent impulses for the maintenance of posture arise
from:
A) Proprioceptors, B) vestibular apparatus and C) retina of
eye and reach the centers in central nervous system (CNS).
• The centers, which maintain the posture, are located at
different levels of CNS particularly:
A) cerebral cortex, B) cerebellum, C) brainstem and D) spinal
cord.
• Postural reflexes are generally classified into two groups:
A. Static reflexes: (reflexes that maintain posture at rest)
B. Statokinetic reflexes: (vestibular apparatus) during
movement.

22. Afferent impulses for the maintenance of
posture arise from: