reflexes maturation in human

1. Growth and Development

2. Objectives of the lecture
Understand definition and concepts of reflexes.
Report the difference between reflex and reaction.
Identify the importance of reflexes.
Recognize classification of reflexes.
Discuss the classifications of reflexes according to level of
C.N.S. maturation, type of stimulus and their time of
appearance.

3. What’s a reflex?
Reflex is "a relatively stereotyped movement or response
elicited by a stimulus applied to the periphery, transmitted to
the central nervous system and then transmitted back to the
periphery.’’
Dominant movement form during the last 4 months of
prenatal life and first 4 months after birth.
Occur subcortically (below the level of the higher brain
centers).

5. What is the difference between reflex and reaction?
A reflex is an involuntary response to an external stimulus,
usually to protect the body.
A reflex is a physical non-conscious action (eg. tendon jerk).
Reaction is a feeling or action in response to something that
has happened.
A reaction is a voluntary response to an external stimulus,
and can be trained to become faster through regular practice.

6. What is the difference between reflex and
reaction?
The speed of a reflex is greater than that of a voluntary
reaction, due largely to the relative complexity of the neural
pathway for a reaction (Fig. 1) compared to that for a reflex
(Fig. 2).
Fig. 1
Fig. 2

7. Types of Reflexes
Primitive
• Survival and protection
Postural
• Reaction to gravity and changes in the equilibrium
Locomotor
• Resemble later voluntary locomotion movements

8. What is the importance of reflexes?
1-Dominant form of movement for last 4 months prenatally and
first 4 months postnatal.
2- Survival Function: Primitive reflexes critical for human
survival.
3- Influence the child normal development.
4- Therapeutic function.
5- Diagnostic function.

9. 2- Survival Function: Primitive reflexes are critical for human
survival.
Human infants essentially helpless. Highly dependent on their
caretakers and reflexes for protection and survival.
Primitive reflexes emerge during gestation or at birth and most
are repressed by 6 months of age.
Primitive reflexes are important for protection, nutrition
(Sucking reflex and Rooting reflex) and survival.
An example is the rooting reflex, which helps a breastfed infant
find the mother's nipple. Babies display it only when hungry
and touched by another person, not when they touch
themselves.
Some reflexes serve protective functions i.e. protect your body
against harm , for example, eye-blink reflex and flexor withdrawal.

10. 3- Influence the child normal development
Future Motor Development
Reflex
Rolling
Neck righting
Upright posture
Labyrinthine
Grasping
Palmar grasp
Reflex integration is essential in normal development. Postural
reflexes believed to be foundation for later voluntary
movements. Response to the reflexes prepares the infant for
progressive development such as rolling over, sitting, crawling,
standing,… etc.

13. 4- Therapeutic function.
Some reflexes are utilized in therapeutic programs for children
with developmental disorders, for example, postural reflexes
are used to promote the upright posture.

14. The presence and strength of a reflex is an important sign of
nervous system development and function.
5- Diagnostic function
A . Presence
Reflexes can determine level of neurological maturation.
Appearance and disappearance are helpful in diagnosing
neurological disorders.
Reflexes are age-specific in normal, healthy infants. Severe
deviations from normal time frame may indicate neurological
immaturity or dysfunction e.g. persistence to an
inappropriate age ( the presence of an infant reflex after the
age at which the reflex normally disappears; can be a sign of
brain damage or damage to the nervous system).

15. B . Strength of
reflex
The reflexes indicate abnormality by their weakness,
absence, excessive strength.
Bilateral absence of Moro reflex may mean damage to the infant's central nervous
system while a unilateral absence could mean an injury due to birth trauma such as
a fractured clavicle or injury to the brachial plexus. Erb's palsy or some other form
of paralysis is also sometimes present in such cases.

16. Reflexes Testing as Diagnostic Tools
Need state of quietness.
Reflexes should be tested carefully :-
If baby restless, crying,
sleepy, or distracted, may
not respond to applied
stimulus.
Especially valuable with
children suspected of
motor delay.

17. Quantification of the level of presence or strength of
primitive reflexes.
4 reflexes: Moro, asymmetric tonic neck, symmetric tonic
neck, + supporting:
-Moro (may signify cerebral birth injury if lacking or asymmetric
e.g Erb’s palsy).
-ATNR (may indicate cerebral palsy or other neurological
problem if persists past normal time).

18. Reflexes as Diagnostic Tools
Milani Comparetti Neuromotor
Development Examination
Measures several infant reflexes from
birth to 24 months.
Develops profile of child’s movement in
relation to what is expected at a specific
age.
Especially valuable with children
suspected of motor delay.

19. Certain points to be considered during reflex testing
1- Name of the reflex and its level.
2- Age of the reflex.
3- Position from which the reflex will be tested.
4- +ve & -ve response of the reflex.

20. 1- According to their function.
2-According to their relation to the normal sequence of motor
development.
3-According to the level of central nervous system maturation.
Classification of reflexes
4- According to the type of stimulus.
5- According to their time of appearance.

21. 1- According to their function.
Some are protective and have a survival value for the infant.
Some promote postural support and balance.

22. 2- According to their relation to the normal sequence of motor
development.
A pedal:
-Spinal and/or brain stem level.
-Primitive reflexes.
-Allow for prone/supine lying.
Quadripedal:
-Midbrain level.
-Righting reactions.
-Allow for crawling and sitting.
Bipedal level:
-Cortical level.
-Equilibrium and protective reactions.
-Allow for standing and walking.

23. 3- According to the level of central nervous system maturation
Spinal reflexes
Cortical reflexes
Brain stem
reflexes
Midbrain reflexes

24. Spinal reflexes
First level of reflexes according to CNS maturation.
Primitive reflexes.
Phasic coordination movement reflexes which coordinate
muscles of extremities in patterns of either total flexion or
extension.
Apedal dominance.
Examples ( Flexor withdrawal, Extensor thrust, Crossed
extension).

25. Is a spinal reflex.
It is polysynaptic reflex.
Aim : To protect the body from damaging stimuli.
Flexor withdrawal reflex, a common
cutaneous reflex consisting of a
widespread contraction of flexor
muscles and relaxation of extensor
muscles. It is characterized by
abrupt withdrawal of a body part in
response to painful or injurious
stimuli. A relatively innocious
stimulation of the skin may result in
a weak contraction of one or more
For example :
Flexor withdrawal reflex ( nociceptive reflex ):-
Spinal reflexes

26. 2nd Level, static postural, apedal.
Complete domination of these primitive brain stem reflexes
results in an apedal (prone , supine - lying) creature.
They affect the distribution of muscle tone either in response
to change position of head & body in space (labyrinths
stimulation) or in response to change of head in relation to
the body (proprioceptive stimulation).
Brain stem
reflexes

27. Examples of Brain Stem Reflexes :-
1- Asymmetrical Tonic Neck Reflex ( ATNR )
2- Symmetrical Tonic Neck Reflex ( STNR )
3- Tonic Labyrinthine Supine and Prone
4- Positive Supporting Reaction
5- Negative Supporting Reaction
6- Associated Reactions
Brain stem
reflexes

28. Righting reactions interact with each other and work toward
establishment of normal head and body relationship in space
as well as in relation to each other.
Their combined actions enable the child to roll over, sit up,
get on his hands and knees, and make him a quadripedal
creature.
They are integrated at the midbrain level above the red
nucleus, not including cortex.
( Righting reactions
)
Midbrain reflexes
There are the first such reactions to develop after birth and
reach maximal concerted effect about age ten to twelve
months. As cortical control increases, they are gradually
modified, inhibited and disappear towards the end of the fifth
year.

29. The righting reflexes involve complicated mechanisms and
processes associated with the structures of the internal ear,
such as the utricle, the saccule, the macula, and the
semicircular canals.
Any change in the position of the head produces a change in
the pressure on the gelatinous membrane of the macula. The
fibers of the nerve (vestibular branch of the eight cranial
nerve) transmit impulses to the brain, producing a sense of
position. The head and trunk are thus kept in alignment. Also
activating righting reflexes are proprioceptors in muscles and
tendons and visual nerve impulses. Also called body righting
reflex.
Midbrain reflexes

30. Types of Righting Reaction
Definition :
A series of righting reactions develop in the first year of life and
serves to maintain head alignment with the body and upper-body
alignment with lower body. When rotation is imposed on the body,
these reactions realign the segments of the body. These reactions also
maintain body alignment during forward flexion of the trunk and
prone suspension.
Types :
1- Neck righting acting on body.
2- Body righting acting on body.
3- Labyrinthine righting acting on head.
4- Optical righting acting on head.
5- Amphibian Reaction.
Midbrain reflexes

31. Automatic Movement Reactions:
They are not strictly righting reflexes, but are reactions produced by
changes in the position of the head and hypothetically involved either
the semicircular canals or labyrinths, or neck proprioceptors.
Types :
1- Moro reflex
2-Landau reflex
3-Protective Extensor Thrust

32. These reactions are mediated by the efficient interaction of
cortex and basal ganglia and cerebellum.
Maturation of equilibrium reactions bring the individual to
human bipedal stage of motor development.
Types of Cortical
Reactions
Cortical reflexes
Equilibrium Reactions
1
Protective Reactions
2

33. Responses to external disturbance [either placing child on
unstable surface, or manual displacement from stationary
supporting surface].
Are reactive or compensatory reactions.
They continue to develop in more upright positions in first 5
years of life.
Equilibrium and Protective Reactions :-
They emerge in lower – level positions [supine, prone] when
the infants is 4 to 6 months of ages.
Cortical reflexes

34. Aim: Serve to return the child’s body to a vertical position
after displacement.
Stimulus: Tilting [anterior, posterior, lateral or diagonal].
Equilibrium Reactions
1
Cortical reflexes
Response: [movement of trunk and extremities that oppose
the displacement to bring COG within BOS]

35. Aim: Protective reactions differ from equilibrium reactions in
that they protect the infant from a fall rather that correct a
displacement.
Stimulus: The amount of displacement needed to elicit
protective reaction must be greater in magnitude than used
to elicit equilibrium reaction.
Protective Reactions
2
( Parachute reactions
)
Response: These reactions are characterized by extension and
abduction of the extremities to “catch” the child as he falls
i.e. to stop the movement. Response occur in the same
direction of fall.
Cortical reflexes

36. 4- According to the type of stimulus
1-Reflexes
respond to touch
• Palmar grasp reflex.
• Plantar reflex.
• Placing reflex.
• Rooting reflex.
2-Reflexes
respond to pressure and pain
• Gallant’s reflex,
• Withdrawal reflex.
• Crossed extension.
• Babiniski reflex.
• Magnet reflex.
• Walking/stepping reflex.
3-Reflexes
respond to kinesthetic stimuli e.g.
 Tendon reflexes
 Asymmetrical tonic neck
reflex.
 Symmetrical tonic neck reflex.
 Moro reflex.
 Head righting on body.
 Body righting on body.
4-Reflexes
respond to visual and auditory stimuli
e.g.
 Blink reflex.
 Optical righting,
 Startle.

37. 5- According to their time of appearance
Primary reflexes (primitive) which are present at birth and
disappear during the first year, then fade to be replaced by
secondary reflexes (postural reaction)which mainly appear in
the second 6 months of first year).
Primitive reflexes ( Time of appearance) :
Survival and protection (Function)
Postural reactions ( Time of appearance) :
Reaction to gravity and changes in the equilibrium
(Function).