Different types of
Primitive Reflexes
Moro Reflex
The Moro reflex is the first of the primitive reflexes to emerge and the first to inhibit after birth. It usually emerges around 9–12 weeks after conception and is normally fully developed at birth. It should switch off around 2- 4 months of age.
The Moro reflex is the baby’s “alarm reflex”. As a newborn baby is incapable of rational thought, it cannot assess whether a threat is real or not. It is therefore protected by the Moro reflex, which is an unconscious, automatic response to a perceived threat. Like the other primitive reflexes, the Moro reflex emanates from the (unconscious) brainstem, the first part of the brain to develop and function.
On startle, the baby will rapidly throw its arms upwards and away from its body with its hands open. This is accompanied by a sharp intake of breath. It is followed by a relaxing of the posture on the out-breath with the baby bringing its arms in across the chest and clenching its fists and may be followed by a cry. These automatic movements are an important survival technique and are a signal to the outside world that the baby is in difficulty and needs parental attention.
When the Moro reflex is triggered , the baby’s ‘fight or flight’ response is activated, releasing adrenaline and cortisol ( the ‘stress hormones’) into its bloodstream .This results in an increase in the baby’s rate of breathing and heart rate, as well as a rise in blood pressure and reddening of the skin.
The Moro is multisensory and can be triggered by any or all of the senses, including an unexpected or loud noise, an unexpected change in light levels, an unexpected or intense touch, pain, a sudden change in temperature and a sudden movement of the body or in the visual field.
If the Moro reflex remains active beyond 6 months, it becomes an automatic, involuntary (over)reaction, which is strong enough to override the higher, decision- making, centres of the brain.
Once the Moro is triggered and our ‘fight or flight’ response is activated, we tend to perceive everything in our environment as a potential threat to our survival. Our fear is exaggerated; we see everyone and everything as a possible enemy. Our system will be in a constant state of over-stimulation, making it even more sensitive to sound, touch, movement and visual information. We find ourselves in constant ‘flight or flight’ and the excess levels of stress hormones in our system can have far-reaching implications, not only impacting on our physical and emotional wellbeing but also affecting our behaviour.
TLR
The Tonic Labyrinthine Reflex has 2 separate patterns, the TLR forwards and the TLR backwards. Each has its origin in the vestibular system ( which is responsible for balance) and is elicited by movement of the baby’s head.
The TLR forwards emerges in the womb ( at around 3-4 months) and should be inhibited by 4 months of age.
When baby’s head is tilted forwards chin to chest, its arms and legs flex. Its arms bend into its body and as its knees bend, its legs are drawn into its tummy.
The TLR backwards emerges at birth and its inhibition is a gradual process involving the maturation of other ‘systems’. It should be inhibited by three and a half years.
When a baby’s head is tilted backwards below the level of its spine, its arms and legs extend. The baby’s back may stiffen and even arch upwards.
The TLR is responsible for helping the brain and senses develop a correct relationship with gravity, allowing us to know where we are in time and space.
It also stimulates and strengthens baby’s muscles and is important for the later development of postural reflexes.
STNR
The Symmetrical Tonic Neck Reflex usually emerges around 6 -9 months after birth and should inhibit when baby is around 9-11 months.
It is not regarded as a primitive reflex but rather as an infant or transitional reflex, being an extension or adaptation of the TLR. Its primary purpose is to help the baby rise up on its hands and knees and prepare it for crawling.
The STNR is a two phase reflex:
When the baby’s head is tilted forwards, its arms flex and its legs extend.
When the baby’s head is tilted backwards, its legs flex and its arms extend.
Children who retain the STNR rarely crawl on their hands and knees. Instead they might “bear walk” on their hands and feet or “bottom shuffle “.
ATNR
The Asymmetrical Tonic Neck Reflex usually emerges around 18 weeks after conception. It should be fully present at birth and should switch off around 6 months after birth.
When a baby’s head is turned to the side, the jaw limbs extend and the occipital (opposite) limbs flex. So when the baby’s head it turned to the right, its right arm and leg will extend and its left arm and leg will flex, and vice versa.
The ATNR stimulates muscle tone and balance mechanisms in the womb and is crucial to the birthing process. The ATNR not only assists the birthing process but is activated and reinforced by it which may explain why babies born by Caesarean or with use of forceps are at higher risk of neuro-developmental delay.
The ATNR is also crucial to survival of the newborn after birth and should ensure a free passage of air when baby is placed on its tummy by helping it turn its head to one side. Furthermore, as well as increasing muscle tone in the extended limbs, it aids in the baby’s ability to reach out for things and provides the first opportunity for baby to use its eyes to shift focus and establish hand-eye coordination.
FPR
The FPR is a withdrawal reflex, rather than a ‘primitive’ reflex, which emerges very early after conception. It is expected to inhibit with the emergence of the Moro reflex at 12 weeks after conception.
The FPR is thought to be the first response to stress and is a protective response. During the early stages of its development, the embryo responds to stress and stimulation by withdrawing and ‘freezing’.
When the FPR is retained beyond birth, it results in limited stress tolerance and hypersensitivity to sensory stimuli. Its persistence beyond birth can also result in difficulties with attachment and issues with understanding the social world around us.
It can be characterised by withdrawal, both mentally and physically. The child may be withdrawn, ‘internalised’, extremely shy and reticent to be involved in anything new. Withdrawal does not necessarily mean quiet withdrawal as the child may scream loudly when faced with a new or uncomfortable situation.
Spinal Galant Reflex
The Spinal Galant Reflex emerges 20 weeks after conception. It should be actively present at birth and should inhibit by 3 to 9 months of age.
If you stroke a baby to either side of its spine, it will cause the hip on that side to flex or rotate.
Like the ATNR , the Spinal Galant Reflexes important in the birthing process as it facilitates movement of the hips as the baby works its way down the birth canal.