Chapter 3 The development of posture and movement

All movement is dependent upon related supporting postures for its control. Posture and movement are interdependent and develop hand in hand.

When observing the posture and movement behavior of people with spinal pain and related disorders one can usually see altered qualities and patterns of response. To help understand and appreciate these patterns, an examination of salient aspects of early motor development is helpful. This is not intended as a comprehensive treatise on the multiple aspects of development, but rather the opportunity to particularly see how movement control of the spine develops. To analyze the important component parts and the patterns of posture and movement as they emerge and contribute to the repertoire of adult movement control – in particular as they pertain to the development of axial and proximal girdle control, and so, effective control of the spine.

Motor development theories

The development of our movement control is a journey with gravity. From birth, the process of development begins to establish the basic components and patterns of all our movements. The evolution of effective postural control underlies the development of a reasonably predictable sequence of movement events and behaviors. For instance we learn to turn over, sit, crawl, stand and walk and so on. Theories of early motor development encompass two principal schools of thought:¹

• Reflex hierarchy has been the more traditional approach to child motor development. This places great importance on the reflex substrate for the emergence of mature human patterns. The development of postural and movement control is dependent on the appearance of these tonic reflexes controlled at lower levels within the central nervous system (CNS). With neural maturation and development of the higher levels in the CNS – the mid brain and cortex, these reflexes are subsequently integrated into more functional postural and voluntary motor responses (Fig. 3.1).

• A ‘dynamic systems control’ approach considers that postural and movement control develop from a complex interaction of musculoskeletal and neural systems including perceptual, cognitive and motor processes collectively called the postural control system. How the elements within the system are organized depends on interactions between the individual, the task and the environment. ‘Systems theory does not deny the existence of the reflexes but considers them as only one of the many influences on the control of posture and movement.’ Trew ² further elaborates: we are ‘observed to perform specific motor tasks in similar ways despite the opportunity to get to the endpoint by a variety of routes. This suggests that, for many movement tasks, there is likely to be an optimum way of moving that requires the least energy for that length and weight of limb as well as the sort of movement required’ However, there is still the opportunity to choose differing qualities of muscle action and performance which allow us to do that particular movement in similar but slightly different individual ways. The amount of skill we develop through practice of a movement determines how flexibly we can accommodate to slightly different circumstances. Motor learning is a process of adjusting movement characteristics to a new task or challenge. This dynamic systems approach tends to link biomechanical and behavioral variables more than other models. Maturation, learning, perception practice and emotional factors all contribute to effective biopsychosocial development.³

Fig 3.1 • Functional levels of the CNS in relation to neuromaturational theory.

Salient aspects of early sensorimotor development

According to Kolar ^4,⁵ motor development is automatic and dependent upon sensory orientation, motivation and emotional need. It is characterized by the development of motor patterns which are genetically predetermined, overlap and allow for:

• the control of posture or position

• achievement of the vertical position

• purposeful phasic movements of the limbs.

Movement patterns occur through the development of muscle co-activation synergies which themselves are dependent on the body posture as a whole, and not that of a particular segment. Each stage of development is characterized by the development of specific partial motor patterns which, with the process of motor development, represent the basic elements of mature motor behavior.

Movement development in utero

Movement is life. It begins as that of cell division in the embryo and as the nervous system begins to mature, movements of the fetus begin to develop. Hartley ⁶ and Bainbridge Cohen⁷ note the importance of intrauterine movements in helping the nervous system develop. The first nerves to myelinate are, according to them, the vestibular nerves. As the fetus moves and is moved within the mother’s body, sensory information from the vestibular nerves begins to be processed within its CNS. This perception of movement stimulates more movement or a change in movement which in turn elicits new sensory information – we are moved and then we receive sensory feedback about the movement. Sensorimotor learning thus begins in utero.

Neonatal period and change birth – 9 months

At birth, the CNS is still undeveloped. The lower centers of the CNS are more operant which is reflected in the infant’s motor activity being largely influenced by neonatal reflexes, which are automatic, stereotyped and predictable. The baby’s movements are crude with no component of voluntary control or meaningful direction. The body responds mechanically and automatically to a number of influences such as touch, sound, head or body position. This results in changes in muscle tone which then effects a posture and or movement response in a number of consistent patterns – termed ‘the primitive reflexes’.⁸

Bobath ⁹ considers that normal motor development can be characterized by two sets of processes which are closely interwoven and dependent upon one another:

• The development of the normal postural reflex mechanism through the development of the righting, equilibrium and other adaptive and protective reactions. The development of these reactions is closely associated with normal postural tone which allows for maintenance of positions against gravity and the performance of normal movements.

• The inhibition of some of the reflex responses of the neonate such as primary standing and walking, and the startle reaction. Inhibition also shows itself in a change in the early total responses, such as the flexor withdrawal response from a total response which involves all segments of a limb to some only. This process of ‘breaking up’ the early total responses, makes possible a re-synthesis of parts of the total patterns in many and varied ways. This, in association with the development of the postural control mechanism mentioned above allows for the performance of selective movements and motor skill.

Primitive postural reflexes: early movement experiences of the neonate

In general, the neonate is flexed and symmetrical in all positions – in supine, prone, vertical or ventral suspension ⁹ due to dominant physiological flexor hypertonus. While he can turn his head he otherwise has poor head control and the only extension is reflex, via the Moro or startle reaction which bilaterally extends the arms. The emerging development of head control begins to initiate the development of extensor tonus. The symmetrical flexor activity starts to be broken up by the appearance of the asymmetrical tonic neck reflex at about 1 month old as the physiological extensor tone starts to appear. The legs are more mobile and show alternate incomplete flexion and extension via the reflex crossed extension kicking which also helps breaks up the symmetrical flexor tonus.

These various automatic reflex postural reactions which make up his early movement repertoire are stimulated by touch or pressure to particular areas of the body, passive movements of the head, torso or limbs, changes of position, changes in relation to gravity, or sudden unexpected sounds, movements, etc. The infant responds to the stimulus by moving toward it or drawing away; these responses support the potential for bonding or defending.⁶ Importantly, these early responses help ensure survival and provide the infant with the experience of movement and support while he is in the process of developing his own higher level control. As this develops they either disappear or become integrated into higher order patterns of movement control. The timing of their appearance and disappearance, symmetry and intensity helps in the evaluation of early motor function. Their retention, under activity or over activity and asymmetry are indicative of potential motor problems.

It is not intended to comprehensively examine all the primitive reflexes but to look at the underlying influence of some towards important aspects of mature motor control.

Oral reflexes: beginning of head control

The rooting reflex is the first postural reflex that initiates movement of the head.⁶ Mouth opening is associated with head extension while sucking or mouth closing is related to a sagittal flexion of the skull rocking on the first vertebra, the movement then transferring down the spine heralding the beginning of spinal movement control initiated from the head. Hartley⁶ notes that if this pattern does not become fully integrated with the closing phase of this action not completely developed, habitual mouth opening and related hyperextended head postures ensue. This very common pattern underlies many neck shoulder and back problems in adulthood.

Other reflexes such as the Babkin and Grasp reflex provide additional stimulus to neck righting (rotation), to neck flexion and the initiation of head righting in supine. They also underlie the pattern for mouth–hand coordination ⁷ and establish midline focus for the mouth and hands.

Anal rooting reflex initiates movements from the tail

When the area around the anus is stimulated the infant will move its tail towards the touch. This reflex underlies the development of spinal movements which are initiated from the tail ⁷(Fig. 3.2). ‘Going long’ from the tailbone also helps achieve a ‘neutral spine’. These important functional actions are invariably difficult in people with back pain.

Fig 3.2 • Leading movements from the tailbone is basic to many daily activities.

Galant’s reaction:precursor to lateral movements

Stroking the back on one side elicits a side bending movement. This contributes towards initiating unilateral trunk movement; provides the initial movement for rotation; is the precursor to the initiation of amphibian movement necessary for crawling, creeping and walking; helps break up the symmetrical patterns of flexor and extensor movement and is the beginning of asymmetrical movements.⁸ If both sides are stimulated together the infant will extend the lumbar spine.⁷

Abdominal reflex underlies trunk flexion

Stimulation on either side of the navel when supine results in the infant ipsilaterally flexing the lumbar spine. If both sides are simultaneously stroked, the infant will flex the lumbar spine.⁷ This reflex balances the galant and both contribute to moving the chest and pelvis through space.

First vertical antigravity experiences

The primary standing, primary stepping and placing reactions of the legs contribute towards the first sense of vertical self support. At this time the support reaction is primitive and incomplete as extensor tone is only present to the knees,⁸ but they assist the infant to overcome the dominant flexor tonus contributing to the development of flexor and extensor tone balance and reciprocal leg movement for future standing and walking.

First extensor experience

The Moro reflex or startle reaction is characterized by reflex extension and abduction of the arms, opening of the hands and crying. It is a response to ‘stress’. The reflex has two phases following the first phase described above, the infant flexes his head, curls his body, flexes and draws his arms across his body and closes its hands as though embracing himself. The legs may extend during both phases, unless they are already extended, in which case they may flex.⁷ It allows the infant to first symmetrically widen through his chest and upper limbs and then to recover with an embrace. It is then a protective action. The reflex helps develop extensor tone in the arms at a time when physiological flexor tonus is dominant and establishes a base for all opening and closing movements of the torso. As stress is a common contemporary phenomenon, it is common to observe people adopting habitual postures which relate to the second stage Moro (Fig. 3.3).

Fig 3.3 • Adults frequently adopt postures reflecting aspects of the second stage Moro reflex.

Early protective responses

The flexor withdrawal reflex and the extensor thrust reflex underlie our neuromuscular patterns of ‘protection’.

• Flexor withdrawal is a defensive (flight) reflex. Upon stimulation of the feet or hands of the extended limb, the infant reacts with a total flexion pattern of withdrawal. It assists in the early balancing of muscle tone between the flexors and extensors.⁸ It underlies all flexion movements of the leg or arm initiated from the feet or hands and leads into the negative supporting reflex of the lower limb, which prepares the hands and feet to release their contact with the ground in crawling, walking and jumping.⁷

• Extensor thrust reflex is elicited when the palm or sole of a flexed limb are stimulated leading to a total extension pattern of the limbs. This is defensive (fight) reflex and underlies all extension movements of the total arm or leg that are initiated from the hand or foot such as kicking, creeping, walking, climbing and equilibrium responses. This reflex leads into the positive supporting reflex of the upper and lower limbs.⁷

Reciprocal limb movements

Crossed extension kicking is a simple spinal reflex where if one leg is extended the other will flex. This is an integration of the flexor withdrawal on one side and the extensor thrust on the other side. It helps to develop alternating extensor tone in the lower extremities; break up symmetrical flexion and extension patterns, and is the precursor to amphibian movements in preparation for later reciprocal limb movements for crawling and walking patterns.

The amphibian reaction is an important appearance at 6 months of age and remains throughout life.¹⁰ When the pelvis is lifted on one side, the arm and leg on the same side automatically flex (Fig. 3.4) This helps further break up the total flexor and extensor responses, produces weight shift and the experience of rotation through the trunk initiated from the pelvis. This is an important functional pattern and with further neuromuscular maturation, the infant develops his own selective control of this movement pattern. It is common that people with spinal pain have difficulty with this movement.

Fig 3.4 • The amphibian action provides important patterns of spinal movement.

Positive supporting reactions underpin antigravity control

Establishment of the positive supporting reactions is an important aspect of developing antigravity control.

• Positive supporting reactions of the arms and legs. This appears around the third month or so in both the legs and arms. The stimulus is initially exteroceptive from touch to the sole or palm, and then pressure adds a proprioceptive stimulus from stretch to the interosseous muscles. This stimulates the extensor muscles; however, the infant learns to co-contract the antagonist flexor muscles in a balanced and coordinated fashion to provide for dynamic stability of the joints ⁸ in weight bearing. Through this reflex, extensor tone begins to develop in the limbs from distal to proximal. It underlies all weight bearing on the upper and lower limbs and the spine. Through its action, forces pass from the support, through the limbs, proximal limb girdles and importantly the baby’s centre – the spine.⁷ This ‘pushing away’ is important in firing up the infants’ antigravity responses. Bainbridge Cohen⁷ notes that if this connection is not well established, the baby will substitute with the Propping Reaction.

• Positive support from the head and tail. Apart from Bainbridge Cohen’s work,⁷ these supporting reactions do not appear to be well appreciated in the literature. She and others¹¹ she has influenced who work in the area of improving movement performance, use the concept of the head and tail as ‘limbs’ from which to bear weight, initiate movement, and improve and refine control. The infants head pushes as it nuzzles. Support through the tail occurs in sitting and can be stimulated through play activities such as bouncing the infant’s bottom on an adult’s knee for ‘Ride a cock horse’ and similar play. Both these early responses are important in establishing the initiation of movement control from the top and bottom of the spine as well as co-activation of antagonist muscles for dynamic control. Support from the tail is important in sitting. Commonly, in those people with back pain, there is difficulty initiating and controlling the spine from the head and tail bone.

Compensations can begin early

Attention parents and carers! According to Bainbridge Cohen (and others ¹⁴), the Propping Response occurs when the infant is placed in a position which is higher in relation to gravity than it could attain by ‘pushing up’ itself. The baby responds by ‘fixing’ its limb(s) in ‘total extension’ and propping its body weight without connecting the lines of force from the ground through its proximal limb girdles and through its centre – the spine. This occurs when the baby has not sorted out his own control and parents try to do it for him. There is excess influence from the Tonic Labyrinthine Reflex and under activity from the positive supporting reaction, which will then require excessive tone in the back muscles (Fig. 3.5). She maintains this is a common occurrence in adults with back problems and it is certainly a common finding in the clinical situation. Back pain research has also shown excess back muscle activity with a lack of the flexion relaxation phenomenon in people with back pain.^12,¹³

Fig 3.5 • Being placed in sitting too early encourages ‘propping’ and early axial imbalance.

Tonic attitudinal postural reflexes: produce changes in postural tone and body posture as a result of head position

These reflexes appear before or at birth and usually become integrated into more complex patterns of movement by 4–6 months of age. They are controlled at the spinal level and brain stem (the low brain). These tonic reflexes are not obligatory in normal development. They produce reliable changes in body posture as a result of a change in the head position.¹ They consist of:

Tonic labyrinthine prone and supine reflex (TLR)

This is apparent from birth to about 6 months after which it becomes integrated and ‘disappears’. Changes in the position of the head and body in space affects the labyrinths which initiates the sensory input for the reflex arc. Increased postural/ muscle tone develops on the underside of the body with respect to gravity. When the infant is supine this reflex produces an increase in extensor tone; when prone an increase in flexor tonus. If lying on the side, the tone in the underside body is facilitated. The subsequent development of more integrated control of flexion when supine and extension when prone modifies this reflex. This helps develop the patterns of flexor/extensor coactivation needed for spinal alignment and control. Bainbridge Cohen sees that the TLR, in increasing postural tone on the underside of the body, is the basis for ‘grounding’, drawing us down to the earth ⁷ – that from and through this, we can begin to move towards finding grounding in our verticality.

Asymmetrical tonic neck reflex (ATNR)

This is readily apparent at birth for two or more months. If the head is turned to the side, the arm and hand on the face side will extend reflexly, while the arm and leg on the skull side will flex. Its contribution in movement development is that it begins to break up the symmetrical flexion and extension patterns of movement; helps develop an alternation of these patterns; and enables each side of the body to be used separately. It also prepares the way for the integration of neck turning, visual fixation and reaching. As such it is fundamental to the establishment of visually directed reaching and eye hand coordination.⁸

Symmetrical tonic neck reflex (STNR)

This appears around the 5th to 6th month and begins to ‘disappear’ around the 9th month. Head flexion causes flexion of the upper extremities and extension of the lower limbs; head extension causes extension of the arms and flexion of the legs. As the prone TLR is being integrated and so becoming less obvious, the STNR develops. As the neck is developing dorsiflexion, stimulated by the labyrinthine and optical righting reflexes, the STNR facilitates the development of extensor tone concurrently in the upper limbs and flexor tone in the lower limbs. This alteration in flexor and extensor tone in the upper and lower body from changes in head flexion and extension facilitates the development of a balance between the flexors and extensors for stable positions against gravity. The infant gradually develops the ability to be prone on elbows and later to push up to extended elbows, to hands and knees and down again.

Integration and contribution of postural reflexes in the development of movement

In the developmental continuum, the postural reflexes supply the basic balance of muscle tone. This is a prerequisite to further control developing.

Bainbridge Cohen ⁷ also considers that the primitive reflexes establish the basic gross patterns of function that utilize and underlie all movements. She says:

They are the alphabet of movement and build and combine together to create more varied patterns of movement. If there is deficient development of these earliest and simplest reflexes, the more advanced patterns will be absent, weak or incomplete. The reflexes depend on each other for efficient functioning. For every reflex there is an opposite reflex which modulates it, each acting as a shadow to the other. In efficient movement, they interface and counter-support one another at all times, creating balanced postural tone and integrated movement.

The primitive reflexes underlie the righting reactions and the equilibrium responses and so, support their development.

In early motor development, primitive reflexes are more obligatorily but not always triggered by specific stimuli. Bainbridge Cohen ⁷ sees that once that reflex has developed and then become appropriately integrated through higher central nervous control, that particular movement pattern will become part of one’s automatic movement repertoire although with or without the stimulus occurring, and in any plane in relation to gravity. When looking at integrated movement in the adult we don’t see the isolated reflexes but rather, their underlying support and influence on the movement.⁷

Importantly, if the reflexes do not develop in synchrony, they remain too static or fixated, and postural tone will be too low, too high or fluctuating and inconsistent. This problem is manifested in extremes in persons having overt brain dysfunction’. Minimal brain dysfunction is often described as ‘clumsiness’.

Part of the thesis of this book is that in general people with spinal pain and related disorders demonstrate various, consistent and often subtle features of more primitive motor behavior. The continuing influence of the primitive and attitudinal reflexes can sometimes be observed in some aspects motor behavior in otherwise ‘normal healthy adults’. For example, when on all fours and turning the head, the skull arm may flex indicating a lingering ATNR influence (Fig. 3.6). Likewise when on all fours the head may drop from the neutral position, the arms may flex somewhat and the patient will find good hip flexion difficult due to lingering STNR influence (Fig. 3.7).

Fig 3.6 • Elements of ATNR behavior can sometimes be observed in the adult.

Fig 3.7 • Elements of STNR behavior is also sometimes observed.

Righting reactions: help develop more integrated control

Collectively these are a chain of actions that sequentially interact with each other to create a smooth transition from one developmental stage to the next and to maintain a proper relationship to the environment – nose vertical and eyes and mouth horizontal. These are more advanced patterns of movement than the primitive and attitudinal reflexes and are controlled by the midbrain. Some of them begin to develop at birth, are most dominant at 10–12 months of age and most of them remain active throughout life. There are five of these as follows:¹

Three righting reactions: orient the head in space

These begin to make their appearance from birth onwards and bring the head into vertical orientation in space and in relationship to gravity.

• Optical righting reaction (ORR) which contributes to reflex orientation of the head using visual inputs – the eyes adjusting to the horizon

• Labyrinthine righting reaction (LRR) which orients the head to an upright vertical position in response to vestibular signals

• Body on the head righting reaction (BOH) which orients the head when the body is in the lateral position as a result of asymmetrical stimulation of proprioceptive and tactile signals as the body makes contact with a hard surface.

Orientation of the body with respect to the head and the ground

These righting reactions make their appearance around 6 months of age and persist through life. They bring the head and torso into mutual alignment in relationship to each other.

• The neck on body righting reaction (NOB). This orients the body in response to cervical afferents, reporting changes in the position of the head and neck. There are two forms of this reflex: the immature form, resulting in log rolling which is present at birth and the mature form which subsequently develops producing segmental rotation of the body.¹

• The body on body righting reaction (BOB). This keeps the body oriented with respect to the ground or surface regardless of the position of the head. This is necessary for the development of the rotary components of movement and for developing higher skills for assuming the sitting and quadruped position.⁸

Landau reaction

This combines the effects of all three head righting reactions ¹ and makes its appearance around 6 months of age. When the infant is supported under the chest in ventral suspension, he will first right his head followed by symmetrical extension which develops cephalocaudal down the spine to the thighs at the hips (Fig. 3.8). If the head is passively flexed the torso and thighs will follow suit and flex also.