Postural Principles Useful to Consider in Voice Production

Original Editor - Mauro Banfi Top Contributors - Jess Bell, Kim Jackson, Tarina van der Stockt, Uchechukwu Chukwuemeka and Rucha Gadgil

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Introduction

Healthcare professionals from different disciplines may have a quite different approach to posture. Physiotherapists and other rehabilitation professionals consider overall body position, whereas dentists look at occlusal posture and speech therapists assess lingual posture. However, considering just one area in isolation can potentially affect a client's outcome. This page introduces some key postural considerations that may be useful in speech therapy.

Posture

“Posture is the position of the body in [...] space, and [it] is controlled by a set of anatomical structures”.

Human posture refers to the relationship between body parts (e.g. head and neck, trunk, upper and lower limbs) in an upright position. There are three recognised reference planes when assessing posture:

• Sagittal
• Coronal
• Transversal

There are also three physiological curves that act to balance the human spine:

• Cervical lordosis
• Thoracic kyphosis
• Lumbar lordosis

These curves form and stabilise once there is propriceptive maturation of the foot, which occurs at around the age of 5 or 6 years. They help to:

• Maintain balance
• Provide support and resistance against longitudinal pressures

Posture encompasses:

• Position
• Body shape
• Neuromuscular mode of operation
• Static and dynamic balance

Considering these concepts separately can lead to therapeutic failures and misunderstandings between different healthcare professionals.

"Good Posture"

As quoted in Czaprowski et al., Kendall and colleagues define good posture as:

“That state of muscular and skeletal balance which protects the supporting structures of the body against the injury or progressive deformity, irrespective of the attitude (erect, lying, squatting or stooping) in which these structures are working or resting. Under such conditions, the muscles will function most efficiently, and the optimum positions are afforded for the thoracic and abdominal organs.”

Good posture is proposed to have certain benefits:

• Enables effective movement
• Supports the function of the internal organs
• Ergonomic advantages while standing

However, it is also important to note that very few people actually adopt this posture.

The following is considered the ideal alignment:

• The head line begins at the external auditory meatus. It runs:

• • Vertically through the acromion, the lumbar vertebral bodies, and the promontory
  • Slightly posteriorly to the hip joint axis
  • Slightly anterior to the knee joint axis
  • And terminates at, or slightly anterior, to the lateral malleolus

• Other points of reference:

• • The line of gravity should pass just anteriorly to the ear and C3 – C4, tangent to L3 - L4, cross the tibial plate and project centrally to the support polygon (i.e. slightly anterior to the line that connects the tibiotarsal joints)
  • Cervical lordosis should be around 60 mm
  • Dorsal kyphosis should be aligned with the gluteal muscles
  • Lumbar lordosis should be around 40mm

From the frontal view, the flowing lines should be parallel and horizontal:

• Bipupillar line
• Bicondilar line
• Bimammillar line
• Bistiloid line
• Biiliac line
• Bipatellar line
• Bimalleolar line

It is beneficial to observe the posture of clients with vocal or swallowing problems to detect any postural anomalies that may be contributing to their complaint. When considering the relationship with speech therapy in particular, it is important to remember that:

• The neck, like the trunk, has many interdependent structures / viscera
• The vocal system is intricately linked to all structures in the neck and skull, as well as the anatomical structures that underlie phonation and swallowing (i.e. the diaphragm, viscera)

Approaches to Posture

The three most commonly used approaches to posture are:

• Posturology
• Postural re-education
• Osteopathy and manual therapy

Posturology

Posturology is the study of posture. It is an interdisciplinary method that evaluates the activity of postural control systems (e.g. the postural tonic system), measured in an upright position, in normalised situations, through specific evaluation tests.

Origins of Posturology

• In 1837, Charles Bell asked: "“How does a man maintain a standing or bending posture against the wind that blows against him?"
• Mortiz Romberg, a 19th century neurologist, explored the role of podalic (i.e. foot) support, vision and perception
• Marie Jean Pierre Flourens (1794–1867) studied the role of the vestibular labyrinth - through his research on pigeons, he hypothesised that the semicircular canals were involved in the maintenance of posture and balance
• Longet (1845) researched propriocetion of the paravertebral muscles
• De Cyon (1911) studied oculomotricity
• Magnus (1926) conducted various foot studies and looked at the physiological mechanisms of postural control
• The first posturographic platform was built in the 1950s
• Gagey and colleagues in 1986:
  • Provided an effective posturographic interpretation (using objective data)
  • They defined standards that are still followed for posturological evaluation and treatment today.

The Fine Postural System

“The fine postural system (FPS) aims to maintain balance in the most economical way possible.”

Postural receptors are found throughout the human body. They contribute to the creation of the body schema and conscious control of the postural state. There are three types:

1. Exteroceptors: detect information about the world around us. Examples include:
   • The retina - sight information
   • Plantar receptors - touch information from the foot
   • Inner ear - sound information
2. Interoceptors: detect information about the condition of our body from internal organs and processes.
3. Proprioceptors: detect information about our pd load and include:
   • Tendon organs
   • Joint receptors
   • Neuromuscular spindles
   • Stomatognathic system

Centres of Postural Control

All the data collected by sensory receptors is received by postural control centres in the central nervous system. The upper centres are:

• Spinoreticular centres
• Vestibular nuclei
• Basal nuclei
• Precortical nuclei
• Cerebellum
• Cerebral cortex

These structures interpret postural information and, accordingly, induce changes in our musculoskeletal system to ensure we can maintain the position of our body.

Fine Postural Control

Standing upright is a dynamic activity - there will always be some motion even when an individual is standing still (i.e. body sway / oscillations). These oscillations are very small - around 0-4 degrees or 1-2 cm. In order to maintain balance, the central nervous system mediates changes in postural muscle tone.

Postural tone is defined as:

“the steady contraction of muscles that are necessary to hold different parts of the skeleton in proper relation to the various and constantly changing attitudes and postures of the body.”

Postural muscle tone is adjusted in response to the information provided by postural receptors. Information provided by the exteroceptors (like vision) is typically prioritised.