Spinecare Topics

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Posture and the Spine
A Overview of Posture and the Spine

Posture refers to the position of the body and the relationship between anatomic regions of the body. Posture is not limited to an upright erect position. It refers to the attitude of the body in any position. Posture refers to the relationship between joints, muscles, and extremities in different planes. In the upright vertical plane posture involves the relationship between the head, shoulders, pelvis, and feet, all of which influences the center of gravity of the body.

Posture is dynamic, biologically controlled, and constantly changing. It is a complex biological function which requires highly coordinated neurological and muscular activity required to maintain stability and to support movement. The effect of gravity on the body is opposed by the dynamic control mechanisms of posture. Good posture refers to positioning of the body in a manner which maintains stability and balance with a minimum of effort. Good posture minimizes energy expenditure, enhances the efficiency of human movement and equally transmits weight-bearing loads on supportive structures such as bones and joints.

Postural Dynamics and Control
Postural control is a dynamic mechanism which refers to an individual's ability to consciously and unconsciously control muscles to maintain stability and to respond to external forces.

Postural control is dependent on the integrity of the central nervous system (brain and spinal cord), visual system (eyes), vestibular mechanisms (inner ear), and musculoskeletal (muscles, bones and joints) system. It is also dependent on information received from specialized (sensory) nerve receptors located within and around joints of the spine and from the bottom of the feet. Most of the postural control mechanisms are reflexive, therefore not requiring conscious decisions or acts. Conscious decisions to change posture arise within the outer layer of the brain referred to as the cortex and involve specialized centers within the deeper portion of the brain referred to as the basal ganglia and cerebellum.

Postural control is perpetual. For example, at all times during an upright posture there is a normal sway of the body in all planes which is controlled by the neuromuscular system. A breakdown in communication between the nervous system and the muscular system can lead to postural instability and abnormal movement patterns. Certain muscles referred to as postural muscles have the ability to maintain an adequate degree of contraction to provide stability. Thisrequires biological energy expenditure. Any metabolic or systemic condition which compromises energy pathways can influence posture. Weight-bearing postures require finely tuned adjustments in nerve signaling and muscular control. Many of these biological signaling pathways are developed or become more efficient through habit and repetitive behaviors. For this reason, postural stability and postural control can be improved through specialized exercises, physical rehabilitation, and general mindfulness of posture.

Impact of Poor Posture
Poor posture can have a significant impact on an individual's overall health and quality of life. For example, poor posture can have an adverse impact on the efficiency of bodily movement, joint health and energy expenditure. Postures which alter chest biomechanics and rib movement can have an adverse impact on respiratory (breathing) rate and volume. Chronic abnormal loading of joint tissues such as cartilage can contribute to earlier wear and tear induced degenerative changes. Poor posture in high-performance settings such as sports can reduce the efficiency of human performance.

There are many causes of poor posture. The general categories include developmental asymmetry, acquired deformity, systemic disease, muscle weakness or paralysis, habitual positioning and tissue remodeling, degenerative disorders, and pain. Psychological states and attitude can also have an influence on posture. Bad habits acquired during childhood can lead to developmental susceptibility to poor posture later in life based upon structural developmentand neurological connectivity. Prolonged occupational positions can lead to inefficient or poor posture due to adverse tissue remodeling and altered neurological control of postural muscles.

Posture: Tissue Adaptation and Remodeling
Biological tissues such as muscles, tendons, ligaments and bone repair and remodel based on the stresses placed upon them. For this reason, chronic postural patterns can lead to structural changes in supportive of tissues which influence flexibility, movement, as well as, the integrity and health of tissues. The deficiency of adequate stress placed upon certain tissues can lead to tissue thinning or atrophy with a loss of structural integrity. In contrast, excessive mechanical stress placed upon tissues can lead to a change in structural contours and density of tissue.

The term neuroplasticity refers to the functional and structural changes in neurologic tissues as a result of firing or signaling patterns. Nerves that fire together wire together. Chronic abnormal posturing leads to alterations in nerve firing patterns which can lead to structural changes in neural pathways resulting in "hardwired" unconscious mechanisms rendering it difficult to assume more efficient postural patterns.

Postural Assessment
Posture can be evaluated through many different approaches. Visual observation is the most common approach is to evaluate posture. In the clinical setting posture is often assessed with an a individual standing in an upright position with the knees straight, the head facing forward, and the arms beside the body. This places most of the joints of the body in a neutral position.

Postural assessment is then typically evaluated from three perspectives which include an anterior (front) view, posterior (behind) view, and a lateral (side) view. Emphasis is commonly placed on assessment of head alignment, curvature of the spine, positioning of the shoulders and arms, pelvic inclination, and the relationship between the hip, knee and ankle joints. Foot positioning and arch mentions are often included in postural assessment. Advanced posturalassessment in some settings may include quantitative gait assessment and dynamic postural measures using sophisticated quantitative technologies. The capability of postural reactivity may also be measured in some laboratory settings.

The Spine and Posture
The spine plays an important role in posture. It provides protection of the spinal cord and weight-bearing support. It also provides the segmental movement required for postural adaptation. From the side the spine is characterized by forward curve in the neck and low back regions referred to as the lordosis. It is characterized by posterior curve in the mid back referredto as the kyphosis. From a front perspective the spine is generally straight.

Postural evaluationof the spine from a front perspective may reveal a lateral (side-to-side) curvature referred to asa scoliosis. The primary types of scoliosis include congenital (developmental), neuromuscular,paralytic, and idiopathic (unknown cause). The most common cause of scoliosis is idiopathic. The phrase non-structural scoliosis refers to a functional curvature of the spine often associated with postural maladaptation associated with athletic overtraining, occupational demands, or habitual postures. Nonstructural scoliosis also may occur in the presence of muscular disease or paralysis of muscles secondary to diseases and/or injury to the central nervous system The relationship between the lower spine and the pelvis influences spinal segment movement patterns and core stability. For example, weakness of the abdominal musculature can contribute
to an increase in the lordotic (forward) curve of the lumbar spine; thus, placing greater load-bearing stress upon the lumbar spinal (facet) joints. Research has demonstrated that a slumped forward posture increases the load on the joints of the neck, mid back and low back. The presence of pain can lead to deviations of posture. For example, research has demonstrated that individuals with chronic pelvic pain are more likely to experience poor balance, impaired reactive postural control, and abnormal gait (walking) patterns.

The Feet and Posture
The foot and ankle plays an extremely important role in posture. The bony and ligamentous structures of the feet provide some stability to the lower body. Specialized sensory receptors located within the joint capsules, tendons and muscles of the lower extremity including the foot and ankle regions provide important feedback for postural control. Foot and ankle stability requires constant biological adjustments in muscular activity and muscular tone in response to
movement, postural sway and sensory input. Neurological conditions which compromise sensory input from the lower extremities, particularly the foot and ankle regions disturbs postural reflexes, muscle firing patterns and subsequently movement efficiency. A loss of mechanical support of the arch of the foot such as pes planus (flat foot) or over pronation can contribute to postural instability and abnormal gait. Abnormal ankle synergy can also lead to excessive bodily
sway and increased risk for falling. Limb length inequality (LLI) due to structural and/or functional causes can contribute to abnormal posture and compensatory postural control mechanisms. Different causes for LLI of include joint replacement, joint degeneration, contractures, foot over pronation, developmental bone length, and pelvic rotation.

Correction of Posture
The first step in the correction of posture is heightened awareness of postural inefficiency and abnormalities. This is often achieved through assessment with a specialist such as a chiropractic physician, physical therapist, neurologist, neurosurgeon or orthopedic surgeon. The correction of posture sometimes requires a multidisciplinary team approach. Some healthcare providers may have special certification and/or training in postural control and rehabilitation. Contributing factors such as an underlying disease process, pain, muscular weakness patterns, and structural deformities must be addressed. The  therapeutic approach to abnormal posture may include mindfulness of posture, therapeutic exercise, biofeedback, nutritional intervention to improve bioenergetics and in rare cases surgical intervention. It is important that all individuals have periodic postural evaluation in order to facilitate early intervention.

The American Academy of Spine Physicians acknowledges the importance of maintaining good posture to improve spine integrity and general health. Good posture supports efficient movement, minimizes energy expenditure, and reduces the risk for chronic pain syndromes.

Educational Partners

To learn more about your spine. spinehealth, and available spinecare go to the International Spine Assocition (ISA) at www.spineinformation.org. The primary mission of the ISA is to improve spinehealth and spinecare through education. The ISA is committed to disseminating need-to-know information throught the World Wide Web in numerous languages covering many topics related to the spine, including information about spine disorders, spine heath, advances in technology and available spinecare



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