THE SPINE AND POSTURE

Dr. Wajeeha MahmoodBSPT, PPDPT

AlignmentBiomechanical Influences on Postural Alignment1. Curves of spine Posterior curves are in the thoracic and sacral regions.

Kyphosis is a term used to denote a posterior curve. Kyphotic posture refers to an excessive posterior curvature of the thoracic spine.

Anterior curves are in the cervical and lumbar regions. Lordosis is a term also used to denote an anterior curve, although some sources reserve the term lordosis to denote abnormal conditions such as those that occur with a sway back.

The curves and flexibility in the spinal column are important for withstanding the effects of gravity and other external forces.

2. Gravity Ankle: For the ankle, the gravity line is anterior to the joint,

so it tends to rotate the tibia forward about the ankle. Stability is provided by the plantar flexor muscles, primarily the soleus muscle

Knee: The normal gravity line is anterior to the knee joint, which tends to keep the knee in extension. Stability is provided by the anterior cruciate ligament, posterior capsule, and tension in the muscles posterior to the knee (the gastrocnemius and hamstring muscles).

Hip: When the line passes through the hip joint, there is equilibrium, and no external support is necessary. When the gravitational line shifts posterior to the joint, some posterior rotation of the pelvis occurs, but is controlled by tension in the hip flexor muscles (primarily the iliopsoas). During relaxed standing, the iliofemoral ligament provides passive stability to the joint, and no muscle tension is necessary. When the gravitational line shifts anteriorly, stability is provided by active support of the hip extensor muscles.

Trunk. Normally, the gravity line in the trunk goes through the bodies of the lumbar and cervical vertebrae, and the curves are balanced

Head. The center of gravity of the head falls anterior to the atlanto-occipital joints. The posterior cervical muscles contract to keep the head balanced

StabilitySpinal stability is described in terms of three subsystems: passive

(inert structures/bones and ligaments), active (muscles), neural control

1. PASSIVE

2. Muscles Global muscle function. In the lumbar spine, the global

muscles, being the more superficial of the two groups, respond to external loads imposed on the trunk that shift the center of mass.

Lumbar regionRectus abdominis, External and internal obliques, Quadratus

lumborum (lateral portion), Erector spinae, IliopsoasCervical regionSternocleidomastoid, Scalene, Levator scapulae, Upper trapezius,

Erector spinae Deep/segmental muscle function. The deeper, segmental

muscles, which have direct attachments across the vertebral segments, provide dynamic support to individual segments in the spine and help maintain each segment in a stable position, so the inert tissues are not stressed at the limits of motion

Lumbar regionTransversus abdominis, Multifidus, Quadratus lumborum (deep

portion), Deep rotatorsCervical regionRectus capitis anterior and lateralis, Longus colli

3. Neural control The muscles of the neck and trunk are

activated and controlled by the nervous system, which is influenced by peripheral and central mechanisms in response to fluctuating forces and activities

Feed forward control and spinal stability. The central nervous system activates the trunk muscles in anticipation of the load imposed by limb movement to maintain stability in the spine

Etiology of pain Effect of Mechanical StressThe ligaments, facet capsules, periosteum of the vertebrae, muscles,

anterior dura mater, dural sleeves, epidural areolar, adipose tissue, and walls of blood vessels are innervated and responsive to nociceptive stimuli. If the mechanical stresses exceed the supporting capabilities of the tissues, breakdown ensues.

Effect of Impaired Postural Support from Trunk MusclesLittle muscle activity is required to maintain upright posture; but with

total relaxation of muscles, the spinal curves become exaggerated, and passive structural support is called on to maintain the posture. When there is continued end-range loading, strain occurs with fluid redistribution in the supporting tissues, making them vulnerable to injury.

Effect of Impaired Muscle EnduranceEndurance in muscles is necessary to maintain postural control, as the

muscles fatigue, the mechanics of performance change and the load is shifted to the inert tissues supporting the spine at the end-ranges. With poor muscular support and a sustained load on the inert supporting tissues, creep and distention occur, causing mechanical stress

Common Faulty Postures:Characteristics andImpairments

Lordotic PostureLordotic posture is characterized by an increase in the lumbosacral angle (the angle

that the superior border of the first sacral vertebral body makes with the horizontal, which optimally is 30°), an increase in lumbar lordosis, and an increase in the anterior pelvic tilt and hip flexion.

Potential Muscle Impairments Mobility impairment in the hip flexor muscles and lumbar extensor muscles

(erector spinae) Impaired muscle performance due to stretched and weak abdominal muscles Potential Sources of Symptoms Stress to the anterior longitudinal ligament. Narrowing of the posterior disc space and narrowing of the intervertebral

foramen. This may compress the dura and blood vessels of the related nerve root or the nerve root itself, especially if there are degenerative changes in the vertebra or intervertebral disc.

Approximation of the articular facets. Weight bearing through the facets may increase, which may cause synovial irritation and joint inflammation and may eventually accelerate degenerative changes if not corrected.

Common Causes Sustained faulty posture, pregnancy, obesity, and weak abdominal muscles are common causes.

Relaxed or Slouched Posture The relaxed or slouched posture is also called swayback. The amount of pelvic

tilting is variable, but usually there is a shifting of the entire pelvic segment anteriorly, resulting in hip extension, and shifting of the thoracic segment posteriorly, resulting in flexion of the thorax on the upper lumbar spine. This results in increased lordosis in the lower lumbar region, increased kyphosis in the thoracic region, and usually a forward head. When standing for prolonged periods, the person usually assumes an asymmetrical stance in which most of the weight is borne on one lower extremity with pelvic drop (lateral tilt) and hip abduction on the unweighted side. A sitting slouched posture occurs when there is an overall kyphotic curve throughout the entire thoracic and lumbar spine.

Potential Muscle Impairments Mobility impairment in the upper abdominal muscles, internal intercostal, hip

extensor, and lower lumbar extensor muscles and related fascia Impaired muscle performance due to stretched and weak lower abdominal

muscles, extensor muscles of the lower thoracic region, and hip flexor musclesPotential Sources of Symptoms Stress to the iliofemoral ligaments, the anterior longitudinal ligament of the

lower lumbar spine, and the posterior longitudinal ligament of the upper lumbar and thoracic spine. With asymmetrical postures, there is also stress to the iliotibial band on the side of the elevated hip. Other frontal plane asymmetries may also be present and are described in the following section.

Narrowing of the intervertebral foramen in the lower lumbar spine that may compress the blood vessels, dura, and nerve roots, especially with arthritic conditions.

Approximation of articular facets in the lower lumbar spine.

Round Back (Increased Kyphosis) with Forward Head The round back with forward head posture is characterized by an increased

thoracic curve, protracted scapulae (round shoulders), and forward (protracted) head.

A forward head involves increased flexion of the lower cervical and the upper thoracic regions

There may be temporomandibular joint dysfunction Potential Muscle Impairments Mobility impairment in the muscles of the anterior thorax , muscles of the

upper extremity originating on the thorax (pectoralis major and minor, latissimus dorsi, serratus anterior), muscles of the cervical spine and head that attached to the scapula and upper thorax (levator scapulae, sternocleidomastoid, scalene, upper trapezius)

Impaired muscle performance due to stretched and weak lower cervical and upper thoracic erector spinae and scapular retractor muscles

With temporomandibular joint symptoms, the muscles of mastication experience increased tension.

Potential Sources of Symptoms Irritation of facet joints in the upper cervical spine Narrowing of the intervertebral foramina in the upper cervical region, which

may impinge on the blood vessels and nerve roots, especially if there are degenerative changes.

Impingement on the neurovascular bundle from anterior scalene or pectoralis minor muscle tightness

Common Causes The effects of gravity, slouching, and poor ergonomic alignment in the

work or home environment

Scoliosis Scoliosis is defined as a lateral curvature in the spine. It

usually involves the thoracic and lumbar regions. Typically, in right handed individuals, there is a mild right thoracic, left lumbar S-curve, or a mild left thoracolumbar C-curve. There may be asymmetry in the hips, pelvis, and lower extremities.

Structural scoliosis. Structural scoliosis involves an irreversible lateral curvature with fixed rotation of the vertebrae. Rotation of the vertebral bodies is toward the convexity of the curve. In the thoracic spine, the ribs rotate with the vertebrae, so there is prominence of the ribs posteriorly on the side of the spinal convexity and prominence anteriorly on the side of the concavity. A posterior rib hump is detected on forward bending in structural scoliosis

Nonstructural scoliosis. Nonstructural scoliosis is reversible and can be changed with forward or side bending and with positional changes, such as lying supine, realignment of the pelvis by correction of a leg-length discrepancy, or with muscle contractions. It is also called functional or postural scoliosis.

Potential Impairments Mobility impairment in joints, muscles, and fascia on the concave side of

the curves Impaired muscle performance due to stretch and weakness in the

musculature on the convex side of the curves If one hip is adducted, the adductor muscles on that side have decreased

flexibility, and the abductor muscles are stretched and weak. The opposite occurs on the contralateral extremity.

With advanced structural scoliosis, there is decreased rib expansion; cardiopulmonary impairments may result in difficulty breathing.

Potential Sources of Symptoms Muscle fatigue and ligamentous strain on the side of the convexity Nerve root irritation on the side on the concavity Joint irritation from approximation of the facets on the side of the concavityCommon Causes: Structural Scoliosis Neuromuscular diseases or disorders (e.g., cerebral palsy, spinal cord

injury, progressive neurological or muscular diseases), osteopathic disorders (e.g., hemivertebra, osteomalacia, rickets, fracture), and idiopathic disorders in which the cause is unknown are common causes of structural scoliosis.

Common Causes: Nonstructural Scoliosis Leg-length discrepancy (structural or functional), muscle guarding or spasm

from a painful stimuli in the back or neck, and habitual or asymmetrical postures are common causes of nonstructural scoliosis.

Tension headache/cervical headache

Etiology Headaches may follow soft tissue injury or may be caused by

sustained postures, greater occipital nerve irritation or impingement, or sustained muscle contraction (from faulty posture or emotional tension) leading to ischemia. With cervical headaches, the joints and ligaments of the upper cervical spine are often inflamed or in dysfunction. This includes inflammation of cranial nerves V, VII, IX, and X . Headaches may be related to TMJ dysfunction or other conditions, such as allergies or sinusitis, or there may be vascular or autonomic involvement as with migraine or cluster headaches. Cervical impairments, which may lead to headaches, can also arise from faulty thoracic joint mobility. Whatever the cause, there usually is a cycle of pain, muscle contraction, decreased circulation, and more pain, which leads to decreased function and potential soft tissue and joint impairments.

Presenting Signs and Symptoms Therapists can effectively treat headaches if they were caused by

trauma or stress or if function triggers the onset and/or pain begins in the neck and becomes a headache.

Musculoskeletal ImpairmentsMusculoskeletal impairments include: Joint impairments in the upper cervical spine and craniovertebral region Impaired muscle performance (in upper and deep cervical flexors and possibly

multifidus and small posterior suboccipital muscles). Impaired shoulder girdle/scapular posture with related muscle imbalances. Impaired lumbar posture with related muscle imbalances. Impaired neural tissue from pressure or inflammation in the upper

cervical/craniovertebral region. Impaired neuromotor control. Impaired upper thoracic mobility.General Management Guidelines Management is directed toward reversing physical impairments, including

posture correction, stress management, and prevention of future episodes.Pain Management Modalities, massage, and muscle-setting exercises are used to break into the

cycle of pain and muscle tension.Mobility Impairments and Impaired Muscle Performance Examine the flexibility and strength of the muscles in the cervical, upper

thoracic, shoulder girdle, and lumbar spineMobility and flexibility. Increase joint mobility in the cervical spine and

flexibility in the suboccipital musclesScapular stabilization and posture. Train the lower trapezius, rhomboids, and

serratus anterior muscles in tonic holding postures to improve control of scapulothoracic posture