Posture and Body Mechanics Quiz

Posture

• Posture is the position or attitude of the body, the arrangement of body parts for a specific activity or characteristic manner of bearing one's body, either sitting, upright, or recumbent.
• Posture is described by the positions of the joints and body segments and also in terms of balance between the muscles crossing the joints.

Base of Support (BoS)

• Defined by an area bounded posteriorly by the tips of the heels and anteriorly by a line joining the tips of the toes; considerably smaller than the quadrupedal BoS.

Center of Gravity (CoG)

• The point where the mass of the body is centered; referred to as the center of mass (CoM).

Curves of the Spine

• Lordosis and kyphosis are important curves in the spine. They contribute to flexibility and withstand the effects of gravity and external forces.

Static and Dynamic Posture

• Static Posture: The body and its segments are aligned and maintained in certain positions (standing, lying, or sitting).
• Dynamic Posture: Refers to postures in which the body and/or segments are moving (walking, running, etc.).

Postural Control

• Can be either static or dynamic.
• Refers to the person's ability to maintain stability of the body or body segments in response to forces that threaten the body's structural equilibrium.

Major Goals and Basic Elements of Postural Control

• Includes absent or altered inputs and outputs, muscle synergies, and sensory & mechanical perturbations.
• Different strategies, using specific muscles, are used for movement and response to force, e.g., ankle, hip strategies.

Static Postural Control

• Involves maintaining a particular posture against gravity.

Dynamic Postural Control

• Involves maintaining stability during movements of the body/segments and/or changes in the supporting surface.

Maintenance/Control of Posture

• Depends on the integrity of the central nervous system (CNS), visual system, vestibular system, musculoskeletal system and inputs from receptors in and around joints, tendons, and ligaments.

Internal & External Forces

• Internal Forces: Muscle activity, passive tension of ligaments, tendons, capsules, and other soft tissue structures.
• External Forces: Inertia, gravity, and ground reaction forces (GRF).

Line of Gravity (LOG)

• Plumb line, anterior, posterior, lateral.
• Combined action line formed by the ground reaction force vector (GRFV) and gravity line.

Spinal Ligaments

• The structures provide stability to the vertebral column; examples include anterior longitudinal, posterior longitudinal, ligamentum flavum, supraspinous, interspinous, etc.

Line of Gravity (LOG) - Joint-Specific Effects

• Describes the relationship between the LOG and resultant forces at various joints. Specific relationships are described for different joints (e.g. A-O joint, cervical, thoracic, etc.).

Postural Analysis

• The goal of any posture is to reduce energy expenditures and stress on supporting structures.

Optimal Posture

• Body segments aligned vertically, LOG close to, but not through, most joint axes.
• Compression forces distributed optimally over weight-bearing surfaces of joints.
• No excessive tension on ligaments and muscles.

Optimal Alignment (Lateral View)

• Specific measurements for the ankle, knee, hip, and sacroiliac and lumbar spine joints.

Lateral View - Deviations from Optimal Knee Alignment

• Describes possible knee deviations or postures. Example: flexed knee posture, hyperextended knee (genu recurvatum).

Excessive Anterior Pelvic Tilt

• Forces the lumbar vertebra anteriorly, resulting in lumbar lordosis and compensatory thoracic kyphosis and forward head.

A/P View

• Bisects the body into two symmetrical halves, joint axes equidistant from the LOG and gravitational line transects the central portion of the vertebral bodies.

Knee Deviations (A/P View)

• Genu valgum or varum, (bowleg, knock knee) are described in terms of forces and stress on associated structures.

Foot & Toes Deviations (A/P View)

• Pes planus/flat foot, rigid/flexible, hallux valgus, claw toes, and hammer toes.

Anterior View (Assessment)

• Describes several features to be assessed in an anterior view of the body, e.g. head, shoulders, clavicles, waist angle, carrying angle, iliac crest/ASIS, patellae, knees, arches of the foot, and out-toeing.

Compression Effects of Malalignment on Body Structures

• Table showing effects of common postural deviations (pelvic tilt, lumbar lordosis, dorsal kyphosis, cervical lordosis), affecting tissues like ligaments, muscles, and discs.

Posterior View

• Describes various features to be assessed in a posterior view of the body from head, knee, shoulders, scapulae, spine, ribs, waist angle, arms from body, PSIS, gluteal folds, etc.

Scoliosis

• Lateral curvature of the spine, possible structural or non-structural.
• Includes etiology (structural- idiopathic, congenital, neuromuscular; non-structural), possible complications, and pathology (e.g., compressed side structures, apical vertebra shape and rotation of vertebral body).

Etiology of Pain

• Ligaments, facet capsules, periosteum, muscles, anterior dura mater, dural sleeves, epidural areolar adipose tissue and walls of blood vessels. These are innervated and responsive to nociceptive stimuli

Effect of Impaired Postural Support from Trunk Muscles

• Curves become exaggerated without muscle support
• Leads to postural impairment, imbalances of muscle strength/flexibility and other soft tissue restrictions (e.g. hypermobility).
• Causes include habitually kept stretched or tight musculature.
• Sustained postures require continual, small adaptations in stabilizing muscles to resist fluctuating forces.

Pain Syndromes Related to Impaired Posture

• Describes postural fault, postural pain syndrome (pain from prolonged faulty posture), postural dysfunction (shortening of soft tissues/muscles).

Common Faulty Postures

• Describes various common faulty postures (e.g. Lordotic posture, relaxed or slouched posture, flat low-back posture, round back (increased kyphosis).).
• Each posture is described with their characteristic features and associated muscle impairments.

Lordotic Posture

• Involves increase in lumbar lordosis and anterior pelvic tilt and hip flexion, potentially associated with kyphosis.
• Possible causes: sustained faulty posture, pregnancy, obesity, and weak abdominal muscles, abnormal dorsal kyphosis, and hip flexion contracture. Possible related effects and impairments, and common causes are also provided.

Relaxed or Slouched Posture

• Characterized by excessive shifting of the pelvic segment, resulting in hip extension and shifting of the thoracic segment posteriorly, resulting in thoracic flexion on the upper lumbar spine..
• This posture results in increased lordosis in the lower lumbar region, increased kyphosis in the thoracic region, and a forward head. Causes of this include prolonged standing, asymmetrical weight bearing and associated muscle issues.
• Possible sources of related symptoms.

Flat Low-Back Posture

• Characterized by a decreased lumbosacral angle, decreased lumbar lordosis, hip extension and posterior tilting of the pelvis.
• Potential sources of related symptoms and common causes.

Round Back (Incarsed Kyphosis) with Forward Head

• Characterized by an increased thoracic curve, protracted scapulae (round shoulders), and forward (protracted) head.
• Possible causes include effects of gravity, poor ergonomic alignment (work/home environment), occupational/functional postures requiring bending, and faulty sitting postures.
• Potential muscle impairments and associated sources and symptoms and common causes are outlined.

Kyphosis

• Anteroposterior curvature of the spine; convexity directed posteriorly.
• Causes include faulty posture, chronic arthritis and Pott's disease.
• May include other disease entities (e.g. Adolescent kyphosis).

Flat Upper Back and Neck Posture

• Characterised by a decrease in thoracic curve, depressed scapulae, and decreased cervical lordosis.
• Potential muscle impairments, sources of symptoms, and common causes are described.

References

• Lists the references used.