Module 11: Posture and Balance Control

Question 1

What is the definition of center of gravity?

Answer 1

The centre of a body where all the weight is considered to be concentrated. The balance point where the entire weight of the body is focused

Question 2

What is the definition of center of mass?

Answer 2

The point about which the mass of the object is evenly distributed. The even mass point where mass is spread out evenly in all directions

Question 3

What is the definition of line of gravity?

Answer 3

Projection of the centre of gravity to the ground. Imaginary line dropping straight down from the COG / balance point to the ground

Question 4

Name the 3 curvatures of the human spine.

Answer 4

Thoracic kyphosis, and cervical and lumbar lordosis.

Question 5

What are the body landmarks to determine the LOG in the sagittal plane?

Answer 5

The mastoid process (thru), shoulder joint (anterior), hip joint (posterior), and the knee and ankle joint (anterior)

Question 6

What is the definition of base of support?

Answer 6

The surface area of the body that is providing support.

Question 7

Name the 3 arches of the foot.

Answer 7

Transverse arch, medial and lateral longitudinal arches

Question 8

Name 2 roles of the foot in maintaining an upright posture.

Answer 8

Stability and propulsion

Question 9

What is the location of the COG in sitting compared to standing posture?

Answer 9

Lower in space, but higher in relation to the trunk

Question 10

In sitting, which body part is responsible for weight distribution?

Answer 10

The ischial tuberosities

Question 11

What does correct sitting posture look like?

Answer 11

Bottom placed at the back of the seat.
Up to two-thirds of thighs supported to avoid knee compression.
Chair height adjusted so knees and ankles are at right angles.
Feet placed hip-distance apart on the floor.

Question 12

In supine lying, what are the body areas most likely to suffer from pressure?

Answer 12

Occipitus, scapula, spinous processes, sacral bone, ischial tuberosities, heels

Question 13

In side lying, what are the body areas most likely to suffer from pressure?

Answer 13

Ears, shoulders, hips, ankles

Question 14

What is the shape of the spine of a newborn?

Answer 14

A concave, forward-facing curve

Question 15

What are the factors that contribute to the development of the cervical lordosis and the spinal lordosis in the infant?

Answer 15

Cervical lordosis: Lifting the head in prone.
Lumbar lordosis: Sitting and weight-bearing through the lower spine

Question 16

What are the characteristics of a baby’s posture when standing?

Answer 16

Flat feet in full contact with the ground.
High, anterior COG (around T12).
Wide BOS for stability.

Question 17

At around what age does the child present with foot arches and spinal curvature similar to those of an adult?

Answer 17

6 years old

Question 18

What are the challenges in terms of posture development faced by teenagers?

Answer 18

Imbalance between bone growth (rapid) and soft tissue growth. Environmental influences like staying a desks, heavy backpacks…

Question 19

What are the challenges in terms of posture faced by adults?

Answer 19

Work and prolonged “forced” postures

Question 20

Name 5 pathological postures.

Answer 20

Scoliosis, hyperkyphosis, hyperlordosis, swayback, flatback

Question 21

Define scoliosis and describe the body’s compensations that may occur.

Answer 21

A lateral curvature of the spine that can be static or mobile. Muscles on the concave side adapt by becoming shorter and more tightened. The muscles on the convex side become elongated and weak.

Question 22

Define kyphosis and describe the body’s compensations that may occur.

Answer 22

An exaggerated anterior curve of the spine in the thoracic region. Increased cervical lordosis, rounded shoulders, reduce thoracic expansion

Question 23

Define hyperlordosis and describe the body’s compensation that may occur.

Answer 23

An exaggerated inward curvature of either the lumbar or cervical spine. Anterior pelvic tilt, pregnancy-related changes, weakness in the gluteal and core muscles, increase shearing forces on the spine

Question 24

Define swayback posture and describe the body’s compensations that may occur.

Answer 24

“Slouched” posture: pelvis forward, knees hyperextended, increased lumbar lordosis and thoracic kyphosis. Uses least amount of muscle work, relies on soft tissue, ligaments, bony back.

Question 25

Define flat back posture and describe the body’s compensations that may occur.

Answer 25

A posterior pelvic tilt, reduced lumbar lordosis, spine appears to be flat. Hip and knee hyperextension, lengthened hip flexors, shortened abdominal muscles, elongated back extensors

Question 26

What are the 3 systems used for postural control?

Answer 26

Vestibular, visual, somatosensory

Question 27

How does the vestibular system contribute to the maintenance of posture?

Answer 27

Sensory Receptors detect changes in head position. These receptors are constantly firing to provide real-time data about the head’s orientation. Any shift in head position alters the rate of firing of these sensory receptors. Postural Adjustments

Question 28

How does the visual system contribute to the maintenance of posture?

Answer 28

Sensory Input: Transmission to the Brain via the optic nerve. Processing in the Brainstem to control eye movements,

Question 29

How does the somatosensory system contribute to the maintenance of posture?

Answer 29

Joint receptors, detect changes in joint position and movement. Muscle spindles sense muscle stretch and tension. Mechanoreceptors in the feet and hands detect pressure and touch. Subconscious Processing. Motor Response

Question 30

How does the central nervous system integrate the sensory information for posture maintenance?

Answer 30

Intermodal Theory of Sensory Organization Hypothesis proposes that all three sensory inputs—visual, vestibular, and somatosensory—contribute equally and simultaneously to posture maintenance. Each system provides critical data about the body’s position in space, helping the CNS to create a cohesive sense of balance and alignment.

Sensory Weighting Hypothesis, the CNS adjusts the weight or importance of each sensory input based on its perceived accuracy and relevance in the current environment. For example, if vision is impaired (e.g., in low light), the CNS might rely more heavily on somatosensory or vestibular information to maintain posture.

Question 31

What is anticipatory balance control? Give an example.

Answer 31

A mechanism in which the body prepares for postural changes before a movement occurs. This allows the body to “anticipate” and compensate for the potential disruptions that specific actions might cause to balance and stability. Before lifting, the muscles of the trunk are activated to stabilize the spine and prevent injury, ensuring the body can maintain balance during the movement.

Question 32

What is compensatory balance control? Give an example.

Answer 32

The body’s ability to react to unexpected perturbations that challenge posture. This is an automatic, reactive process that helps restore balance when the body is displaced. If the body is slightly displaced forward, the calf muscles contract to pull the body back into balance without conscious effort

Question 33

How does the body deal with minor balance perturbations?

Answer 33

Elastic properties of muscles and spinal reflexes help restore balance.

Question 34

What are the 3 balance strategies used to restore balance?

Answer 34

Ankle, Hip and Stepping

Question 35

Describe the ankle strategy.

Answer 35

Corrects small perturbations to the COG. The body makes small adjustments at the ankles to maintain balance. Dorsiflexors (tibialis anterior) and plantarflexors (gastrocnemius and soleus) help correct the position by either tilting the body forward or backward.

Question 36

Describe the hip strategy.

Answer 36

Used when the perturbation is larger or quickly applied, and the ankle strategy is insufficient. The body shifts its balance using movements at the hips and knees. For forward sway, the abdominal muscles and quadriceps are activated to pull the body back.
For backward sway, the hamstrings and paravertebral muscles (muscles along the spine) contract to restore balance.

Question 37

Describe the stepping strategy.

Answer 37

Used when the perturbation is large enough to move the COG outside the BOS. The body takes a step (or multiple steps) to expand the BOS and bring the COG back within the stable base. This strategy is used when the COG is so displaced that it cannot be corrected with ankle or hip adjustments alone. The stepping strategy re-establishes stability by moving the body’s support point.

Question 38

How is balance affected by aging?

Answer 38

Increased Body Sway, Decreased Muscle Strength and Flexibility, Reduced Joint ROM, Declining Sensory System Accuracy, Slower Nerve Conduction and Central Processing