Posture and Balance

Question 1

What is posture?

Answer 1

The relative position of body parts with respect to each other, the environment, and gravity.

Question 2

What is postural equilibrium?

Answer 2

A state where all forces acting on the body are balanced.

Question 3

What are the two types of postural equilibrium?

Answer 3

Static (still) and dynamic (during movement).

Question 4

What type of muscle tone is essential for posture?

Answer 4

Extensor tone – extensor muscles remain active to maintain upright posture.

Question 5

What pathways are involved in postural control?

Answer 5

Ventromedial pathways:

Vestibulospinal
Tectospinal
Pontine reticulospinal
Medullary reticulospinal

Question 6

What do ventromedial tracts control?

Answer 6

Posture by affecting axial and proximal musculature.

Question 7

What is the function of the vestibulospinal tract?

Answer 7

Maintains upright posture and balance via leg extensors; originates from vestibular nuclei.

Question 8

What is the function of the tectospinal tract?

Answer 8

Directs head/eyes toward visual or auditory stimuli (orienting reflex); originates from superior colliculus.

Question 9

What is the function of the pontine reticulospinal tract?

Answer 9

Enhances antigravity reflexes and facilitates extensors for standing.

Question 10

What does the medullary reticulospinal tract do?

Answer 10

Inhibits extensor muscles, counteracts pontine effects, and allows voluntary movement.

Question 11

What is decerebrate rigidity?

Answer 11

Excessive extensor tone due to loss of cerebral inhibition over brainstem nuclei.

Question 12

What causes decerebrate rigidity in humans?

Answer 12

Severe cortical damage leading to unopposed brainstem control.

Question 13

What are the main vestibular structures?

Answer 13

Otolith organs (utricle & saccule) and semicircular canals.

Question 14

What do otolith organs detect?

Answer 14

Head tilt and linear acceleration (utricle = horizontal, saccule = vertical).

Question 15

What do semicircular canals detect?

Answer 15

Angular (rotational) acceleration.

Question 16

What are otoconia?

Answer 16

Calcium carbonate crystals on the otolith organs that respond to gravity.

Question 17

What is the ampulla?

Answer 17

The sensory region in semicircular canals containing hair cells embedded in cupula.

Question 18

What is the function of the Vestibulo-Ocular Reflex (VOR)?

Answer 18

Keeps vision stable during head movement by moving eyes in opposite direction of head rotation.

Question 19

What cranial nerves are involved in Vestibulo-Ocular Reflex (VOR)?

Answer 19

CN III (oculomotor), CN VI (abducens), CN VIII (vestibulocochlear).

Question 20

What is caloric testing?

Answer 20

A method to stimulate the VOR by irrigating the ear with warm or cold water.

Question 21

What is a protective postural reflex?

Answer 21

Reflex extending arms/legs to protect the body during falls.

Question 22

What initiates the limb placing reflex?

Answer 22

Contact of foot/limb with ground triggers muscle stiffening via brainstem and spinal circuits.

Question 23

What is the hopping reaction?

Answer 23

Movement to a new position to restore balance when posture is destabilised.

Question 24

What is anticipatory postural control?

Answer 24

The body prepares for movement by adjusting posture before voluntary motion.

Question 25

What is the difference between feedback and feedforward in posture?

Answer 25

Feedback: Reaction to postural disturbance. Feedforward: Anticipatory adjustment in preparation for movement.

Question 26

What does posture platform testing study?

Answer 26

Muscle responses and balance control when the platform or visual input is altered.

Question 27

What is vestibular plasticity?

Answer 27

The ability of the vestibular system to adapt to new environments (e.g. sea or space).

Question 28

What causes Ménière’s Syndrome?

Answer 28

Endolymphatic hydrops – excess endolymph in the inner ear.

Question 29

What are Ménière’s symptoms?

Answer 29

Vertigo, tinnitus, temporary hearing loss.

Question 30

What causes BPPV?

Answer 30

Dislodged otolith crystals disrupt semicircular canal function.

Question 31

What are symptoms of BPPV?

Answer 31

Sudden dizziness when changing head position.

Question 32

What is vestibular neuronitis vs. labyrinthitis?

Answer 32

Neuronitis: Vestibular branch inflammation Labyrinthitis: Affects both vestibular and cochlear branches (hearing + balance affected)

Question 33

What is the difference between static and dynamic postural equilibrium?

Answer 33

Static: maintaining balance while still. Dynamic: maintaining balance during movement.

Question 34

What type of muscles primarily maintain posture?

Answer 34

Extensor muscles (through continuous low-level contraction).

Question 35

What is the function of postural systems?

Answer 35

To stabilise and maintain the position of the body automatically.

Question 36

Which brainstem nuclei are responsible for posture?

Answer 36

Vestibular, reticular, and tectal nuclei.

Question 37

Which tract originates in the superior colliculus and directs head/eye orientation?

Answer 37

Tectospinal tract.

Question 38

What is the role of the lateral vestibular nucleus?

Answer 38

Facilitates extensor tone in trunk and limbs to maintain upright posture.

Question 39

What is a decerebrate preparation?

Answer 39

Brain transection at the midbrain, removing cerebral input, leaving brainstem and spinal cord functional.

Question 40

What is the effect of decerebrate preparation on muscle tone?

Answer 40

Increased extensor tone (decerebrate rigidity) due to loss of cortical inhibition.

Question 41

What part of the vestibular system detects linear acceleration and head tilt?

Answer 41

Otolith organs – utricle and saccule.

Question 42

What detects angular (rotational) acceleration?

Answer 42

Semicircular canals (anterior, posterior, and lateral).

Question 43

What are otoconia?

Answer 43

Calcium carbonate crystals that move in response to gravity/acceleration and stimulate hair cells.

Question 44

What happens when vestibular hair cells bend toward the kinocilium?

Answer 44

They depolarize and increase firing of the vestibular nerve.

Question 45

What happens when they bend away from the kinocilium?

Answer 45

They hyperpolarize and reduce firing.

Question 46

What is the purpose of the VOR?

Answer 46

Stabilize gaze during head movement to maintain clear vision.

Question 47

What triggers the VOR?

Answer 47

Rotational acceleration sensed by semicircular canals.

Question 48

In the VOR, what muscles move the eyes?

Answer 48

Right lateral rectus and left medial rectus when head turns left (eyes move right).