Bipedalism and Locomotion Anatomy

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Questions and Answers

What is a significant advantage of bipedalism related to locomotion?

Access to non-locomotor forelimb tasks (correct)

Increased stability compared to quadrupedalism

Increased speed over short distances

Improved climbing capability

Which of the following describes a disadvantage of bipedal locomotion?

More efficient energy usage compared to quadrupedalism

Decreased visibility to predators

Increased risk of injury from single limb involvement (correct)

Enhanced climbing abilities in trees

Which factor does NOT contribute to the determination of stable walking?

Body segment coordination

Kinematics of gait

Forelimb utilization (correct)

Environmental factors

What evolutionary change does bipedalism primarily encompass?

Compromised stability for better visual access Signup and view all the answers

What is a key descriptor of gait that is crucial for its quantification?

Translational progress of the body Signup and view all the answers

What does bipedalism primarily allow in terms of environmental adaptation?

Enhanced capacity to gather and hunt Signup and view all the answers

Which aspect of bipedalism could potentially expose individuals to greater risks?

Exposure of vulnerable body parts Signup and view all the answers

Which of the following is NOT associated with the disadvantages of bipedalism?

Limited mobility on flat surfaces Signup and view all the answers

What is a significant consequence of not maintaining a proper single limb stance during walking?

Collapse of body weight support Signup and view all the answers

Which observation is most likely to indicate a hemiplegic gait following a right hemisphere stroke?

Prolonged stance phase on the affected side Signup and view all the answers

What factor is least likely to influence abnormal gait patterns?

Breathing techniques Signup and view all the answers

How does pain associated with a disorder directly affect walking ability?

It leads to a forced, compensatory movement Signup and view all the answers

Which statement accurately describes a characteristic of step length asymmetry?

It can indicate potential underlying disorders. Signup and view all the answers

What adaptation in humans allows the pelvis to sit directly under the skull?

Change in spinal curvature Signup and view all the answers

Which factor is NOT a requirement for efficient bipedal locomotion in humans?

High upper body mass Signup and view all the answers

What major change in the femur angle in humans contributes to bipedal locomotion?

Increased angle of the femur Signup and view all the answers

What is a significant evolutionary change in the foot structure of humans?

Raised arches Signup and view all the answers

The foramen magnum in humans sits in which position relative to the skull?

Directly under the vertex of the skull Signup and view all the answers

What is the primary advantage of bipedal locomotion in humans, according to the content?

Energetically efficient movement Signup and view all the answers

Which structure in humans has NOT adapted significantly due to the requirement for upright gait?

Nasal structure Signup and view all the answers

What adaptation regarding body mass has contributed to maintaining balance in upright gait?

Reduced mass above the waist Signup and view all the answers

Which of the following changes is primarily responsible for the shearing forces at the head of the femur during bipedal gait?

Angle of the femur Signup and view all the answers

What is NOT a determinant of stable walking in bipedal locomotion?

Adaptations in upper body musculature Signup and view all the answers

What percentage of the gait cycle is primarily composed of the stance phase?

60-65% Signup and view all the answers

Which component is NOT considered a distance variable in gait analysis?

Step duration Signup and view all the answers

Which phase of ankle motion corresponds to propulsion during walking?

Active plantarflexion Signup and view all the answers

How is walking speed calculated in relation to cadence and step length?

Speed = cadence x step length Signup and view all the answers

Which joint phase involves knee extension preparatory to contact?

Extension pre-contact Signup and view all the answers

What is one of the determinants of gait economy that helps minimize vertical movements of the center of gravity?

Knee flexion Signup and view all the answers

Which of the following statements is true regarding joint kinematics during walking?

Effective joint rotations contribute to propulsion and force absorption. Signup and view all the answers

Which gait feature contributes to reducing lateral movements of the center of gravity?

Physiologic valgus at the knee Signup and view all the answers

What is the effect of forward and backward pelvic rotation during walking?

Helps maintain extended leg positions. Signup and view all the answers

Which of the following variables is assessed to differentiate efficient from inefficient gait patterns?

Base of support width Signup and view all the answers

Study Notes

Locomotion

Defined as a translatory progression of the body as a whole, produced by coordinated rotary movement of body segments.
Upright gait has evolved many times.

Why Bipedalism?

Energetically efficient, Improves predator sighting, Striking display, Allows non-locomotor forelimb use, Improved thermoregulation.
Less stable, Makes one more obvious to predators, Exposes vulnerable body parts to predators, Slower than quadrupedal running over short distances, Single limb injuries are more disabling, Energetically expensive to pump blood against gravity, Significantly more loading on spine, pelvis, hips, knees, ankles - increased injury risk, Makes climbing more difficult.

Implications of Bipedalism

Significant anatomical changes are required for bipedal gait.
Large upper body mass is undesirable.
Strong pelvis/hip muscles are required.
The vestibular system is relied on more.

Anatomical Adaptations for Bipedalism

Foramen Magnum: Positioned directly under the vertex of the skull, in early hominoids it was positioned towards the back of the skull.
Spinal Curvature: Humans have developed additional lumbar spine curvature to allow the pelvis to sit directly under the skull.
Pelvic Shape: Modified to accommodate bipedal locomotion.
Leg Structure: Humans have a greater angle of the femur than other hominoids. This allows the feet to be placed below the pelvis during stance phase of gait, but increases shearing forces at the head of the femur.
Mass Distribution: Humans have reduced mass above the waist, which makes maintaining balance easier.
Foot Structure: Reduced size of primary toe, elimination of opposable digits, raised arches.

Kinematics of Human Upright gait

Phases of the Gait Cycle: Stance phase (60-65%), Swing phase (35-40%), Double support phase (22%).

Quantifying Gait

Distance & Temporal Variables:
- Stride length: Linear distance between two successive events accomplished by the same lower extremity during gait.
- Step length: Linear distance between two successive points of contact of opposite extremities.
- Stride duration: Time taken to complete one stride.
- Step duration: Time taken to complete one step.
- Cadence: Number of steps taken per minute.
- Speed: Cadence x Step length, Stride length x Stride length.
- Width of Base of Support: Distance between the feet when walking.
- Degree of toe out: Angle of the foot in relation to the direction of travel.

Joint Angles

Ankle Motion: Slight plantarflexion (during contact), Passive dorsiflexion, Active plantarflexion (propulsion), Active dorsiflexion (during leg swing), Neutral position (pre‐contact).
Knee Motion: Flexion (after contact), Extension (support), Flexion (propulsion), Further flexion (ground clearance), Extension (pre‐contact).
Hip Motion: Extension (loading and trunk translation), Flexion (propulsion), Slight extension (pre‐contact).
Motion Beyond the Sagittal Plane: Frontal plane pelvic rotation, Transverse plane pelvic rotation.

Determinants of Gait Economy

Minimising vertical movement of the CoG: Lateral pelvic tilt (pelvic drop), Knee flexion, Interaction of joint actions.
Minimising drop in the body’s CoG: Lateral pelvic tilt reduces the peak CoG position.
Minimising drop in the body’s CoG: Forward and backward pelvic rotation allows legs to remain in a more extended position.
Minimising lateral movements of the CoG: Physiologic valgus at the knee reduces the width of the base of support.
Trunk Motion: Torques produced around vertical axis cancel to promote forward motion.
Upper Extremity Motion: Torques produced around vertical axis cancel to promote forward motion.

Analysing Gait

Ten Critical Elements of Gait Assessments:
- Step length asymmetry
- Ankle at contact
- Knee at contact
- Stance phase knee flexion
- Duration of single-limb support
- Ankle and foot angles during push-off
- Swing phase knee flexion
- Trunk angle
- Frontal plane: excess hip drop (Trendelenburg sign)
- Transverse plane: posture

Requirements for Normal Gait

Each leg in turn must be able to support the body weight without collapsing.
Balance must be maintained (statically or dynamically) during single limb stance.
The swinging leg must be able to advance to a position where it can take over the supporting role.
Sufficient power must be provided to make the necessary limb movements and to advance the trunk.

Abnormal Gait

If someone does not meet one of these 4 requirements they are unable to walk. This can result from a disorder in any part of the body's system, the presence of pain, or compensation for another problem.
Movement may be forced due to weakness, spasticity, or deformity.
Movement may be a compensation to correct for some other problem that must be identified.

Factors that Affect Gait

Age, Injury, Fitness, Clothing, Disease, Footwear, Environment.

Stroke - Hemiplegic Gait Analysis

Example of abnormal gait caused by stroke.
Right hemisphere stroke, left hemiplegia.
Observations: Slow gait, short stride, Short LT step length, LT ankle limited dorsiflexion, LT knee limited flexion, LT hip hiking, LT arm in fixed flexion.
Observations: Why? Short LT mid-stance phase (not providing sufficient stability), Prolonged RT stance phase (compensatory stability/propulsion), Short LT GRF (reduced propulsion on left side), Minimal change in LT knee/ankle joint positions (paralysis/weakness), Underactive left TA/Gastroc (lack of central drive).

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Description

This quiz explores the concept of bipedalism and its significance in locomotion. It covers the reasons behind the evolution of bipedal gait, the anatomical adaptations required, and the implications for movement and stability in various environments.