Gait and Gait Cycle Overview

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Questions and Answers

What is the primary task during the single limb support phase of the gait cycle?

One limb supports body weight while providing truncal stability (correct)

The limb is stationary in mid-air

Both limbs support body weight

Neither limb supports body weight

Which phase of the stance involves the foot being flat on the ground?

Toe off

Loading response (correct)

Mid-stance

Heel strike

How is the swing phase characterized in the gait cycle?

Foot swinging forward through three positions (correct)

Foot flat on the ground

Both feet on the ground

Foot in contact with the ground

Which of the following is NOT a component of the stance phase of gait?

Midswing Signup and view all the answers

What occurs during the heel off to toe off phase of the stance?

The foot lifts off the ground in preparation for swing Signup and view all the answers

In which phase does propulsion occur during the gait cycle?

Toe off Signup and view all the answers

Which type of nerve injury involves a transient block with rapid and complete recovery?

Neurapraxia Signup and view all the answers

What is a characteristic of Axonotmesis?

Intact surrounding connective tissue Signup and view all the answers

How many parts make up the swing phase of the gait cycle?

Three Signup and view all the answers

What role do the double limb support periods play in the gait cycle?

They provide stability during limb advancement Signup and view all the answers

What type of nerve injury is classified as a complete section of the nerve trunk?

Neurometsis Signup and view all the answers

Which degree of Sunderland classification indicates only the epineurium remains intact?

Fourth-degree Signup and view all the answers

What occurs in the case of a third-degree nerve injury?

Endoneurium is damaged Signup and view all the answers

Which nerve fibers are responsible for sharp pain sensation?

A-delta fibers Signup and view all the answers

What happens to the nerve cell body in severe damage?

Degeneration of the entire neuron Signup and view all the answers

Which type of nerve injury is most commonly caused by pressure?

Neurapraxia Signup and view all the answers

What is the correct definition of a single gait cycle?

The period between two foot contacts from the same foot. Signup and view all the answers

Which phase of the gait cycle involves the foot being in contact with the ground?

Stance Phase Signup and view all the answers

What is considered the most demanding task in the gait cycle?

Weight acceptance Signup and view all the answers

Which of the following components is NOT essential for normal walking?

Cardiac endurance Signup and view all the answers

What best describes the term 'gait'?

A series of rhythmic alternating movements for locomotion. Signup and view all the answers

Which physiological system is NOT mentioned as a component crucial for the mechanism of walking?

Endocrine system Signup and view all the answers

What occurs during the swing phase of the gait cycle?

The foot moves forward without ground contact. Signup and view all the answers

Which of the following statements is true regarding nerve lesions?

They can disrupt normal gait patterns. Signup and view all the answers

What occurs during Wallerian degeneration?

The axon distal to the injury becomes swollen and irregular. Signup and view all the answers

Which statement about the proximal segment changes is true?

They extend only proximally above the lesion to the first node of Ranvier. Signup and view all the answers

What is the role of Schwann cells following axonal injury?

They begin to proliferate rapidly. Signup and view all the answers

What happens to the nucleus of the cell body after axonal injury?

It migrates toward the periphery of the cell. Signup and view all the answers

What is the term used for the changes occurring in the cell body following axonal injury?

Chromatolysis Signup and view all the answers

What factors are crucial for the regeneration of axons in the peripheral nerves?

Endoneurial tubes and Schwann cells Signup and view all the answers

How long may recovery and regeneration of the nerve cell body take?

Months Signup and view all the answers

What happens to the myelin sheath after axonal injury?

It is converted into lipid droplets. Signup and view all the answers

Study Notes

Gait

Gait is the study of human locomotion, including walking and running.
Walking consists of a series of gait cycles, each cycle known as a stride.

Gait Cycle/Stride

A single gait cycle or stride is the period when one foot contacts the ground until the same foot contacts the ground again.
Each stride has two phases: stance phase and swing phase.
Stance phase: the foot is in contact with the ground (approximately 60% of the gait cycle). Further divided into:
- Heel strike to foot flat
- Foot flat to mid-stance
- Mid-stance to heel off
- Heel off to toe off
Swing phase: the foot is not in contact with the ground (approximately 40% of the gait cycle). Further divided into:
- Initial swing
- Mid-swing
- Terminal swing
Stride has two periods of double limb support (both feet on the ground)
- Loading response (right) and toe off (left)
- Loading response (left) and toe off (right)

Gait: Physiology

Gait depends on the integrated function of bones, muscles, and the nervous system (Central and peripheral).
The degree of integration determines the different gait patterns.
Defects in any part of this system will lead to pathological gait.

Gait: Mechanical

Gait is a form of bipedal locomotion achieved by rhythmic alternating actions between the lower extremities.
One leg supports, restrains, and propels, while the other leg is in the swing phase to initiate the next step.
Movements of the arms, legs, and trunk create the forward movement of the body.

Normal Walking Requirements

Equilibrium: the ability to maintain balance and assume an upright posture.
Locomotion: the ability to initiate and maintain rhythmic stepping.
Musculoskeletal Integrity: normal bone, joint, and muscle function.
Neurological control: must receive and send messages telling the body how and when to move (visual, vestibular, auditory, and sensorimotor input).

Nerve Lesions

A neuron is the basic functional unit of the nervous system.
In mature humans, if a neuron is destroyed, it is not replaced.
Nerve injuries can be caused by cutting, crushing, pulling, or applying pressure.
Nerve injuries are categorized by the extent of damage sustained.
Seddon (1944) described 3 clinical types of nerve injury:
- Neurapraxia (Class 1): a transient block; paralysis is incomplete; recovery is rapid and complete; no nerve degeneration. Pressure is a common cause.
- Axonotmesis (Class 2): a nerve lesion with damaged axons but intact surrounding connective tissue; Wallerian degeneration occurs peripherally; functional recovery is more rapid than if the nerve trunk is completely severed. Crush injuries, traction, and compression are among the most frequent causes.
- Neurotmesis (Class 3): complete section of the nerve trunk; typically caused by severe contusion, stretch, or laceration.
Sunderland (1951) expanded the classification to 5 degrees, with some overlap with the Seddon classifications (first-degree = neurapraxia; second-degree = axonotmesis).

Types of Nerve Injuries (Sunderland Classification):

First-degree: Similar to Seddon's neurapraxia; minimal damage, with rapid and good recovery
Second-degree: Similar to Seddon's axonotmesis; axon damage with intact connective tissue; moderate recovery, but takes more time compared to first degree
Third-degree: Lesion of endoneurium, with intact epineurium and perineurium; possible recovery with or without surgery
Fourth-degree: Epineurium only remaining intact; surgical repair needed. Possible but often needing surgical intervention
Fifth-degree: Complete transection of the nerve; complete loss of function, likely needing surgical intervention

Nerve Injury: Changes (general)

Wallerian degeneration: distal changes in the injured axon
Chromatolysis: changes in nerve cell body (nucleus shifted to the periphery, swelling)
Regeneration considerations:
- Peripheral nerves have good regenerative capacity due in part to the endoneurial tubes and Schwann cells.
- CNS regeneration is less effective due to a lack of functional Schwann cell counterparts, and possible presence of growth inhibiting factors

Terminology

Paralysis: complete loss of motor function.
Paresis: incomplete loss of motor function.
Anesthesia: loss of all sensation.
Hyperesthesia: excessive sensory input.
Hypoesthesia: diminished sensory input.
Hyperalgia: excessive sensitivity to painful stimuli.
Hypoalgesia: decreased sensitivity to painful stimuli.

Nerve Fiber Types

A-alpha: largest fiber, fastest conduction, fine touch, position (balancing)
A-beta: proprioception (balancing)
A-delta: sharp pain, fast
C fibers: slow pain

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Description

This quiz explores the fundamentals of human locomotion, focusing on gait cycles and strides. Learn about the phases of the gait cycle, including stance and swing phases, and their significance in walking and running.