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Flashcards in Biomechanics of Human Locomotion Deck (17):
1

A 28-year-old soldier was fitted with a new prosthesis for his right lower limb and was having his gait analyzed. The photograph in image B was taken at the same point in the gait cycle that is represented by subdivision indicated by the arrow in image A. Which subdivisions of the gait cycle are represented (i) for the right limb and (ii) for the left limb?

A) Midswing; Terminal stance

B) Pre-swing; Loading response

C) Midstance; Midswing

D) Initial contact; Midstance

E) Terminal stance; Loading response

F) Loading response; Initial swing

G) Terminal swing; Initial contact

H) Initial swing; Terminal stance

Q image thumb

C

The right limb is clearly in midstance in both images. While the left limb in image B looks marginal between initial swing and midswing, image A is clearly in midswing.

See: Slides 21 and 26.

2

A stride contributes to what percentage of the gait cycle?

A) 25%

B) 40%

C) 50%

D) 60%

E) 75%

F) 100%

F

See: Slide 21 and understand the definitions from Slides 7 and 8.

3

In a typical walking gait cycle, what is the correct order of subdivisions for the swing phase?

 

A) Pre-swing → initial swing → midswing → terminal swing

B) Initial contact → midswing → terminal swing

C) Initial swing → midstance → terminal swing

D) Initial swing → midswing → terminal swing

E) Pre-swing → initial contact → midswing → terminal swing

F) Initial contact → pre-swing → midstance → terminal stance

D

See: Slide 19 and Slide 21.

4

In the accompanying image, the man and woman are observed to be adopting a high steppage gait in order for their flippers to clear the ground during swing phase. During normal gait, which of the following muscles is responsible for helping accomplish the main mechanical goal during midswing?

A) Extensor digitorum longus

B) Semitendinosus

C) Tibialis posterior

D) Gluteus medius

E) Rectus femoris

Q image thumb

A

This question is closely integrated with the “Popliteal Fossa and Leg” lecture from week 4.

See: Slide 38 and Slide 41.

5

A 21-year-old woman is on a night out with her friends when she falls down a flight of stairs, consequently injuring her femoral nerve when she lands on large shards of broken glass from the bottle she was carrying.
With the femoral nerve damaged (i) which one of the following muscles would be directly inhibited and (ii) what subdivision of the gait cycle would gait anomalies most likely present as a result of inactivation from this muscle?

A) Gastrocnemius – Midswing

B) Vastus intermedius – Midstance

C) Adductor brevis – Pre-swing

D) Gluteus medius – Loading response

E) Gastrocnemius – Pre-swing

F) Vastus intermedius – Midswing

G) Adductor brevis – Loading response

H) Gluteus medius – Midstance

B

This question is closely integrated with the “Anterior and Medial Thigh” lecture from week 4.

See: Slide 27 and Slide 41.

6

A 20-year-old man is breaking into his own apartment after locking his keys inside when he falls off the balcony, consequently severing his tibial nerve when he lands on a security fence below.
With the tibial nerve damaged (i) which one of the following muscles would be directly inhibited and (ii) what phase of the gait cycle would gait anomalies most likely present as a result of inactivation from this muscle?

A) Vastus lateralis – Midstance

B) Gluteus maximus – Loading response

C) Soleus – Terminal stance

D) Adductor longus – Pre-swing

E) Gastrocnemius – Terminal swing

F) Vastus medialis – Midswing

C

See: Slide 29 and Slide 41. This question is closely integrated with the “Popliteal Fossa and Leg” lecture from week 4.

7

During midstance, what is the main mechanical goal that is achieved through the action of the quadriceps femoris muscle?

A) Controlled dorsiflexion at the ankle joint ensures the foot clears the ground

B) Controlled plantarflexion at the ankle joint preserves momentum

C) Flexion of the leg stabilizes the knee joint

D) Extension of the leg stabilizes the knee joint

E) Flexion of the thigh at the hip joint accelerates the limb F) Extension of the thigh at the hip joint decelerates the limb

D

See: Slide 27. Try this at home: Actively replicate midstance and attempt to walk with a flexed leg at the knee joint...it is extremely difficult to stand on one leg, bend the same weight bearing limb and then try to move forwards. The quadriceps muscles extend the leg at the knee joint to keep our limb straight and stable to help us “carry” our body weight with a forward momentum! Think of canal vaulting (https://www.youtube.com/watch?v=YP32iWoqjnQ) which requires a stiff, straight pole for individuals to cross a river and this is essentially what we want our limb to do.

8

A 13-year-old girl is walking home from school when a large dog from a neighboring garden escapes and attacks her from behind. The girl is admitted to the emergency department suffering from a large penetrating wound located on the lateral aspect of her leg. Upon examination, the physician notes the lateral head of her gastrocnemius muscle is badly damaged. With this muscle injury, at which point during the gait cycle would the physician best observe an associated deficiency in the patient’s gait?

A) Initial contact

B) Loading response

C) Midstance

D) Terminal stance

E) Pre-swing

F) Initial swing

G) Midswing

H) Terminal swing

D

See: Slide 29 and Slide 41.

9

A 38-year-old man suffered a superior gluteal nerve injury in a motorcycle crash in which his right lower limb was caught beneath the bike. The patient was stabilized in the emergency department. Later the patient is examined and the physician observes that he exhibits a “waddling” gait and a positive Trendelenburg sign. In this patient, what would be the most likely physical finding?

A)  Difficulty in standing from a sitting position

B)  Difficulty in sitting from a standing position

C)  The left side of the pelvis sags (drops) when attempting to stand with

his weight supported by the right lower limb

D)  The right side of the pelvis sags (drops) when attempting to stand with

his weight supported by the left lower limb

E)  Weakened flexion of the right leg at the knee joint

F)  Weakened extension of the left leg at the knee joint

C

See: Slide 47.

10

During terminal stance, what is the main mechanical goal that is achieved through the action of triceps surae muscle group?

A) Dorsiflexion at the ankle joint ensures the foot clears the ground

B) Plantarflexion at the ankle joint to accelerate the limb

C) Flexion of the leg stabilizes the knee joint

D) Extension of the leg stabilizes the knee joint

E) Flexion of the thigh at the hip joint to accelerate the limb F) Extension of the thigh at the hip joint to decelerate the limb

B

See: Slide 29. Think of your heel raising off the ground and the foot acting as a rigid lever to propel the trunk/body/axial skeleton forwards.

11

In the accompanying photograph, the physician has asked the patient to dorsiflex both feet at the ankle joint to test whether the common fibular nerve has been damaged. In this case, (i) tibialis anterior muscle is no longer able to contract on which side and (ii) which subdivision of the gait cycle would this injury be best observed?

 

A) Right; Initial contact

B) Left; Initial contact

C) Right; Midstance

D) Left; Midstance

E) Right: Pre-swing

F) Left; Pre-swing

Q image thumb

B

See: Slide 23 and Slide 41. Remember that tibialis anterior muscle is part of the anterior compartment group of muscles in the leg and Midswing could also be considered as an acceptable answer. In this case it is not an answer choice but think about which points you need to have your foot “dorsiflexed” to be able to walk efficiently – it is less efficient contacting the ground with a flat foot when walking.

12

Which one of the following is considered to be an example of kinetic data?

A) Ground reaction force (GRF)

B) Step length

C) Rotational motion

D) Cadence

E) Stride time

A

See: Slides 6, 7, and 9.

13

A 22-year-old researcher was working with a gait analysis software company to test the repeatability of the newest version of an automated labelling feature. The researcher’s sister helped by wearing the equipment and having her movements tracked by the infra-red cameras. The accompanying image shows a photograph of the sister and the virtual reconstruction at the same point of time. From the image it can be noted that both the right and left limb are in direct contact with the ground. (i) What term is used to describe this and (ii) at which two subdivisions of the gait cycle does this occur?

A) Single support → Midstance and midswing
B) Single support → Loading response and midstance C) Double support → Pre-swing and loading response D) Double support → Terminal stance and pre-swing

Q image thumb

C

See: Slide 21.

14

A 32-year-old woman is unable to dorsiflex her right foot at the ankle joint and the physician provides her with an orthotic device that is shown in the accompanying image. In this case, the patient will no longer have to compensate her right foot dropping during the swing phase of the gait cycle. (i) What type of gait had the patient most likely adopted prior to using the foot brace and (ii) which muscle receives motor innervation via the injured nerve?

A) Antalgic – Adductor magnus

B) Ataxic – Fibularis (peroneus) longus

C) Crouch – Rectus femoris

D) Trendelenburg – Gluteus medius

E) Steppage – Tibialis anterior

Q image thumb

E

See: Slide 48.

15

A 23-year-old surfer presents to the Health Center after stepping on a sea urchin. In the accompanying photograph, the dark needle-like projections can be seen on the plantar surface of his foot which are very painful during the weight bearing phase of the gait cycle for the right foot. During a typical stride, the right foot of an individual will not be in contact with the ground for approximately what percentage of the walking gait cycle?

A) 25%

B) 40%

C) 50%

D) 60%

E) 75%

F) 100%

Q image thumb

B

See:Slide21. Remember this will be the same for the left foot in a healthy/typical gait cycle as we expect to see symmetry. If asymmetry present (e.g. left step length is significantly shorter than right step length) then we would look for a pathology or cause for this difference between sides.

16

A 36-year-old diabetic patient presents to the physician for an annual check-up. Physical examination reveals the patient has developed bilateral foot ulcers (see accompanying image A) as a result of increased plantar pressures. Although the ulcers are painless, the physician is concerned and admits the patient to hospital to undergo immediate debridement and treatment. One recommendation of preventing reoccurrence of the ulcers, is for the patient to wear specially adapted shoes to evenly distribute body weight across the foot while at the same time supporting the ankle, arch and heel. The patient has his gait analyzed while walking barefoot and this is compared with the biomechanical data obtained when walking with custom made orthoses and specially designed shoes. Image B represents the measurement of one spatio-temporal parameter labelled X (heel strike to contralateral heel strike) that was calculated to be 0.62 meters. What parameter was measured in this case?

A) Step length

B) Stride length

C) Cadence

D) Step time

E) Stride time

Q image thumb

A

See: Slide 8. The SI unit was in meters therefore it must have been the right step length that was measured – this is the distance that the right foot travels in front of the left.

17

In the accompanying image, the left limb (indicated by the arrow) is in which subdivision of the gait cycle?

A) Initial contact

B) Loading response

C) Midstance

D) Terminal stance

E) Pre-swing

F) Initial swing

G) Midswing

H) Terminal swing

Q image thumb

B

See: Slides 24 and 30. Remember that the initial contact subdivision is extremely short (only 2% of a stride), so to differentiate it from loading response you often need to look at the contralateral leg. In this image the right leg is slightly flexed and the foot is neutral, indicating that the right limb is in early pre-swing. At initial contact, the contralateral leg should be extended and the contralateral foot should be dorsiflexed (the final positions of terminal stance).