MSK #1- General Principles of Biometrics

Question 1

4 general principles of Biomechanics

Answer 1

1. Levers
2. Selected Kinematics
3. Capsular positions
4. Muscle Substitutions

Question 2

3 Types of Levers

Answer 2

1. First class
2. second class
3. Third class

Question 3

First class levers

Answer 3

Occurs when two forces are applied on either axis

Question 4

Second class levers

Answer 4

Occurs when two forces are applied on one side of an axis

Question 5

Third class levers

Answer 5

Occurs when two forces are applied on one side of an axis

Question 6

What is the effort and resistanc in a first class lever?

Answer 6

Effort- force that attempts to cause movement

Resistance- force that opposes movement

Example- in human body contraction of tricps at elbow

Question 7

What is resistance in second class lever?

Answer 7

Resistance- lies between the effort and axis of rotation

example- toe rises

Question 8

What is effort in third class lever?

Answer 8

The effort force lies closer to the axis than the resistance force

Most muscles in the human body are third class levers e.g. elbow flexion

Question 9

4 Characteristics of Selected Kinematics

Answer 9

1. Arthrokinematics
2. Osteokinematics
3. Convex concave rule
4. Three motions that describe the movement of one joint surface on another

Question 10

Arthrokinematics

Answer 10

Movement between joint surfaces

Question 11

Osteokinematics

Answer 11

Movement between two bones

Question 12

Convex Concave rule

Answer 12

Describes relationship between arthrokinematics and Osteokinematics

1. Convex on concave= movement in opposite direction of the shaft of the bony lever
2. Concave on convex = mvmt same direction
3. In the spine, the convex rule applies at the atlanto occipital joint and concave rule applies below the 2nd vertebra

Question 13

Three motions that describes one joint surface on another include

Answer 13

1. roll
2. Glide
3. Spin
   
   1. Combinations of all three motions can occur at joints (joint surfaces of humerus and scapula of shoulder

Question 14

Motions: Roll

Answer 14

Consists of one joint surface rolling on another, such as a tire rolling on a road

e.g mvmt between femoral and tibial articular surfaces of the knee

Question 15

Motons: Glide

Answer 15

Consists of pure translatory motion of one surface gliding on another as when a braked wheel skid

e.g. mvmt of the joint surface of the proximal phalanx at the head of the MCP bone of the hand

Question 16

Motion: Spin

Answer 16

Consists of rotation of the movable component of the joint

e.g. mvmt between joint surfaces of radial head with humerus

Question 17

5 Characteristics of Capsular Position

Answer 17

1. Resting or loose-packed position
2. Close-pack position
3. Selected capsular patterns
4. End-feels
5. Grading of accessory joint moveent

Question 18

Resting or loosed pack position

Answer 18

1. Joint position where capsule and other soft tissues are in most relaxed position
2. Minimal joint surface contact
3. May perform joint play and mobilization techniques in this joint position

Question 19

Close-packed position

Answer 19

1. Joint position where capsule and other soft tissue are maximally tensed

• Max contact between joint surfaces
• Joint play and mobilizations cannot be performed in this position

Question 20

End-feels

Answer 20

1. Normal Physiological
   
   1. Soft: occurs with soft tissue approximation
   2. Firm: capsular and ligamentous stretching
   3. Hard: when bone and /or cartilage meet
2. Pathological
   
   1. Boggy: edema, joint swelling
   2. Firm with decreased elasticit: fibrosis of soft tissue
   3. Rubbery: muscle spasms
   4. Empty: loose, then very hard; assoc with muscle guarding or patient avoiding painful part of range
   5. Hypermobility: end-feel at a later time than on opposite side

Question 21

Why is accessory Joint movements graded?

Answer 21

To assess arthrokinematic motion of the joint and/or when it is impractical or impossible to measure joint motion with a goniometer

Question 22

Muscle Substitutions

Answer 22

• Occur when muscles have become shortened/ lengthened, weakened, lost endurance, developed impaired coordination, or paralyzed
• Stronger muscles compensate for loss of motion

Question 23

Common muscle substitutions include

Answer 23

• Use of scapular stabilizers to initiate shoulder motion when shoulder abductors are weakened
• Use of lateral trunk muscles or TFL when hip abductors are weak
• Use of passive finger flexion by contraction of wrist extensors when finger flexors are weak (tenodesis)
• Use of long head of biceps, coracobrachialis, ad anterior deltoid when pectoralis major is weak
• Use of lower back extensors, adductor magnus, & quadratus lumborum when hip extensors are weak
• Use of lower abdominal, lower obliques, hip adductors and lats when hip flexors are weak