Kinesiology Lecture 2

The Analysis of Human Motion

Objectives

• identify and describe the types of motion

• use anatomic and kinesiologic language to describe areas, positions, directions, and areas of the human body

• identify and describe the planes of motion of the human body and use them to describe human movement

• define and utilize the terms force and torque appropriately

Motion

change in position or place

• most human motion is called general motion

general motion

a complex combination of linear motion and angular motion

• can be reticular (straight line) or curvilinear (curved line)

linear motion/ translation

all parts of a system moving in same direction at same speed

angular motion

rotation about/around a central axis which is perpendicular to the plane of rotation

Anatomical position

erect standing, feet slightly separated, arms relaxed at sides with palms forward

Fundamental position

Identical to anatomical position, but with arms hanging at sides and palms facing body (inward)

Superior (cranial)

closer to head, towards head end of body, or higher/above

Inferior (caudal)

away from head, lower/under

Posterior (dorsal)

toward back of body

Anterior (ventral)

front of or in front of (abdominal muscles are on anterior side of the body)

Medial

toward the midline

lateral

away from the midline

intermediate

between 2 structures

proximal

nearest point of attachment to limb or structure, closer to trunk

• knee is proximal to ankle

• ankle is proximal to toe

distal

farthest away from attachment or origin, farther from trunk

• ankle is distal to knee

• toe is distal to ankle

superficial

towards body surface

deep

inside body away from surface

anatomical planes

• cardinal planes

cardinal planes

3 imaginary planes that bisect the body

• sagittal

• frontal(coronal)

• transverse (horizontal)

sagittal plane

bisects the body into right and left halves, splitting it at the midline into halves with equal mass

frontal plane (coronal)

bisects the body into anterior and posterior halves with equal mass

transverse (horizontal) plane

bisects the body into superior and inferior (top bottom) halves of equal mass

movement in planes

• human body can move in each of the planes, often it can move in more than one plane simultaneously

• when the body or a body segment moves in a plane it, it also moves about a corresponding axis of rotation

reference axis

• anteroposterior axis

• mediolateral axis

• longitudinal (vertical) axis

anteroposterior axis

when the body or a segment moves in the frontal plane, that body or segment rotates about the anteroposterior axis, perpendicular to the plane of motion

Mediolateral axis

when the body moves in the sagittal plane, the body or segment rotates about the mediolateral axis, perpendicular to the sagittal plane

Longitudinal (vertical) axis

when the body or body segment moves in the transverse plane, it rotates about the longitudinal (vertical) axis, perpendicular to the transverse plane

The rule of 3

1. motion of a

2. bone or segment at or about a

3. joint/articulation

ex: flexion of the humerus at the glenohumeral articulation

Sagittal plane of movements

about the mediolateral axis

• flexion

• extension/hyperextended position

flexion about the mediolateral axis

• anteriorly: directed sagittal plane rotation of head, trunk upper arm, forearm, hand, hip

• posteriorly: directed sagittal plane movements of lower leg

  • dorsiflexion: (extension) reduction of joint angle at the ankle

  • plantarflexion: increase in joint angle at the ankle (pointing toes downward)

extension/hyperextended about mediolateral axis

movement that returns body to/beyond anatomical position from flexion

Frontal plane movements

• abduction

• adduction

• lateral flexion

Abduction about front plane

movement of a body segment away from the midline

Adduction about frontal plane

movement of a body segment towards the midline

lateral flexion about frontal plane

frontal plane, sideways movement of the spine/trunk

• radial/ulnar deviation: rotation of hand at wrist towards radius (thumb) side and ulna (5th finger) side

transverse plane movements

• rotation

rotation about transverse plane

• head, neck, and trunk rotate about a vertical axis

types of rotation about transverse plane

• medial/lateral rotation- arm/leg segments rotate toward or away from the midline of the body in transverse plane

• pronation/supination- rotational movements of forearm at radioulnar joint

• horizontal ab/adduction- movement of an arm or leg, flexed to 90 degrees, in the transverse plane either toward or away form the midline of the body

Circumduction

• a combination of movements in to produce a conical trajectory of the moving segment (arm circles)

  • only joints with 3 degrees of freedom can truly circumduct

    • those with 2 can perform modified circumduction

Musculoskeletal Torques

• force: a strength or energy

  • muscles contracting apply “force” to the bone (internal)

  • gravity applies “force” to our body (and anything with mass) (ext)

  • in the body, ext and int forces

• a force applied on the body can have 2 effects depending on where the force is applied and the constraints on the area of force application

A force applied on the body can have 2 effects depending on where the force is applied and the constraints on the area of force application

• translation (linear motion)

• rotation (rotary motion)

torque

forces applied to a segment thats free to move on one end

• torque= force x distance

  • the magnitude of a torque is equal to the magnitude of the force multiplied by the distance between the point of force application and the axis of rotation

magnitude of a torque