OVRT Resources for the Humanoid Animation Working Group

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Useful information for the Humanoid Animation Working Group of the VRML Consortium.


Joints

from Biomechanical Basis of Human Movement by Joseph Hamill and Katheen M. Knutzen, Williams & Wilkins 1995, ISBN: 0-683-03863-X

Types of Diarthrodial Joints

Simple, Compound, and Complex Joints
The articulating surfaces found in the different joints in the body vary in size and shape. There is typically a concave surface on the adjacent bone, termed female and male surfaces, respectively. Also, there can be more than two contact points or articulating surfaces. A joint with only two articulating surfaces is termed a simple joint, while a joint with three or more articulating surfaces is known as a compound joint. A joint with more than two articulating surfaces and with a disc or fibrocartilage is called a complex joint. An example of a simple joint is the hip or the ankle (talotibial), of a compound joint is the wrist, and of a complex joint is the knee.
Close-Packed vs Loose-Packed Positions
As movement occurs through a range of motion, the actual contact area varies between the articulating surfaces.
The Plane or Gliding Joint
The first type of joint is the plane or gliding joint, found in the foot between the tarsals and in the hand among the carpals. Movement at this type of joint does not occur about an axis and is termed non-axial since it consists of two flat surfaces that slide over each other to allow movement. In the hand, for example, the carpals will slide over each other as the hand is moved to positions of flexion, extension, radial deviation, or ulnar deviation. Likewise, in the foot, the tarsals shift during pronation and supination, sliding over each other in the process.
The Hinge Joint
The hinge (ginglymus) joint allows movement in one plane (flexion, extension) and is termed uniaxial. Examples of the hunge joint in the body are the interphalangeal joints of the phalanges in the foot and hand, and the ulnohumeral articulation at the elbow.
The Pivot Joint
The pivot joint also allows movement in one plane (rotation; pronation, supination) and is uniaxial. Pivot joints are located at the superior and inferior radioulnar joint and the atlantoaxial articulation at the base of the skull.
The Condylar Joint
The condylar joint is a joint allowing primary movement in one plane flexion, extension) with small amounts of movement in another plane (rotation). It is found at the knee joint and the temporomandibular joint.
The Ellipsoid Joint
The ellipsoid joint allows movement in two planes (flexion, extension; abduction, adduction) and is biaxial. Examples of this joint can be found at the radiocarpal articulation at the wrist and the metacarpophalangeal articulation in the phalanges.
The Saddle Joint
The saddle joint only found at the carpometacarpal articulation of the thumb, allows two planes of motion (flexion, extension; abduction, adduction) with a small amount of rotation also allowed. It is similar to the ellipsoid joint in function.
The Ball-and-Socket Joint
The last type of diarthrodial joint, the ball-and-socket joint allows movement in three planes (flexion, extension; abduction, adduction; rotation) and is the most mobile of the diarthrodial joint. The hip and shoulder joints are example of ball-and-socket joints.

Other Types of Joints

Synarthrodial or Fibrous Joints
There are other articulations that are limited in movement characteristics but, nonetheless, play an important role in stabilization of the skeletal system. Some bones are held together by fibrous articulations, such as those found in the sutures of the skull. These articulations, referred to as synarthrodial, allow little or no movement to occur between the bones and hold the bones firmly together.
Amphiarthrodial or Cartilaginous Joints
There are also cartilaginous joint, called amphiarthodial, that are bones held together by either hyaline cartilage, such as is found at the epiphyseal plates , or by fibrocartilage, found at the pubic symphysis and the intervertebral articulations. The movement at these articulations is also very limited, although not to the degree of the synarthodial joints.
Major Joints of the Body
Joint Type Degrees of Freedom
Vertebrae Amphiarthroidial 3
Hip Ball-and-Socket 3
Shoulder Ball-and-Socket 3
Knee Condyloid 2
Wrist Ellipsoid 2
Metacarpophalangeal (fingers) Ellipsoid 2
Carpometacarpal (thumb) Saddle 2
Elbow Hinge 1
Radioulnar Pivot 1
Atlantoaxial Pivot 1
Ankle Hinge 1
Interphalangeal Hinge 1

range tables taken from Human Factors Design Handbook 2nd ed, Woodson, Tillman, Tillman published by McGraw Hill 1992, ISBN: 0-07-071768-0

Range of Movement at the Joints of the Hand and Arm of Male Air Force Personel
Movement Range(deg) Avg. Range(deg) S.D.
Wrist flexion 90 12
Wrist extension 99 13
Wrist adduction 27 9
Wrist abduction 47 7
Forearm supination 113 22
Forearm pronation 77 24
Elbow flexion 142 10
Shoulder flexion 188 12
Shoulder extension 61 14
Shoulder adduction 48 9
Shoulder abduction 134 17
Range of Movement at the Joints of the Foot and Leg of Male Air Force Personel
Movement Range(deg) Avg. Range(deg) S.D.
Ankle flexion 35 7
Ankle extension 38 12
Ankle adduction 24 9
Ankle abduction 23 7
Knee flexion
      Standing 113 13
      Kneeling 159 9
      Prone 125 10
Knee rotation
      Medial 35 12
      Lateral 43 12
Hip flexion 113 13
Hip adduction 31 12
Hip abduction 53 12
Hip rotation (sitting)
      Medial 31 9
      Lateral 30 9
Hip rotation (prone)
      Medial 39 10
      Lateral 34 10

Neck (image) - data in 2nd image

Average Increase in Range of Joint Movement of Women over Men
Movement Difference(deg)
Wrist flexion and extension 14
Wrist adduction and abduction 11
Elbow flexion and extension 8
Shoulder abduction (rearward) 2
Ankle flexion and extension 4
Knee flexion and extension 0
Hip flextion 3

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