The Skeletal System

Articulations

Classification Classified based on the type of movement they allow. 3 major types:

Fibrous Joint – immovable and connected by fibrous connective tissue (ex: plates in skull, periodontal ligaments)

Cartilaginous Joint – slight movement and fibrocartilage is between the 2 bones (ex: betw. spinal vertebrae & pubic bones)

Synovial Joint – free motion no direct contact of bones associated with synovial membranes (Ex: elbow, ankle, shoulder)

Fibrous Joints: minimal movement Sutures: seams between bones, found

between skull bones, form fontanels in children (e.g. coronal)

Syndesmoses: bones farther apart than in a suture and are joined by ligaments (e.g. radioulnar)

Gomphoses: specialized joints consisting of pegs that fit in sockets (e.g. dentoaveolar)

Cartilaginous Joints: Growth Synchondroses: 2 bones joined by hyaline

cartilage (e.g. epiphyseal plates- cartilaginous region betw. epiphysis & diaphysis of a growing bone)

Symphyses: fibrocartilage uniting 2 bones (e.g. symphyses pubis, manubriosternal (ribcage))

Synovial Joints: Movable Plane or gliding: 2 opposed flat surfaces, movement

confined to one plane (e.g. intervertebral) Saddle: 2 saddle-shaped articulating surfaces oriented

at right angles (e.g. carpometacarpel- wrist/hand) Hinge: convex cylinder in one bone applied to a

corresponding concave portion on another bone (e.g. elbow and knee)

Pivot: rotation around a single axis. A process that rotates within a ring (e.g. atlantoaxial-neck)

Synovial Joints Ball and Socket: ball (head) at the end of

one bone and a socket on another bone (e.g. coxal-hip and glenohumeral-shoulder)

Ellipsoid: modified ball-and-socket the head is more ellipsoid in shape rather than round (e.g. atlanooccipital- betw.head & neck i.e. allows nodding)

Types Movements Flexion (anterior or ventral direction) and extension (posterior or

dorsal direction) Dorsiflexion (flex toes) and plantar flexion (point toes) Abduction (away from midline) and adduction (toward midline) Medial and lateral rotation (turning around long axis) Circumduction (combination of flexion, extension, abduction, and

adduction) Elevation (superior motion) and depression (inferior motion) Protraction (moving in anterior direction) and retraction (moving in

posterior direction) Supination (face up palm) and pronation (face down palm) Opposition (thumb to finger) and reposition Lateral excursion (bottom jaw lateral) Inversion (ankle medial turn) and eversion (ankle lateral turn)