NPTE: Convex-Concave

Convex-Concave Rule

Describes the relationship between arthrokinematics (movement between joint surfaces: roll, spin, glide) and osteokinematics (movement between two bones). When a CONVEX surface moves on a fixed CONCAVE surface, the convex surface moves OPPOSITE to the direction of the shaft of the bony lever. When a CONCAVE surface moves on a fixed CONVEX surface, the concave surface moves in the SAME direction of the shaft of the bony lever.

IP joints of the fingers: flexion/extension

Moving component: distal phalanx, concave moving on convex, osteo/arthrokinematic motion occurs in the same direction

Metacarpal-phalangeal joints: ab-adduction

Moving component: proximal phalanx, concave moving on convex, osteo/arthrokinematic motion occurs in the same direction

Radiocarpal joint: flexion/extension

Moving component: capitate, scaphoid, lunate, triquetrum,trapezoid, convex moving on concave (except for the trapezoid which is concave moving on convex), osteo/arthrokinematic motion occurs in the opposite direction

Distal radioulnar joint: pronation/supination

Moving component: radius, concave moving on convex, osteo/arthrokinematic motion occurs in the same direction

Proximal radioulnar joint: pronation/supination

Moving component: radius, convex moving on concave, osteo/arthrokinematic motion occurs in opposite directions

Humeroradial joint: flexion/extension

Moving component: radius, concave moving on convex, osteo/arthrokinematic motion occurs in the same direction

Humeroulnar joint: flexion/extension

Moving component: ulna, concave moving on convex, osteo/arthrokinematic motion occurs in the same direction

Glenohumeral joint: all movements

Moving component: humerus, convex moving on concave, osteo/arthrokinematic motion occurs in opposite directions

Sternoclavicular joint: elevation/depression

Moving component: clavicle, convex moving on concave, osteo/arthrokinematic motion occurs in opposite directions

Sternoclavicular joint: protraction/retraction

Moving component: clavicle, concave moving on convex, osteo/arthrokinematic motion occurs in the same direction

Acromioclavicular joint: all movements

Moving component: scapula (acromion), concave moving on convex, osteo/arthrokinematic motion occurs in the same direction

IP joints of the toes: flexion/extension

Moving component: distal phalanx, concave moving on convex, osteo/arthrokinematic motion occurs in the same direction

Metatarsophalangeal joints: ab/adduction

Moving component: proximal phalanx, concave moving on convex, osteo/arthrokinematic motion occurs in the same direction

Temporomandibular joint: all motions

Moving component: mandible, convex moving on concave, osteo/arthrokinematic motion occurs in opposite directions

Atlanto-occipital joint

Convex rule, C2 and below = concave rule

Hip joint: all movements

Moving component: femur, convex moving on concave, osteo/arthrokinematic motion occurs in opposite directions

Tibiofemoral joint: all movements

Moving component: tibia, concave moving on convex, osteo/arthrokinematic motion occurs in the same direction

Patellofemoral joint

Moving component: patella, convex moving on concave, osteo/arthrokinematic motion occurs in opposite directions

Proximal tibiofibular joint

Moving component: fibula, concave moving on convex, osteo/arthrokinematic motion occurs in the same direction

Distal tibiofibular joint

Moving component: fibula, convex moving on concave, osteo/arthrokinematic motion occurs in opposite directions

Talocrural joint: DF/PF

Moving component: talus, convex (talus) moving on concave (tibia and fibula), osteo/arthrokinematic motion occurs in opposite directions

Subtalar joint (meeting point of talus and calcaneus)

Moving component: navicular, cuneiform concave moving on convex, osteo/arthrokinematic motion occurs in the same direction *For inversion/eversion - Moving component: cuboid, calcaneus, convex moving on concave, osteo/arthrokinematic motion occurs in opposite directions