Presentation By

Nabeel AmjadDPT-FA12-036

Department of Physical TherapyThe University of Faisalabad

Biomechanics of Joints and joint architecture

Reference:…….Basic Bio Mechanics by Susan J hall

Topic

Anatomist classified joints on basis ◦ Joint Complexity◦ Number of axis present◦ Joint Geometry◦ Movement capabilities

Classification of Joints

On basis of motion capabilities joints are classified as 1. Immovable joints2. Slightly moveable joints3. Freely moveable joints

Classification of Joints

Fibrous Joints Attenuate applied force (absorb shocks) Permit very little or no movement Subtypes are

a Suturesb Syndesmoses

(1) Immoveable jointsSynarthroses (Syn=together arthron= Joint)

Irregularly grooved articulating bone sheets mete closely

Tightly connected by fibers that are continuous with periostium

Fibers ossify in early childhood and evetually replaced by bones

Examples◦ Sutures of skull

aSutures

Syndesmosis=held by bands Dense fibrous tissur binds the bones

togather Permit extreamly limited movements Examples

◦ Coracoacromial joint◦ Mid radioulnar◦ Mid tibiofibular◦ Inferior tibiofibular

bsyndesmoses

Cartilagenious joints Attenuate applied forces Permit relatively more motion than

synarthroses Subtypes

a Synchondrosesb Symphyses

(2) Slightly moveable jointsAmphiarthroses (slightly moveble)amphi= on both sides

Synchondrosis= Held by cartilage Bones are held together by thin layer of

hyaline cartilage Examples

◦ Sternocostal joints◦ Epiphysial plates

before ossification

aSynchondroses

Thin plates of hyaline cartilage separate disk of fibro cartilage from bones

Examples◦ Vertibral joints ◦ Pubis symphyses

b Symphyses

Only slight limitation to movement

Articulating bone surfaces are covered with hyaline cartilage

Articular capsule surrounds joint

Synovial membrane on inner surface of capsule secretes synovial fluid

(3)Freely moveable jointsDiarthroses or synovialDiarthroses= Through joints

a) Gliding (plane arthrodial)

b) Hinge (ginglymus)c) Pivot (screw; trochoid)d) Condyloid (ovoid

Ellipsoidal)e) Saddle (sellar)f) Ball and Socket

(Spheroidal)

Types of synovial joints

Flat auricular surfaces Only movement permitted is non axial

gliding Examples

◦ Inter metatarsal joints

◦ Facet joints of vertibrae

a Gliding (plane arthrodial)

One articulating bone surface is convex other is concave

Strong collateral ligaments restrict movements to a single plane

Hing like motion Examples

◦ Ulnohumeral joints

◦ Inter phalengeal joints

b Hinge (ginglymus)

Rotation is permitted around one axis

Examples◦ Atlantoaxial joint

◦ Proximal radioulnar joint

◦ Distal radioulnar joint

c Pivot (screw; trochoid)

One articulating bone surface is an ovular convex shape and other is reciprocally shaped concave surface

Flexion, extension, adduction, abduction and circumduction are permitted

Examples◦ 2-5 metacarpophylengeal joints

◦ Radiocalpal joints

d Condyloid (ovoid Ellipsoidal)

Both articulating surfaces are shaped like a seats of a saddle

Movement capabilities are same as in condyloid joints but at greater range

Example◦ Carmometacarpal joint of thumb

e Saddle (sellar)

Surfaces of articulating bones are reciprocally convex and concave

Rotation in all three planes of movement is permitted

Examples◦ Hip joint◦ Shoulder joint

e Ball and Socket (Spheroidal)

Synovial joints are catagorized according to number of axis of rotation present

There are four types◦ Uniaxial: permit movement about

one axis◦ Biaxial: permit movement about two

directions◦ Triaxial: permit movement about

three directions

Classification of synovial joints

Joint motion capabilities also sometimes described in terms of degrees of freedom (df)

A uniaxial joint has one df A biaxial joint has two df A triaxial joint has three df

Degrees of freedom (df)

Two synovial structures are associated with diarthroidal joints◦ Bursae

◦ Tendon sheaths

Synovial structures associated with joints

Bursae:◦ capsules lined with synovial

membrane and filled with synovial fluid

◦ Cousions th structures they separate

◦ Mostly they separate tendons from bones

◦ Some bursae separate bone from skin eg olicronon bursae

Tendon sheaths:◦ Doubled layered synovial structures◦ Srounds tendons that are placed in close

association with bones◦ Many of long tendons passing from wrist joints are

protected by tendon sheaths