Joints (a.k.a. Articulations)

I. Introduction

A.A.JointJoint

1. 1. Also called an articulationarticulation 2. Defined:

A joint is a point of contact between bones, cartilage and bones, or teeth and bone

I. Introduction

B. FunctionB. Function

1. 1. they hold the skeletal bones together

22.. Allows the rigid skeleton some flexibility so that

gross movements can occur

C. C. Relationship between Joints Relationship between Joints and and MovementsMovements

1. The closer the fit between bones at a joint, the

stronger the joint.2. Strong joints exhibit restricted

movements.3. The greater the distance

between articulating bones the greater range of

movements

II. Classification

A. Based on eitherA. Based on either

1. S1. Structure

based on the nature of the material comprising them

2. Function

based on degree of movement they allow

II. Classification

B. Functional B. Functional ClassificationsClassifications

1. 1. Synarthroses

arthrose=joint, syn=together

• Immovable jointsImmovable joints

• Examples: suturesExamples: sutures

Synarthroses

II. Classification

C. Functional ClassificationsC. Functional Classifications

2. 2. Amphiarthroses

arthrose=joint, amphi=both

• Slightly movable joints• Between tibia and fibula

Amphiarthroses

II. Classification

C. Functional C. Functional ClassificationsClassifications

3. 3. Diarthroses

arthrose=joint, dia=apart

a. freely movable joint

b. example: knee joint

II. Classification

b. no joint cavity

C. Structural C. Structural classificationsclassifications

1. 1. Fibrous Jointsa. joints held

together by fibrous connective tissue

SUTURESSUTURESBones are held together by a thin layer of dense fibrous tissue and also by interlocking projections of the bones.

Found only in the skull

GOMPHOSESGOMPHOSES

a peg-in-socket fibrous joint

Bones are held together by a cord or sheet of dense fibrous connective tissue

SYNDESMOSESSYNDESMOSES

II. Classification

B. Structural ClassificationsB. Structural Classifications

2. 2. Cartilaginous Jointsa.held together by

cartilaginous tissue

b. no joint cavity

SynchondrosSynchondroseses •

immovable

• only hyaline cartilage

SYMPHYSISSYMPHYSIS

VERY limited movement

Hyaline and fibrous cartilage

B. Structural ClassificationsB. Structural Classifications

3. 3. Synovial joints

a.held together by a synovial capsule

b. Have a joint cavity

c. Includes most joints

Gliding Gliding JointsJoints •Plane (=

gliding). Opposite bone surfaces are flat or slightly curved.

•Only sliding motion in all directions are allowed.

Hinge JointsHinge Joints

Convex surface of one bone fits smoothly into concave surface of the second bone .

Pivot JointsPivot Joints A rounded, pointed or conical surface of one bone is inserted into a ring made partly of another bone and partly of a ligament.

only movement allowed is the rotation of one bone around its own axis

Ellipsoidal (= condyloid) Ellipsoidal (= condyloid) JointsJoints

Oval-shaped surface fits into an oval-shaped cavity

Saddle JointsSaddle Joints

First bone's articular surface is concave in one direction and convex in the other while the second bone is just the opposite.

Ball and Socket JointsBall and Socket Joints

• head fits into a cup-shaped depression

• most freely moving of all joints

V. Joints (a.k.a. Articulations)C.C.Types of Movement Types of Movement

in Synovial Jointsin Synovial Joints1.1. GlidingGliding• slight movementslight movement • example:

vertebrae2.2.RotationRotation

• Movement around the long axis of limb

• Shoulder joint

V. Joints (a.k.a. Articulations)C.C.Types of Movement Types of Movement

in Synovial Jointsin Synovial Joints3. Angular

a.a. flexionflexion • decreasing angle

b.b. extensioextensionn• Increasing

angle

C. Types of Movement in C. Types of Movement in Synovial Synovial JointsJoints

C. Angular a.a. hyperextensionhyperextension • extension beyond

anatomical position

b.b. circumductioncircumduction • limb movement

with limb describing a cone

V. Joints (a.k.a. Articulations)C.C.Types of Types of

Movement in Movement in Synovial JointsSynovial Joints

3. Angular d. abduction abduction

movement away from midline

e.e. adductionadduction toward midline

C.C.Types of Movement in Types of Movement in Synovial JointsSynovial Joints4. Rotation

turns right to left

4. Rotationa.a. pronation

turns wrist so palm is facing dorsally

b.b. supinationsupination palm turned anteriorly

C. Types of Movement in C. Types of Movement in Synovial JointsSynovial Joints

5. Special Casesa.a. plantar

flexion and dorsiflexion

b.b. dorsiflexiondorsiflexion

C. Types of Movement in C. Types of Movement in Synovial JointsSynovial Joints