Joints

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Human Anatomy

Chondrology & Arthrology

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Cartilage Connective Tissue

Characteristics: Weaker than bone More flexible than bone

Cells in an abundant matrix. Cell Types

Chondroblasts Chondrocytes in lacunae

Avascular

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3 Major Functions of Cartilage Supporting soft tissues. Providing a gliding surface at

articulations (joints) Providing a model for the

formation of most of the bones in the body.

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Types of Cartilage Three types of cartilage:

Hyaline cartilage Most abundant kind Has a perichondrium (membrane) Associated with synovial joints Most bones first modeled in hyaline cartilage

Fibrocartilage Has collagen fibers Intervertebral discs, pubic symphysis

Elastic cartilage Has elastic fibers Ear, respiratory tubing

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Articulations A joint, or articulation, is the place of

contact between bones, between bone and cartilage, or between bones and teeth.

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Naming of Joints Usually derived from the names of

the articulating bones.

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Mobility and Stability in Joints Motion permitted ranges from none to various

extensive motions. Structure determines both its mobility and its

stability. more mobile = less stable

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StructuralClassification of Joints A fibrous joint occurs where bones are held

together by dense regular (fibrous) connective tissue.

A cartilaginous joint occurs where bones are joined by cartilage.

A synovial joint has a fluid-filled synovial cavity bones are enclosed within a capsule bones are joined by various ligaments

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Classification of Joints Functionally based on the extent of movement

they permit: Synarthrosis is an immovable joint. Amphiarthrosis is a slightly movable joint. Diarthrosis is a freely movable joint.

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Fibrous Joints Union is due to dense fibrous tissue. Most are immovable or only slightly

movable. Have no joint cavity. Three types.

Gomphosis sutures syndesmosis

Sutures Joints of skull bone Fixed Affected by sutural ligaments Sites of active bone growth Process of obliteration of sutures is

called synostosis.

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Gomphosis(peg & socket joints) Fibrous joints in which teeth fit into

their sockets. Periodontal ligament connects the

tooth with socket or alveolus.

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Varieties of sutures. Depends on shape of articulating surfaces and

mode of fusion of articulating bones. Serrate sutures (sagittal suture). Denticulate suture (lambdoid suture). Squamous Plane sutures (temporo parietal

suture). Limbus suture Plane sutures ( inter palantine suture). Wedge and groove suture(vomero sphenoid

suture)

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Cartilaginous Joints Bones are attached to each other by cartilage. Lack a joint cavity. Two types.

Primary cartilaginous joint or synchondrosis Symphyses, secondary cartilaginous joints.

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Synovial Joints Freely movable articulations Classified as diarthroses Bones are separated by a space called a

joint cavity Most of the commonly known joints in

the body glenohumeral (shoulder) joint temporomandibular joint elbow joint knee joint

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Insert Fig. 9.4 Synovial Joints

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General Anatomy of Synovial Joints Basic features:

articular capsule joint cavity synovial fluid articular cartilage ligaments nerves blood vessels

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General Anatomy of Synovial Joints – Accessory Structures Bursae

fibrous, saclike structure that contains synovial fluid and is lined by a synovial membrane

Fatpads often distributed along the periphery of a synovial

joint act as packing material and provide some protection

for the joint fill the spaces that form when bones move and the

joint cavity changes shape Tendons

attaches a muscle to a bone help to stabilize joints

STRUCTURES COMPRISING A SYNOVIAL JOINT

• ARTICULAR BONY SURFACES• THE CONTIGUOUS BONY SURFACES, WHICH ARE TAKING

PART IN THE FORMATION OF A JOINT, ARE CALLED ARTICULAR BONY SURFACES. THESE SURFACES ARE NOT IN CONTINUITY WITH EACH OTHER BUT ARE RATHER WELL ADAPTED TO EACH OTHER.

• EACH BONY ARTICULAR SURFACE IS COVERED BY BLUISH-WHITE ARTICULAR-WHICH IS AVASCULAR, ANERVOUS AND DEVOID OF PERICHONDRIUM.

• IT DERIVES ITS NUTRITION BY DIFFUSION FROM THREE SOURCES

• SYNOVIAL FLUID.• EPIPHYSEAL VESSELS.• SYNOVIAL VESSELS (CIRCULUS VASCULOSUS ARTICULI)

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JOINT CAVITY (SYNOVIAL CAVITY)

• EVERY SYNOVIAL JOINT HAS A SPECIAL CAVITY LINED BY SYNOVIAL MEMBRANE. THIS CAVITY IS NOT AN EMPTY SPACE, BUT IS FILLED WITH A LUBRICATING FLUID CALLED SYNOVIAL FLUID.

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ARTICULAR CAPSULE AND ITS THICKENINGS (CAPSULAR LIGAMENTS)

• EACH JOINT IS SURROUNDED BY A TUBULAR DENSE FIBROUS CAPSULE, WHICH IS ATTACHED TO THE ARTICULAR LINES OF THE PARTICIPATING BONES.

• EXAMPLES– EPIPHYSEAL LINE OF HEAD OF FEMUR IS COMPLETELY

INTRACAPSULAR.– EPIPHYSEAL LINE OF LOWER END OF FEMUR IS

COMPLETELY EXTRA CAPSULAR.– EPIPHYSEAL LINE OF UPPER END PARTLY EXTRA

CAPSULAR.

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ARTICULAR CAPSULE

• THE FIBROUS CAPSULE OF THE JOINT MAY BE STRENGTHENED BY ADJACENT MUSCLES, TENDONS AND ACCESSORY LIGAMENTS OR TRUE LIGAMENTS.

• SMALL NERVES AND VESSELS ARE PIERCING THE CAPSULE. THE SYNOVIAI MEMBRANE MAY PROTRUDE OUT OF THE CAPSULE THROUGH HOLES AND FORM BURSAE, WHICH REDUCE FRICTION DURING MOVEMENTS.

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ARTICULAR CAPSULE EXAMPLE

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Types of Synovial Joints Classified by the shapes of their articulating

surfaces Types of movement they allow

uniaxial if the bone moves in just one plane biaxial if the bone moves in two planes multiaxial (or triaxial) if the bone moves in

multiple planes

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Types of Synovial Joints From least movable to most freely movable,

the six specific types of synovial joints are: Plane (gliding) joints intercarpal joint. hinge joints Elbow joint. pivot joints ,atlanto axial ,proximal radio ulnar

joint condyloid (ellipsoid) joints , knee

joint,metacarpophalangeal joint. saddle joints.ankle joint,carpometacarpal joint. ball-and-socket joints.shoulder joint ,hip joint.

MOVEMENTS OF THE SYNOVIAL JOINTS

THE MOVEMENTS PERMITTED AT A JOINT (e.g., SYNOVIAL) ARE OF FOLLOWING TYPES-

GLIDING. ANGULAR. ROTATION. CIRCUMDUCTION. MISCELLANEOUS.

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I.GLIDING MOVEMENTS

IT IS THE SIMPLEST KIND OF MOVEMENTS IN WHICH ONE SURFACE CRAWLS OVER THE OTHER WITHOUT ANY ANGULAR OR ROTATORY MOVEMENTS.EXAMPLES

INTER CARPAL JOINTS INTER TARSAL JOINTS (ONLY GLIDING IS

POSSIBLE) MANY SYNOVIAL JOINTS

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II.ANGULAR MOVEMENTS

IT IMPLIES DECREASE OR INCREASE IN ANGLE BETWEEN THE ADJOINING BONES.

THE ANGULAR MOVEMENTS ARE OF FOUR TYPES

A) FLEXION B) EXTENSION C) ADDUCTION D) ABDUCTION

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Arthritis A group of inflammatory or degenerative

diseases of joints that occur in various forms.

swelling of the joint pain stiffness

Most prevalent crippling disease in the United States.

gouty arthritis osteoarthritis rheumatoid arthritis

Joints

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