chapter 8

Joint

Junction between bones

Functions of Joints

hold bones together and may permit movement

Joint are classified in 2 ways

functional classification and structural classification

Functional Classification

Degree of movement

Structural Classification

Tissues and anatomy

Synostosis

Joints fusing together

Functional Classifications

1. synarthrosis 2. amphiarthrosis 3. diarthosis

Synarthrosis

Immoveable

Amphiarthrosis

Slightly moveable

Diarthrosis

Freely moveable

Structural Classifications

1. fibrous 2. cartilaginous 3. synovial

Fibrous Joints

1. sutures 2. syndesmoses 3. gomphosis

Sutures

Synarthosis between skull/facial bones

Formation of sutures

Result of intramembranous ossification and the bones making contact

Sutural Ligament

Dense fibrous CT between bones

Syndesmoses

Amphiarthrosis joints that limit movement of other joints and keeps them separated

syndesmoses joint location

Between limb bones

Syndesmoses Joints ex

1. Distal tibiofibular ligaments

2. Radioulnar and tibiofibular interosseous membranes

Anatomy of Syndesmoses Joints

Sheets of dense regular CT between bones

Gomphosis

Synarthrosis joints in between maxillary/mandibular alveoli and teeth roots

Anatomy of Gomphosis

Root connects to alveolus via dense fibrous CT

Formation of Gomphosis

1. Epithelial migrates into mesenchyme

2. Epithelial becomes tooth enamel and mesenchyme becomes tooth bulb and ligament

Cartilaginous Joints

1. Synchondrosis

2. Symphysis

Synchondrosis

Synarthrosis found at epiphyseal plates and costal cartilage

Anatomy of Synchondrosis

Rigid hyaline cartilage between 2 bones

Formation of Synchondrosis

Result of incomplete endochondral ossification

Synchondrosis Ex

1. Between ribs and sternum

2. Epiphyseal plate

Symphysis

Amphiarthrosis found at intervertebral discs and pubic symphysis

Anatomy of Symphysis

Fibrous cartilage between 2 bones

Pubic Symphysis results of

incomplete endochondral ossification

Formation of Intervertebral Discs

1. Endochondral ossification replaces notochord with bone tissue

2. Fibrous cartilage grows in between vertebrae and surround notochord

Fibrous cartilage becomes the

outer annulus fibrosus

Notochord becomes the

inner nucleus pulposus

Synovial Joints

Diarthrosis found between appendicular skeleton, jaw, and vertebrae

Joint is encased

1. Dense regular CT joint capsule

2. Lined on inside by synovial membrane

3. Epithelium in membrane produces synovial fluid

Composition of Synovial Fluid

1. Blood filtrate

2. Hyaluronan

3. Glycoproteins

Function of Synovial Fluid

1. Lubricates

2. Absorbs shock

3. distributes nutrients

Articular cartilage

Cartilage on the ends of bones leftover from endochondral ossification

Accessory Structures of Synovial Joints

1. Menisci

2. Fat pads

3. Bursae

4. Labrum

5. Accessory Ligaments

Menisci

Pads of fibrous cartilage that subdivide the cavity

Function of Menisci

1. Channel synovial fluid

2. modify articular surfaces

3. Restrict Movement

4. Cushion

Location of Menisci Ex

Ulnolunate, tempomandibular, knee

Fat Pads

1. Adipose tissue surrounding the synovial capsule

Function of Fat pads

Protect articular cartilage, packing material, fills spaces

Location of Fat pads ex

1. Knee

2. Hip

3. Elbow

Bursae

Small pockets of Ct lined with synovial membranes and fluid

Location of Bursae

In the hypodermic

Function of bursae

1. cushion

2. support

3. reduce friction between tendons and ligaments

Location of bursae ex

1. Glenohumerol

2. Elbow

3. knee

Labrum

Raised ring of dense irregular CT around margin of socket

Function of Labrum

Deepens the socket to prevent dislocation

Location of Labrum ex

glenohumeral and hip

Accessory Ligaments

dense regular Ct between bones in addition to normal joint capsules

Capsular Ligaments

thickened additions to the joint capsule

Examples of capsular ligaments

1. Glenohumeral

2. Aeromioclavicular

3. iliofemoral

4. Ischiofemoral

5. Pubofemoral

Extracapsular ligament

ligaments outside the capsule

Examples of extracapsular ligament

1. coraco acromial

2. coraco clavicular

Intracapsular ligaments

ligaments found inside the joint capsule

Examples of intrascapular ligaments

Cruciate ligaments

Monoaxial Joints

1. Plain Joint

2. Pivot Joint

3. Hinge Joint

Plain Joint

1. Bone surfaces are flat

2. Side to side gliding

Examples of plain joints

1. intercarpals

2. intertarsals

3. sternoclavicular

Pivot Joint

1. Rounded surfaces articulates with ring around another bone

2. Spin movement only

Example of pivot joint

Proximal Radioulnar

Hinge Joint

1. Convex surface of one bone fits into concave surface of another

2. changes angle over a single plane

Examples of hinge joints

1. knee

2. humeroulnar

3. interphalanges

Biaxial Synovial Joints

1. Condylar Joint

2. Sattle Joint

Condylar Joint

1. Oval bone projection fits into an oval depression

2. Changes angle over two planes

Examples of Condylar Joint

1. Radiocarpals

2. metacarpophalangeal

3. Metatarsophalangeal

Saddle Joints

1. Bisected surface straddling a concave surface

2. changes angle over 2 planes

Example of saddle joint

carpometacarpal 1

Triaxial Joint

Ball and Socket

Ball and Socket Joint

1. Ball fitting into a cup like depression

2. wide range of motions including angular changes, rotation, and circumduction

Example of ball and socket

1. Glenohumeral

2. Hip

Types of movement

Angular and Rotational Movements

Abduction

Move away from midline

Adduction

Moves towards midline

Flexion

Decrease angle of joint

Extension

Increase angle of joint

Rotational Movements

Pronation and Supination

Pronation

Turns palm posterior

Supination

turns palm anterior

Eversion/inversion

turns plantar surface out/in

Dorsiflexion/plantar flexion

lift/lower toes

Lateral flexion

bend the vertebral column to one side

Protraction/retraction

anterior/posterior movements

elevation/ depression

superior/inferior movement

Opposition/reposition

move thumb in/out