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The structural classification of joints is based on:
- 1) absence or presence of a synovial cavity (space between articulating bones)
- 2) type of connective tissue that binds bones together
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Structural joint classifications:
- 1) Fibrous joint - no synovial cavity - Dense irregular CT (collagen fibers)
- 2) Cartilaginous joint - no synovial cavity - cartilage
- 3) Synovial joints - synovial cavity - dense irregular CT in articular capsule
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Functional joint classifications:
- 1) Synarthrosis - immovable joint
- 2) Amphiarthrosis - slightly movable joint
- 3) Diarthrosis - freely moving joint - ALL diarthroses are synovial joints
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Fibrous joint
types of fibrous joint
- fibrous joints - no synovial cavity - articulating bones held close together by dense irregular CT - little or no movement -
- 1) sutures
- 2) syndesmoses
- 3) interosseous membranes
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suture
fibrous joint composed of a thin layer of dense irregular CT - only occur between bones in the skull
Synarthrosis - no movment
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syndesmosis
gomphosis
- fibrous joint where there is greater distance between the articulating surfaces and more dense irregular CT than in a suture
- tibia & fibula connected by ligaments
- amphiarthrosis - slight movement
- gomphosis - called a dentoalveolar joint - type of syndesmosis - cone shape pet fits in socket (roots of teeth and their sockets)
- synarthrosis - no movement
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interosseous membrane
- sheet of dense irregular CT that binds neighboring long bones - permits slight movement -
- amphiarthrosis - slight movement
- radius & ulna of forearm
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cartilaginous joint
types of cartilaginous joint
- no synovial cavity - little or no movement
- articulating bones connected by hyaline cartilage or fibrocartilage
- 1) synchondroses
- 2) symphyses
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synchondroses
- cartilaginous joint - hyaline cartilage
- epiphyseal plate
- synarthrosis - no movment
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symphyses
- cartilaginous joint - ends of articulating bones are covered with hyaline cartilage and a broad flat disk of fibrocartilage connects the bones.
- ALL symphyses occur in the midline of the body
- pubic symphysis - amphiarthrosis - slight movement
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Synovial joint
parts of a synovial joint
have a synovial cavity - diarthrosis - freely loving
- 1) synovial cavity - space between articulating bones
- 2) articular cartilage - bones at a synovial joint are covered with hyaline cartialge
- 3) articular capsule - surrounds a synovial joint, encloses the synovial cavity, and unites the articulating bones. Composed of two layers:
- a) fibrous membrane - outer - dense irregular CT (collagen fibers arranged in bundles = ligaments) that attaches to the periosteum of articulating bones
- b) synovial membrane - areolar CT (elastic fibers) - inner layer -secretes synovial fluid - synovial membrane can include Articular Fat Pads - accumulations of adipose tissue
- 4) Synovial fluid - viscous, clear or pale yellow fluid
- forms a film over surfaces in articular capsule
- supplies O2 & nutrients and removes waste form chrondrocytes in articular cartilage
- 5) Accessory ligaments
- extracapsular ligaments = outside the capsule
- intracapsular ligaments = within the capsule but excluded from synovial cavity by a fold in the synovial membrane
- 6) articular discs - menisci - pads of fibrocartilage that lie between the articular surfaces of the bones and are attached to the fibrous capsule
- subdivide the synovial cavity
- allows different shape bones to fit together
- help maintain stability of a joint
- allow for separate movement in different joint compartments
- direct the flow of synovial fluid to areas of most friction
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sprain
forcible wrenching or twisting of a joint that stretches or tears its ligaments but does not dislocate the bones -occurs with ligaments are stretched beyond normal capacity
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strain
stretched or partially torn muscle or muscle and tendon - occurs when a muscle contracts suddenly and powerfully
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bursa (bursae)
- purses - saclike structures that alleviate friction in some joints (shoulder and knee) cushion movement of body parts against one another
- resemble synovial capsules because walls consists of connective tissue lined by synovial membrane - filled with small amount of fluid similar to synovial fluid
- can be located between skin and bones, tendons and bones, muscles and bones, ligaments and bones
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tendon sheath
- reduce friction at joints
- tubelike bursae that wrap around certain tendons and experience considerable friction (where tendons pass through synovial cavities
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bursitis
- acute or chronic inflammation of a bursa
- caused by irritation from: repeated excessive exertion of a joint, trauma, acute or chronic infection , rheumatiod arthritis
- symptoms include: pain, swelling, tenderness, limited movement
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gliding
- simple movement in which relatively flat bones move back-and-forth and side-to-side with respect to one another
- intercarpal joints
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flexion
movement where there is a decrease in the angle between articulating bones (bend arm at elbow)
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extension
movement where there is an increase in the angle between atriculating bones (unbend bent elbow)
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hyperextension
continuation of an extension beyond anatomical position - (moving palm backward at the wrist joint)
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lateral flexion
movement of the trunk in the frontal plane (movement of trunk sideways to the right or left at the waist)
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abduction
movement of bone away from the midline, usually in the frontal plane (lifting arm laterally at the shoulder)
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adduction
movement of a bone toward the midline, usually in the frontal plane (lowering arm laterally to anatomical position)
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circumdiction
moving the distal end of a body part in a circle
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rotation
- movement of bone around its longitudinal axis; in the limbs it may be medial (toward midline) or lateral (away from midline)
- shaking head no
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elevation
upward movement of a body part (close mouth, shrug shoulders)
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Depression
downward movement of part of the body (open mouth, returning shrugged shoulder to original position)
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protraction
movement of a part of the body anteriorly in the transverse plane (thrusting jaw forward, protract clavicle by crossing arms)
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retraction
- posterior movement of a body part in the transverse plane
- returning protracted part of the body back to anatomical position (moving thrust forward mandible back to normal position)
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inversion
medial movement of the sole
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eversion
lateral movement of the sole
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dorsiflexion
Bending the foot in the direction of the dorsum (superior surface) - stand on heels
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plantar flexion
Bending the foot in the direction of the plantar surface (sole) - standing on toes
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supination
movement of the forearm that turns the palm anteriorly
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pronation
movement of the forearm that turns the palm posteriorly
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opposition
movement of the thumb across the palm to touch fingertips on the same hand
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Planar joints
- articular surfaces of bones are mostly flat
- primarily gliding movements
- non-axial - motion doesn't occur around an axis
- ex intercarpal joints
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Hinge joint
- Convex surface of one bone fits into the concave surface of another bone
- angular opening and closing motion
- most often one bone stays still and the other moves around an axis
- mon-axial (uni-axial) - motion around a single axis
- hinge allow only flexion and extension - knee, elbow
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Pivot joints
- rounded or pointed surface of one bone articulates with a ring formed partly by another bone and partly by a ligament
- mon-axial because it only allows rotation around its own logitudinal axis - atlanto-axial joint (shake head no)
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Condyloid joints (ellipsoidal joints)
- convex oval shaped projections of one bone fits into an oval shaped depression of another bone
- bi-axial movement it permits is around two axes (wrist)
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Saddle Joints
- The articular surface of one bone is saddle shaped - the articular surface of the other bone fits into the "saddle" like a rider
- bi-axial - two axes (joint between trapezium and metacarpal of the thumb)
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ball-and-socket joints
- ball like surface of one bone fits into a cup-like depression of another bone
- multi-axial - permit movement around three axes plus all directions in between (shoulder joint, hip joint)
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Factors affecting contact & range of motion (ROM)
- 1. structure or shape of articulating bones - shape determines how close bones fit together
- 2. strength and tension (tautness) of the joint ligaments -tense ligaments restrict range of motion
- 3. arrangement and tension of the muscles
- 4. contact of soft parts
- 5. hormones
- 6. disuse
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TMJ temporomandibular joint
combined hinge and planar joint formed by the condylar process of the mandible and the mandibular fossa and articular tubercle of the temporal bone
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dislocation
displacement of a bone from a joint with tearing of ligaments, tendons, and articular capsules
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glenoid labrum
- part of shoulder joint
- narrow rim of fibrocartilage around the edge of the glenoid cavity that slightly deepens and enlarges the glenoid cavity
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acetabular labrum
- part of hip joint
- fibrocartilage rim attached tot he margin of the acetabulum that enhances the depth of the acetabulum
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rotator cuff injury
- strain or tear in the rotator cuff muscles (sometimes due to vigorous circumdiction - baseball pitchers)
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anterior cruciate ligament (ACL)
posterior cruciate ligament (PCL)
part of knee joint
- ACL - extends posteriorly and laterally from a point anterior to the intercondylar area of the tibia to the posterior part of the medial surface of the lateral condyle of the femur
- limits hyperextention of the knee
PCL - extends anteriorly and medially from a depression on the posterior intercondylar area of the tibia and lateral meniscus to the anterior part of the lateral surface of the medial condyle of the femur
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arthroplasty
joints that have been severly damaged by diseases such as arthritis, or injury, may be replaced surgically with artificial joints - knee, hip, shoulder
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rheumatism
- any painful disorder of the supporting structures of the body - bones, ligaments, tendons, or muscles that are not caused by infection or injury
- 1. arthritis - joints are swollen, stiff, and painful
- 2. Osteoarthritis - degenerative joint disease in which joint cartilage is gradually lost - results from aging, obesity, irritation of the joints, muscle weakness, and wear and abrasion - most common type of arthritis
- 3. rheumatoid arthritis - autoimmune disease in which the immune system of the body attacks its own tissues - cartilage and joint linings -RA is characterized by inflammation of the joint, which causes swelling, pain, and loss of function
- 4. Gout - excessive amount of uric acid cause uric acid buildup in the blood - reacts with sodium to form sodium urate crystals in soft tissue and joints
- 5. Gouty arthritis - sodium urate in joints feet. crystals irritate and erode cartilage causing inflammation, swlling , and pain
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