Principles of articulation Flashcards
What is structural classification dependent on?
- Presence or absence of a synovial cavity and the type of connective tissue
- Described as either fibrous, cartilaginous or synovial
What is functional classification dependent on?
- Based on the degree of movement permitted:
synarthrosis (immovable), amphiarthrosis (partially moveable), diarthrosis (freely moveable)
Describe fibrous joints
structural and functional features, types
- no synovial cavity
- held together by a fibrous connective tissue
- permits little/no movement
- 3 types: suture, syndesmosis, interosseous membrane
Describe suture joints
(type of joint, location, structure, function)
What is a synastosis?
- Fibrous joint
- Unite skull bones
- Thin layer of dense connective tissue
- Irregular, interlocking edges provide strength but permit no movement
- Ossification of a suture
Describe syndesmosis joints
(type of joint, location, structure, function)
Give 2 examples
- Fibrous joints
- More CT than in suture
- Connective tissue typically arranged into bundles (ligament)
- Permit slight movement (amphiarthrosis)
- e.g. anterior tibiofibular ligament, gomphosis (or dentoalveolar)
Describe interosseous membrane joints
(type of joint, structure, function)
e.g.
- Fibrous
- Sheet of dense connective tissue
- Binds adjacent long bones
- Amphiarthrosis
Between radius and ulna, tibia and fibula
Describe cartilaginous joints
- No synovial cavity
- Held together by a fibrocartilage or hyaline cartilage
- Permits little/no movement
- Types: synchrondosis, symphysis
Describe syndchrondosis joints
(type of joint, structure, function, example)
What happens at skeletal development?
- Cartilaginous
- CT= Hyaline cartilage
- Synarthrosis
- Epiphyseal plate (at skeletal maturity, epiphysis, metaphysis and epiphyseal plate fuse forming a synostosis)
Describe symphysis joints
type of joint, structure, function, example
- Cartilaginous
- CT= fibrocartilage
- Adjacent bones lined with hyaline cartilage but with a broad disc of fibrocartilage connecting them
- Amphiarthrosis
- All occur in midline of body
1. junction of manubrium and sternum
2. invertebral discs
3. Pubic symphysis
Describe synovial joints
- Synovial joint cavity between articulating bones
- Freely moveable- diarthrosis
- Layer of hyaline cartilage called articular cartilage
Describe the articular cartilage found at synovial joints
Location
Vascular supply
Composition
- Covers the bones at synovial joints
- Avascular
- Composed of collagen and proteoglycan
- Orientation of collagen structure imparts resistance to compression and an extremely low resistance surface
Describe the articular capsule found at synovial joints
Location
Compostition
- Encapsulates synovial joint
Composed of 2 layers
1: outer fibrous membrane which connects to periosteum
- flexibility permits movement
- fibres arranged into bundles- high tensile strength
2: Inner layer (synovial membrane)
- areolar connective tissue rich in elastic fibres
- occasionally contains structural articular fat pads
Describe the synovial fluid found at synovial joints
Where does it come from?
Composition
Function
- Secreted by synovial membrane
- Rich in hyaluronic acid, secreted by fibroblast-like cells and interstitial fluid from plasma
- Lubricates articular surface - reducing friction
- Shock absorption
- Supplies nutrition and removes waste from avascular articular cartilage. Phagocytes remove microbes and debris
Describe the accessory ligaments found at synovial joints
INTRACAPSULAR LIGAMENTS
- excluded from synovial fluid by folds in synovial membrane
e. g. anterior and posterior cruciate ligaments
EXTRACAPSULAR LIGAMENTS
- fibular and tibial collateral ligaments of knee
Describe the accessory articular discs found at synovial joints
What are they?
Function?
Pathology?
- Fibrocartilage pads lie between articular cartilage of some synovial joints e.g. meniscus of knee
- Help maintain joint stability and direct flow of synovial fluid
- Meniscal tears (common in athletes)
Describe the nerve and blood supply of synovial joints
- Nerve endings same as those that supply associated muscles
- Distributed to the articular capsule and associated ligaments
- pain and proprioception
**Many compartments are avascular. Otherwide rely on numerous branching of arteries and veins to supply tissue
What type of joint have associated bursae?
What are they?
What is their function?
- Synovial joints
- Fluid filled sacs lined with synovial like membrane
- Cushion movement between body parts which otherwise cause friction
What type of joint have associated tendon sheaths?
What are they?
Where are they found?
- Synovial joints
- Specialised membranes that wrap around tendons. Especially where many tendons come together and/or pass through a synovial joint capsule
What types of synovial joints are there?
Planar, hinge, pivot, condyloid, saddle, ball and socket
PLANAR (Synovial) joints
Structure
Movement
Eg
- Surfaces flat or slight curved
- permit back and forth, side-to-side movement
- Intercarpal and intertarsale
HINGE (Synovial) joints
Structure
Movement
Eg
- Concave surface of one bone fits the convex surface of another
- motion in a single axis (flexion/extension)
- knee, elbow
PIVOT (Synovial) joints
Structure
Movement
Eg
- Rounded or pointed surface of one bone pivots inside a ring formed by the other bone and a ligament
- rotation in a longitudinal axis (monoaxial)
- radioulnar joints, atlanto-axial joint
CONDYLOID (Synovial) joints
Structure
Movement
Eg
- Convex oval projection of one bone fit into oval depression of the other
- biaxial (flex/extend AND ab/adduct)
- MCP, wrist
SADDLE (Synovial) joints
Structure
Movement
Eg
- One bone fits into the saddle shaped bone it opposes
- Biaxial (flex/extend AND ab/adduct) + sometimes limited rotation
- e.g. carpometacarpal joint of d1
BALL & SOCKET (Synovial) joints
Structure
Movement
Eg
- Ball like surface of one bone fits into cup-like depression of another
- triaxial movement (flex/extend, ab/adduct, rotate)
- shoulder, hip
Describe the glenohumeral joint
What kind of joint is it? Which bones are involved? How does its structure impact mobility? What is the function of the glenoid labrum? Which ligaments stabilise it? How many associated bursae?
- Synovial ball and socket joint
- Proximal humerus and the scapula (glenoid fossa)
- Due to the shallowness of the glenoid cavity, it is the most mobile joint in the body
- Deepens glenoid fossa
- Glenohumeral, coracohumeral, transverse humeral
- 4
How do the rotator cuff muscles relate to the shoulder?
- Encircle the joint and fuse with joint capsule
- Join the scapula with the humerus
Describe the acromioclavicular joint
What kind of joint is it?
Which bones are involved?
Which ligaments stabilise it?
What movement does it permit?
- Synovial gliding joint (planar) but acts as pivot
- Acromion of scapula and clavicle
- Acromioclavicular, coracoacromial, coracoclavicular
- Allows the movement of the scapula permitting greater arm rotation (above head)
Describe the sternoclavicular joint
What kind of joint is it? Which bones are involved? Structure Which ligaments stabilise it? What movement does it permit?
- Synovial saddle joint
- Medial clavicle and hollow formed by superlateral surface of manubrium and medial costal cartilage of 1st rib
- Fibrocartilaginous articular disc divides joint into 2 synovial cavities
- Reinforced by interclavicular, anterior, and posterior sternoclavicular ligaments
- Passive triaxial movment
