Lecture 4- Principles of Articulation Flashcards
what are the
joint structural classification?
- Presence or absence of a synovial cavity and the type of connective tissue.
- Described as either fibrous, cartilaginous, or synovial
what are the
joint fuctional classification?
Based on the degree of movement permitted:
Synarthrosis (immovable)
Amphiarthrosis (partially moveable)
Diarthrosis (freely moveable)
Describe the features of fibrous joints?
- No synovial cavity
- Held together by a fibrous connective tissue
- Permits little or no movement (synarthrosis/amphiarthrosis)
What are the three types of fibrous joints?
- Suture 2. Syndesmosis 3. Interosseous membrane
Describe the suture joints?
- Unite skull bones
- Thin layer of dense connective tissue
- Irregular
- Interlocking edges provide strength, permit no movement (synarthrosis)
- Ossification of a suture forms a synostosis
Describe the syndesmosis joint?
- More connective tissue than seen in a suture
- Crosses a greater distance than a suture
- Connective tissue typically arranged into bundles (ligament)
- Typically permit slight movement (amphiarthrosis)
Describe the interosseous membranes joints?
- Sheet of dense connective tissue
- Binds adjacent long bones
- Amphiarthrosis
- Two main examples between the radius and ulna in forearm, and tibia and fibia in the leg
Describe the cartilaginous joints features?
- No synovial cavity
- Held together by a fibrocartilage or hyaline cartilage
- Permits little or no movement (synarthrosis/amphiarthrosis)
- Two types of cartilaginous joint: 1. Synchrondosis
2. symphysis
Describe cartilaginous joints - synchrondosis?
-The connective tissue is hyaline cartilage
-Synarthrosis
Example: epiphyseal plate (growth plate)
describe the Cartilaginous joints as symphysis?
-Connective tissue is fibrocartilage
-Adjacent bones lined with hyaline cartilage, but with a broad disc of fibrocartilage connects the bones
-Amphiarthrosis
All symphysis occur in the midline of the body:
-Junction of the manubrium and sternum
-Intervertebral discs
-Pubic symphysis
Describe the synovial joints?
- Synovial (joint) cavity between articulating bones
- Freely moveable - diarthrosis
- Layer of hyaline cartilage called articular cartilage
Synovial joint structure: Articular cartilage
- Covers the bones at synovial joints
- Avascular
what is the synovial joint composed of?
- Composed of collagen and proteoglycan
- Orientation of collagen structure imparts resistance to compression & an extremely low resistance surface
Synovial joint structure: Articular capsule
- Encapsulates a synovial joint
- Composed of two layers
Synovial joint structure: Articular capsule layers
- Outer fibrous membrane connects to periosteum:
1) Flexibility permits movement 2) Fibres arranged into bundles – high tensile strength - Inner layer termed synovial membrane 1) areolar connective tissue rich in elastic fibres
2) occasionally contains structural articular fat pads
Synovial joint structure- Synovial fluid:
- Secreted by synovial membrane
- Rich in hyaluronic acid, secreted by fibroblast-like cells, and interstitial fluid from blood plasma
- Lubricates articular surface – reducing friction
- Provides some shock-absorbing properties
- Supplies nutrition to, and removes waste products from the avascular articular cartilage
- Phagocytes remove microbes and debris
Synovial joint structure: Accessory ligaments- Intracapsular
- Intracapsular ligaments lie within the joint capsule -Excluded from synovial fluid by folds in synovial membrane
- e.g. anterior and posterior cruciate ligaments of the knee
Synovial joint structure: Accessory ligaments- extracapsular
Extracapsular ligaments lie outside the joint capsule
- e.g. fibular and tibial collateral ligaments of the knee
Synovial joint structure: Accessory articular discs
-Fibrocartilage pads lie between articular cartilage of some synovial joints e.g.meniscus of the knee
Called meniscii or articular discs
-Help maintain joint stability
-Direct the flow of synovial fluid
injury of Accessory articular discs called?
-Meniscal tears (common in athletes)
Synovial joint structure: Nerve and blood supply
- Nerve endings same as those that supply associated muscles
- Distributed to the articular capsule and associated ligaments
- Pain and proprioception
Synovial joint blood supply?
- Many synovial joint are avascular
- Rely on branching of arteries and veins to supply associated tissue
Synovial joint structure: Bursae
- Moving parts of joints can cause friction
- Bursae are fluid filled sacs lined with synovial like membrane
- Bursae cushion movement between body parts
Synovial joint structure: Tendon sheath
- Tendon sheaths are similar to bursae
- Specialised membranes that wrap around tendons
- Especially where many tendons come together and/or pass through a synovial joint capsule
Types of synovial joints - movement
- Planar
- Hinge
- Pivot
- Condyloid
- Saddle
- Ball & Socket
Types of synovial joints - planar
-Surfaces flat or slightly curved
-Permit back and forth, and side to side movements
Examples include:
- intercarpal joints (between carpal bones at the wrist)
- intertarsal joints (between tarsal bones at the ankle)
Types of synovial joints - hinge
-Concave surface of one bone fits the convex surface of another
-Permits motion in a single axis (flexion and extension)
Examples include:
- knee joints - elbow joints
Types of synovial joints - pivot
-Rounded or pointed surface of one bone
pivots inside a ring formed by the other bone and a ligament
-Permits rotation in it’s longitudinal axis (monoaxial)
Examples include: - radioulnar joints - atlanto-axial joint
Types of synovial joints - condyloid
-Convex oval projection of one bone fit into the oval depression of the other.
-Permits movement around two axis (biaxial; flexion and extension, and abduction and adduction)
Examples include: -wrist joint
-metacarpophalangeal joints
Types of synovial joints - saddle
-One bone fits into the saddle shaped bone it opposes
-Modified condyloid joint
-Permits movement around two axis (biaxial; flexion and extension, abduction and adduction, (sometimes limited rotation))
Examples include: - carpometacarpal joint
Types of synovial joints: ball and socket
-Ball-like surface of one bone fits into the cup-like depression of the other
-Triaxial movement around three planes (triaxial;
-flexion and extension, abduction and adduction, and rotation)
Examples include: - shoulder joint
- hip joint
Glenohumeral (shoulder) joint- Ball socket joint
- Synovial ball and socket joint
- Joint between the proximal humerus and the scapula (glenoid fossa)
- Due to the shallowness of the glenoid cavity, it is the most mobile joint in the body
Glenohumeral (shoulder) joint- Ball socket joint consist of?
-Glenoid labrum; a narrow rim of fibrocartilage – deepens glenoid
-Stabilised by three ligaments:
1) glenohumeral
2) coracohumeral
3) transverse humeral
and Four associated bursae
Glenohumeral joint – name the rotator cuff muscles
- Most strength from rotator cuff muscles
1) supraspinatus 2) infraspinatus
3) teres minor
4) subscapularis
Glenohumeral joint function?
- Join the scapula with the humerus
- Encircle the joint and fuse with joint capsule
Describe the movements caused by rotator cuff muscles?
- Supraspinatus - abducts and externally rotates humerus
- Infraspinatus - externally rotates humerus
- teres minor - externally rotates humerus
- Subscapularis - internally rotates humerus
Acromioclavicular joint
- Technically a synovial gliding joint (planar) but it acts like a pivot
- Joint between the acromion (part of the scapula) and the clavical
Acromioclavicular joint stabilised by?
- acromioclavicular
- coracoacromial -coracolclavicular (conoid and trapezoid)
- Allows the movement of the scapula, permitting greater arm rotation (above the head)
Sternoclavicular joint
- Synovial saddle joint
- Medial clavicle fits into a hollow formed by the superlateral surface of the manubrium and the medial costal cartilage of the first rib.
- Fibrocartilagenous articular disc divides the joint into two synovial cavities
Sternoclavicular joint reinforced by?
Reinforced by interclavicular, anterior, and posterior sternoclavicular ligaments
what is special about Sternoclavicular joint movement?
Although a saddle joint – is capable of triaxial movement – all movement is passive
