Principles of articulation

Question 1

What is an articulation/joint/arthrosis?

Answer 1

a point of contact between:
neighbouring bones
bone and cartilage
bone and teeth

Question 2

How are different types of joint classified?

Answer 2

• structure
• function
• movement

Question 3

Give some examples of shoulder articulation

Answer 3

glenohumeral
sternoclavicular
acromioclavicular

Question 4

Describe structural classification of a joint

Answer 4

Presence or absence of a synovial cavity and the type of connective tissue.

Described as either fibrous, cartilaginous, or synovial

Question 5

Describe the functional classification of a joint

Answer 5

Based on the degree of movement permitted:
Synarthrosis (immovable)
Amphiarthrosis (partially moveable)
Diarthrosis (freely moveable)

Question 6

Describe the structure of fibrous joints

Answer 6

No synovial cavity

Held together by a fibrous connective tissue

Question 7

What is the function of fibrous joints?

Answer 7

Permits little or no movement (synarthrosis/amphiarthrosis)

Question 8

List the 3 types of fibrous joint

Answer 8

1. Suture
2. Syndesmosis
3. Interosseous membrane

Question 9

Describe a suture

Answer 9

Unite skull bones
Thin layer of dense connective tissue
Irregular
Interlocking edges provide strength, permit no movement (synarthrosis)

Question 10

hat does ossification of a suture form?

Answer 10

synostosis

Question 11

Give an example of a synostosis

Answer 11

left & right sides of frontal bone fuse ~6 years of age

Question 12

Describe a syndesmosis

Answer 12

More connective tissue than seen in a suture
Crosses a greater distance than a suture
Connective tissue typically arranged into bundles (ligament)

Question 13

What is the function of a syndesmosis

Answer 13

Typically permit slight movement (amphiarthrosis)

Question 14

Give some examples of a syndesmosis

Answer 14

Anterior tibiofibular ligament

Gomphosis

Question 15

Describe interosseous membranes

Answer 15

Sheet of dense connective tissue
Binds adjacent long bones
Amphiarthrosis

Question 16

Give some examples of interosseous membranes

Answer 16

between the radius and ulna in forearm, and tibia and fibia in the leg

Question 17

Describe cartilaginous joints

Answer 17

No synovial cavity
Held together by a fibrocartilage or hyaline cartilage
Permits little or no movement (synarthrosis/amphiarthrosis)

Question 18

Give some examples of cartilaginous joints

Answer 18

Synchrondosis

Symphysis

Question 19

Describe synchrondosis

Answer 19

The connective tissue is hyaline cartilage

Synarthrosis

Question 20

Give an example of a synchrondosis

Answer 20

epiphyseal plate (growth plate)

Question 21

What happens to the epiphysis, metaphysis and epiphyseal plate at skeletal maturity?

Answer 21

fuse forming a synostosis

Question 22

Describe a symphysis

Answer 22

Connective tissue is fibrocartilage
Adjacent bones lined with hyaline cartilage, but with a broad disc of fibrocartilage connects the bones
Amphiarthrosis

Question 23

Where do symphysis occur? Give examples

Answer 23

All symphysis occur in the midline of the body:
Junction of the manubrium and sternum
Intervertebral discs
Pubic symphysis

Question 24

Describe synovial joints

Answer 24

Synovial (joint) cavity between articulating bones
Freely moveable - diarthrosis
Layer of hyaline cartilage called articular cartilage

Question 25

Describe the articular cartilage

Answer 25

Covers the bones at synovial joints Avascular Composed of collagen and proteoglycan Orientation of collagen structure imparts resistance to compression & an extremely low resistance surface

Question 26

Describe the articular capsule

Answer 26

Encapsulates a synovial joint Composed of two layers Outer fibrous membrane connects to periosteum Flexibility permits movement Fibres arranged into bundles – high tensile strength Inner layer termed synovial membrane areolar connective tissue rich in elastic fibres occasionally contains structural articular fat pads

Question 27

Describe synovial fluid

Answer 27

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 Supplyies nutrition to, and removes waste products from the avascular articular cartilage Phagocytes remove microbes and debris

Question 28

Describe the accessory ligaments of the synovial joint

Answer 28

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 Extracapsular ligaments lie outside the joint capsule - e.g. fibular and tibial collateral ligaments of the knee

Question 29

Describe the accessory articular discs

Answer 29

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

Question 30

What pathology can happen in the accessory articular discs

Answer 30

Meniscal tears - common in athletes

Question 31

Describe the nerve supply of the synovial joint

Answer 31

Nerve endings same as those that supply associated muscles Distributed to the articular capsule and associated ligaments Pain and proprioception

Question 32

Describe the blood supply of the synovial joint

Answer 32

Many components of the synovial joint are avascular | Rely on numerous branching of arteries and veins to supply associated tissue

Question 33

What are bursae?

Answer 33

Bursae are fluid filled sacs lined with synovial like membrane Bursae cushion movement between body parts

Question 34

What are tendon sheaths?

Answer 34

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

Question 35

List the different types of synovial joint based on movement

Answer 35

``` Planar Hinge Pivot Condyloid Saddle Ball & Socket ```

Question 36

Describe planar joints and give examples

Answer 36

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)

Question 37

Describe hinge joints and give examples

Answer 37

``` 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 ```

Question 38

Describe pivot joints and give examples

Answer 38

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

Question 39

Describe condyloid joints and give examples

Answer 39

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

Question 40

Describe saddle joints and give examples

Answer 40

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

Question 41

Describe ball and socket joints and give examples

Answer 41

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

Question 42

Describe the structure of the ball and socket joint

Answer 42

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 Glenoid labrum; a narrow rim of fibrocartilage – deepens glenoid Stabilised by three ligaments: glenohumeral coracohumeral transverse humeral Four associated bursae

Question 43

Describe the rotator cuff muscles

Answer 43

``` Most strength from rotator cuff muscles supraspinatus infraspinatus teres minor subscapularis Join the scapula with the humerus Encircle the joint and fuse with joint capsule ```

Question 44

Describe the acromioclavicular joint

Answer 44

Technically a synovial gliding joint (planar) but it acts like a pivot Joint between the acromion (part of the scapula) and the clavical Stabilised by three ligaments: acromioclavicular coracoacromial coracolclavicular (conoid and trapezoid) Allows the movement of the scapula, permitting greater arm rotation (above the head)

Question 45

Describe the sternoclavicular joint

Answer 45

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 Reinforced by interclavicular, anterior, and posterior sternoclavicular ligaments Although a saddle joint – is capable of triaxial movement – all movement is passive