Joints I

Question 1

Joint/Articulation

Answer 1

site of contact between bones or between cartilage and bone (bones/joints develop from the same embryonic tissue)

Question 2

Surfaces of the bone covering the joint is …

Answer 2

articular surfaces, the covering articular cartilage

Question 3

Role of Joints

Answer 3

to allow movement amongst rigid bones, however not all joints allow movement - e.g. sutures in the skull and temporary joints

Question 4

Temporary Joint - 4 points

Answer 4

designed to allow growth of bone, found in immature bones with bony epiphysis and a bony diaphysis - epiphyseal plate/growth plate, not designed for movement, eventually obliterated by ossification of growth plate

Question 5

2 categories for classifying joints

Answer 5

Function and Structure

Question 6

Function category - 3 types based on the degree of movement

Answer 6

synarthroses, amphiarthroses and diarthroses

Question 7

synarthroses

Answer 7

immoveable

Question 8

amphiarthroses

Answer 8

slightly moveable

Question 9

diarthroses

Answer 9

freely moveable

Question 10

Structure category - 3 types based on presence/absence of a joint cavity & type of connective tissue

Answer 10

Fibrous, cartilaginous and synovial

Question 11

Define a fibrous joint

Answer 11

bones connected by fibrous tissue with no joint cavity

Question 12

Define a cartilaginous joint

Answer 12

bones connected by cartilage with no joint cavity

Question 13

Define a synovial joint

Answer 13

bones not connected, form joints and have a joint cavity

Question 14

3 types of fibrous joint

Answer 14

Sutures, Syndesmoses and Gomphoses

Question 15

Describe sutures - 6 points

Answer 15

connected by fibrous tissue, found only in the skull, bones of the skull vault bound tightly with fibrous tissue = sutural ligaments - this immobility is important to give protection to brain/special sense organs, found where the margins of the bone meet, sutural surfaces = designed to interlock

Question 16

serrated

Answer 16

saw-like (sutures)

Question 17

denticulate

Answer 17

tooth-like (sutures)

Question 18

Describe sutures in a foetus/young child - 3 points

Answer 18

bones of cranial vault have not yet met so there are gaps covered only by fibrous tissue = fontanelles - allow for further growth in size of the brain, when growth is complete the sutural ligament is replaced with bone (late 20s) = synostosis

Question 19

Describe Syndesmoses - 3 points

Answer 19

held together by fibrous connective tissue but not as firmly as sutures, only 1 true syndesmoses - between the distal ends of the tibia & fibula = inferior tibiofibular joint, permits some movement but no true movement, superior tibiofibular joint and the radius & ulna joints are joined by sheet of fibrous tissue (interosseous membrane) which have much larger fibres and so aren’t true syndesmoses

Question 20

Describe Gomphosis - 2 points

Answer 20

specialised fibrous joints between teeth and supporting bones of the jaw, tooth root anchored to bony walls of socket by thin fibrous membrane = periodontal membrane

Question 21

3 types of cartilaginous joints

Answer 21

Primary cartilaginous joints, secondary cartilaginous joints and synovial

Question 22

Describe primary cartilaginous joints (synchondroses) - 2 points

Answer 22

held together by a plate of hyaline cartilage, mostly temporary joints - allows for growth (e.g. between epiphyses and diaphyses of long bone) and for growth of skull base until about 25 yrs

Question 23

Example of a primary cartilaginous joint

Answer 23

Between ribs and costal cartilages - cost-chondral joints

Question 24

Describe secondary cartilaginous joints (symphyses) - 5 points

Answer 24

have articular surfaces and bones are covered by hyaline cartilage, bones held together by plate of fibro-cartilage, allows slight movement, not all are permanent joints, the 2 halves of the mandible are joined by symphyseal joint in midline - united after 1st year of life

Question 25

Examples of secondary cartilaginous joints

Answer 25

Inter-vertebral discs between vertebral bodies - permanent joint, pubic symphysis forms between 2 pubic bones - permanent joint, joint between manubrium and body of sternum = manubrio-sternum joint - obliterated by bone later in life

Question 26

Describe synovial joint - 4 points

Answer 26

form the majority of joints in the body, the articular joint capsule is attached around the articular margins and between the articulating bones, bony surfaces covered by articular hyaline cartilage, joint cavity and joint capsule

Question 27

Joint cavity in synovial joint

Answer 27

v small space and separates articulating bone

Question 28

Joint capsule in synovial joint

Answer 28

double-layered, outer = strong & fibrous capsule, inner = synovial membrane

Question 29

Describe the fibres of the fibrous capsule found in a synovial joint - 4 points

Answer 29

firmly joined to periosteum by ligaments holding the bone together, ligaments can be intrinsic (capsular) extrinsic and distinctly separated from the joint capsule (extracapsular), some joints become strengthened internally by having intracapsular ligaments located within the synovial cavity (e.g. knee joint which has the cruciate ligaments) - also has 2 articular discs = medial & lateral menisci inside the joint cavity

Question 30

Examples of Intra-articular surfaces in synovial joints

Answer 30

e.g. articular discs, tendons & ligaments, all additional features to some synovial joints but not common to all

Question 31

Smooth synovial membrane in synovial joints - 5 points

Answer 31

found within joint capsule, lines entire joint cavity, doesn’t cover surfaces of articular cartilage, often thrown into folds which project into joint cavity, produces a viscous fluid = synovial fluid which lubricates joint surfaces