Lecture 6 terms

Question 1

Synovial joints

Answer 1

Synovial joints allow movement through a very wide range, far more than fibrous or cartilaginous joints.
Free-moving, make up most limb joints and the amount of and direction of movement is determined by the joint ( comes down to the shape of bones and how they interact with each other as well as some of the other soft tissues surrounding that joint.)

Question 2

Synovial joint features

Answer 2

Facilitation of free movement AND control of movement

Bone ends determine range of motion at a joint

The bone ends and their associated articular cartilages, the joint capsule which is formed of DFCT, synovial membrane which lines the interior of the joint capsule and secretes synovial fluid to lubricate, joint cavity which is a potential space, specific ligaments - as thickenings of the capsule (e.g. collateral ligaments) or potentially inside the joint itself ( cruciate ligaments)

Question 3

The amount and direction of movement is determined by…

Answer 3

Joint structure … Bone end shape, capsule and ligaments (location and length) and body surface contact.

Question 4

Describe the structure of synovial joints

Answer 4

The bones of a synovial joint are surrounded by a synovial membrane (thin membrane of epithelial cells), which secretes synovial fluid to lubricate and nourish the joint while acting as a shock absorber.

The ends of the bones are covered with hyaline cartilage which reduces friction. Hyaline cartilage is good at holding water in its ECM and limits friction by becoming slippery and smooth. It consists of 95% ECM and 5% cells (chondrocytes which build cartilage)

The walls of this space are formed by the joint capsule, a fibrous connective tissue structure that is attached to each bone just outside the area of the bone’s articulating surface. The bones of the joint articulate with each other within the joint cavity.

Unlike fibrous or cartilaginous joints, the articulating bone surfaces at a synovial joint are not directly connected to each other with fibrous connective tissue or cartilage. This gives the bones of a synovial joint the ability to move smoothly against each other, allowing for increased joint mobility.

Intracapsular ligaments are made of DFCT and restricts movement between bones.

Joint capsule - This must be loose enough to allow for movement but tight enough to keep the bones together. It is perforated by nerves and vessels, and may also have ligaments for reinforcement of the joint. There’s are 2 layers of the capsule…
Outer fibrous layer (DFCT) - Collagen fibres continuous with periosteum. Thicker parts are the capsular ligaments where more support is required. Looser parts where movement is allowed. The overall function of it is to resist tension/movement, hold bone ends together and protect joint and synovial membrane

Question 5

Synovial membrane

Answer 5

The synovial membrane is very thin layer of epithelial and covers structures within the synovial cavity other than those covered with articular cartilage. It can be thought of as the inner lining of the joint capsule. It is highly secretory and makes and releases synovial fluid.

Question 6

Hyaline cartilage in synovial joints

Answer 6

Hyaline (articular) cartilage covers the bone ends where they articulate and move over each other. Subchondral bone, the layer of bone just below the cartilage in a joint, is very smooth.

Question 7

Two types of ligaments in synovial joints and what they are made of…

Answer 7

Capsular ligaments - made up of DFCT
Intracapsular ligaments - made up of DFCT
(All ligaments are made up of DFCT)

Question 8

Capsular ligament

Answer 8

Ligaments that are presented as the local thickening of the articular capsule are called the capsular ligaments. These ligaments hold bones together. They are tight and thick where more support is required and loose (looseness of the cspsule) where movement is allowed

Question 9

Describe collateral ligaments of the knee

Answer 9

Example of a capsular ligament
The medial collateral ligament and the lateral collateral ligament make up the collateral ligaments of the knee. These prevent abduction and adduction because if these movements were possible it would be problematic in locomotion (running, walking, doing sports etc.)

Question 10

Medial collateral ligament

Answer 10

Medial collateral ligament restricts abduction. (prevents lateral movement of the tibia on the femur)

Question 11

Lateral collateral ligament

Answer 11

Lateral collateral ligament restricts adduction (prevents medial movement of the tibia on the femur)

Question 12

Intracapsular ligament

Answer 12

Ligaments located inside the capsule are known as intracapsular ligaments. These ligaments help hold bone ends together and prevent unwanted movements (restricts movement between bones)

Question 13

Describe cruciate ligaments

Answer 13

Example of an intracapsular ligament which are particular to the knee joint and help to increase the stability between the femur and tibia. These ligaments arise from tibia and insert into the femur.They are named relevant to where they arise from on the tibia.

Question 14

Anterior cruciate ligament

Answer 14

Runs from the anterior aspect of the tibia towards the posterior aspect of the lateral femoral condyle. It restricts posterior displacement of the femur.

Question 15

Posterior cruciate ligament

Answer 15

Runs from the posterior aspect of the tibia towards the anterior aspect of the medial femoral condyle. It restricts anterior displacement of the femur.

Question 16

What would happen if the femur was to slid forward over the surface of the tibia?

Answer 16

With the PCL, you can imagine that if the femur was to slide forward over the surface of the tibia, that the ligament would need to become tight to prevent that movement from occurring. So that means it would prevent anterior displacement of the femur.

Question 17

Discuss the fibrocartilaginous menisci

Answer 17

The amount of soft tissue required to supplement the structure of the knee is significant.
Menisci are little crescent structures that sit in-between the tibia and the femur. These c-shaped rings’ job is to hug the condyles (distal surface of the femur) and deepen the articulation of that joint. Deepening the socket increases stability and being made of fibrocartilage it means the structure can resist compression and provide cushioning between two articulating bones.

Question 18

Summary of joints

Answer 18

Fibrous and cartilaginous have no space in-between bones whereas synovial joints have free bone ends which makes them more mobile but les stable.

Question 19

Stability vs mobility

Answer 19

There is a trade-off between the two in synovial joints. If you increase mobility then you decrease the amount of stability which increases the risk of injury or dysfunction.

Question 20

Range of movement (ROM) and what is it determined by?

Answer 20

ROM is the type and amount of movement that is determined by the structure of the joint. Determined by…Bone end shape, ligament location and length, and body surface contact

Question 21

List all the movements that occur in the sagittal plane

Answer 21

Flexion
Extension
Dorsiflexion
Plantarflexion

Question 22

List all the movement that occur in the transverse plane

Answer 22

Rotation
Pronation
Supination

Question 23

List all the movements that occur in the frontal plane

Answer 23

Adduction
Abduction
Inversion
Eversion

Question 24

Name all the synovial joint shapes (Hint- Harry Potter Shouldn’t Ever Consider Playing Basketball)

Answer 24

Hinge 
Pivot 
Saddle 
Ellipsoid 
Condylar 
Plane 
Ball and socket 

As you go down this list you get increased movement

Question 25

Plane joint + examples

Answer 25

Axis(es)- Multiaxial
Movements - Sliding and gliding
Example - Between carpal and tarsal bones (intercarpal and intertarsal joints) - between bones that have flat articular surfaces/flat ends

Question 26

Hinge joint + examples

Answer 26

Axis(es)- Uniaxial
Movements - Flexion, extension
Example - Interphalangeal joints (allows for precise grip), elbow joint (humerus with ulna), ankle

Question 27

Pivot joint + examples

Answer 27

Axis(es)- Uniaxial (only in transverse plane?)
Movements - Rotation
Example - C1-C2 vertebrae, radioulnar joint

Question 28

Condylar joint + examples

Answer 28

Axis(es)- Biaxial
Movements - Flexion, extension and slight rotation (when semi-flexed because condyles make poor contact with menisci and then ligament capsule becomes loose therefore can use some muscles in the thigh to rotate the knee)
Example - Knee joint, TMJ (temporomandibular joint)

Question 29

Ellipsoid joint + examples

Answer 29

Axis(es)- Biaxial (move through sagittal and coronal plane not the transverse as there is no rotation)
Movements - Flexion, extension, adduction, abduction and circumduction
Example - Wrist joint (radio-carpal joint)

Question 30

Saddle joint + examples

Answer 30

Axis(es)- Biaxial
Movements - Flexion, extension, adduction, abduction and circumduction (obligatory rotation-opposition based on the anatomy of the carpometacarpal joint- which allows for the manipulation of the external environment)
Example - Thumb (carpometacarpal joint- five joints in the wrist that articulate the distal row of carpal bones and the proximal bases of the five metacarpal bones.)

Question 31

Ball and socket joint + examples

Answer 31

Axis(es)- Multiaxial
Movements - Flexion, extension, adduction, abduction, rotation (for example the pivot of the humerus within the socket) and circumduction
Example - Shoulder joint, hip joint

Question 32

Upper vs lower limb joints

Answer 32

Upper limb (going down from the shoulder) - Ball and socket joint, hinge joint at the elbow, pivot joints at the radius and ulna, biaxial joint at the wrist, various hinge and saddle joints associated with fingers and parts of our hands. These make our upper limb very good at interacting with our external environment.

Lower limb - Bones get a bit bigger so you lose a bit of that dexterity but there is still a good range of motion at the hip, restricts a little bit when we get to the knee then it certainly restricts when we get down towards our ankle and out foot because at that point our lower limb is more about mobility and stability

Question 33

Example of a low bony congruence and high bony congruence

Answer 33

The knee - The tibia and femur have low bony congruence which means that if it wasn’t stabilised with extra tissues then the knee would fall apart very easily
The hip - The head of the femur and the socket in the hip has high bony congruence. This facilitates movement sin lots of different plants

Question 34

Uniaxial

Answer 34

One axis

Question 35

Biaxial

Answer 35

Two axes

Question 36

Multiaxial

Answer 36

Multiple axes

Question 37

The knee is an example of _____ joint

Answer 37

Condylar

Question 38

Name 3 tissues/structures located at a synovial joint that are essential for movement

Answer 38

1 - muscles
2- DFCT (tendons/ligaments)
3- Cartilage (hyaline)

Question 39

Collateral ligaments are thickened regions of what structure of the synovial joint?

Answer 39

Thickened region of the joint capsule, they restrict movement in the coronal plane and therefore help to stabilise the joint.

Question 40

Which 2 specific ligaments restrict movements in the sagittal plane?

Answer 40

The cruciate ligaments (posterior cruciate ligament and anterior ligament) are intracapsular, they restrict movement in the sagittal plane.

Question 41

Synovial cavity/joint cavity

Answer 41

The potential space between bone ends, allowing the bones to move easily at the joint.

Question 42

Head of fibula is on the _____ aspect of the knee joint

Answer 42

Lateral

Question 43

What are tendons and ligaments so white?

Answer 43

Because their main component is collagen and they are relatively avascular

Question 44

Muscles are

Answer 44

Parallel bundles (fasciuli) of myocytes (muscle fibres)

Question 45

What factors influence the stability of a synovial joint?

Answer 45

Bony congruence, joint capsule and ligaments, and tendons/muscles crossing the joint.

Question 46

What factors influence the range of movement at a synovial joint?

Answer 46

Bony congruence, joint capsule and ligaments, and tendons/ muscles surrounding the joint, and body surface contact.

Question 47

Why is it that cartilage cells proliferate at the growth plate, but this later does not get relatively thicker over time?

Answer 47

Because the tissue is ossified during growth

Question 48

List two possible uses for an accurate knowledge of the age at which growth plates become ossified

Answer 48

1 - Allows age estimation of human remains.

2- Treatment of bone damage/types of fractures/region of fractures may be different with age.

Question 49

What structures do not appear on radiographs and why?

Answer 49

Articular cartilage, periosteum and blood vessels are not visible on radiographs as they are soft tissues with relatively low electron density, and therefore x-rays pass through them easily.