Types of Joint

Question 1

Articular capsule

Answer 1

a joint capsule or articular capsule is an envelope surrounding a synovial joint. Each joint capsule has two parts: an outer fibrous layer or membrane, and an inner synovial layer or membrane

Question 2

Articular cartilage

Answer 2

a dense layer of connective tissue which covers the articulating surface of bones with a smooth slippery surface. The articular cartilage reduces friction between bones in the joint during movement and helps to absorb shock

Question 3

Ball and socket joint

Answer 3

Consists of a ball like surface of one bone iftting into a cuplike depression of another bone. These joints are multiaxial because they permit movement around three axes plus all directions inbetween.

E.g.

shoulder - humerus fits into glenoid cavity of scapula

hip - head of femur fits into acetabelum of of hip bone

Question 4

Bursa

Answer 4

A cushioning sac strategically situated to reduce friction in synovial joints.

Their walls consist of connective tissue lined by a synovial membrane and they are filled with a fluid similar to synovial fluid.

usually between skin and bone, tendon and bone, and ligaments and bone (to rduce friction)

the bursal sacs cushion movment of one body part over another.

small fat pads can also fulffill the same job

Question 5

Bursitis

Answer 5

Inflamation of a bursa (or fat pad) within a joint, caused by pressure or firction

Question 6

Collagen fibres

Answer 6

Consists of the protein collagen. (25% of total body protein)

Found in connective tissue, bone, cartilage, tendon, and ligaments

Very strong and resist pulling forces, but they are not stiff to allow flexibility

Lots of types of collagen fibres and have highly diff properties - collagen fibres in cartilage attract more water to provide a cushioning quality

Question 7

Condyloid joints

Answer 7

1. Convex oval shaped prjection of one bone fits into the oval shaped depression in another bone.
2. Movement is biaxial
3. e.g. wrist and MCPJ

Question 8

Diarthrosis

Answer 8

1. freely movable. All diarthrosis joints (diarthroses = pleural) are synovial joints (e.g., shoulder, hip, elbow, knee, etc.),
2. the terms “diarthrosis” and “synovial joint” are considered equivalent by Terminologia Anatomica.

Question 9

Fibrous Capsule

Answer 9

The fibrous membrane of the joint capsule is attached to the whole circumference of the articular end of each bone* entering into the joint, and thus entirely surrounds the articulation. It is made up of dense irregular connective tissue.

permits considerable movement, but with great tensile strength (avoida stretching)

helps prevent dislocation

* periosteum - a dense layer of vascular connective tissue enveloping the bones except at the surfaces of the joints

Question 10

Planar joints

Answer 10

The articulating surfaces are flat or slightly curved.

Permit side to side and back and fourth movments

non axial movement

e.g. intercarpal, intertarasal, sternoclavicular , acromioclavicular

Question 11

saddle Joints

Answer 11

Articular surface of one bone is saddle shaped and the articular surface of another fits into the saddle.

modified condyloid joints where movment is freer

bi-axial

e.g. carpometacarpal joint

Question 12

Hinge joint

Answer 12

common class of synovial joint that includes the ankle, elbow, and knee joints. Hinge joints are formed between two or more bones where the bones can only move along one axis to flex or extend.

Question 13

Sprain

Answer 13

damage to ligaments, but does not dislocate the bone

can damage surrounding blood vessels, muslces, tendons, and nerves

Question 14

Strain

Answer 14

stretched or partially torn muscle.

often occurs when a muscle contracts suddenly and powerfully

Question 15

Synovial joint

Answer 15

Synovial joints are the most common type of joint in the body. These joints vary in structure - for example, the shoulder is a ball-and-socket joint and the knee is a hinge joint - but all synovial joints have the following in common:

1. Synovial joints allow for movement.
2. Where the bones meet to form a joint, the bones’ surfaces are covered with a thin layer of strong, smooth articular cartilage.
3. A very thin layer of slippery, viscous joint fluid, called synovial fluid, separates and lubricates the two cartilage-covered bone surfaces. A healthy knee joint has up to 4 mL, or less than a teaspoon, of synovial fluid.2
4. A synovial membrane encapsulates the joint surfaces and synovial fluid. The synovial membrane is very thin, often just a few cells thick (about 50 microns, or the approximate width of a human hair) and produces synovial fluid. The synovial membrane is backed by a slightly thicker subsynovial membrane.

Question 16

Tendon

Answer 16

1. strong cord like structure made up of parallel bundles of collagen fibres which extend from the connective tissues surrounding the muscle and its compartments
2. attaches the muscle fibres at one end to the bone via the pereosteum at the other end
3. muscle contraction pulls the tendon, being inelastic, pulls bone
4. allows 5% stretch to absorb sudden force

Question 17

Tendon sheaths

Answer 17

tube like bursae that wrap around tendons where there is considerable friction, where tendons pass through synovial cavities (joints)

Question 18

Types of joints

Answer 18

1. Synovial - freely moveable - e.g. knee, shoulder,
2. Cartilaginous - slightly moveable - e.g. vertebral bodies of spine
3. Fibrous - Immovable - skull structures

Question 19

Types of synovial joints

Answer 19

1. Spheroidal - convex surface in concave - wide range of movement - eg. shoulder and hip
2. Hinge - flat/planar - motion in one plane (felx/ex) - e.g. IPJ, elbow
3. Condylar - convex or concave - movement of 2 articualting surfaces not dissociable - e.g. TMJ