Tendons

Question 1

What is the definition of a tendon

Answer 1

a physical link between bone and muscle

Question 2

What are the basic qualities of a tendon

Answer 2

• produce movement at a distance
• elastic qualitities are limited
• poor blood supply (but not avascular)
• dense regular connective tissue

Question 3

What are the different tendon types/shapes

Answer 3

• round
• oval
• flat sheets = aponeurosis
• some named ligaments are actually tendons

Question 4

What are the characterisitics of positional tendons

Answer 4

• stiff/less elastic (compared to elastic T.)
• steeper stress-strain curve
• fail at low strains, 5-6%
• used to guide limb placement
• usually on extensor muscles

ex. CDE tendon

Question 5

What are some characteristics fo elastic tendons

Answer 5

• elastic
• flatter stress-strain curve than positional T
• fail at high strains, 19-21%
• used to absorb landing shocks
• usally on flexor muscles

Ex. DDF tendon, SDF Tendon, TIOM

Question 6

What are the gross qualities of Ligaments

Answer 6

• bands of CT which cross the joint space and therefore support and modify joint movement
• join Bone to Bone
• thickened regions of the joint capsule (not seperate structures
• exist outside the synovial cavity

Question 7

What is a tendon composed of

think on the molecular level

Answer 7

• WATER (v important to function.) 55-70%
• collagen
• non-collagenous matrix (holds water, provides other mechanical properties
• fibroblasts (tenoblasts/tenocytes) (longer and thinner than fibroblasts in other CT but still fibroblasts, just called tenoblast)

Question 8

What % of the dry mass of a tendon is collagen

Answer 8

60-85%
- 60-80% type 1
- 0-10% type 3
- 2% type 4
- small amounts of other types

Question 9

what are the components of non-collagenous extracellular matrix of a tendon

Answer 9

• cartilage oligometric matrix protein (3%)
• elastin (1-2%)
• Proteoglycans (1-5%)
• inorganic components such as copper, manganese and calcium (0.2%)

Question 10

What type of collagen is more abundant in Ligaments than tendons

Answer 10

type 3

Question 11

Label

Answer 11

Question 12

What is the name of the cells found in tendons

Answer 12

tenocytes

Question 13

How does collagen synthesized in the tendon

Answer 13

1. procollagen (the triple helical protein) is made inside the fibroblast
2. procollagen migrates out of the cell
3. procollagen in trimmed into a collagen molecule (ends)
4. collagen self polymerizes, creating fibrils

Held together by hydrogen bonds

Question 14

What is crimp

Answer 14

• formed by contracted tenocytes
• appears wavy when reaxed, straight when loaded
• tenocytes are in contact with eachohter via fin cytoplasmic processes to form a synctium, whihc pulls on collagen fibres

Question 15

What gives a tendon elasticity

Answer 15

spiral collagen fibres and cross linking of collagen fibres by glycosaminoglycans which packs the collagen fibres correctly and allows them to slide past each other under load

Question 16

What are the 2 types of tendon insertion

Answer 16

• indirect (fibrous)
• direct (fibrocartilagenous)

Question 17

what are the qualities of indirect/fibrous insertion of tendons

Answer 17

• low angle of insertion
• collagen fibres/muscle/ligament cary on into the bone
• attached to the periosteum to allow appositional bone growth
• bone at insertion point is immature and constantly remodelling
• Sharpey’s fibres (type 1 collagen) carry the force into the bone

Question 18

What are the qualities of direct/fibrocartilagenous insertion of tendon

Answer 18

• high angle of insertion
• gradation from tendon to fibrocartilage to mineralized fibrocartilage to bone (gradual increase of stiffness)
• cpollagen fibres of tendon/ligament/tooth carry on into the bone
• attaches to the periosteum
• Sharpey’s fibres (type 1 collagen) carry the force into the bone
• bone at the tendon/lig/tooth insertion points is immature and constantly remodelling

Question 19

What is a tendon sheath

Answer 19

• a balloon like structure (pads or tubes)
• fibrous capsule around the tendon
• contains synovial fluid
• located at joints to lubricate the tendon as it passes distally

Question 20

how is blood supply carried in sheathed tendons

Answer 20

by the mesotenon (where the sheath folds inwards)

Question 21

What is bursa

Answer 21

• tough CT sac containing synovial fluid
• located under area of pressure
• usually under tendons near their insertion points where there is a steep angle

Question 22

what is the most abundant component of the tendon extracellular matrix

Answer 22

water

Question 23

what is the most important organic component of the tendon

Answer 23

collagen