Ligaments And Tendons

Question 1

What is the functions of ligaments

Answer 1

Attach bone to bone
Augment mechanical stability of joints
Guide joint motion
Prevent excessive motion

Question 2

What are the functions of tendons

Answer 2

They connect muscle to bone
They transmit tensile loads from muscle to bone to produce joint torque, stabilise the joint during contractions, enable joint motion
Aid joint stability

Question 3

What is the general tissue composition of tendons and ligaments

Answer 3

Dense connective tissues consisting of mainly parallel fibres which enables tissue to sustain high tensile strains

Cells - fibroblasts or tenocytes - synthesis and remodel the extracellular matrix

Extracellular matrix makes up 80% of tissue volume - 70% is water 30% solids such as collagen and ground substances, has a hierarchical structure

Sparsely vascularised - poor capacity for healing

Question 4

Why do ligaments have a crimped structure in the longitudinal fibres

Answer 4

Increases ligament length duration tension

Question 5

What makes up a tendon

Answer 5

Tropocollagen
Microfibril
Subfibril
Fibril
Fascicle
Endotenon
Paratenon/epitenon
Tendon

Question 6

What is the major component of tendon and ligament fibres

Answer 6

Collagen
Mainly type I collagen
Some type III

Question 7

1-5% of the dry weight of ligaments and tendons is proteoglycan why is this important

Answer 7

They act as a lubricant which aids the collagen fibres to glide over each other

Question 8

Where is collagen synthesised

Answer 8

Collagen is synthesised within the fibroblast as pro collagen which is a precursor to collagen

Question 9

What is a collagen fibre made up of

Answer 9

3 individual polypeptide chains coiled in a left hand helix

Question 10

What makes up type I collagen

Answer 10

3 alpha chains combined in a right handed triple helix

Question 11

What enhances the strengthens the collagen molecules

Answer 11

Cross links bonds between the alpha chains

Question 12

Where does assembly of the collagen fibril occur

Answer 12

Outside the cell in the extracellular matrix when the terminal regions are cleaved off

Question 13

Explain the steps of fibrillogensis

Answer 13

Collagen molecules group to form microfibrils

Microfibrils combine to form subfribrils

Subfibrils combine to form fibrils

Fibrils combine to form fibres

Fibres combine to form fascicles

Fascicles group together to form the tendon fibres

Question 14

What are the differences between ligaments and tendons

Answer 14

Ligaments
- connect bone to bone
- lower collagen I
- higher elastic content
- fibres = random organisation
- blood from insertion point

Tendon
- connect muscle to bone
- higher collagen I
- little elastin
- fibres = organised
- vascular = surrounded by paratenon
- avascular = surrounded by tendon sheath

Question 15

What is a fibrous insertion

Answer 15

Formed through intramembranouse ossification
Calcified anchorage is by calcified collagen fibres known as sharpens fibres into bone
Example of this is seen on the distal medial collateral ligament

Question 16

What is fibrocartilage insertion

Answer 16

Formed through endochondral ossification
Gradual change from collagenous ligament into fibrocartilage into mineralised cartilage into bone
Example of this is the proximal medial collateral ligament

Question 17

what is essential for healthy tendons

Answer 17

Load bearing

Question 18

Describe each point on the graph

Answer 18

1 - toe region = small increase in load as crimped fibres straighten

2- linear region = fibres straighten and stiffness increases with loading

3- maximum deformation and tensile strength of tissue, beyond this progressive failure of collagen

4- yield point = complete failure of the tissue to support the load

Question 19

Where can golgi tendon organs be found

Answer 19

They are found in the tendons near the junction with the muscle

Question 20

What is a golgi tendon organ

Answer 20

Encapsulated sensory receptors proprioceptors which become activated by stretch or active muscle contraction

Question 21

What factors can affect the mechanical properties f ligaments and tendons

Answer 21

Maturation and aging
- up to 20yrs - number of cross links between the molecules increase tensile strength and collagen fibrils increase tensile strength

Aging
- collagen contents decreases

Pregnant/postpartum
- tensile strength and stiffness due to hormonal influence

Question 22

when do tendons and ligaments remodel

Answer 22

Physical training to increase tensile strength and ligament bone interface strength, so they become stronger and stiffer

Immobilisation you would decrease tensile strength and less cross links

Question 23

How can a tendon and ligament become injuryed

Answer 23

Direct trauma
Acute tensile failure
Indirect tensile failure
Injuries that limit mobility and joint function

Question 24

What is the general healing of a typical wound healing

Answer 24

Short inflammatory phase
Proliferative phase
Remodelling and maturation phase