Tendons And Ligaments

Question 1

Connective tissue types

Answer 1

▪️loose connective tissue (elastin)
▪️dense fibrous connective tissue (tendons and ligaments)
▪️bone 
▪️adipose tissue
▪️cartilage
▪️blood

Question 2

Tendon and ligament structure

Answer 2

▪️collagen, collagen fibril, collagen fibre, collagen fibre bundle, collagen fascicle, tendon/ligament.
▪️each section is grouped together to form the next section
▪️in between collagen fascicles is a loose collagen fibre septum, called endotenum in tendon and endoligament in ligament (interfascicular matrix (IFM))

Question 3

Function of ligament

Answer 3

▪️bone to bone
▪️prevents excessive movements (stabilise joint)
▪️shock absorber and protects bone in joint
▪️eg- ACL, PCL, MCL, LCL

Question 4

Function of tendon

Answer 4

▪️muscle to bone
▪️transmits force generated by muscle to bone
▪️modulates locomotion
▪️two groups:
-energy storing tendon: high strain rate so more elastic-more commonly injured
-positional tendon: less strain so less elastic

Question 5

Tears

Answer 5

▪️grade 1- small tears
▪️grade 2-large but incomplete tears
▪️grade 3- complete tear

Question 6

Strain and sprain

Answer 6

▪️strain- tendon is torn or overstretched

▪️sprain- ligament is torn or overstretched

Question 7

Differences

Answer 7

▪️tendons- non elastic and tough, fibres are compact and parallel, fibroblast cells( tenocytes) type I collagen, proteoglycans, some elastin
▪️ligaments- elastic and strong, fibres compact but not parallel, fibroblasts cells (ligamentocytes), type I collagen, more proteoglycans , more elastin, more cartilaginous proteins (aggrecan, type II collagen)

Question 8

Tendons development

Answer 8

▪️divided into head, axial and limb
▪️head tendons originate from neural crest cells
▪️axial tendons originate from somites (from sclerotome cells)
▪️limb tendons originate from limb lateral plate
-limb-initiation is done without muscles but along the development muscle is required
-axial-muscle is needed from the beginning

Question 9

Tendon development markers

Answer 9

▪️scleraxis- marker of T progenitor cells
▪️induces expression of T genes (collagen I gene)
▪️Fibroblast growth factor 8 (FGF8) induces expression of scleraxis
▪️TGFbeta and GDF are also involved
▪️after birth, T progenitor cells lay down a small diameter of collagenous fibrils