Tendon

Tendon

1. TENDON BY Dr Vyshnav Srinivasan JUNIOR RESIDENT DEPT OF ORTHOPAEDICS RLJH TAMAKA KOLAR

2. LESSON PLAN Name of the lecturer: Dr Vyshnav Srinivasan Date: 15.09.2020 Time: 8mins Subject: Orthopaedics Topic: TENDON

3. Specific learning objectives At the end of the class, every one should be able to know Structure of tendon Tendon substance Peritendonous structures Muscle tendon junction Tendon insertion into bone

4. INTRODUCTION It is a specialized musculoskeletal dense fibrous tissue . It have major role in providing the stability and mobility of musculoskeletal system. They get inserted into bone and their ability is to resist large tensile load with minimal deformation. Tendon transmit muscle force to bone that produce joint movements. Disease or injuries to it can destabilize joints or leads to loss of muscle function.

5. STRUCTURE It consist highly oriented dense fibrous tissue. High degree matrix organization and density of matrix distinguish these tissue from irregular dense fibrous tissue and loose fibrous tissue. longitudinal section transverse section

6. Tendon consist of three parts, * Substance of tendon itself * The muscle tendon junction ( MYOTENDINOUS JUNCTION) * Bone insertion (ENTHESIS)

7. Connective tissue surrounding tendon allow low friction gliding and access for blood vessels to the tendon substance. Mesotendon attaches the tendon to the surrounding connective tissue and consists of loose elastic connective that can stretch and recoil with the tendon and provide blood supply to tendon substance .

8. TENDON SUBSTANCE Multiple fascicles or bundles, consisting of fibroblast and dense linear array of collagen fibrils forms tendon substance. *Collagen molecule is about 300nm long, 1-2nm wide, and diameter of fibrils range from 50-500nm. *Fibrils then assemble to form fascicles, which are about 10mm in length with diameter of 50-300µm. *Tendon fibre with a diameter of 100-500µm.

9. Endotendon - a less dense connective tissue containing fibroblast, blood vessels, nerve, and lymphatics . Endotendon tissue continues to form epitenon , a thin layer of connective tissue that covers surface of tendon. Fibrous tissue of the epitenon continues as thin fibrous covering of attached muscle called the epimysium .

10. MUSCLE TENDON JUNCTION Muscle-tendon junctions must efficiently transmit the force of muscle contraction to the tendon. The attachment occurs through continuation of the collagen fibrils of the fibrous tissue layer of muscle into the collagen fibrils of the tendon.

11. Inter digitaion of muscle cells and tendon has the appearance of interlocking fingers when examined by electron microscopy. It provides a strong bond between muscle and tendon.

12. PERITENDONOUS STRUCTURES Normal tendon gliding, efficient transmission of muscle forces to move joints and tendon nutrition, depends on the peritendonous connective tissue structures called PERITENON. It consists of an interlacing meshwork of thin collagen fibrils and elastic fibers filled with abundant soft, almost fluid ground substance. Where tendon change course between their muscle attachment and their bone insertion, the surrounding connective tissue may form a bursa or a discrete tendon sheath.

13. Tendon sheaths and bursa resembles synovial joint and consist of cavities lined with synovial-like cells, they contain synovial-like fluid, and facilitate low friction gliding between two surfaces .

14. COMPOSITION * Fibroblast forms the predominant cell. * Fibroblast surrounds themselves with a dense fibrous tissue matrix and throughout life continue to maintain the matrix. * Younger tissue have higher cell density and cells with a larger cytoplasmic volume. * With increasing age, the cell density usually decreases and cells appear to become less active.

15. MATRIX Tissue fluid contributes 60% of the wet weight of most dense fibrous tissue. Macromolecules contribute 40%. Components 60-85% collagen *60-80% collagen 1 *0-10% collagen 3 *2% collagen 4 *Small amounts of collagen 5,6 and others. 15-40% non-collagenous extracellular matrix. *3%cartilage oligomeric matrix protein,

16. *1-2% elastin *1-5% proteoglycans * 0.2% inorganic components such as copper, manganese and calcium. Major GAG components of tendon are dermatan sulfate and chondroitin sulfate , which associate with collagen and are involved in the fibril assembly process during tendon development .

17. INSERTION INTO BONE DIRECT INSERTION: Most of the collagen fibrils at the insertion pass directly from substance of the tendon into bone cortex, usually entering at a right angle to bone surface. Deeper collagen fibers that enter the bone pass through four zones of increasing stiffness. The substance of dense fibrous tissue structure, fibrocartilage, mineralised fibrocartilage and bone

18. Toludine blue stained section

19. INDIRECT INSERTION I t covers more bone surface area and large proportion of collagen fibrils join periosteum . It has superficial and deep collagen fibrils, but most of their collagen fibrils form the superficial layer that joins the fibrous layers of periosteum .

20. BLOOD SUPPLY Vascular system follows the longitudinal pattern of the collagenous matrix, also have multiple anastamoses between parallel vessels. Some blood vessels in tendon enter the bone.

21. Nerve supply It has specialised nerve endings that lie on the surface or within the substance of the tissue. It function as pain receptors, vasomotor efferents , and mechanoreceptors sensitive to stretching or distortion.

22. APPLIED ASPECTS ENTHESITIS

23. TENDON RUPTURE

24. THANK YOU