4. anatomy of Joints and Suporting structures.pptx

this is detailed explanation about, joints, tendons, cartilages and other supporting structures at the region of joints.

1. Joints and supporting structures Joints Joints are points or regions where two or more adjacent bones are capped and held together firmly by ligaments, tendons and other connective tissues. These junctions are supported by a variety of soft tissue structures, and their prime functions are either to facilitate growth or to allow movement between bones. Joints exhibit a variety of forms and functions Joints are also called articulations of bones Arthrology is the study of joints/articulations 1

2. Ligaments It is a tiny band of dense, white, fibrous, elastic tissue . Ligaments create a joint by joining the ends of bones together. The majority of ligaments restrict dislocation or stop specific motions that could break bones. Because they are elastic, pressure causes them to elongate more and more. When this happens, the ligament might be torn and the joint might become unstable . Ligaments can also limit certain actions, such as hyperextension and hyperflexion . Ligaments also inhibit specific directions of movement. 2

3. Bursae A bursa is a tiny sac filled with fluid that is composed of fibrous white tissue and has synovial membrane lining it. A synovial membrane that protrudes outside of the joint capsule can also form a bursa. Bursa , which surround practically all of the body's major joints, are filled with synovial fluid and act as a cushion between bones and tendons or muscles surrounding a joint. 3

4. Classification of joints functional classification; into three. These are: Synarthrose s -are immovable joints Amphiarthroses are slightly movable joints Diarthroses -are freely movable joints. Diarthroses predominate in the limbs, whereas synarthroses and amphiarthroses are to axial skeleton . Structural classification; also into three. These are: fibrous: join bones by dense connective tissue Cartilaginous: join bones by cartilaginous structure synovial joint : bone are joined by synovial structures 4

5. Fibrous joints Bones are connected by dense regular fibrous connective tissue that allow little movements No joint cavity is present. Immovable or only slightly movable. Subtypes: sutures , syndesmoses , and gomphoses 5

6. 1. Sutures immovable and held by thin layer of dense regular connective tissue common in skull Serrate suture – saw like articulation. e.g saggital suture Squamous suture – margin of the bone overlaps with that of articulating bone. e.g. squamous suture Plane suture – margins of articulating bones are fairly smooth. e.g . median palatine suture Sutures allow growth so that the skull can expand with the brain during childhood . Movement of the cranial bones would damage the brain ( so immovable sutures) 6

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8. Syndesmoses connected by bands of fibrous tissue longer than those that occur in sutures. Short fibers -little to no movement. e.g. distal tibiofibular articulation and posterior region of the sacroiliac joint Long fibers- large amount of movement. e.g. interosseous membrane between the radius and ulna. 8

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10. 3. Gomphoses are the immobile joints b/n the teeth and their sockets in the mandible and maxillae. The periodontal ligament is the fibrous tissue that connects tooth to the socket . 10

11. Cartilaginous joints Articulating bones are united by hyaline or fibrocartilage Lack a joint cavity and are not highly movable. Depending on the type of cartilage involved, they are primary and secondary cartilaginous joints . Primary cartilaginous joints ( synchondroses ) involve hyaline cartilage. may be slightly mobile (amphiarthroses) or immobile E.g. epiphyseal plates, b/n first rib’s costal cartilage and manubrium of sternum. 11

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13. may involve either hyaline or fibrocartilage. These joints are slightly mobile (amphiarthroses). Fibrocartilage unites the bones. Hyaline cartilage is also present in the form of articular cartilages on the bony surfaces . The articular cartilages function to reduce friction between the bones during movement. E.g. manubriosternal , intervertebral discs and pubic symphysis. 13 Secondary cartilaginous joint (Symphysis)

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15. Synovial joints - diarthroses ( freely movable ). Are the most movable joints of the body Most joints of the body-especially those in the limbs. 15

16. Synovial joints have the following basic features: Articular cartilage - a specialized type of hyaline cartilage covers the ends of opposing bones and act as a spongy cushion. Joint cavity - a potential space that holds a small amount of synovial fluid. Articular capsule - joint cavity is enclosed by a two layered articular capsule. Fibrous capsule: outer, dense irregular CT that is continuous with the periosteum layer of joining bones. Synovial membrane: inner, loose connective tissue and produce synovial fluid . 16

17. Synovial membrane is characterized by two specialized cells with distinctly different functions and origins. Macrophage cells , type A cells , are derived from blood monocytes and remove wear-and-tear debris from the synovial fluid. Fibroblastic– like cells , type B cells , are proper synoviocytes produce hyaluronan that contribute to the synovial fluid. Synovial fluid- a slippery lubricant that eases movement at the joint. it is clear or pale yellow, viscous fluid fluid occurs in the joint cavity and within articular cartilages 17

18. Reinforcing ligaments - Most often intrinsic or capsular : thickened parts of the fibrous capsule. Extracapsular ligaments -outside the capsule. E.g.. fibular and tibial collateral ligaments of the knee. Intracapsular ligaments are covered with a synovial membrane and are internal to the capsule. E.g.. anterior and posterior cruciate ligaments in the knee. 18

19. 6.Articular disc or meniscus- disc of fibrocartilage that occur in some joints. Such a disc extends internally from the capsule and completely or partly divides the joint cavity into two. Articular discs occur in joints whose articulating bone ends have somewhat different shapes. It fills the gaps and improves the fit; minimizing wear and damage by distributing the load more evenly . Eg . Knee joint 19

20. 7. Nerves and vessels – Rich in blood and nerve supply articular arteries; arise from vessels around the joint and often anastomose to form networks to ensure a blood supply to and across the joint. innervation is according to Hilton's law Hilton’s law states that the nerves supplying the muscles extending directly across and acting at a given joint also innervate the joint. Articular nerves transmit sensory impulses from the joint that contribute to the sense of proprioception . The synovial membrane is relatively insensitive . Pain fibers are numerous in the fibrous layer of joint capsule and accessory ligaments, causing pain when joint is injured. 20

21. Bursae and Tendon Sheaths Bursae saclike structures situated to lessen friction in some joints, such as shoulder and knee joints. are not part of joints, but they resemble joint capsules; because their walls consist of outer fibrous membrane lined by synovial membrane. filled with small amount of fluid that is similar to synovial fluid. located b/n the skin and bones, tendons and bones, muscles and bones, or ligaments and bones. This fluid-filled bursal sacs cushion the movement of these body parts against one another . 21

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23. Tendon sheaths are tube like bursae that wrap around tendons that experience higher friction as they pass through tunnels formed by connective tissue and bone. the visceral layer, inner layer attached to the surface of tendon. the parietal layer, outer layer attached to bone. Between the layers is a cavity that contains a film of synovial fluid. Protects all sides of a tendon from friction as the tendon slides back and forth. Eg . tendon of biceps brachii muscle at shoulder joint. 23

24. 24 Simple joint: two articulation surfaces; eg . Hip, shoulder joints Compound joint: three or more articulation surfaces; eg . Elbow, radiocarpal joints. Complex joint: two or more articulation surfaces and articular disc or meniscus; eg . Knee joint Classification

25. Types of Synovial Joints Classified by Shape Plane joints - gliding movment : articular surface in flat plane Short side-to-side; back-and forth movement in gliding manner E.g . intertarsal , intercarpal, TMJ, Intervertebral b/n articular processes, Sternocostal (2 nd to 7 th ribs), Vertebrocostal (b/n transverse process or bodies and ribs, Acromioclavicular, Carpometacarpal of digits 2–5, Knee (femoropatellar), proximal tibiofibular, Tarsometatarsal 25

26. Hinge joint - uniaxial; cylindrical end of a bone fits into trough shape of other angular movement is allowed in one plane: E.g .. elbow joint, ankle joint, interphalangeal, Knee/tibiofemoral 26

27. Pivot joint- Uniaxial movement; rounded end of one bone fits into a ring that is formed by another bone plus an encircling ligament Rotation occur on the long axis eg . Atlatoaxial (b/n atlas-C1 and axis-C2 ), proximal radio-ulnar 27

28. Condyloid joint - biaxial movement: egg-shape articular surface + oval concavity One bone "sits" in the saddle of another; side-to-side, back-and-forth movement E.g .. Metacarpophalengeal joint, Atlanto-occipital, wrist joints, Metatarsophalangeal 28

29. Saddle joint - Biaxial movement: articular surface of one bone is saddle-shaped, and the articular surface of the other bone fits into the “saddle” as a sitting rider would sit . Side-to-side, back-forth movement E.g . Carpometacarpal joint of 1 st digit, Sternoclavicular 29

30. Ball-and-socket joint - multiaxial movement: It consists of ball-like surface of one bone fitting into a cuplike depression of another bone Works just like a joy-stick in all directions E.g .. hip and shoulder joint 30

31. Stability of Synovial Joints Depends on three factors: shapes of articular surfaces, number and position of stabilizing ligaments muscle tone. Articular Surfaces- bones in a joint fit together in a complementary manner. Seldom play a major role in joint stability Most joint sockets are just too shallow. Still, some joint surfaces have deep sockets or grooves that do provide stability. E.g. Hip joint 31

32. Ligaments- capsules and ligaments of synovial joints help hold the bones together and prevent excessive or undesirable motions. Ligaments located on the medial or inferior side of a joint resist excessive abduction ; lateral and superiorly located ligaments resist adduction . Anterior ligaments resist excessive extension and lateral rotation ; posterior ligaments resist excessive flexion and medial rotation . As a rule, the more ligaments a joint has, the stronger it is. 32

33. Muscle Tone- constant , low level of contractile force generated by a muscle even when it is not causing movement. So , muscle functions like a ligament holding the adjoining bone surfaces together. This stabilizing factor is especially important in reinforcing the shoulder and knee joints and in supporting the joints in the arches of the foot 33

34. Thank You! 34