classification of joints and characteristics of each type joint

classification of joints and characteristics of each type joint

1. WHAT IS A JOINT?

2. JOINT When two or more bones or cartilages come in contact with each other an articulation or a joint is formed.

3. The study of joints is known as ARTHROLOGY (G. Arthron = joint). The joints vary considerably in their structure and function.

4. OBJECTIVE CLASSIFICATION OF JOINTS A: STRUCTURE FIBROUS JOINTS CARTILAGINOUS JOINTS SYNOVIAL JOINTS B: DEVELOPMENT C: FUNCTION

5. CLASSIFICATION OF JOINTS: The joints could be classified on the basis of STRUCTURE DEVELOPMENT FUNCTION

6. All joints are MESODERMAL in origin. The mesodermal element intervening between the developing bones and cartilages is differentiated into various structural components of a joint like joint capsule, synovial membrane, ligaments, etc.

7. The joints show varied degree of freedom of movements, i.e. Immovable Slightly moveable Freely moveable according to the functional need of a particular joint.

8. CLASSIFICATION ON THE BASIS OF STRUCTURE A) FIBROUS JOINTS (Fibrous; Fixed, Immovable; skull) B) CARTILAGINOUS JOINTS (Cartilaginous; slightly movable; vertebral ) C) SYNOVIAL JOINTS (Movable; limb )

9. A- FIBROUS JOINTS In these joints the union is due to dense fibrous tissue . They are usually fixed, immovable and mainly limited to the skull.

10. Subdivided into three major groups depending upon the location. I. SUTURES II. GOMPHOSIS (Peg and Socket Joint) III. SYNDESMOSIS

11. I. SUTURES Features: These are the joints of skull bones. They are immovable and fixed. The union is affected by sutural ligament.

12. In the vault of the skull the veins of sutural ligaments communicate with Diploic veins and Intracranial venous sinuses. Sutures are the sites of active bone growth. They show gradual ossification from within outwards, which commences at the age of twenty and finishes in old age. The process of obliteration of a suture is called SYNOSTOSIS.

13. VARIETIES OF SUTURES There are following varieties of sutures depending upon : The shape of articulating surfaces. The mode of fusion of articulating bones.

14. 1-Serrate Sutures Example: Sagittal suture between two parietal bones. Here the shape of articulating surfaces is saw like.

15. 2. Denticulate suture Example: Lambdoid suture present between parietal and occipital bones. The shape of articulating surfaces is tooth-like. Here the two bones are more firmly united as compared with the serrate sutures.

16. 3. Squamous sutures Example: Temporo -parietal suture present between temporal and parietal bones. Here the two articulating bones OVERLAP each other and are bevelled reciprocally, i.e., one bone internally and the other externally.

17. 4. Limbous suture It is a slight modification of squamous suture. Here the bevelled surfaces may be mutually serrated or ridged. Example: Modified Temporo -parietal suture.

18. 5. Plane Sutures Examples: i ) Suture between horizontal plates of two palatine bones ( Interpalatine suture). ii) Palato -maxillary suture. iii) Zygomatico -palatine suture. Here the interlocking surfaces are slightly rough and irregular. Pure plane surfaces are seldom found. They can resist extreme torsional forces

19. 6. Wedge and groove sutures ( Schindylesis ) Example: Vomero -sphenoid suture — the suture between vomer bone and rostrum of sphenoid bone. Here a ridged-bone fits into the groove present on a neighbouring bone.

20. II. GOMPHOSIS (Peg and Socket Joint) : It is a specialized fibrous joint in which the teeth fit into their sockets situated in the maxilla and mandible (i.e., upper and lower jaws). The ligament which connects the tooth with the socket or alveolus is called PERIODONTAL LIGAMENT . It provides an independent and firm suspension for each tooth.

21. III SYNDESMOSIS: It is a type of fibrous joint in which the two bones are united with each other by INTEROSSEOUS LIGAMENTS . In this joint a slight degree of movements could be observed which is due to twisting or stretching of an interosseous ligament.

22. This ligament never shows signs of ossification. Examples: i ) Inferior tibio -fibular joint. ii) Old sacro -iliac joint (it is a synovial joint which is converted into syndesmosis in older age). iii) Coracoclavicular joint. iv)Some joints between the vertebrae (i.e., joints between vertebral arches). v) Interosseous membranes of fore-arm and leg which connect: a. Radius with ulna b. Tibia with fibula

23. B- CARTILAGINOUS JOINTS In these joints the bones are united by a cartilage. They are usually slightly movable and are found in those places where stability and strength is required instead of free movements.

24. The opposed bony surfaces are firmly bound together in order to minimize the risk of dislocations, which may produce serious effects in these places. They are mainly limited to the axial skeleton, e.g., vertebral column.

25. They are subdivided into two major groups on the basis of morphology and function: I.PRIMARY CARTILAGINOUS JOINTS (SYNCHONDROSES) II. SECONDARY CARTILAGINOUS JOINTS (SYMPHYSES)

26. PRIMARY CARTILAGINOUS JOINTS (SYNCHONDROSES) These are the joints seen mainly in developing appendicular bones. The bony ends and the shaft remain united with each other by a plate of HYALINE CARTILAGE . This cartilaginous plate is known as EPIPHYSEAL PLATE . These joints are temporary because at the age of 18-20 years the epiphyseal cartilage is ossified. They are completely immovable.

27. Examples: Joints between the ends and shaft of growing long bones. Neurocentral joints of vertebrae. Spheno -occipital synchondrosis . 1st sternocostal joint. Petrobasilar synchondrosis .

28. II. SECONDARY CARTILAGINOUS JOINTS (SYMPHYSES). Mainly seen in axial bones. Formed by WHITE FIBRO-CARTILAGE which connects the articular surfaces covered by hyaline cartilage. These joints are permanent .

29. Slightly movable and mobility depends upon sufficient amount of white-fibro cartilage. Frequently a cavity is seen which is not lined by synovial membrane. This cavity contains tissue fluid.

30. Examples: Public symphysis.

31. Manubriostemal joint. In early life it is primary but in later life it becomes secondary due to conversion of hyaline cartilage into white-fibro cartilage. Joints between the bodies of vertebrae.

32. C- SYNOVIAL JOINTS Seen in all vertebrates and show modifications according to functional needs. All synovial joints possess a definite joint cavity lined by synovial membrane and filled with a lubricating-synovial fluid.

33. CHARACTERISTICS The bony articular surface are covered by articular cartilage and are not attached to each other. The bony articular surfaces are connected with each other by tubular fibrous capsule (articular capsule). The fibrous capsule is lined by mesothelial membrane called synovial membrane . This membrane does not cover the articular cartilage covering the articular bony ends.

34. Between the articular bones a specific joint cavity is present. The joint cavity is filled with synovial fluid secreted by the synovial membrane. The joint capsule is strengthened by the presence of accessory ligament. The joint cavity may be divided partially or completely by an articular disc composed of white-fibro cartilage. Different types of movements are always possible.

35. SYNOVIAL JOINTS CLASSIFICATION can be classified according to A)- DEPENDING UPON THE SHAPE OF ARTICULATING SURFACES : 1 . Homomorphic : When the two articulating surfaces are plane ,the synovial joint is called homomorphic , e.g. i ) Plane joint ( Intermetatarsal joints). ii) Saddle joint ( Carpometacarpal joint of thumb).

36. 2. Hetromorphic : When there is varied appearance of two articulating surfaces, then the synovial joint is called hetromorphic , e.g., i ) Ball & Socket Joint (shoulder and hip joints). ii) Condyloid joint (Temporomandibular joint and knee joint. iii) Ellipsoid joint ( Radiocarpal joint).

37. B) DEPENDING UPON COMPLEXITY OF ORGANIZATION: 1. Simple : When only two bones are participating, the joint is called simple joint, e.g., i ) Acromio-clavicular joint. ii) Shoulder joint. 2. Compound : These are formed by participation of more than two bones, e.g., i ) Elbow joint ii) Knee joint. 3. Complex : When intra articular discs or menisci are present, the joint is called complex, e.g., i ) Knee joint. ii) Temporomandibular join.

38. C) DEPENDING UPON AXIS OF MOVEMENT: 1. Uniaxial : In these joints movements take place on one axis only, i.e., on transverse or longitudinal axis, e.g., Elbow joint. 2. Biaxial : In these joints movements take place on two axes, i.e., i ) Transverse axis, ii) Longitudinal axis, e.g., Wrist Joint. 3. Polyaxial : In these joints movements take place on more than two axis, e.g., i ) Shoulder joint ii) Hip joint

39. D) DEPENDING UPON THE TYPES OF MOVEMENTS: 1. Gliding : e.g., plane joint ( Intermetatarsal joints). 2. Angular : e.g., Condyloid joint ( Temporo -mandibular joint; knee joint). , 3. Rotatory : e.g., Pivot joint (Superior radio- ulnar joint). 4. Circumductory : e.g., Ball and socket joint (shoulder joint and hip joint).

40. E) ARCHITECTURAL OR STRUCTURAL CLASSIFICATION: 7 verities have been recognized: 1. Plane joints: These are formed by the apposition of fairly flat articular surface, e.g., i ) Intermetatarsal joints. ii) Some intercarpal joints.

41. Hinge joints: They roughly resemble the hinges of a door, where the articulating surface are so moulded that they restrict the to-and-fro movements to one plane, i.e., they are uni -axial. The sides of the joint are typically provided with strong collateral ligaments, e.g. i ) Elbow joint ii) Interphalangeal joints

42. 3. Pivot joints: These are uni-axial joints (in which movements take place around the longitudinal axis). They are composed of pivot surrounded by an osseo-ligamentous ring. Movement is restricted to a rotation around a longitudinal axis passing through the centre of the pivot, e.g., i) Proximal radio ulnar joint. ii) Atlanto-axial joint.

43. The pivot may habitually rotate within the ring as in case of Proximal radioulnar joint in which the head of the radius rotates within a ring formed by the annular ligament and radial notch of ulna. Conversely the ring may rotate around the pivot as in the articulation between the dens of the axis and ring formed by anterior arch of the atlas and its transverse ligament, i.e., Atlantoaxial joint, the ring rotates around the pivot, i.e., odontoid process of axis or 2nd cervical vertebra.

44. 4.Condylar or condyloid Joints Here two condyles (male surfaces) are received into two concave (female surfaces) cavities. It allows the principal movement occurring in one plane, but a limited amount of rotation is possible about a second axis set at 90° to the first one, e.g., i ) Temporo -mandibular joint ii) Knee joint

45. 5.Ellipsoid joints : These are biaxial joints formed by reception of an oval, convex male surface into an elliptical female concavity. Primary movements are possible about two axes situated at right angles, e.g., Flexion and extension and abduction & adduction. These movements may be combined as a movement of circumduction . There is little appreciable rotation around the third axis, as this is prevented by overall shape of articular surfaces, e.g., i ) Radiocarpal joint ii) Metacarpophalengeal joints.

46. 6-Saddle joints ( Sellar Joints): These are biaxial joints which are formed by reception of concavo-convex opposing surfaces. Primary movements occur in two planes at right angles to each other but because of the articular geometry, these are accompanied by a degree of axial rotation of moving bones, e.g., ( i ) Carpometacarpal joint of thumb (ii) Ankle joint. (iii) Calcaneocuboid joint.

47. 7. Ball and socket joints ( Spheroidal joints): They are polyaxial joints and are formed by reception of globular head (male surface) into a cup like concavity or socket (female surface). All types of movements are possible, e.g., i ) Shoulder joint ii) Hip joint

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