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Joints Dr. Anderson GCIT. Joints Where two or more bones meet Function – Connection (ligaments) – Movement (muscles) – Protection (joint capsule)

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Presentation on theme: "Joints Dr. Anderson GCIT. Joints Where two or more bones meet Function – Connection (ligaments) – Movement (muscles) – Protection (joint capsule)"— Presentation transcript:

1 Joints Dr. Anderson GCIT

2 Joints Where two or more bones meet Function – Connection (ligaments) – Movement (muscles) – Protection (joint capsule)

3 Joint Classification StructuralFunctional Fibrous – synostoses (immovable), syndesmoses (variable movement), gomphoses (peg-in-socket) Synarthroses – bones don’t move relative to each other Cartilaginous – synchondroses, symphyses Amphiarthroses – “slightly” moveable Synovial – articulating bones are separated by a fluid-filled cavity (most joints) Diarthroses – freely moveable

4 Sutures Fibrous joints, slightly mobile in youth, immobile as adult (e.g. cranial sutures) – Limited mobility allows brain to grow during development – Immovability as adult serves as a protective function Top of Skull (newborn baby)

5 Syndesmoses Bones connected exclusively by ligaments Movement varies according to length of the ligaments forming the joint, e.g.: – Very limited movement between tibia and fibula – Very pronounced movement of ulna around radius

6 Gomphoses Peg-in-socket, fibrous joint Only example is the teeth in their alveolar cavities connected by the periodontal ligament

7 Cartilaginous Joints Articulating bones are united by cartilage – Synchondroses and symphyses

8 Synchondroses Cartilage that unites two bones (such as the epiphyses to the diaphyses in the long bones of children and young adults) E.g. Epiphyseal plates

9 Symphyses Where articulating bones are lined with cartilage, which is fused to a pad or plate of fibrocartilage – E.g. – intervertebral discs, pubic symphysis

10 Synovial Joints Features 1. Articular cartilage – covers opposing bone surface 2. Synovial cavity – space that contains synovial fluid 3. Articular Capsule – provides tensile strength and covers all surfaces not lines with cartilage 4. Synovial fluid – provides joint lubrication, released from the cartilage itself during activity (weeping lubrication) 5. Reinforcing ligaments 6. Nerves and blood vessels -

11 Joint Structure

12 Articular Discs (Menisci) Fibrocartilage pads that partially or completely divide the synovial cavity – (Knee, jaw meniscus) Improve the fit of some articular surfaces in the joint

13 Bursae and Tendon Sheaths Fibrous connective tissue that serves as a pliable “ball bearing” for some joints (e.g. shoulder) and closely packed tendons (e.g. wrist) Bursa rolls in opposing direction of movement

14 What holds joints together? Articular Surfaces -Deeply fitting articulations more stable than shallow ones Ligaments – “cables” of dense regular connective tissue that hold the joint together – Relatively little stretch (can snap) Muscle Tone – low levels of contractile activity – more tone = more stable joints

15 Synovial Joint Structure

16 Joint Movements Originates from muscle contraction (of course) Degree of joint movement is called “range of motion” Three main types – Gliding – Angular – Rotation

17 Gliding joints Simplest movement – One or more flat (usually) bone surfaces glide over another Wrist bones Ankle bones Between vertebrae

18 Angular Movement Flexion – pulling the joint angle closed Extension – opening the joint angle – Hyperextension – greater than normal extension Abduction – moving a limb away from the median line of the body Adduction – moving a limb toward the median line of the body Circumduction – moving a limb in a cone-shaped path in space

19 Rotation Turning of a bone around its long axis – Medial rotation – turning toward the midline – Lateral rotation – turning away from the midline

20 Supination and Pronation Refer to movement of radius around the ulna With arms down at sides: – Supination is a lateral rotation of the palms (palms anterior or up) – Pronation is a medial rotation of the palms (palms face posteriorly, radius and ulna cross each other, forming an ‘X’)

21 Ankle and Foot Movement Dorsi flexion – moves foot up (superiorly) Plantar flexion – moves foot down (inferiorly) Inversion – sole of foot turns medially Eversion – sole turns laterally

22 Jaw movements Protraction and retraction – jutting jaw out and bringing it back, respectively Elevation and Depression – Moving a body part superiorly or inferiorly (e.g. jaw)

23 Synovial Joint Types Plane (Gliding) – allow only short, gliding movements (wrist and ankle) Hinge (One angular direction) - allows motion only along a single plane (flexion and extension only) Pivot (Rotation) – allows the bone to rotate around its axis Condyloid (All angular directions)– Oval articulating surfaces that permit movement in all directions Saddle (All angular directions)– both articular surfaces have a convex AND a concave side that articulate together Ball-and-Socket - (Universal movement) allows movement in all directions, including limited rotation

24 Knee Joint Very Complex – 4 bones Femur, tibia, fibula, patella – Ligaments often injured in sports or accidents

25 Knee Injuries Cruciate Ligaments – ACL (anterior) – PCL (posterior) Deep in joint cavity of knee (intracapsular) – Can tear and separate femur from the tibia – Most often happens when the knee is rotated during full extension Torn ACL (Arthroscopic view)

26 Knee Injuries Most dangerous injuries are lateral blows to the fully extended knee – Torn menicsi – Torn collateral ligaments Tibial (Medial or MCL)– outside hit Fibular (Lateral or LCL)– inside hit

27 Jaw Joint Problems Jaw Joint (mandible and mandibular fossa) is called the tempero- mandibular joint (TMJ) Loosely connected – has a greater range of motion than other hinge joints – Condyle of mandible can move out of the fossa, (anterior disarticulation)


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