Joints!  3 types of joints if we classify by function (i.e., by the degree of movement possible): 1.Diarthroses  Freely moveable joints  Shoulder, knee, hip, elbow, interphalangeal, tarsal, and carpal joints 2.Amphiarthroses  Slightly moveable joints  Intervertebral discs, costosternal joints, pubic symphysis 3.Synarthroses  Joints with little or no movement  Skull sutures, mental symphysis, teeth in sockets, 1 st costosternal joint.

Joint Classification  We can also classify joints by structure: 1.Synovial joints:  Bones separated by a joint cavity; lubricated by synovial fluid; enclosed in a fibrous joint capsule.  Shoulder, hip, elbow, knee, carpal, interphalangeal How would we classify these joints functionally?

Joint Classification 2.Fibrous joints:  Bones held together by collagenous fibers extending from the matrix of one bone into the matrix of the next.  No joint cavity  Skull sutures, teeth in joints, distal radioulnar joints & tibiofibular joints

Joint Classifications 3.Cartilaginous joints:  Bones held together by cartilage; no joint cavity  Epiphyseal plates of long bones, costosternal joints, pubic symphysis, intervertebral discs

Structure and Function  Joints are designed for their function.  Let’s look at sutures as our 1 st example:  Name 4 sutures!  What function do you suppose sutures are designed for?

Structure and Function  Let’s look at some symphyses.  What kind of joint is a symphysis? What kind of movement is possible?  Name a symphysis! (an obvious one is in the picture)  What connects the bones in these joints?

Structure and Function  Now let’s talk about synovial joints.  How do they differ from the previous 2?  5 main structural characteristics: 1.Articular cartilage  What kind of cartilage is it? (H _ _ _ _ _ _ )  Where do we find it?  What does it do?

Structure and Function 2.Articular capsule  2 layered. Surrounds both articular cartilages and the space btwn them.  External layer is made of dense irregular CT & is continuous w/ the perisoteum.  Inner layer is a synovial membrane made of loose connective tissue.  It covers all internal joint surfaces except for those areas covered by the articular cartilage.

Structure and Function 3.Joint (Synovial) Cavity  The potential space within the joint capsule and articular cartilage 4.Synovial Fluid  A small amount of slippery fluid occupying all free space w/i the joint capsule  Formed by filtration of blood flowing thru capillaries in the synovial membrane  Synovial fluid becomes less viscous as joint activity increases.

Structure and Function 5.Reinforcing Ligaments  What kind of tissue are they?  What do you suppose their function is?  Double-jointed-ness results from extra- stretchy ligaments and joint capsules. Is this necessarily a good thing?

Other Synovial Structures  The knee and hip joints have cushioning fatty pads btwn the fibrous capsule and the synovial membrane or bone.  Discs of fibrocartilage (i.e., menisci) which improve the fit btwn bone ends, thus stabilizing the joint.  Found in the knee, jaw, and sternoclavicular joint.  Bursae are basically bags of lubricant - fibrous membrane bags filled w/ synovial fluid. Often found where bones, muscles, tendons, or ligaments rub together.

Types of Synovial Joints 1.Plane joints  Articular surfaces are flat and allow short slipping or gliding movements.  Intercarpal and intertarsal joints 2.Hinge joints  A cylindrical projection of one bone fits into a trough- shaped surface on another (like a hotdog in a bun)  Movement resembles a door hinge.  Elbow joint – ulna and humerus; Interphalangeal joints

Type of Synovial Joints 3.Pivot joints  Rounded end of one bone protrudes into a ring formed by another bone or by ligaments of that bone.  Proximal radioulnar joint  Atlas-axial joint 4.Condyloid joints  Oval articular surface of one bone fits into a complementary depression on another.  Radiocarpal joints  Metacarpophalangeal joints

Types of Synovial Joints 5.Saddle joints  Each articular surface has convex and concave areas. Each articular surface is saddle- shaped.  Carpometacarpal joints of the thumbs. 6.Ball-and-Socket joints  Spherical or semi-spherical head of one bone articulates with the cuplike socket of another.  Allow for much freedom of motion.  Shoulder and hip joints.

The Knee  Largest and most complex diarthrosis in the body.  Primarily a hinge joint, but when the knee is flexed, it is also capable of slight rotation and lateral gliding.  Actually consists of 3 joints:  Patellofemoral joint  Medial and lateral tibiofemoral joints  The joint cavity is only partially enclosed by a capsule – on the medial, lateral, and posterior sides.

The Knee  The lateral and medial condyles of the femur articulate with the lateral and medial condyles of the tibia.  Btwn these structures, we have the lateral and medial menisci.  Anteriorly, the patellar ligament binds the tibia (where?) to the inferior portion of the patella. The superior portion of the patella is then connected to the quadriceps femoris muscle

The Knee  At least a dozen bursae are associated with the knee.  Multiple ligaments are present.  The fibular collateral ligament extends from the lateral epicondyle of the femur to the head of the fibula.  The tibial collateral ligament connects medial epicondyle of the femur to the medial condyle of the tibial shaft and is also fused to the medial meniscus.  Both of these ligaments prevent excessive rotation

The Knee  The anterior and posterior cruciate ligaments are also very important.  ACL connects the anterior intercondylar area of the tibia to the medial side of the lateral femoral condyle.  Prevents forward sliding of the tibia and hyperextension of the knee.  PCL connects the posterior intercondylar area of the tibia to the lateral side of the medial femoral condyle.  Prevents backward displacement of the tibia or forward sliding of the femur.

Clinical Conditions  Arthritis describes about 100 different types of inflammatory or degenerative joint diseases.  Osteoarthritis  Most common arthritis.  Normal joint use prompts the release of cartilage- damaging enzymes. If cartilage destruction exceeds cartilage replacement, we’re left with roughened, cracked, eroded cartilages.  Eventually bone tissue thickens and forms spurs that can restrict movement.  Most common in C and L spine, fingers, knuckles, knees, and hips.

Clinical Conditions  Rheumatoid arthritis  Chronic inflammatory disorder  Marked by flare-ups  Autoimmune disease.  Body creates antibodies which attack the joint surfaces  The synovial membrane can inflame and eventually thicken into a pannus – an abnormal tissue that clings to the articular cartilage.  The pannus erodes the cartilage and eventually scar tissue forms and connects the 2 bone ends. This scar tissue can later ossify, fusing the bones together. This is known as ankylosis.

 Gouty arthritis  When nucleic acids (such as ????) are metabolized uric acid is produced. Normally uric acid is excreted in the urine.  If blood [uric acid] rises due to decreased excretion or increased production, it may begin to form needle-shaped crystals in the soft tissues of joints.  Inflammation ensues causing painful arthritis. Clinical Conditions