Anatomy Presentation Ho 4(joints)

 Formed where a bone joins another bone, or where a cartilage joins a bone  The closer the fit, the stronger the joint, the more restricted the movement  The looser the fit, the weaker the joint, the greater degree of movement, the greater the chance of dislocation

Classification of Joints!

3 types of joints if we classify by function (i.e., by the degree of movement possible):

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Diarthroses  

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Amphiarthroses  

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Freely moveable joints Shoulder, knee, hip, elbow, interphalangeal, tarsal, and carpal joints Slightly moveable joints Intervertebral discs, costosternal joints, pubic symphysis

Synarthroses  

Joints with little or no movement Skull sutures, mental symphysis, teeth in sockets, 1st costosternal joint.

Joint Classification We can also classify joints by structure:

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Synovial joints: 

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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 Fibrous joints:

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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 Cartilaginous joints:

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Bones held together by cartilage; no joint cavity Epiphyseal plates of long bones, costosternal joints, pubic symphysis, intervertebral discs

Functions of joints • Hold bones together • Allow for mobility

Structural Classification

 A. Fibrous joints - held together by fibrous CT  1. Gomphosis - coneshaped peg in a socket; teeth roots in maxillae and mandibles

 2. Sutures - may become a synostosis; found only in the 

skull 3.Syndesmosis - tibia and fibula distally, between shafts of ulna and radius

B. C ar ti laginous joi nt s  1. Synchondrosis

- hyaline cartilage connects; between epiphysis and diaphysis (synarthrotic), costal cartilage between sternum and ribs (amphiarthrotic)

 2. Symphysis - fibrocartilage connects; symphysis pubis, intervertebral discs (amphiarthrotic)

Structure and Function  Joints are designed for their function.  Let’s look at sutures as our 1st 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.

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How do they differ from the previous 2?

5 main structural characteristics:

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Articular cartilage   

What kind of cartilage is it? (H _ _ _ _ _ _ ) Where do we find it? What does it do?

Structure and Function 1. Articular capsule  

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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 Joint (Synovial) Cavity

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2.

The potential space within the joint capsule and articular cartilage

Synovial Fluid  

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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.

St ructure a nd Function Reinforcing Ligaments

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What kind of tissue are they? What do you suppose their function is? Double-jointed-ness results from extrastretchy 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 Plane joints

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2.

Articular surfaces are flat and allow short slipping or gliding movements. Intercarpal and intertarsal joints

Hinge joints 

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A cylindrical projection of one bone fits into a troughshaped 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 1.

Pivot joints 

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2.

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

Condyloid joints   

Oval articular surface of one bone fits into a complementary depression on another. Radiocarpal joints Metacarpophalangeal joints

Types of Synovial Joints 1. Saddle joints 

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Each articular surface has convex and concave areas. Each articular surface is saddleshaped. Carpometacarpal joints of the thumbs.

2. 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.

 1. Angular - increase or decrease the angle between bones  a. Flexion - except at the knee and toe joints, it decreases the angle between the anterior surfaces of the bones.  b. Extension - except at the knee and toe joints, it increases the angle between the anterior surfaces of the bones. Continuation behind the anatomical position - hyperextension

c. Adduction - movement toward midline  d. Abduction - movement away from midline. Includes spreading the fingers or toes.  2. Rotation - movement of a bone around its longitudinal axis - atlas around the axis, moving head to say no  3. Circumduction - distal end of bone moves in a circle while the proximal end is stable 

 4. Gliding - one flat surface moves back and forth and side to side over the other - intercarpal and intertarsal joints  5. Inversion - move sole of foot inward  6. Eversion - move sole of foot outward  7. Dorsiflexion - flexion of foot at ankle joint  8. Plantar flexion - extension of foot at ankle joint

 9. Protraction - movement of

mandible or clavicle forward  10. Retraction - move a protracted part back; squaring your shoulders  11. Elevation - upward movement of a bone - mandible, shrugging shoulders  12. Depression - downward movement of a bone

 13. Pronation - move forearm to turn palm posterior or inferior; lowering the medial part of the foot  14. Supination - move forearm to turn palm forward or superior; raising the medial part of the foot

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 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.

The Knee

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 cartilagedamaging 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.

 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.

Clinical Conditions

Clinical Conditions  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.