Anatomy & Physiology (CH.8): Joints and Movements

Bar or plate of hyaline cartilage unites bones. Almost all are synarthrotic (immovable)

Ex: Temporary epiphyseal plate joints (become synostoses after plate closure). Cartilage of 1st rib with manubrium of sternum

Bones united by fibrocartilage. They are strong & slightly movable (amphiarthrotic). Examples: intervertebral discs (sandwiched b/t hyaline catilage) and pubic symphysis.

3. Articular capsule (2 layers thick)-External fibrous layer: dense irregular connective tissue

• Inner synovial membrane: loose connective tissue that makes synovial fluid.

Bursae: reduce friction where ligaments, muscles, skin, tendons, or bones rub together.

Tendon sheaths: elongated bursae wrapped completely around tendons subjected to friction

1. Shape of articular surface (minor role)-Shallow surfaces less stable than ball-and-socket. 2. Ligament number & location (limted role)-more ligaments, stronger the joint 3. Muscle tone (most important)-reinforces shoulder and knee joints & arches of the foot

Nonaxial (slipping), uniaxial (movement of one plane), biaxial (movement of two planes), multiaxial (movement in or around all three planes).

One flat bone surface glides or slips over another similar surface. Examples: intercarpal joints, intertarsal joints, & b/t articular processes of vertebrae (gliding movements of the wrist)

Increase or decrease angle between two bones (sagittla plane)

Ex: Flexion: decreased angle of the joint. Extension: Increases angle of the joint (Hyperextension: movement beyond the anantomical position),

Turning of a bone around its own long axis; toward midline or away from it. Medial rotation: rotation toward midline. Lateral: rotation away from midline. (Ex: Rotation between C1 and C2 vertebrae. Rotation of humerus and femur)

Supination & pronation: rotation of radius and ulna. Supination: palms face anteriorly (Radius and ulna= parallel). Pronation: palms face posteriorly (Radius rotates over ulna)

Dorsiflexion & plantar flexion of foot: Dorsiflexion: bending foot toward shin. Plantar flexion: pointing toes

Plane, hinge, pivot, condylar, saddle, and ball-and-socket joints.

(based on shape of articular surface, as well as movement joint is capable of)

includes femoropatellar joint-plane joint, allows gliding motion during knee flexion. Lateral. & Medial joints; Femoral condyles with lateral and medial menisci of tibia. Allow flexion, extension, and some rotation when knee partly flexed

Simultaneous injury to the anterior cruciate ligament, tibial collateral ligament, and medial meniscus. Ruptured ACL, ruptured tibial collateral ligament, and

torn meniscus.

Two types of movement: Hinge: depression and elevation of mandible. Gliding: side-to-side (lateral excursion) grinding of teeth

-Most easily dislocated joint in the

body

Cartilage tears, sprains (ligament tears), and dislocations (luxations).

B: Inflammation of bursa, usually caused by blow or friction. Treated with rest and ice and, if severe, anti- inflammatory drugs. T: Inflammation of tendon sheaths, typically caused by

overuse. Symptoms and treatment similar to those of bursitis

>100 different types of inflammatory or degenerative diseases that damage joints. Most widespread crippling disease in the U.S. Symptoms: pain, stiffness, and swelling of joint. Acute forms: caused by bacteria, treated with antibiotics

Irreversible, degenerative (“wear-and-tear”) arthritis. Cartilage is broken down faster than it is replaced. Bone spurs may form from thickened ends of bones. Joints may be stiff and make crunching noise referred to as crepitus, especially upon rising

Immune system attacks own cells. Usually arises between ages 40 and 50, but may occur at any age; affects three times as many women as men. Signs and symptoms include joint pain and swelling (usually bilateral), anemia, osteoporosis, muscle weakness, and cardiovascular problems

Typically affects joint at base of great toe. In untreated gouty arthritis, bone ends fuse and

immobilize joint. Treatment: drugs, plenty of water, avoidance of alcohol and foods high in purines, such as liver, kidneys, and sardines

Advancing years take toll on joints. Ligaments and tendons shorten and weaken. Intervertebral discs more likely to herniate. Most people in 70s have some degree of OA. Full-range-of-motion exercise key to postponing joint problems

called articulations: where 2+ bones meet. give skeleton mobility and hold skeleton

together

A. Have six general features

B. Have bursae and tendon sheaths associated with

them

C. Stability is influenced by three factors

D. Allow several types of movements

E. Classified into six different types

5. Reinforcing liga. (Capsular: thickened part of fibrous layer. Extracapsular: outside capsule. Intracapsular: deep to capsule; covered by synovial membrane 6. Nerves & blood vessels (Nerves detect pain; monitor joint position and stretch. Capillary beds supply filtrate for synovial fluid)

Fatty pads: For cushioning between fibrous layer of capsule and synovial

membrane or bone. Articular discs (menisci): Fibrocartilage separates articular surfaces to improve “fit” of bone ends, stabilize joint, and reduce wear and tear

All muscles attach to bone or connective tissue at no fewer than 2 points

• Origin: attachment to immovable bone. Insertion: attachment to movable bone

-Muscle contraction causes insertion to move toward origin

(insertion=moving part when you flex)

Gliding, angular movements, rotation

Abduction: movement along frontal plane, away from the midline. Adduction: movement along frontal plane, toward the midline. Circumduction: Involves flexion, abduction, extension, and adduction of limb. Limb describes cone in space

Inversion and eversion of foot. Inversion: sole of foot faces medially. Eversion: sole of foot faces laterally. Protraction and retraction: movement in lateral plane

Protraction: mandible juts out. Retraction: mandible is pulled toward neck

Elevation and depression of mandible. Elevation: lifting body part superiorly (Ex: shrugging shoulders). Depression: lowering body part (Ex: opening jaw).

Opposition: movement of thumb (Ex: touching thumb to tips of other fingers on same

hand or any grasping movement)

Flat articular surfaces, nonaxial movement (gliding)

Ex: intercarpal joints, intertarsal joints, joints b/t vertebral articular surfaces

Humerus, Ulna: contains cylinder & trough. Uniaxial movement: Medial /lateral axis, flexion & extension

Ex: elbow joints, interphalangeal joints

Ulan, Radius: contains sleeve, (bone & ligament), Axle (rounded bone). Uniaxial movement: vertical axis, rotation.

Ex: proximal radioulnar joints, atlantoaxial jpint

Phalanges, metacarpals (oval articular processes) . Biaxial movement: medial/lateral axis (flexion and extension), anterior/posterior axis (adduction & abduction).

Ex: Metacarpophalangeal (knuchle) joints, wrist joints

Metacarpal 1, trapezium (articular surfaces are both concave & convex). Biaxial movemnent: Adduction & Abduction (medial/lateral axis). Flexion & extension (anterior/posterior axis)

Ex: carpometacarpal joints of the thumbs

Scapula , Humerus: cup (socket), spherical head (ball). Multiaxial movement: Flexion & extension (medial/lateral axis). Adduction & abduction (anterior/posterior axis). Rotation (vertical axis)

Ex: shoulder and hip joints

Collateral ligaments, Cruciate ligaments, and Cartilages (menisci)

-Knee absorbs great amount of vertical force; however, it is vulnerable to horizontal blows,

especially laterally blows to extended knee

Anteriorly, quadriceps tendon gives rise to three broad ligaments that run from patella to tibia. Medial & lateral patellar retinacula that flank the patellar ligament

• Doctors tap patellar ligament to test knee-jerk reflex

• At least 12 bursae associated with knee joint

Anterior cruciate ligament (ACL): Attaches to anterior tibia.Prevents forward sliding of tibia and stops hyperextension of knee. Posterior cruciate ligament (PCL): Attaches to posterior tibia. Prevents backward sliding of tibia and forward sliding of

femur

Cartilage rarely repairs itself. Repaired with arthroscopic surgery. Meniscal transplant possible in younger patients. Perhaps meniscus grown from own stem cells in future

Common sites are ankle, knee, and lumbar region of back. Partial tears repair very slowly because of poor vascularization. Three options if torn completely 1. Ends of ligaments can be sewn together. 2. Replaced with grafts. 3. Just allow time and immobilization for healing

Bones forced out of alignment. Accompanied by sprains, inflammation, and difficulty

moving joint. Caused by serious falls or contact sports. Must be reduced to treat

-Subluxation: partial dislocation of a joint