Chapter 8

anular ligament of radius

wraps around head of radius; helps to hold it in place at radial notch of ulna

Cartilage tears (menisci)

occur when a meniscus is subjected to compression and shear stress at the same time

coracohumeral ligament

provides the only strong thickening of the capsule and helps support the weight of the upper limb

Synovial fluid (synovial joint)

thin, lubricating film that covers the surface of a joint; complex mixture of polysaccharides, proteins, fat and cells; Hyaluronic acid - Provides slippery, lubricating effect

arthroscopic surgery

The arthroscope, a small instrument bearing a tiny lens and fiber-optic light source, enables the surgeon to view the joint interior, as in Figure 8.13. The surgeon can then repair a ligament or remove cartilage fragments through one or more tiny slits, minimizing tissue damage and scarring.

elevation/depression

Elevation - moves structure superior Depression - moves structure inferior EX-shrugging shoulders (scapular movement), opening/closing mouth (mandible movement)

Movements allowed by synovial joints

1. angular 2. gliding 3. rotation

Symphyses (Cartilaginous Joint)

A joint where fibrocartilage unites the bones.

Rheumatism

A lay term referring to disease involving muscle or joint pain; may be used to apply to arthritis, bursitis, etc.

Anterior Cruciate Ligament (ACL)

A ligament in the knee that attaches to the anterior aspect of the tibial plateau. restricting anterior movement of the tibia on the femur

Posterior Cruciate Ligament (PCL)

A ligament in the knee that attaches to the posterior aspect of the tibial plateau, restricting posterior movement of the tibia on the femur

Ankylosing Spondylitis (AS)

A variant of rheumatoid arthritis that chiefly affects males; it usually begins in the sacroiliac joints and progresses superiorly along the spine. The vertebrae become interconnected by fibrous tissue, causing the spine to become rigid.

What does the term "arthritis" mean?

Answer: Arthritis means inflammation of the joint.

How do bursae and tendon sheaths improve joint function?

Answer: Bursae and tendon sheaths help to reduce friction during joint movement.

PREDICT Babies are sometimes diagnosed with a condition called craniosynostosis. Using the definition you just learned, describe what you think this condition is and predict what problems it might cause.

Answer: Cranio- refers to the skull bones (see Chapter 7, p. 201) and synostosis refers to ossification of skull bone sutures. Craniosynostosis is a disorder in which the sutures in the skull close prematurely (in babies). Premature closing of sutures prevents the brain from growing normally.

MAKE CONNECTIONS Evan is 25 years old. Would you expect to find synchondroses at the ends of his femur? Explain. (Hint: See Chapter 6, p. 187.)

Answer: Evan would not have synchondroses at the ends of his femur. By age 25, his epiphyseal plates have fused and become synostoses.

How are joint mobility and stability related?

Answer: In general, the more stable a joint, the less mobile it is.

What is the cause of Lyme disease?

Answer: Lyme disease is caused by spirochete bacteria and transmitted by a tick bite.

What functional joint class contains the least-mobile joints?

Answer: The synarthroses are the least mobile of the joint types.

Menisci of the knee

C shaped disks Prevent side to side rocking Medial and Lateral

3 common knee injuries

Collateral ligaments Cruciate ligaments Cartilages (menisci)

ulnar collateral ligament

Connects the medial epicondyle of the humerus to the ulna

chondromalacia patellae (CMP)

Damage and softening of the articular cartilages on the posterior patellar surface and the anterior surface of the distal femur; most often seen in adolescent athletes. Produces a sharp pain in the knee when the leg is extended (in climbing stairs, for example). May result when the quadriceps femoris, the main group of muscles on the anterior thigh, pulls unevenly on the patella, persistently rubbing it against the femur in the knee joint; often corrected by exercises that strengthen weakened parts of the quadriceps muscles.

plantar flexion and dorsiflexion (feet)

Dorsiflexion: Lifting the foot so that its superior surface approaches the shin Plantar Flexion: depressing the foot (pointing the toes)

synostoses

During middle age, the fibrous tissue ossifies and the skull bones fuse into a single unit

articular discs (menisci)

Fibrocartilage separates articular surfaces to improve "fit" of bone ends, stabilize joint, and reduce wear and tear

Autologous chondrocyte implantation

Healthy chondrocytes are removed from the body and seeded onto a supporting matrix of tissue-engineered collagen. When subjected to mechanical pressure in the lab, the cells produce new cartilage, which is then implanted.

Synovitis

Inflammation of the synovial membrane of a joint. Caused by injury, infection, or arthritis. Excess synovial fluid accumulates in the joint cavity, a condition called effusion that causes the joint to swell, limiting joint movement.

Bone marrow stimulation

Small holes poked through to the bone marrow allow mesenchymal stem cells from the bone marrow to migrate into the joint and produce new cartilage.

iliofemoral ligament (Y ligament)

Thick, strong ligament resembling an inverted Y Attaches proximally to anterior-superior aspect of acetabular rim, and distally to intertrochanteric line of femur Limits excessive extension of hip

Mesenchymal stem cell regeneration

Undifferentiated mesenchymal cells are removed from bone marrow and placed in a gel, which is packed into an area of eroded cartilage.

opposition movement

allows thumb to touch the tips of the fingers on the same hand (opposable thumb)

Lyme disease

an inflammatory disease caused by spirochete bacteria transmitted by the bite of ticks that live on mice and deer.

intracapsular ligaments of the knee

anterior cruciate ligament (ACL) posterior cruciate ligament (PCL)

arcuate popliteal ligament

arcs superiorly from the head of the fibula over the popliteus muscle and reinforces the joint capsule posteriorly

reinforcing ligaments of synovial joints

capsular, extracapsular, intracapsular

gliding movement of synovial joints

carpals, tarsals, vertebrae occurs when one flat, or nearly flat, bone surface glides or slips over another without appreciable angulation or rotation

ischiofemoral ligament

connects ischium to femur

Articular Surfaces

determines what movements are possible at a joint (minor role)

glenoid labrum

fibrocartilage ring that deepens glenoid cavity

Bursae

flattened fibrous sacs lined with synovial membrane and containing a thin film of synovial fluid - They occur where ligaments, muscles, skin, tendons, or bones rub together.

structural classification

focuses on the material binding the bones together and whether or not a joint cavity is present: fibrous, cartilaginous, and synovial joints

diarthroses (functional)

freely movable joints

Synchondroses (cartilaginous)

hyaline cartilage unites bones (epiphyseal) Virtually all synchondroses are synarthrotic (immovable).

Synarthroses (functional)

immovable joints

gouty arthritis (gout)

inflammation and painful swelling of joints caused by excessive uric acid in the body

Circumduction

is moving a limb so that it describes a cone in space (circum = around; duco = to draw). The distal end of the limb moves in a circle, while the point of the cone (the shoulder or hip joint) is more or less stationary.

Pannus

rheumatoid arthritis

supination and pronation of forearm

rotational movement, results in the palm facing upward/downward

Amphiarthroses (functional)

slightly movable joints

glenoid cavity

socket in scapular that receives head of humerus

oblique popliteal ligament

stabilizes posterior knee joint

glenohumeral ligaments (superior, middle, inferior)

strengthen the front of the capsule somewhat but are weak and may even be absent

dislocation (luxation)

the total displacement of a bone from its joint

Rheumatoid arthritis (RA)

chronic joint condition with inflammation and pain; caused by an autoimmune reaction against joint tissue, particularly the synovial membrane

Patellar ligament (tendon)

connects patella to tibia

pubofemoral ligament

connects pubis to femur

radial collateral ligament

connects the lateral epicondyle of the humerus to the radius

synovial joints

created where two bones articulate to permit a variety of motions

Prostheses

custom-built artificial limbs

arthritis

inflammation of a joint

The stability of a synovial joint depends chiefly on three factors:

- The shapes of the articular surfaces - The number and positioning of ligaments - Muscle tone

To what functional class do most fibrous joints belong?

Answer: Most fibrous joints are synarthroses (immovable).

APPLY Nick bent over to pick up a dime. What movement was occurring at his hip joint, at his knees, and between his index finger and thumb?

Answer: Nick's hip joint was flexed and his knees extended and his thumb was in opposition (to his index finger).

APPLY From an arthritis patient's history and physical examination, how would you determine if he or she might have OA or RA?

Answer: RA typically produces pain, swelling, and joint deformations that tend to be bilateral and crippling. OA patients tend to have pain, particularly on arising, which is relieved by gentle exercise, and enlarged bone ends (due to spurs) in affected joints. Affected joints may exhibit crepitus.

On the basis of movement allowed, which of the following joints are uniaxial? Hinge, condylar, saddle, pivot.

Answer: The hinge and pivot joints are uniaxial joints.

Of the five joints studied in more detail—hip, shoulder, elbow, knee, and temporomandibular—which two have menisci? Which act mainly as a uniaxial hinge? Which depend mainly on muscles and their tendons for stability?

Answer: The knee and temporomandibular joints have menisci. The elbow and knee each act mainly as a uniaxial hinge. The shoulder depends largely on muscle tendons for stability.

Generally speaking, what factor is most important in stabilizing synovial joints?

Answer: The muscle tendons that cross the joint are typically the most important factor in stabilizing synovial joints.

Name the category (according to its shape and movement allowed) of each of the synovial joints labeled a-d below.

Answer: The synovial joint categories are (a) ball-and-socket, (b) hinge, (c) pivot, and (d) condylar.

mandibular fossa of temporal bone

Articulates with the head of the mandible to form the temporomandibular joint. The mandible (lower jaw) joins with the skull at this site.

Ligaments

Connect bone to bone, the more ligaments a joint has, the stronger it is. a ligament can stretch only about 6% of its length before it snaps

Osteochondral grafting

Healthy bone and cartilage removed from one part of the body and transplanted to the injured joint.

articular cartilage of synovial joint

Glassy-smooth hyaline cartilage covers the opposing bone surfaces as articular cartilage. These thin (1 mm or less) but spongy cushions absorb compression placed on the joint and thereby keep the bone ends from being crushed.

General Structure of Synovial Joints

Have following basic features: 1. Articular cartilage 2. Joint cavity (synovial cavity) 3. Articular capsule 4. Synovial fluid 5. Reinforcing ligaments 6. Nerves and vessels

Inversion and Eversion of foot

Inversion: sole of foot faces medially Eversion: sole of foot faces laterally

temporomadibular joint (TMJ)

Jaw joint, is a modified hinge joint. At this joint, the condylar process of the mandible articulates with the inferior surface of the squamous part of the temporal bone

Nerves and blood vessels of synovial joints

Nerves detect pain; monitor joint position and stretch Capillary beds supply filtrate for synovial fluid

Range of motion allowed by synovial joints

Nonaxial—slipping movements only Uniaxial—movement in one plane Biaxial—movement in two planes Multiaxial—movement in or around all three planes

Muscle origin and insertion

Origin: is attached to the immovable (or less movable) bone Insertion: is attached to the movable bone

protraction and retraction of mandible

Protraction: is going out Retraction: is bringing in

Arthroplasty

Replacing a diseased joint with an artificial joint.

joint (articular) cavity

The joint cavity is a feature that is unique to synovial joints. It contains a small amount of synovial fluid. The joint cavity is a potential space because it is normally almost nonexistent, but can expand if fluid accumulates (as happens during inflammation).

articular capsule of synovial joint

The joint cavity is enclosed by a two-layered articular capsule, or joint capsule. The tough external fibrous layer is composed of dense irregular connective tissue that is continuous with the periostea of the articulating bones. It strengthens the joint so that the bones are not pulled apart. The inner layer of the joint capsule is a synovial membrane composed of loose connective tissue. Besides lining the fibrous layer internally, it covers all internal joint surfaces that are not hyaline cartilage. The synovial membrane's function is to make synovial fluid.

crepitus

a crackling or grating sound usually of bones

autoimmune disease

a disorder in which the body's immune system attacks its own tissues.

acetabular labrum of hip

a fibrocartilaginous rim attached to acetabulum which deepens the cavity. Fills up the inequality of surface bone; protects rim, helps keep head of femur from dislocating

synovial joints (diarthroses)

are those in which the articulating bones are separated by a fluid-containing joint cavity. This arrangement permits substantial freedom of movement, and all synovial joints are freely movable diarthroses. Nearly all joints of the limbs—indeed, most joints of the body—fall into this class.

functional classification

based on the amount of movement allowed at the joint. synarthroses, amphiarthrosis, diarthroses

fibrous joints

bones are joined by the collagen fibers of connective tissue. No joint cavity is present. most fibrous joints are immovable. Sutures, syndesmosis, gomphoses

tendon sheath

elongated bursa that wraps around a tendon

fatty pads of synovial joints

for cushioning between fibrous layer and synovial membrane or bone - this is only in select joints, such as the hip and knee joints

lateral patellar retinacula

one of three ligaments from patella to tibia; continuations of the tendon of the bulky quadriceps muscle of the anterior thigh

articular tubercle of temporal bone

front boundary of mandibular fossa

Sutures

immovable joints of the skull, The wavy articulating bone edges interlock, and the junction is completely filled by a minimal amount of very short connective tissue fibers that are continuous with the peri-osteum.

angular movements of synovial joints

increase or decrease the angle between two bones. These movements may occur in any plane of the body and include flexion, extension, hyperextension, abduction, adduction, and circumduction.

Bursitis

inflammation of a bursa and is usually caused by a blow or friction.

Tendonitis

inflammation of tendon sheaths, typically caused by overuse.

femoropatellar joint

intermediate between patella and inferior end of femur (this is plane joint)

ligament of the head of the femur

intracapsular ligament that runs from the acetabulum of the hip bone to the head of the femur

Tumor necrosis factor (TNF)

involved in the inflammation of autoimmune diseases - this drug can help to dramatically slow the course of RA

Extension

involves movement along the sagittal plane that increases the angle between the articulating bones and typically straightens a flexed limb or body part. Examples include straightening a flexed neck, body trunk, elbow, or knee

Hip (Coxal) Joint

is a ball-and-socket joint. It has a good range of motion, but not nearly as wide as the shoulder's range. Movements occur in all possible planes but are limited by the joint's strong ligaments and its deep socket.

Flexion

is a bending movement, usually along the sagittal plane, that decreases the angle of the joint and brings the articulating bones closer together. Examples: bending the head forward on the chest; bending the body trunk or the knee from a straight to an angled position

Gomphoses (fibrous)

is a peg-in-socket fibrous joint, the only example is the articulation of a tooth with its bony alveolar socket

Abduction

is movement of a limb away from the midline or median plane of the body, along the frontal plane. Raising the arm or thigh laterally is an example of abduction

Adduction

is the opposite of abduction, so it is the movement of a limb toward the body midline or, in the case of the digits, toward the midline of the hand or foot

Rotation

is the turning of a bone around its own long axis. It is the only movement allowed between the first two cervical vertebrae and is common at the hip and shoulder joints.

tibiofemoral joint (knee joint)

lateral and medial joints between condyles of femur and C shaped menisci of tibia (these are hinge joints)

Muscle tone (tonus)

low levels of contractile activity in relaxed muscles that keep the muscles healthy and ready to react to stimulation.

rotator cuff

part of the capsule of the shoulder joint - The Four Muscles of the rotator cuff: subscapularis, supraspinatus, infraspinatus, and teres minor

Subluxation

partial dislocation of a joint

fibular and tibial collateral ligaments

prevent lateral or medial rotation or flexion when knee is extended

lateral ligament of TMJ

prevents posterior displacement of the mandible

lateral excursion of mandible

right or left movement from the zero position. the mandible moves with a side-to-side movement

Arthrology

study of joints

cartilaginous joints

the articulating bones are united by cartilage. Like fibrous joints, they lack a joint cavity and are not highly movable. The two types of cartilaginous joints are synchondroses and symphyses.

syndesmoses (fibrous)

the bones are connected exclusively by ligaments (syndesmos = ligament), cords or bands of fibrous tissue. The amount of movement allowed at a syndesmosis depends on the length of the connecting fibers.

sprain

the ligaments reinforcing a joint are stretched or torn. Common sites of sprains are the ankle, the knee, and the lumbar region of the spine. Partially torn ligaments will repair themselves, but they heal slowly because ligaments are so poorly vascularized. Sprains tend to be painful and immobilizing.

Osteoarthritis (OA)

the most common chronic arthritis. A chronic degenerative condition, OA is often called "wear-and-tear arthritis." OA is most prevalent in the aged and is probably related to the normal aging process (although it is seen occasionally in younger people and some forms have a genetic basis). More women than men are affected, and nearly all of us will develop this condition by the age of 80.