Chapter 9 Flashcards
Joint
AKA an articulation or arthrosis; is a point of contact between two bones, between bone and cartilage, or between bone and teeth.
How are joints classified?
Structurally and functionally.
What two criteria is the structural classification of joints based on?
- The presence of a synovial cavity.
- The type of connective tissue that binds the bones together.
What are the three structural classifications of joints?
- Fibrous joints
- Cartilaginous joints
- Synovial joints
Fibrous joints
There is no synovial cavity, and the bones are held together by dense irregular connective tissue that is rich in collagen fibers.
Cartilaginous joints
There is no synovial cavity, and the bones are held together by cartilage.
Synovial joints
The bones forming the joint have a synovial cavity and are united by the dense irregular connective tissue of an articular capsule, and often by accessory ligaments.
What are the three functional classifications of joints?
- Synarthrosis
- Amphiarthrosis
- Diarthrosis
Synarthrosis
An immovable joint.
Amphiarthrosis
A slightly moveable joint.
Diarthrosis
A freely moveable joint. All diarthroses are synovial joints. They have a variety of shapes and permit several different types of movement.
What are the three types of fibrous joints?
- Suture
- Syndesmosis
- Interosseous membrane
Suture
Articulating bones united by a thin layer of dense irregular connective tissue, found between skull bone. Are synarthrosis (immovable) in adults, but amphiarthrosis (slightly moveable) in infants and children.
Synostosis
Sutures that are present during growth of the skull and then replaced by bone in adulthood; complete fusion of two separate bones into one (Eg. The frontal bone grows in halves that join together across a suture line. Usually they are completely fused by age 6 and the suture becomes obscure).
Syndesmosis
Is a fibrous joint in which there is a greater distance between the articulating surfaces and more dense irregular connective tissue than in a suture. The dense irregular connective tissue is typically arranged as a bundle (ligament), allowing the joint to permit limited movement.
Interosseous membranes
Is a substantial sheet of dense irregular connective tissue that binds neighboring long bones and permits amphiarthrosis (slight movement).
What are the three types of cartilaginous joints?
- Synchondrosis
- Symphysis
- Epiphyseal cartilages
Synchondrosis
Is a cartilaginous joint in which the connecting material is hyaline cartilage and is amphiarthrosis (slightly movable) to synarthrosis (immovable).
Symphysis
Is a cartilaginous joint in which the ends of the articulating bones are covered with hyaline cartilage, but a broad, flat disc of fibrocartilage connects the bones. All symphyses occur in the midline of the body. Are amphiarthrosis (slightly moveable)
Epiphyseal cartilages
Are hyaline cartilage growth centers during endochondral bone formation, not joints associated with movements. Are synarthrosis (immovable joint).
Synovial cavity
AKA joint cavity; a space between articulating bones; is a unique characteristic of synovial joints that distinguish them from other joints. Because the synovial cavity allows considerable movement at a joint, all synovial joints are classified functionally as freely movable (diarthrosis).
Articular cartilage
Layer of hyaline cartilage; covers the articulating surfaces of the bones with a smooth, slippery surface but does not bind them together. Articular cartilage reduces friction between bones in the joint during movement and helps to absorb shock.
Articular capsule
AKA joint capsule; a sleeve-like capsule that surrounds a synovial joint, encloses the synovial cavity, and unites the articulating bones. The articular capsule is composed of two layers, 1.) an outer fibrous membrane and 2.) an inner synovial membrane.
Fibrous membrane
Consists of dense irregular connective tissue (mostly collagen fibers) that attaches to the periosteum of the articulating bones. The fibrous membrane is literally a thickened continuation of the periosteum between the bones. The flexibility of the fibrous membrane permits considerable movement at a joint, while its great tensile strength (resistance to stretching) helps prevent the bones from dislocating (the displacement of a bone from a joint).
Synovial membrane
Is composed of areolar connective tissue with elastic fibers.
Ligaments
Parallel fiber bundles of dense regular connective tissue that are highly adapted for resisting strains; one of the principal mechanical factors that hold bones close together in a synovial joint.
Articular fat pads
Accumulations of adipose tissue. Found at many synovial joints within the synovial membrane (Eg. The infrapatellar fat pad in the knee).
Synovial fluid
Secreted by the synovial membrane; a viscous (gel-like), clear or pale yellow fluid. Synovial fluid consists of hyaluronic acid and interstitial fluid. It forms a thin film over the surfaces within the articular capsule. Its functions include reducing friction by lubricating the joint, absorbing shocks, and supplying oxygen and nutrients to and removing carbon dioxide and metabolic wastes from the chondrocytes within articular cartilage.
When a synovial joint is immobile for a time, the fluid becomes quite ______, but as joint movement increases, the fluid becomes less ______. One of the benefits of warming up before exercise is that it stimulates the production and secretion of synovial fluid; within limits, ______ fluid means ______ stress on the joints during exercise.
Viscous; viscous; more; less
Accessory ligaments
Extracapsular ligaments and intracapsular ligaments; many synovial joints contain these.
Extracapsular ligaments
Lie outside the articular capsule (Eg. The fibular and tibial collateral ligaments of the knee joint).
Intracapsular ligaments
Occur within the articular capsule but are excluded from the synovial cavity by folds of the synovial membrane (Eg. The anterior and posterior cruciate ligaments of the knee joint).
Articular discs
AKA menisci; crescent-shaped pads of fibrocartilage that lie between the articular surfaces of the bones and are attached to the fibrous capsule (Eg. Inside some synovial joints, such as the knee). The discs bind strongly to the inside of the fibrous membrane and usually subdivide the synovial cavity into two spaces, allowing separate movements to occur in each space.
What are the functions of the articular discs?
Not completely understood but are known to include the following: 1.) shock absorption; 2.) a better fit between articulating bony surfaces; 3.) providing adaptable surfaces for combined movements; 4.) weight distribution over a greater contact surface; and 5.) distribution of synovial lubricant across the articular surfaces of the joint.
Labrum
Prominent in the ball-and-socket joints of the shoulder and hip. Is a fibrocartilaginous lip that extends from the edge of a joint socket. The labrum helps deepen the joint socket and increases the area of contact between the socket and the ball-like surface of the head of the humerus or femur.
Describe the nerve and blood supply of synovial joints
Contain many nerve endings that are distributed to the articular capsule and associated ligaments. Although many of the components of synovial joints are avascular, arteries in the vicinity send out numerous branches that penetrate the ligaments and articular capsule to deliver oxygen and nutrients. Veins remove carbon dioxide and wastes from the joints. The chondrocytes in the articular cartilage of a synovial joint receive oxygen and nutrients from synovial fluid derived from blood; all other joint tissues are supplied directly by capillaries.
Bursae
Sac-like structure that is strategically situated to alleviate friction in some joints, such as the shoulders and knee joints. They are filled with a small amount of fluid that is similar to synovial fluid. Bursae can be located between the skin and bones, tendons and bones, muscles and bones, or ligaments and bones.
Tendon sheath
AKA synovial sheaths; also reduce friction at joints; are tube-like bursae; wrap around certain tendons that experience considerable friction as they pass through tunnels formed by connective tissue and bone. A tendon sheath protects all sides of a tendon from friction as the tendon slides back and forth.
Gliding
Movement of relatively flat bone surfaces back-and-forth and side-to-side over one another; little change in angle between bones.
Angular movements
Increase or decrease in angle between bones.
Flexion
Decrease in angle between articulating bones,
usually in sagittal plane.
Lateral flexion
Movement of trunk in frontal plane.
Extension
Increase in angle between articulating bones, usually in sagittal plane.
Hyperextension
Extension beyond anatomical position.
Abduction
Movement of bone away from midline, usually in frontal plane.
Adduction
Movement of bone toward midline, usually in frontal plane.
Circumduction
Flexion, abduction, extension, adduction, and rotation in succession (or in the opposite order); distal end of body part moves in circle.
Rotation
Movement of bone around longitudinal axis; in limbs,
may be medial (toward midline) or lateral (away from midline).
Elevation
Superior movement of body part.
Depression
Inferior movement of body part.
Protraction
Anterior movement of body part in transverse plane.
Retraction
Posterior movement of body part in transverse plane.
Inversion
Medial movement of sole.
Eversion
Lateral movement of sole.
Dorsiflexion
Bending foot in direction of dorsum (superior surface).
Plantar flexion
Bending foot in direction of plantar surface (sole).
Supination
Movement of forearm that turns palm anteriorly.
Pronation
Movement of forearm that turns palm posteriorly.
Opposition
Movement of thumb across palm to touch fingertips on same hand.
Plane joint Know what kind of axial(s) it is
Are flat or slightly curved; primarily permit back-and-fourth and side-to-side movements between flat surfaces of bones, but they also may rotate against one another. Many are biaxial (permit movement in 2 axes), and some are triaxial (movement in 3 axes).
Hinge joint Know what kind of axial(s) it is
The convex surface of one bone fits into the concave surface of another bone; produce an angular, opening-and-closing motion like that of a hinged door. Are uniaxial (monoaxial) (movement in 1 axis).
Pivot joint Know what kind of axial(s) it is
The rounded or pointed surface of one bone fits with a ring formed partly by another bone and partly by a ligament. Are uniaxial (monoaxial) (movement in 1 axis).
Condyloid joint
The convex oval-shaped projection of one bone fits into the oval-shaped depression of another bone. Are biaxial (movement in 2 axes).
Saddle joint
The articular surface of one bone is saddle-shaped, and the articular surface of the other bone fits into the “saddle” as a sitting rider would. Are biaxial (movement in 2 axes).
Ball-and-socket joint
Ball-like surface of one bone fits into a cuplike depression of another bone. Are triaxial (movement in 3 axes).
Temporomandibular joint (TMJ)
Is a combined hinge and plane joint formed by the condylar process of the mandible and the mandibular fossa and articular tubercle of the temporal bone. The temporomandibular joint is the only freely movable joint between skull bones (with the exception of the ear ossicles); all other skull joints are sutures and therefore immovable or slightly movable.
Describe the movements of the TMJ
In the TMJ, only the mandible moves because the temporal bone is firmly anchored to other bones of the skull by sutures. Accordingly, the mandible may function in depression (jaw opening) and elevation (jaw closing), which occurs in the inferior compartment, and protraction, retraction, lateral displacement, and slight rotation, which occur in the superior compartment.
Articular capsule of the shoulder joint
Extends from the glenoid cavity to the anatomical neck of the humerus. The inferior part of the capsule is its weakest area.
Coracohumeral ligament of the shoulder joint
Extends from the coracoid process of the scapula to the greater tubercle of the humerus. The ligament strengthens the superior part of the articular capsule and reinforces the anterior aspect of the articular capsule.
Glenohumeral ligaments of the shoulder joint
Three thickenings that extend from the glenoid cavity to the lesser tubercle and anatomical neck of the humerus. These ligaments are often indistinct or absent and provide only minimal strength. They play a role in joint stabilization when the humerus approaches or exceeds its limits of motion.
Transverse humeral ligament of the shoulder joint
Narrow sheet extending from the greater tubercle to the lesser tubercle of the humerus. Functions as a retinaculum (retaining band of connective tissue) to hold the long head of the biceps brachii muscle.
Glenoid labrum of the shoulder joint
Narrow rim of fibrocartilage around the edge of the glenoid cavity that slightly deepens and enlarges the glenoid cavity.
Articular capsule of the elbow joint
The anterior part of the articular capsule extends from the coronoid fossae of the humerus to the coronoid process of the ulna and the anular ligament of the radius. The posterior part extends from the capitulum, olecranon fossa, and lateral epicondyle of the humerus to the anular ligament of the radius, the olecranon of the ulna, and the ulna posterior to the radial notch.
Ulnar collateral ligament of the elbow joint
Thick, triangular ligament that extends from the medial epicondyle of the humerus to the coronoid process and olecranon of the ulna. Part of this ligament deepens the socket for the trochlea of the humerus.
Radial collateral ligament of the elbow joint
Strong, triangular ligament that extends from the lateral epicondyle of the humerus to the anular ligament of the radius and the radial notch of the ulna.
Annular ligament of the radius
Band that starts at the ulna, wraps around the radius, and connects back to the ulna. Holds the head of the radius in the radial notch of the ulna.
Articular capsule of the hip joint
Extends from the rim of the acetabulum (part of the pelvis that the head of the femur articulates with) to the neck of the femur. One of the strongest structures of the body. Consists of circular and longitudinal fibers.
Ligaments of the head of the femur
Flat, triangular band within the articular capsule that extends from the fossa of the acetabulum to the fovea capitis of the head of the femur. Usually contains a small artery that supplies the head of the femur.
Articular capsule of the knee joint
No complete, independent capsule unites the bones of the knee joint. The ligamentous sheath surrounding the joint consists mostly of muscle tendons or their expansions. There are, however, some capsular fibers connecting the articulating bones.
Medial and lateral patellar retinacula
Fused tendons of insertion of the quadriceps femoris muscle and the fascia lata (fascia of thigh) that strengthen the anterior surface of the joint.
Patellar ligament
Extends from the patella to the tibial tuberosity. Strengthens the anterior surface of the joint.
Tibial collateral ligament
Extends from the medial condyle of the femur to the medial condyle of the tibia. Is firmly attached to the medial meniscus.
Fibular collateral ligament
Extends from the lateral condyle of the femur to the lateral side of the head of the fibula. It strengthens the lateral aspect of the joint.
Anterior cruciate ligament (ACL)
Extends posteriorly and laterally from a point anterior to the intercondylar area of the tibia to the posterior part of the medial surface of the lateral condyle of the femur. The ACL limits hyperextension of the knee and prevents the tibia from moving anteriorly.
Posterior cruciate ligament (PCL)
Extends anteriorly and medially from a depression on the posterior intercondylar area of the tibia and lateral meniscus to the anterior part of the lateral surface of the medial condyle of the femur. The PCL prevents the the tibia from moving posteriorly.
Articular discs
AKA menisci; two fibrocartilage discs between the tibial and femoral condyles that act as cushions for the femur. Also provide some stability.
Medial meniscus
Semicircular piece of fibrocartilage (C-shaped). Its anterior end is attached to the anterior intercondylar fossa of the tibia, anterior to the anterior cruciate ligament. Its posterior end is attached to the posterior intercondylar fossa of the tibia between the attachments of the posterior cruciate ligament and lateral meniscus.
Lateral meniscus
Nearly circular piece of fibrocartilage (incomplete O in shape). Its anterior end is attached anteriorly to the intercondylar eminence of the tibia, and laterally and posteriorly to the anterior cruciate ligament. Its posterior end is attached posteriorly to the intercondylar eminence of the tibia, and anteriorly to the posterior end of the medial meniscus.
Bursae of the knee joint
Three bursae are associated with the knee joint.
