Chapter 9 Flashcards
The joints of the skeletal system contribute to homeostasis by:
holding bones together in ways that allow for movement and flexibility.
2 other names for Joint
Articulation and arthrosis
Joint
is a point of contact between two bones, between bone and cartilage, or between bone and teeth.
The scientific study of joints is termed
arthrology
The study of motion the human body is called
kinesiology
The structural classification of joints is based on two criteria:
(1) the presence or absence of a space between the articulating
bones, called a synovial cavity, and (2) the type of connective tissue
that binds the bones together.
Structurally, joints are classified as one
of the following types:
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 oft en by accessory ligaments
Functionally, joints are classified into these categories:
Synarthrosis, Amphiarthrosis, Diarthrosis
Synarthrosis
An immovable
joint. The plural is synarthroses.
Amphiarthrosis
A slightly movable joint. The plural is amphiarthroses
Diarthrosis
A freely movable
joint. The plural is diarthroses. All diarthroses are synovial joints.
They have a variety of shapes and permit several different types of movements.
fibrous joints lack
a synovial cavity
Suture
is a fibrous joint
composed of a thin layer of dense irregular connective tissue; sutures
occur only between bones of the skull. In older individuals, sutures are
immovable (synarthroses), but in infants and children they are slightly
movable (amphiarthroses)
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. . It permits slight movement (amphiarthrosis).
interosseous membrane
a substantial sheet of dense irregular connective tissue that binds neighboring long bones and permits slight
movement (amphiarthrosis).
Two principal interosseous membranes:
One occurs between the radius and ulna in the forearm and the other occurs between the tibia and fibula in the leg.
Fibrous Joints
Suture, syndesmosis, interosseous membrane
cartilaginous joint lacks:
a synovial cavity and allows little or no movement
The three types of cartilaginous joints are:
synchondroses, symphyses, and epiphyseal cartilages.
synchondrosis
is a cartilaginous joint in which the connecting
material is hyaline cartilage and is slightly movable (amphiarthrosis) to immovable (synarthrosis).
Symphyses
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. slightly movable joint
(amphiarthrosis).
Epiphyseal Cartilages
actually hyaline cartilage growth centers during endochondral bone formation, not joints associated with movements. Functionally, epiphyseal cartilage is an
immovable joint (synarthrosis)
Synovial joints
The unique characteristic of a synovial joint is the
presence of a space called a synovial cavity or joint cavity between
the articulating bones. all synovial joints are classified functionally
as freely movable (diarthroses).
The bones at a synovial joint are covered by a layer of hyaline cartilage called:
articular cartilage
articular capsule
surrounds a synovial joint, encloses the synovial cavity, and unites the articulating bones.
The articular capsule is composed
of two layers:
an outer fibrous membrane and 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 fibers of some fibrous membranes are arranged as parallel bundles of dense regular connective tissue that are highly adapted for resisting strains. The strength of these fiber bundles are called
Ligaments
Ligaments
one of the principal mechanical factors that hold bones close together in a synovial joint. Ligaments are often designated by individual names.
The inner layer of the articular capsule
Synovial membrane
Synovial Membrane
composed of areolar
connective tissue with elastic fibers
At many synovial joints the synovial membrane includes accumulations of adipose tissue, called
Articular fat pads
Synovial Fluid
consists of hyaluronic acid secreted by synovial cells in the synovial membrane and interstitial fluid filtered from blood plasma. more fluid means less stress on the joints during exercise.
accessory ligaments
extracapsular (outside) ligaments and intracapsular (Inside) ligaments
Articular discs
depict the lateral and medial menisci in the knee
joint. 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.
The functions of
the menisci are:
(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-andsocket joints of the shoulder and hip. 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
bursae
are strategically situated to alleviate friction in some joints, such as the shoulder and knee joints
Tendon sheaths
are tubelike bursae; they wrap around certain tendons that experience considerable friction as they pass through tunnels formed by connective tissue and bone
Movements at synovial joints are grouped into four main categories:
(1) gliding, (2) angular movements, (3) rotation, and (4) special movements, which occur only at certain joints.
Gliding
a simple movement in which nearly flat bone surfaces move
back-and-forth and from side-to-side with respect to one another