Structural Classification Flashcards
Structural classifications are based on whether…
fibrous tissue, cartilage, or a joint cavity separates the bony regions at the joint
In fibrous joints, the bones are united by…
fibrous tissue
The sutures of the skull are examples of what joint?
fibrous joint – in sutures, the irregular edges of the bones interlock and are bound tightly together by connective tissue fibers.
Syndesmoses are examples of what joint?
fibrous joint
In comparison to sutures, the connecting fibers in syndesmoses are
longer, so the joint has more “give”
The joint connecting the distal ends of the tibia and fibula is a
syndesmosis
In cartilaginous joints, the bone ends are connected by
fibrocartilage
The pubic symphysis of the pelvis is specifically what kind of joint?
symphysis, or an amphiarthrotic cartilaginous joint
Intervertebral joints of the spinal columns are specifically what kind of joints?
symphyses (amphiarthrotic cartilaginous joints,) where the bone surfaces are connected by discs of fibrocartilage
The hyaline-cartilage epiphyseal plates of growing long bones are what kind of joints?
synchondroses (synarthrotic cartilaginous joints)
The joints between the first ribs and the sternum are what kind of joints?
synchondroses (synarthrotic cartilaginous joints)
Joints in which the articulating bone ends are separated by a joint cavity are called ____ and contain ____
synovial joints; synovial fluid
All synovial joints have these four distinguishing features:
- Articular (hyaline) cartilage covers the ends
- Articular capsule encloses joint surfaces; it is lined with a smooth synovial membrane
- Articular capsule encloses a joint cavity, which contains lubricating synovial fluid
- Fibrous layer of the articular capsule is usually reinforced with ligaments
Not strictly part of synovial joints, but are often found closely associated with them
Bursae and tendon sheaths
Bursae and tendon sheaths are essentially
bags of lubricant, acting like ball bearings to reduce friction between adjacent structures during joint activity
What are bursae defined to be?
flattened fibrous sacs lined with synovial membrane and containing a thin film of synovial fluid; common where tissues rub together
What are tendon sheaths defined to be?
Essentially elongated bursae that wrap completely around tendons subjected to friction (like a bun around a hot dog)
When a dislocation happens, bone is
forced out of its normal position in the joint cavity
The process of returning bone to its proper position is called
reduction, which should only be done by a physician
The shapes of articulating bone surfaces determine what?
what movements are allowed at a joint
Sutures are amphiarthrotic as
fontanels (colloquially “soft spots” on the infant skull)
Sutures can become …
synostoses, or fused together as bony joints (osseous union)
Define interosseous membrane.
broad and thin plane of fibrous tissue; commonly found in syndesmoses
What are ligaments?
bands of dense regular connective, or fibrous, tissue bundles that connect bones to bones to form joints
Gomphosis is the only joint between
teeth and bone (a.k.a dentoalveolar joint)
Describe gomphosis
synarthrotic joint; cone-shaped peg in socket
Synovial joints are connected by
dense irregular connective tissue
What are the two layers of the articular capsule
the fibrous capsule and synovial membrane
The fibrous capsule is made of what tissue and attaches where?
It is dense regular connective tissue that attaches to the periosteum or ligaments
The synovial membrane is made of what tissue and does what?
It is loose areolar connective tissue and produces synovial fluid.
What are the functions of synovial fluid?
Shock absorption, nutrients, removes microbes & debris, reduces friction
Reinforcing (accessory) ligaments are found at
larger joints, or joints under much stress that need more stablization/support e.g. the cruciate ligaments (anterior, medial and posterior) at the knee
What are articular discs?
Also known as menisci; cartilage that helps maintain stability and fit different shapes together at joint (e.g. temporomandibular joint, knee)
Name the 6 classifications of synovial joints based on shape.
Plane, hinge, pivot, condylar, saddle, and ball-and-socket joints
Describe a plane joint.
articular surfaces are essentially flat; only short slipping/gliding movements allowed; movements are nonaxial (no rotation around any axis)
The intercarpal and intertarsal joints are the best examples of
plane joints, gliding movement
What are the four main categories of movement for synovial joints?
Gliding, angular, rotational, and special
Angular movements that involve angular change include:
flexion & extension; lateral flexion & lateral extension; hyperextension; abduction & adduction; circumduction
Describe a hinge joint
cylindral end of one bone fits into a trough-shaped surface of another (convex fits into concave); uniaxial, movement allowed in just one plane
The elbow joint, ankle joint and the joints between the phalanges of the fingers are classified as
hinge joints
Head shaking no and foot moving laterally and medially are examples of what kind of movement
rotational
What are the special movements?
Elevation & depression; protraction & retraction; inversion & eversion; dorsiflexion & plantar flexion; supination & pronation; opposition
Describe a pivot joint
rounded end of one bone fits into a sleeve/ring of bone (and possibly ligaments); uniaxial, rotating bone can only turn around its long axis
The proximal radioulnar joint and the joint between the atlas and dens are classified as
pivot joints
Describe a condylar joint (ellipsoid)
egg-shaped articular surface of one bone fits into an oval concavity in another; biaxial, allows side to side and back and forth movement but no rotating around its long axis
Knuckle (metacarpophalangeal) joints are classified as
condylar joints
Describe a saddle joint
each articular surface has both concave and convex areas (like a saddle); biaxial, allows essentially the same movements as condylar joints
Carpometacarpal joints in the thumb are the best examples of
saddle joints
Describe a ball-and-socket joint
spherical head of one bone fits into a round socket in another; multiaxial, allows movement in all axes (including rotation); most freely moving synovial joints
The shoulder and hip are examples of
ball-and-socket joints
Factors affecting range of motion of synovial joints:
structure/shape of articulating bones; strength/tension of ligaments; arrangement & tension of muscles; contact of soft parts (e.g. adipose); hormones; disuse
