Week 6 – Support II 1
ONE – Explain what is meant by the terms synarthrotic, diarthrotic, and amphiarthrotic as
descriptions of the functional classes of joints.
Joints are classified in terms of their structure and function. The functions relate to their degree of movement.
Synarthrotic – joint that is not movable
Diarthrotic – freely movable joint
Amphiarthrotic – slightly movable joint
TWO – Describe the structure of the following types of fibrous joints, the movements allowed by
each and specify an example of each.
Fibrous joints are where bones are connected by dense fibrous connective tissue. There is no cavity between
joints, bones are held very close together, and there is little or no movement between the bones. 3 types!
1. Sutures – found between the bones of the skull; jagged edges that fit like a puzzle; bones are connected
by dense fibrous tissue; provides strength and prevents movement; synarthrotic
2. Syndesmosis – bones are held tightly together by dense fibrous tissue but are still slightly movable
because they are farther apart than sutures; located between the distal end of tibia and fibula;
3. Gomphosis – dense fibrous connections between the teeth, maxilla, and mandible; these joints are
usually immovable so they are synarthrotic
THREE – Describe the structure of the following types of cartilaginous joints, the movements
allowed by each, and specify an example of each.
Articulating bones in cartilaginous joints are held together by cartilage, with little or no movement between bones.
Synchondrosis – the epiphyseal plate in each growing bone is a synchondrosis – a temporary joint that
will be replaced by bone after growth is complete; synarthrotic
Symphysis – broad, flat cartilaginous discs between the vertebrae and pubic bones are symphysis joints;
FOUR – Describe the structure of a synovial joint and specify the function of each of the following
components of the knee joint.
Synovial joints have a synovial cavity between the articulating bones. They are diarthrotic. Most joints of the
appendicular skeleton are synovial joints which allow greater mobility compared to the axial skeleton.
a. Joint capsule (articular capsule) – a sleeve-like layer of fibrous CT that surrounds the joint; holds the
synovial fluid in place and attaches to the periosteum of the articulating bones to hold them together;
portions may be thickened to form ligaments Week 6 – Support II 2
b. Synovial membrane – lines the inner surface of the joint capsule except over the articular cartilage;
secretes synovial fluid into the synovial cavity
c. Synovial cavity – the space between the two articulating bones that contains synovial fluid
d. Synovial fluid – slippery fluid that lubricates joints and serves as a shock absorber by dispersing the shock
energy and lessening pressure on the bone; helps supply nutrients to and remove metabolic wastes from
the articular cartilage
e. Articular cartilage – the ends of articulating bones in synovial joints are covered with cartilage that
reduces friction and serves as a shock absorber to prevent damage to ends of bones
f. Ligaments – bands of fibers that give added strength to the joint and hold bones together; ligaments may
be external (e.g., tibial collateral ligament) or internal (e.g., anterior/posterior cruciate ligaments)
g. Meniscus – a cartilage pad that acts as a spacer in a joint; prevents bone from smashing together
h. Bursa – fluid-filled sac that is strategically located to reduce friction associated with joint movement;
enclosed by synovial membranes that produce the bursa fluid
FIVE – Describe each of the following movements found in synovial joints and specify an example
a. Gliding movement – simplest type of movement at synovial joints; side-to-side and back-and-forth