9.1 Classification of Joints
● A joint, or an articulation, is the place of contact between bones, between
bone and cartilage, or between bones and teeth.
● Bones are said to articulate with each other at a joint.
● The scientific study of joints is called Arthrology.
● Joints are classified by both their structural characteristics and their
functions characteristics, which are the movements they allow.
○ A fibrous joint has no joint cavity and occurs where bones are held
together by dense regular connective tissue.
○ A cartilaginous joint has no joint cavity and occurs where bones are
joined by cartilage.
○ A synovial joint has a joint cavity (filled with a lubricating fluid) that
separates the articulating surfaces of the bones. The articulating
surfaces are enclosed within a connective tissue capsule, and the
bones are attached to each other by various ligaments.
Joints are classified functionally based on the extent of movement they permit.
● A synarthrosis is an immobile joint. Two types of fibrous joints and one
type of cartilaginous joint are synarthroses.
● An amphiarthrosis is a slightly mobile joint. One type of fibrous joint and
one type of cartilaginous joint are amphiarthroses.
● A diarthrosis is a freely mobile joint. All synovial joints are diarthroses.
- The more mobile a joint, the less stable the joint. In contrast, the less mobile
the joint, the more stable the joint is.
- If a joint is immobile, it has maximum stability.
9.2 Fibrous Joints
- Articulating bones in fibrous joints are connected by dense regular connective
tissue.
- Fibrous joints have no joint cavity; thus, they lack a space between the articulating
bones.
- Most fibrous joints are immobile or at most only slightly mobile; their primary
function is to hold together two bones.
Fibrous Joints- Dense regular connective tissue bonds the articulating bones in fibrous
joints to prevent or restrict movement.
, ● A gomphosis resembles a “peg in a socket.” The only gomphoses in the human
body are the articulations of the roots of individual teeth with the alveolar
processes (sockets) of the mandible and the maxillae.
● A tooth is held firmly in place by fibrous periodontal membranes. This joint is
immobile and thus is functionally classified as a synarthrosis.
● Sutures are fibrous joints found only between certain bones of the skull. Sutures
are functionally classified as synarthroses, since they are immobile joints. Sutures
have distinct, interlocking, usually irregular edges that both increase their stability
and decrease the number fractures at these articulations.
● When the bones have completely fused across the suture line, these obliterated
sutures are now called synostoses.
● Syndesmoses are fibrous joints in which articulating bones are joined by long
strands of dense regular connective tissue only. Because syndesmoses allow for
slight mobility, they are classified functionally as amphiarthrosis.
● The shafts of the two articulating bones are bound to a broad, ligamentous sheet
called an interosseous membrane. The interosseous membrane provides a pivot
where the radius and ulna (or the tibia and fibula) can move relative to one
another.
9.3 Cartilaginous Joints
- Cartilaginous joints have cartilage between the articulating bones. Like fibrous
joints, cartilaginous joints also lack a joint cavity.
Cartilaginous joints- Articulating bones are joined by cartilage in cartilaginous joints.
● An articulation in which bones are joined by hyaline cartilage is called a
synchondrosis. Functionally, all synchondroses are immobile and thus are
classified functionally as synarthroses.
- The hyaline cartilage of epiphyseal plates in children forms synchondroses that
bind the epiphysis and diaphysis of long bones. When the hyaline cartilage stops
growing, bone replaces the cartilage and a synchondrosis no longer exists.
- The spheno-occipital synchondrosis is found between the body of the sphenoid
and the basilar part of the occipital bone. The synchondrosis typically fuses 18 and
25 years of age, making it a useful tool for assessing the age of the skull.
● Other examples of synchondroses involve costal cartilage. The costochondral
joint, the joint between each bony rib and its respective costal cartilage, is a
synchondrosis.
● A symphysis has a pad of fibrocartilage between the articulating bones. The
fibrocartilage resists both compression and tension stresses and acts as a resilient
● A joint, or an articulation, is the place of contact between bones, between
bone and cartilage, or between bones and teeth.
● Bones are said to articulate with each other at a joint.
● The scientific study of joints is called Arthrology.
● Joints are classified by both their structural characteristics and their
functions characteristics, which are the movements they allow.
○ A fibrous joint has no joint cavity and occurs where bones are held
together by dense regular connective tissue.
○ A cartilaginous joint has no joint cavity and occurs where bones are
joined by cartilage.
○ A synovial joint has a joint cavity (filled with a lubricating fluid) that
separates the articulating surfaces of the bones. The articulating
surfaces are enclosed within a connective tissue capsule, and the
bones are attached to each other by various ligaments.
Joints are classified functionally based on the extent of movement they permit.
● A synarthrosis is an immobile joint. Two types of fibrous joints and one
type of cartilaginous joint are synarthroses.
● An amphiarthrosis is a slightly mobile joint. One type of fibrous joint and
one type of cartilaginous joint are amphiarthroses.
● A diarthrosis is a freely mobile joint. All synovial joints are diarthroses.
- The more mobile a joint, the less stable the joint. In contrast, the less mobile
the joint, the more stable the joint is.
- If a joint is immobile, it has maximum stability.
9.2 Fibrous Joints
- Articulating bones in fibrous joints are connected by dense regular connective
tissue.
- Fibrous joints have no joint cavity; thus, they lack a space between the articulating
bones.
- Most fibrous joints are immobile or at most only slightly mobile; their primary
function is to hold together two bones.
Fibrous Joints- Dense regular connective tissue bonds the articulating bones in fibrous
joints to prevent or restrict movement.
, ● A gomphosis resembles a “peg in a socket.” The only gomphoses in the human
body are the articulations of the roots of individual teeth with the alveolar
processes (sockets) of the mandible and the maxillae.
● A tooth is held firmly in place by fibrous periodontal membranes. This joint is
immobile and thus is functionally classified as a synarthrosis.
● Sutures are fibrous joints found only between certain bones of the skull. Sutures
are functionally classified as synarthroses, since they are immobile joints. Sutures
have distinct, interlocking, usually irregular edges that both increase their stability
and decrease the number fractures at these articulations.
● When the bones have completely fused across the suture line, these obliterated
sutures are now called synostoses.
● Syndesmoses are fibrous joints in which articulating bones are joined by long
strands of dense regular connective tissue only. Because syndesmoses allow for
slight mobility, they are classified functionally as amphiarthrosis.
● The shafts of the two articulating bones are bound to a broad, ligamentous sheet
called an interosseous membrane. The interosseous membrane provides a pivot
where the radius and ulna (or the tibia and fibula) can move relative to one
another.
9.3 Cartilaginous Joints
- Cartilaginous joints have cartilage between the articulating bones. Like fibrous
joints, cartilaginous joints also lack a joint cavity.
Cartilaginous joints- Articulating bones are joined by cartilage in cartilaginous joints.
● An articulation in which bones are joined by hyaline cartilage is called a
synchondrosis. Functionally, all synchondroses are immobile and thus are
classified functionally as synarthroses.
- The hyaline cartilage of epiphyseal plates in children forms synchondroses that
bind the epiphysis and diaphysis of long bones. When the hyaline cartilage stops
growing, bone replaces the cartilage and a synchondrosis no longer exists.
- The spheno-occipital synchondrosis is found between the body of the sphenoid
and the basilar part of the occipital bone. The synchondrosis typically fuses 18 and
25 years of age, making it a useful tool for assessing the age of the skull.
● Other examples of synchondroses involve costal cartilage. The costochondral
joint, the joint between each bony rib and its respective costal cartilage, is a
synchondrosis.
● A symphysis has a pad of fibrocartilage between the articulating bones. The
fibrocartilage resists both compression and tension stresses and acts as a resilient
