JOINTS
OBJECTIVES
• Be able to classify the joints of the
body both structurally and
functionally
• Be able to identify example
classification of joint
• Be able to describe the structure of
a synovial joint
JOINTS
• A joint is the location at which two or
more bones make contact
• Function is to allow movement and
provide mechanical support
• Joints are classified in two ways:
• Structurally
• Functionally
STRUCTURAL CLASSIFICATION
OF JOINTS
• Is based on how the bones are connected to
each other
• Fibrous joint: bones joined by fibrous
connective tissue
• Example: skull and pelvis
• Cartilaginous joint: bones joined by cartilage
• Example: spine and ribs
• Synovial joint: bones not directly joined, but
separated by cavities filled with synovial fluid,
which lubricates and protects the bones
• Example: shoulder, hip, knee, etc
FUNCTIONAL CLASSIFICATION OF
JOINTS
• Is based on the degree of mobility a joint will
allow
• Synarthrosis: joints that permits little or no
mobility; most are fibrous joints
• Example: skull & pelvis
• Amphiarthrosis: joints that permit slight
mobility; most are cartilaginous joints
• Example: the vertebrae
• Diarthrosis: joints that permit a variety of
movements; all of them are synovial joints
• Example: knees and elbows
TYPES OF SYNOVIAL JOINTS
• Hinge
• Saddle
• Ellipsoid/Condyloid
• Ball and Socket
• Pivot
• Gliding
JOINT STRUCTURE
• The bones that ends in a synovial joint are
covered and protected by a special type
of cartilage called articular cartilage
• Articular cartilage is smooth and slightly
compressible
• Surrounding the joint is the joint capsule,
which is made of strong connective tissue
• Lining the joint capsule is a delicate
tissue called the synovial membrane
JOINT STRUCTURE CONT.
• The synovial membrane constantly
secretes synovial fluid into the synovial
cavity
• Synovial fluid lubricates the joint,
nourishes the cartilage with fats and
proteins
• Its like uncooked egg white
• Ligaments attach the bone ends
together to prevent them from moving
too far or in unnatural directions
SPECIAL CASE
• Some synovial joints are partially or completely
divided into two compartments by discs of
fibrocartilage called menisci (meniscus s.) between
the articular surfaces
• In the knee, they help to cushion the articulating
surfaces and help distribute body weight on the
surfaces
• Fluid-filled sacs called bursae are also sometimes
present
• Bursae contain synovial fluid and are located
between the skin and underlying bony
prominences
• They aid in the movement of tendons that glide
over bony parts or other tendons as well as provide
cushion
SYNOVIAL JOINT OF
THE KNEE