Outline 6
Joints
Joints and their Classification – Joints are classified according to the manner in which the
adjacent bones are _____________ to each other
 _____________ Joint (also called synostosis)
o Immovable joint formed when the gap between two bones ossifies and the
bones become, in effect, a single bone
 An infant is born with right and left mandibular bones and
_____________ bones, but these fuse into a single mandible and
frontal bone
 Fibrous Joint (also called synarthrosis)
o It is a point at which adjacent bones are bound by ___________ fibers that
emerge from the matrix of one bone, cross the space between them, and
penetrate into the matrix of the other bone
o Three kinds of fibrous joints
 Sutures –
 _______________ sutures – appear as wavy lines along the
adjoining bones, firmly interlocking them
o Example: Sagittal suture
 _______________ sutures (squamous sutures) – occur
where two flat bones have overlapping edges
o Example: squamous suture
 _________________ sutures – occur where two bones have
straight, non-overlapping edges
o Example: suture between right and left palatine
processes of the maxilla
 Gomphoses –
 The attachment of a tooth to its socket
o The tooth is held in place by a periodontal
______________
 The ligament allows the tooth to move a
little under the stress of chewing
 Syndesmoses –
 Fibrous joints in which the bones are bound by longer
collagenous fibers than in a suture or gomphosis, giving the
bones more mobility
o Example: the shafts of the ulna and radius are
connected by an interosseous membrane which
allows the forearm to ________________
 Cartilaginous Joint (also called amphiarthroses)
o Bones are linked by ____________________
o Kinds of cartilaginous joints:
 Synchondroses – joints in which the bones are bound by hyaline
cartilage

Example 1: temporary joint between the epiphysis and
diaphysis of a long bone in a child, formed by the
________________ plate
 Example 2: Attachment of a rib to the sternum by a hyaline
costal cartilage
 Symphyses – joints in which bones are joined by fibrocartilage
 Example 1: pubic symphysis that connects the right and
left ______________ bones
 Example 2: cartilage between the bodies of two vertebrae
Synovial Joints (also called diarthroses) – freely movable joints
 General Anatomy
o Articular cartilage – a thin layer of ________________ cartilage covering
the connecting surface of a bone at a synovial joint, serving to reduce
friction and ease joint movement
o Joint cavity – narrow space between the ____________ in a synovial joint
o Synovial fluid – a lubricating fluid similar to eggwhite in consistency,
found in the synovial joint cavities and bursae
o Joint capsule – capsule of connective tissue that encloses the joint cavity
and retains fluid
 Fibrous capsule – outer portion of the joint capsule
__________________ with the periosteum of the bones
 Synovial membrane – inner portion with fibroblast-like cells that
secrete ______________ fluid and macrophages that remove
debris from the joint cavity
o Articular disc – fibrocartilage that grows inward from the joint capsule to
form a pad between the articular bones
o Meniscus – crescent-shaped cartilages in the knee that absorb shock and
guide bones across each other
o Tendon – a collagenous band or cord associated with a muscle, usually
attaching it to a ________________ and transferring muscular tension to it
o Ligament – a cord or band of tough collagenous tissue binding one organ
to another, especially one bone to another, and serving to hold organs in
place
o Bursa – a sac filled with synovial fluid at a synovial joint, serving to
facilitate muscle or joint action
o Tendon sheath – bursae that are elongated cylinders wrapped around a
__________________
o Bursitis – Inflammation of a bursae, usually due to overexertions of a joint
o Tendinitis – inflammation of a tendon ______________
 Types of Synovial Joints
o Hinge joint – joints that can move only in one plane, like a door hinge
 One bone has a convex surface that fits into a concave depression
of the other
 Examples: ____________, knee, interphalangeal joints (within
finger or toe)
o Gliding joint – joints that slide over each other with limited twisting

 Articular surfaces are flat or only slightly concave and convex
 Examples: ____________ and ankle bones, sternoclavicular joint
o _____________ joint – joints in which the first bone rotates on its
longitudinal axis relative to the other
 Example 1: the atlas bone rotates on the dens of the axis bone, so
the head can rotate to gesture “no”
 Example 2: a ligament on the ulna wraps around the head of the
radius, which allows the radius to rotate as the forearm is turned
o Saddle joint – joints that allow movement in two axes (providing a wide
range of movement)
 the articular surface of each bone is shaped like a _____________
(concave in one direction and convex in the other)
 Example: attachment of the thumb to the hand
o Condyloid joint – joints that allow movement in two axes (but more
limited than in the saddle joint)
 The articular surface of one bone is oval and convex, while the
other bone is a similarly shaped depression
 Example: attachment of the index finger to the hand
(metacarpophalangeal joint)
o Ball-and-socket joint – joints that provide the greatest range of movement
(they are multiaxial)
 A smooth hemispherical head of one bone fits into a cuplike
depression on another
 Examples: humerus into ________________, femur into os coxae
Movement of Synovial Joints
o Flexion – movement that decreases the angle of a joint on an anteriorposterior plane
 Examples: bending the elbow or knee, bending the neck to look
down at the floor
o Extension – movement that __________________ a joint and generally
returns a body part to anatomical position
 Examples: straightening the elbow or knee, raising the head to look
directly forward
o ____________extension – extension of a joint beyond 180O.
 Examples: raising the back of your hand “as if admiring a new
ring” or bending the neck to look upward
o Abduction – movement of a body part ___________________ the median
plane
 Examples: raising the arm to one side of the body, or moving the
feet away from each other while standing; also spreading the
________________ apart on one hand
o Adduction – movement of a body part toward the median plane
 Examples: bringing the arms to the sides or sliding the feet closer
together while standing; also putting the fingers close together on
one hand
o Elevation – movement of a body part to _______________ it vertically


Example: shrugging the shoulders to raise the scapulae and
clavicles
o Depression – movement of a body part downward
 Example: lowering the shoulders
o Protraction – movement of a body part _______________________ on
plane parallel with the ground
 Example: moving the mandible forward, or moving the shoulders
forward
o Retraction – movement of a body part posteriorly on a plane parallel with
the ground
 Example: moving the mandible __________________, or moving
the shoulders backward
o Lateral excursion – sideways movement to the right or left
 Example: movement of the jaw away from midline
o Medial excursion – movement back to midline
 Example: movement of the jaw back to midline
o Circumduction – movement in which one end of an appendage remains
relatively stationary while the other end makes a circular motion
 Example – winding up for a pitch in baseball, making “big arm
circles” in gym class
o Rotation - movement in which a bone turns on its ___________________
axis
 Examples: twisting the thigh at the femur to os coxae joint, or
twisting the arm at the glenohumeral joint.
o Supination – movement of the forearm so that the palm faces forward or
upward
o Pronation – movement of the forearm so that the palm faces
________________ or downward
o Opposition – movement of the thumb to approach or touch the
______________
o Reposition – movement of the thumb to anatomical position, parallel to
the index finger
o Dorsiflexion – movement in which the toes are raised
o Plantar flexion – movement in which the toes are pointed
____________________
o Inversion – movement that lifts the medial border of the foot to turn the
soles of the feet medially (inward)
o Eversion – movement that lifts the lateral border of the foot to turn the
soles of the foot away from each other
Range of Motion
o Structure and action of the muscles
 Tendons, ligaments, and muscles have proprioceptors that monitor
joint angle and muscle tension.
 When the ________________________ receives this information,
it sends signals back to the muscles to increase or decrease their
state of contraction
 This adjusts the position of the joint and the tautness of tendons
o Structure of the articular surfaces of the ______________
 Some joints cannot be hyperextended
 The olecranon of the ulna fits into the olecranon fossa of
the humerus, and prevents further movement in that
direction
o Strength and tautness of ___________________, tendons, and joint
capsule
 The knee cannot be hyperextended because its cruciate ligament is
pulled tight as the knee is extended
Anatomy of Selected Synovial Joints
 The Jaw Joint
o Type: condyloid, hinge, and gliding
o Movements: elevation, depression, protraction, retraction, excursion
 The Shoulder Joint
o Type: ball-and-socket
o Movements: adduction, abduction, flexion, __________________,
circumduction, medial and lateral rotation
 The Elbow Joint
o Type: hinge and pivot
o Movements: flexion, extension, pronation, supination, ________________
 The Hip (Coxal) Joint
o Type: ball-and-socket
o Movements: adduction, abduction, ________________, extension,
circumduction, medial and lateral rotation
 The Knee Joint
o Type: primarily hinge
o Movements: flexion, extension, slight rotation
 The Ankle Joint
o Type: hinge
o Movements: dorsiflexion, plantar flexion, extension
Clinical Perspectives
 ___________________ – inflammation of a joint
o Osteoarthritis (wear-and-tear arthritis)
 As joints age, the articular cartilage softens and degenerates
 As cartilage becomes roughened by wear, joint movement may be
accompanied by crunching or crackling sounds
 As the articular cartilage wears away, exposed bone tissue often
develops _____________ that grow into the cavity, restricting
movement and causing pain
o Rheumatoid arthritis
 Results from autoimmune attack against the joint tissues
 Misguided antibodies attack the synovial membrane.
 Inflammatory cells accumulate in the synovial fluid and produce
enzymes that degrade the articular cartilage


The synovial membrane thickens, fluid accumulates in the capsule,
and the capsule is invaded by fibrous connective tissue
As the cartilage degenerates, the bones become solidly
_______________