Anatomy & Physiology
Chapter 10: Articulations
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Introduction
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Articulation—point of contact
between bones
Joints are mostly very movable, but
some are immovable or allow only
limited motion
Movable joints allow complex, highly
coordinated, and purposeful
movements to be executed
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Classification of Joints
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Joints may be classified by using a
structural or functional scheme (Table 101)
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Structural classification—joints are
named according to:
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Type of connective tissue that joins bones
together (fibrous or cartilaginous joints)
Presence of a fluid-filled joint capsule
(synovial joint)
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Classification of Joints
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Joints (cont)
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Functional classification—joints are
named according to the degree of
movement allowed
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Synarthroses—immovable joint
Amphiarthroses—slightly movable
Diarthroses—freely movable
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Classification of Joints
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Fibrous joints (synarthroses)—bones of
joints fit together closely, thereby allowing
little or no movement (Figure 10-1)
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Syndesmoses—joints in which ligaments
connect two bones
Sutures—found only in the skull; teethlike
projections from adjacent bones interlock
with each other
Gomphoses—between the root of a tooth
and the alveolar process of the mandible
or maxilla
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Classification of Joints
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Cartilaginous joints
(amphiarthroses)—bones of joints are
joined together by hyaline cartilage or
fibrocartilage; allow very little motion
(Figure 10-2)
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Synchondroses—hyaline cartilage
present between articulating bones
Symphyses—joints in which a pad or
disk of fibrocartilage connects two
bones
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Classification of Joints
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Synovial joints (diarthroses) —freely
movable joints (Figure 10-3)
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Structures of synovial joints
 Joint capsule—sleevelike casing
around the ends of the bones that
binds them together
 Synovial membrane—membrane that
lines the joint capsule and also
secretes synovial fluid
 Articular cartilage—hyaline cartilage
covering the articular surfaces of bones
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Classification of Joints
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Structures of synovial joints (cont)
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Joint cavity—small space between the
articulating surfaces of the two bones of the
joint
Menisci (articular disks)—pads of
fibrocartilage located between articulating
bones
Ligaments—strong cords of dense white
fibrous tissue that hold the bones of a synovial
joint more firmly together
Bursae—synovial membranes filled with
synovial fluid; cushion joints and facilitate
movement of tendons
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Classification of Joints
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Synovial joints (cont)
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Types of synovial joints (Figure 10-4)
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Uniaxial joints—synovial joints that permit
movement around only one axis and in only
one plane
 Hinge joints—articulating ends of bones
form a hinge-shaped unity that allows
only flexion and extension
 Pivot joints—a projection of one bone
articulates with a ring or notch of another
bone
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Classification of Joints
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Types of synovial joints (cont)
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Biaxial joints—synovial joints that permit
movements around two perpendicular
axes in two perpendicular planes
Saddle joints—synovial joints in which the
articulating ends of the bones resemble
reciprocally shaped miniature saddles; only
example in the body is in the thumbs
 Condyloid (ellipsoidal) joints—synovial
joints in which a condyle fits into an
elliptical socket
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Classification of Joints
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Types of synovial joints (cont)
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Multiaxial joints—synovial joints that permit
movements around three or more axes in
three or more planes
 Ball-and-socket (spheroid) joints—most
movable joints; the ball-shaped head of
one bone fits into a concave
depression
 Gliding joints—relatively flat articulating
surfaces that allow limited gliding
movements along various axes
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Representative Synovial Joints
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Humeroscapular joint (Figure 10-5)
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Shoulder joint
Most mobile joint because of the
shallowness of the glenoid cavity
Glenoid labrum—narrow rim of
fibrocartilage around the glenoid cavity
that lends depth to the glenoid cavity
Structures that strengthen the shoulder
joint are ligaments, muscles, tendons,
and bursae
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Representative Synovial Joints
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Elbow joint (Figure 10-6)
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Humeroradial joint—lateral articulation of
the capitulum of the humerus with the head
of the radius
Humeroulnar joint—medial articulation of
the trochlea of the humerus with the
trochlear notch of the ulna
Both components of the elbow joint
surrounded by a single joint capsule and
stabilized by collateral ligaments
Classic hinge joint
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Representative Synovial Joints
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Elbow joint (cont)
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Medial and lateral epicondyles are
externally palpable bony landmarks
Olecranon bursa independent of elbow
joint space
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Inflammation called olecranon bursitis
Trauma to nerve results in unpleasant
sensations in the fingers and part of the
hand supplied by the nerve
Severe injury may cause paralysis of
hand muscles or reduction in wrist
movements
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Representative Synovial Joints
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Proximal radioulnar joint—between
the head of the radius and the medial
notch of the ulna
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Stabilized by the annular ligament
Permits rotation of the forearm
Dislocation of the radial head called a
“pulled elbow”
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Representative Synovial Joints
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Distal radioulnar joint—point of
articulation between the ulnar notch
of the radius and the head of the ulna
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Acts with the proximal radioulnar
joint
Permits pronation and supination of
the forearm
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Representative Synovial Joints
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Radiocarpal (wrist) joints (Figure 10-7)
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Only the radius articulates directly with
the carpal bones distally (scaphoid
and lunate)
Joints are synovial
Scaphoid bone is fractured frequently
Portion of the fractured scaphoid may
become avascular
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Representative Synovial Joints
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Carpometacarpal joints—total of
three joints
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One joint for the thumb—wide range
of movements
Two joints for the fingers—
movements largely gliding type
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Representative Synovial Joints
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Carpometacarpal joints (cont)
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Thumb carpometacarpal joint is unique
and important functionally
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Loose-fitting joint capsule
Saddle-shaped articular surface
Movements—extension, adduction,
abduction, circumduction, and opposition
Opposition—ability to touch the tip of the
thumb to the tip of other fingers—
movement of great functional significance
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Representative Synovial Joints
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Metacarpophalangeal joints (Figure
10-8)
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Rounded heads of metacarpal
bones articulate with concave
bases of the proximal phalanges
Capsule surrounding joints
strengthened by collateral
ligaments
Primary movements are flexion and
extension
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Representative Synovial Joints
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Interphalangeal joints
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Typical diarthrotic, hinge-type, synovial
joints
Exist between heads of phalanges and
bases of more distal phalanges
Two categories:
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PIP joints—proximal interphalangeal
joints (between proximal and middle
phalanges)
DIP joints—distal interphalangeal joints
(between middle and distal phalanges)
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Representative Synovial Joints
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Hip joint (Figure 10-9)
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Stable joint because of the shape of the head of the femur
and the acetabulum
A joint capsule and ligaments contribute to the joint’s stability
Knee joint (Figures 10-10 and 10-11)
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Largest and one of the most complex and most frequently
injured joints
Tibiofemoral joint is supported by a joint capsule, cartilage,
and numerous ligaments and muscle tendons
Permits flexion, extension, and with the knee flexed, some
internal and external rotation
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Representative Synovial Joints
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Ankle joint (Figure 10-12)
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Synovial-type hinge joint
Articulation between the lower ends of
the tibia and fibula and the upper part
of the talus
Joint is “mortise” or wedge shaped
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Lateral malleolus lower than
medial malleolus
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Representative Synovial Joints
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Ankle joint (cont)
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Internal rotation injury results in
common “sprained ankle”
 Involves anterior talofibular
ligament
Other ankle ligaments also may be
involved in sprain injuries—example
is deltoid ligament
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Representative Synovial Joints
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Ankle joint (cont)
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External ankle rotation injuries generally
involve bone fractures rather than
ligament tears
 First-degree ankle injury—lateral
malleolus fractured
 Second-degree ankle injury—both
malleoli fractured
 Third-degree ankle injury—fracture
of both malleoli and articular surface
of tibia
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Representative Synovial Joints
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Vertebral joints (Figures 10-13 and 10-14)
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Vertebrae are connected to one another by
several joints to form a strong flexible
column
Bodies of adjacent vertebrae are connected
by intervertebral disks and ligaments
Intervertebral disks are made up of two
parts
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Annulus fibrosus—disk’s outer rim, made of
fibrous tissue and fibrocartilage
Nucleus pulposus—disk’s central core, made
of a pulpy, elastic substance
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Types and Range of
Movement at Synovial Joints
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Measuring range of motion (Figure 10-15)
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Range of motion (ROM) assessment used
to determine extent of joint injury
ROM can be measured actively or
passively; both are generally about equal
ROM measured by instrument called a
goniometer
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Types and Range of
Movement at Synovial Joints
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Angular movements—change the size of the angle
between articulating bones
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Flexion—decreases the angle between bones; bends
or folds one part on another (Figures 10-16, A; 1018; and 10-19)
Extension and hyperextension (Figure 10-18)
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Extension—increases the angle between bones, returns a
part from its flexed position to its anatomical position
Hyperextension—stretching or extending a part beyond its
anatomical position (Figures 10-19, 10-21, and 10-23)
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Types and Range of
Movement at Synovial Joints
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Angular movements (cont)
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Plantar flexion and dorsiflexion (Figure 10-25)
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Plantar flexion—increases the angle between the top of the
foot and the front of the leg
Dorsiflexion—decreases the angle between the top of the
foot and the front of the leg
Abduction and adduction (Figures 10-19 and 10-23)
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Abduction—moves a part away from the median plane of
the body
Adduction—moves a part toward the median plane of the
body
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Types and Range of
Movement at Synovial Joints
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Circular movements
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Rotation and circumduction
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Rotation—pivoting a bone on its own axis
(Figure 10-16, D)
Circumduction—moves a part so that its distal
end moves in a circle
Supination and pronation (Figure 10-20, B)
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Supination—turns the hand palm side up
Pronation—turns the hand palm side down
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Types and Range of
Movement at Synovial Joints
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Gliding movements—simplest of all
movements; articular surface of one
bone moves over the articular surface of
another without any angular or circular
movement
Special movements
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Inversion and eversion (Figure 10-25, B)
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Inversion—turning the sole of the foot inward
Eversion—turning the sole of the foot
outward
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Types and Range of
Movement at Synovial Joints
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Special movements (cont)
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Protraction and retraction (Figure 10-17,
A)
 Protraction—moves a part forward
 Retraction—moves a part backward
Elevation and depression (Figure 10-17,
B)
 Elevation—moves a part up
 Depression—lowers a part
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Cycle of Life: Articulations
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Bone development and the sequence of
ossification between birth and skeletal
maturity affect joints
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Fontanels between cranial bones
disappear
Epiphysial plates ossify at maturity
Older adults
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ROM decreases
Changes in gait
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Cycle of Life: Articulations
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Skeletal diseases manifested as
joint problems
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Abnormal bone growth (lipping)—
influences joint motion
Disease conditions can be
associated with specific
developmental periods
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Cycle of Life: Articulations
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Hand—“reason for the upper extremity”;
thumb—“reason for the hand”
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Examples of “big picture” thinking when used
in functional context
Mobility of the upper extremity is extensive
because of the following:
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Arrangement of bones in the shoulder girdle,
arms, forearm, wrist, and hand
Location and method of attachment of muscles
to bones
Proper functioning of joints
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Cycle of Life: Articulations
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Mobility and extensive ROM needed
to position upper extremity and hand
to permit grasping and manipulation of
objects, thus enabling effective
interaction with objects in the external
environment
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