Chapter 8 anatomy

joints

Bony joint or synostosis

an immobile
joint formed when the gap between two
bones ossifies, and the bones become, in
effect, a single bone

Can occur in either fibrous or cartilaginous
joint

Bony joint

what joint are these examples of:

Left and right mandibular bones in infants
• Cranial sutures in elderly
• Attachment of first rib and sternum with old age

Fibrous joint

adjacent bones are
bound by collagen
fibers that emerge
from one bone and
penetrate into the
other

a fixed joint (synarthrosis) where collagenous fibrous connective tissue unites 2 bones

what is a fibrous joint

cartilaginous joint

two bones are linked by cartilage

what joint are these examples:

First rib
attachment to sternum
• Pubic symphysis joins
right and left pubic
bones with interpubic
disc (two bones joined
by fibrocartilage)
• Bodies of vertebrae
joined by intervertebral
discs

Synovial joint

joint in which two
bones are separated by a joint cavity

Most familiar type of joint
• Most are freely mobile
• Most structurally complex type of joint
• Most likely to develop painful dysfunction
• Most important joints for physical and
occupational therapists, athletic coaches,
nurses, and fitness trainers
• Mobility makes them important to quality of life

synovial fluid

similar in composition to ground substances in loose connective tissue

slippery lubricant in joint cavity

Rich in albumin and hyaluronic acid
Gives it a viscous, slippery texture like raw
egg whites Nourishes articular cartilage and removes waste
Makes movement of synovial joints almost
friction free

articular cartilage

layer of hyaline
cartilage that covers the facing
surfaces of two bones. Usually 2 or 3 mm
thick

articular join cavity

separates articular surfaces

lubrication

what function of synovial fluid is: With articular cartilage compression, synovial fluid is
squeezed out & reduces friction between moving
surfaces

Nutrient distribution

Provide nutrients and oxygen, as well as waste
disposal for the chondrocytes of articular cartilages
• Compression and re-expansion of articular cartilages
pump synovial fluid in and out of cartilage matrix

Shock absorption

Distributes compression forces across articular
surfaces and outward to joint capsule

functions of synovial fluid

Lubrication, nutrient distribution, shock absorption

Joint (articular) capsule

connective tissue that encloses
the cavity and retains the fluid
Outer fibrous capsule:
continuous with periosteum of
adjoining bones

synovial membrane

composed mainly
of fibroblast-like cells that
secrete synovial fluid and
macrophages that remove
debris from the joint cavity

Hyaline cartilage

what cartilage is located in articular surfaces, larynx, trachea, and nasal septum

what cartilage has the functions, stiff but flexable, reduces friction between bony surfaces

Bursa

Small pocket filled with synovial fluid, a pouch

Meniscus

Pad of fibrous cartilage between
bones of synovial joint, a crescent

dislocation

also known as luxation, means that a bone is out of its place

Examples: an arm can be out of place

Can happen with many bones such as fingers, arms, or legs

Flexion

movement that
decreases joint angle
• Common in hinge joints

forward-bending movements at the waist or neck

Extension

movement that
straightens a joint and returns a
body part to the zero position

straightens trunk or neck

Hyperextension

extension of a
joint beyond the zero position

bending over backward

Lateral flexion

tilting head or trunk to right or left at the midline

Abduction

movement of a body part in the frontal plane away
from the midline of the body

Adduction

movement in frontal plane back toward the midline

Elevation

movement that raises a body part vertically in
the frontal plane

Depression

movement that lowers a body part in the same
plane

Protraction

the anterior
movement of a body part
in the transverse
(horizontal) plane

Retraction

posterior
movement

Circumduction

one end
of an appendage remains
stationary while other end
makes a circular motion

Rotation

movement in
which a bone spins on its
longitudinal axis
• ——- of trunk, thigh,
head, or arm

Medial (internal) rotation

rotation
turns the bone inward

Lateral (external) rotation

rotation
turns the bone outward

Supination

forearm
movement that turns palm
to face anteriorly or upward

Pronation

forearm
movement that turns palm
to face either posteriorly or
downward

Radial flexion—

tilting hand toward thumb

Ulnar flexion

tilting hand toward little finger

Abduction versus adduction of the fingers

spreading them apart
versus bringing them together

Flexion versus extension of fingers

curling versus straightening them

Dorsiflexion

elevating toes as you do while swinging foot
forward to take a step (heel strike)

Plantar flexion

—extending foot so that toes point downward as
in standing on tiptoe (toe-off)

Inversion

—movement in which the soles are turned medially

Eversion

—movement in which the soles are turned laterally

Knee joint

Internal support
• Cruciate ligaments limit anterior/posterior movement
of femur & maintain alignment of condyles

Medial and lateral menisci

Fibrous cartilage pads between tibial and femoral
condyles. Act as cushions and provide lateral stability to
joint

glenohumeral joint

articular surface, synovial ball and socket articulation, hyaline cartilage, joint stability is provided by: rotator cuff muscles, long hear of biceps bracii, extrascapular ligaments. Moments: flexion, extension, abduction, adduction, medial rotation, lateral rotation, and circumdocution

osteoarthritis

aging, wear, break down of articular cartilage

Rheumatoid arthritis

autoimmune attack
against the joint tissues

inflammation

Misguided antibodies
(——— factor)
attack synovial
membrane. Synovial
membrane becomes
inflamed and thickened

articular cartilage

what covers the surface of bone at the articulating surfaces within a synovial joint

synovial fluid

what is the source of nourishment for articular cartilage

synovial membrane

what is the bursa composed of

flexion of the forearm

what term is used to refer to bending at the elbow

inversion

what refers to moving the sole of the foot medially

opposition

what movemnt is unique to the thumb

osteoarthritis

what is another name for degenerative joint disease

articular cartilage

what part of the joint shows damage early in degenerative joint disease