Bones and Joints

Bones and Joints
Synovial Joints
Makes up most of our permanent joints
All of these joints allow greatest range of
movement
The end of bone at articulation is covered
with smooth hyaline cartilage
The joint is lubricated by thick fluid called
synovial fluid
The joint is covered by flexible articular
capsule
Joint capsule
Outer:
dense irregular connective tissue
Continuous with periosteum
Inner:
Areolar connective tissue
Synovial membrane
Produces and secretes synovial fluid that
fills the joint cavity
Slippery, reduces friction and nourish the
articular cartilage
Menisci
Cushions
Deepens the joint
Makes bones fit together better
Temporomandibular joint
Has extra cartilage to divide joint cavity
Provides more movement
Bursa(e)
A fibrous sac filled with synovial fluid and it
rolls
Found between skin and bone, muscle and
bone, ligament and bone, or tendon and
bone
Tendon Sheath
Wraps "like a hot dog bun" around
tendons
Located in various places including wrists
and ankles
Examples
Hinge joint
The convex surface of one bone fits on
concave surface of other bone
This permits uniaxial movement
Example: knee joint, elbow joint, ankle joint
Pivot joint
Composed of central bony pivot
surrounded by a collar made partly of bone
and partly of ligament
Movement of pivot joint is uniaxial and is
able to rotate around a central axis
Example: atlantoaxial joint between atlas
and axis
Condyloid joint
Modifications of ball and socket joints
Movement is biaxial because of ligaments
and muscles
Example: metacarpophalangeal joint of
fingers (except thumb)
Gliding joint
Always small and formed by flat articular
surface so that one bone slides on another
bone
Movement is multiaxial
Example: articular process of vertebrae,
clavicular joint
Saddle Joint
Both bones at articulation are shaped like a
saddle
Bones have both concave and convex area
at right angle to each other
Example: carpometacarpal joint of thumb
Ball and socket joint
Composed of globe like head of one bone
that fits into a cup like cavity on another
bone
Most freely movable joint of all joints
Movement is multiaxial
Example: shoulder and hip joints
Cartilaginous Joints
Synchondroses
Epiphyseal plate
Connects first rib and manubrium
Contains hyaline cartilage
Permits growth of bone but not movement
Replaced by bone when large bone stops
growth (a few are still present in adults)
Immovable
Example: sternoclavicular joint
Symphyses
In this joint two bones are covered by a thin
layer of hyaline cartilage
Presence of a disk of fibro-cartilage
between two bones that acts as a shock
absorber
Intervertebral joints
Slightly movable
Example: pubis symphysis
Fibrous Joints
Suture
A tight union between two or more bones
in a skull of an adult
No movement
Example: sagital suture, lamboidal suture,
and coronal suture
Fontanelles
"Soft spots" in an infants skull
A membrane between cranial bones before
they come together completely
Syndesmosis
In this joint bones are close together but
not touching
Bones are held together by collagen fibers
Little to no movement
Example: distal tibio-fibular joint and
radius-ulna joint
Gomphosis
Where the tooth meets the mandible and
maxillae
Connected by perioclontal ligaments
Immovable
Fibrous joint made up of peg and socket
Types of Bone Cells
Osteogenic stem cells
Found in the stratum basal in the epidermis
when it reproduces it creates a stem cell
and an osteoblast
Found in endosteum and periosteum
Function: to produce osteoblasts
Osteoblasts
Create bone extra cellular matrix
Hardens with the addition of minerals
Osteocytes
Maintain bone health
Osteoclast
Multinucleate
Formed from several leukocytes
Have microvilli
There for secretion of enzymes that break
down bone tissue
This liberates (frees) calcium and
phosphorus
These two things then go into the blood
stream
They are mobile
Found in endosteum and periosteum
Components of Long Bones
Epiphysis
The head of the bone
Diaphysis
The shaft of the bone
Articular Cartilage
Type of cartilage is hyaline
Covers the end of the epiphysis
Spongy bone
This area is porous
Bone tissue is filled with red bone marrow
Important for producing blood cells
Found in the ends of long bones
Periosteum
Outer layer
Made of dense irregular connective tissue
Is used for protection
An attachment place for ligaments
Inner layer
Made of osteogenic tissue
Capable of generating new bone
Is a membrane that covers the outer
surface, except at the joints of long bones
Located
Compact bone
Any part of the actual bone that isn't
spongy bone
Not porous
Medullary cavity
Also known as the marrow cavity
Central cavity of bone shafts
Where red bone marrow and/or yellow
bone marrow are stored
Endosteum
Covers the inside of bones
Surrounds the medullary cavity
Thin vascular membrane of connective
tissue
Perforating fibers
Connects periosteum to compact bone
Bundles of strong collagenous fibers
Nutrient blood vessels
Enters shaft through the nutrient foramen
Runs through the cortex
Divides into ascending and descending
branches in the medullary cavity
Supplies to the meduallary cavity, inner
two-thirds of cortex, and metaphysis
Epiphyseal Plate
Also known as the epiphyseal line
Where the epiphysis and metaphysis meet
Responsible for the lengthwise growth of
long bone
After epiphyseal fusion happens the bone
can no longer grow
A cartilaginous plate
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