Chapter 8, Section 1
Joints
Joints, also called articulations, are functional junctions
between two bones
The science of joints is called arthrology.
Functions of joints
1. Bind skeleton together
2. Enable body movements
3. Makes growth possible
4. Permit changes in skeleton for childbirth
Classification of Joints
Classifications based on amount of movement
1. Synarthrotic = immovable
2. Amphiarthrotic = slightly moveable
3. Diarthrotic = fully movable
Classifications by types of tissue:
1. Fibrous joint = dense connective tissue
2. Cartilaginous joint = bones connected by cartilage
3. Synovial joint = contains a synovial membrane
Fibrous Joints
There are three (3) types of fibrous joints:
• Syndesmosis
• Suture
• Gomphosis
1. Syndesmosis:
Bones are connected by a sheet
or bundle of fibrous tissue.
Examples include the
interosseous membrane and
interosseous ligaments
between the tibia and fibula.
Interosseous membrane between tibia
and fibula is a syndesmosis joint.
Fibrous Joints
2. Suture:
• Thin layer of dense
connective tissue
• Connects flat bones of the
skull (sutural ligaments)
•Synarthrotic
3. Gomphosis:
• Cone-shaped bony process
in a bony socket
• Example includes a tooth
anchored into a bony socket
Cartilaginous Joints
• There are two (2) types of cartilaginous joints:
• Synchondrosis
• Symphysis
1. Synchondrosis
• Bones are united by a band of
hyaline cartilage.
•
Located between manubrium
of sternum & 1st rib
•
Also located at epiphyseal
plates of developing bone
•
Movement is synarthrotic
Cartilaginous Joints
2. Symphysis
• A pad of fibrocartilage
between two bones
•
Examples include the pubic
symphysis and intervertebral
discs
•
Movement is amphiarthrotic.
General Structure of Synovial Joints
Synovial Joints are Freely movable (Diarthrotic)
Structures include:
• Articular cartilage
•
Synovial membrane –
secretes synovial fluid
•
Joint cavity – filled with
synovial fluid
•
Joint capsule – dense
connective tissue that
stabilizes and protects joint
Figure 8.7 The generalized
structure of a synovial joint.
General Structure of Synovial Joints
Structures include:
• Ligaments – bundles of
collagenous fibers that
reinforce the joint capsule
•
Menisci (sing. Meniscus) –
pad of fibrocartilage that
separates some joints.
•
Bursa – sac filled with
synovial fluid.
• Bursitis = inflammation
of bursa
Figure 8.8 Menisci separate the articulating surfaces
of the femur and tibia. Several bursae are
associated with the knee joint.
Types of Synovial Joints
1. Ball-and-socket
•
•
•
•
rounded head + cup-shaped socket.
Movement in all planes (multi-axial).
Allows for rotation
Includes hip joint and shoulder joint.
2. Condylar joint
•
•
•
•
Oval condyle + elliptical socket
Movements in most planes (bi-axial)
No rotational movement
Joints between metacarpals and
phalanges/
Types of Synovial Joints
3. Plane (Gliding) Joint
• Flattened bones slide across each
other
• Includes carpals and tarsals
• ribs 2-7 articulate with sternum
4. Hinge joint
• Increases or decreases angel
between bones
• Includes elbow joint
• Joints between phalanges
Types of Synovial Joints
5. Pivot Joint
• Rotation around a central axis
(uni-axial)
• Joint between radius and ulna
• Joint between atlas (C1) and
axis (C2).
6. Saddle Joint
• 2 concave bones positioned at
right angles
• Includes metacarpal and carpal
of thumb
End of Chapter 8, Section 1
Section 2, Chapter 8
Types of Joint Movements
Types of Joint Movements
Movement at a joint occurs when a muscle contracts and its
fibers pull its moveable end (insertion) towards its fixed end
(origin).
Abduction = movement away from the midline
(think of someone being abducted, or taken away)
Adduction = movement towards the midline
(think of adding together)
Types of Joint Movements
Flexion = decreases the angle of a joint
• Bend elbow
Extension = increases the angle of a joint
• Extend elbow
Hyperextension = extension beyond the
anatomical position
• bend hand back, bend head back beyond
anatomical position
Types of Joint Movements
Rotation = movement around a central axis
• Twisting the head from side to side
Circumduction = movement so end
follows a circular path
• moving the finger in a circular motion
without moving the hand.
Types of Joint Movements
Elevation = raising a part
• Shrugging the shoulders
Depression = lowering a part
• Drooping the shoulders
Protraction = moving a part forward
• thrusting head forward
Retraction = moving a part backward
• pulling the head backward
Types of Joint Movements
Supination = turning the hand so the palm
faces upward or anteriorly
Example: turning a doorknob
clockwise with your right hand.
Pronation = turning the hand so the palm
faces downward or posteriorly
Dorsiflexion = movement at the ankles
that points toes towards the sky
Plantar flexion = movement at the ankles
that points toes towards the ground
Types of Joint Movements
Eversion = turning the foot so the planter
surface faces laterally
Inversion = turning the foot so the plantar
surface faces medially
End of Chapter 8, Section 2
Chapter 8, Section 3
The Knee Joint and Joint Disorders
Knee Joint
The knee joint is the largest and most complex synovial joint in body.
Two distal condyles of the femur
articulate with two proximal condyles
of the tibia. This is a condylar joint.
Figure 8.21
The femur also articulates anteriorly
with the patella. This is a plane joint.
Figure 8.20
Knee Joint
General structures of a synovial joint in the knee
1. Synovial Membrane
• Secretes synovial fluid
2. Joint Cavity
• Stores synovial fluid
3. Joint Capsule
• Relatively thin support
• Reinforced by several
ligaments and tendons
Figure 8.20
Knee Joint
Several ligaments and tendons
strengthen the knee joint.
1. Patellar tendon - The patella is
partially enclosed in tendons
fused together from the thigh
muscle.
2. Patellar ligament – continuation of
patellar tendon. Extends from
patella to the tibial tuberosity.
Knee Joint
Ligaments continued:
3. Tibial collateral ligament –
connects medial condyle of femur
with medial condyle of tibia.
4. Fibular collateral ligament –
connects lateral condyle of femur
with head of fibula.
5. Anterior & Posterior Cruciate
ligaments – provide additional
support to medial surface of tibia
and femur
Figure 8.21a Anterior right knee
with patella removed.
Knee Joint
Two menisci (medial & lateral meniscus)
separate the femur and tibia, and align them.
Figure 8.20 (a) sagittal section of the knee joint.
(b) Photograph of the left knee joint (frontal section)
Knee Joint
Three major bursae surround the knee joint.
1. Suprapatellar bursa
•
Largest bursa in body
2. Prepatellar bursa
•
•
Between patella and skin
Housemaid’s knee =
prepatellar bursitis
3. Infrapatellar bursa
Figure 8.20a
Sprain = overstretching or tearing of
connective tissue (tendons, ligaments, or
cartilage) associated with a joint.
However, the bones are not disarticulated.
Arthritis = inflamed, swollen, and painful joints.
1. Osteoarthritis
• Most common arthritis
•
Occurs with aging
•
Articular cartilage degenerates,
causing bone to rub against bone.
•
Results in stiff and painful joints
•
Fingers may appear gnarled and
knee may bulge.
Osteoarthritic fingers often take
on a gnarled appearance.
2. Rheumatoid Arthritis
• Autoimmune disorder (immune
system attacks tissue)
•
Synovial membrane thickens &
becomes inflamed
•
Mass of fibrous connective tissue
(Pannus) invades synovial space.
•
Fibrous pannus destroys articular
cartilage, and the joints may swell
and ossify.
Other symptoms of Rheumatoid Arthritis:
• low-grade fever, fatigue, appetite, stiffness.
Knuckles may swell as a result of
rheumatoid arthritis.
End of Chapter 8, Section 3