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Joints of the Skeletal System
Chapter 8
What’s a Joint? Is it legal?
• Functional junctions between bones
• Also called articulations
• Classified by the type of tissue that
attaches the bones at the junction
• Also classified by the way in which
they move at
Joints Classified by Tissue
1.
Fibrous Joints
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•
•
2.
Dense connective tissue abundant in collagenous fibers found in these
joints
Usually found between bones that lie very close to each other
3 types of fibrous joints: Syndesmosis, Suture and Gomphosis
Cartilaginous Joints
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•
3.
Either Hyaline cartilage or Fibrocartilage connects the bones in these
joints
2 types of cartilaginous joints: Synchondrosis and Symphysis
Synovial Joints
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•
•
•
•
The most common type of joint in the skeletal system
Allow free movement
More complex than fibrous or cartilaginous joints
Consist of: 1) articular cartilage 2) Joint capsule 3) synovial membrane
that secretes synovial fluid
6 types of synovial joints: Ball-and-socket, Condyloid, Gliding joint,
Hinge joint, Pivot joint, and Saddle joint.
Joints Classified by Degree of Movement
• Synarthrotic – immovable
• Amphiarthrotic – partially movable
• Diarthrotic – freely movable
Fibrous Joints
1. Syndesmosis
•
•
•
Amphiarthrotic (allows slight movement)
Bones in this type of joint are connected to
each other with long stands of connective
tissue that are collectively called an
interosseous ligament (between bones)
Found in places such as the distal ends of
fibula and tibia, between the tarsals and
carpals
Syndesmosis
Interosseous
Fibrous Joints
2. Suture
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•
•
•
Synarthrotic - immovable
Exist between flat bones of the skull only –
joined by a thin layer of dense connective
tissue
Starts out as a fontanel – wide membranes
of dense connective tissue between the skull
bones, and allows compression of skull
during childbirth, as well as room for growth
Fontanels are replaced by sutures
Sutures
Fibrous Joints
3. Gomphosis
•
•
•
Synarthrotic - immovable
A strange joint that is formed when a coneshaped process of a bone is located within a
socket of another bone
The root of a tooth located within the
jawbone and held together by the
periodontal ligament is a good example
Gomphosis
Tooth enamel
Blood vessels and nerve
endings
Periodontal ligament
Root of tooth
Jawbone
Cartilaginous Joints
1. Synchondrosis
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•
•
•
•
Synarthrotic – immovable
Bands of hyaline cartilage join parts of bones
Much of this cartilage disappears upon maturity
Example: epiphyseal plate – replaced by bone
when full growth is reached (before age 25) – no
more movement after this point
Another example: articulation between manubrium
and first rib by costal cartilage (also synarthrotic and
permanent)
Synchondrosis
Cartilaginous Joints
2. Symphysis
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•
•
•
Amphiarthrotic – slightly movable
Bones that meet at these joints have a layer of
hyaline cartilage covering their ends
The hyaline cartilage is also attached to a pad of
fibrocartilage which allows a “spring” to movement
Examples: Pubic symphasis and joints formed
between adjacent vertebrae separated by
intervertebral discs
Intervertebral discs are also made up of fibrocartilage that
surrounds a gelatinous core
Symphysis
Synovial Joints
• Diarthrotic – freely moving
• Most common type of joint in the body
• More complex than fibrous and
cartilaginous joints
• Consist of:
– Articular cartilage
– Joint capsule
– Synovial membrane
Synovial Joints
• Articular cartilage – made up of hyaline cartilage and
cover the articular surfaces of bones in the joint – these
bone ends are made up of spongy bone (like in
epiphysis). The articular cartilage minimizes friction and
wear
• Joint Capsule – Holds the bones in a synovial joint
together.
– The outer layer of the capsule is made up of dense connective
tissue and reinforced with collagenous fibers called ligaments.
The outer layer attaches to the periosteum of the bones in the
joint
– A inner layer of the joint capsule is made of a shiny vascular
lining of loose connective tissue called the synovial membrane
• Synovial Membrane – only a few cells thick, surrounds a
closed sac called the synovial cavity that is filled with
synovial fluid (secreted by the cells of the synovial
membrane
A Typical Synovial Joint
(Joint)
Some synovial joints…
• Are divided (partially or completely) into 2
compartments by discs of fibrocartilage called
menisci or meniscus (singular). These are
located between the articular surfaces of the
bones
• Found in joints like the knee, where the menisci
cushion the articulating surfaces
• Other synovial joints have synovial fluid filled
sacs called bursae near them – usually between
the skin and the bones of the synovial joint
Meniscus and Bursa
• Menisci are crescent-shaped and attach to
the joint capsule on its lateral sides
View of menisci from the top
Synovial fluid
• A thick, stringy fluid found in the cavities of synovial
joints. With its egg-like consistency (synovial comes from
Latin for “egg"), synovial fluid reduces friction between
the articular cartilage and other tissues in joints to
lubricate and cushion them during movement.
• Normal synovial fluid contains hyaluronic acid and a
glycoprotein called Lubricin
• Synovial fluid is secreted by cells of the synovial
membrane and supply nutrients to the articular cartilage
(remember – the synovial membrane is made of loose
connective tissue and therefore has blood vessels)
Arthrocentesis: extraction of synovial fluid
from joint
The sample can be examined to determine
the cause of joint problems
pus-like fluid aspirated from a patient with
acute bacterial infectious arthritis
cloudy but translucent inflammatory synovial fluid
taken from a patient with rheumatoid arthritis (left)
and gout (right) respectively.
bloody fluid aspirated from a patient with a
tibial fracture into the joint space
Types of Synovial Joints
1. Hinge Joint
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•
•
Movement in one
plane only
Convex surface of
one bone fits into
concave surface of
another
Example: trochlea of
humerus into
trochlear notch of
ulna
2. Gliding Joint
• Articulating surfaces
of both bones in this
joint are almost flat –
or maybe very slightly
curved
• Back-and-forth and
twisting movements
• Example – carpals,
tarsals, vertebrae,
clavicle
3. Saddle Joint
• Between bones that
have both concave as
well as convex
regions on their
articulating surfaces
• 2 planes of movement
– Forward and back
– Side-to-side
4. Ball-and-Socket Joint
• Bone with a round
protrusion at the
articular end fits into a
cup-shaped cavity of
another bone
• Movement in all
planes
• Example: femur head
and acetabulum of
coxa
5. Pivot Joint
• Cylindrical surface of
one bone rotates
within another bone
• Examples: the dens
(odontoid process) of
the axis within a facet
of the atlas
6. Condyloid Joint
• A condyle of one
bone articulates with
an elliptical cavity of
another bone
• Example: Joints
between carpals and
metacarpals, Occipital
condyles with facets
of atlas
Types of Joint Movement
• Flexion – Bending the lower limb at the knee or bending the hand downward
at the wrist
• Extension – Straightening lower limb at the knee or straightening the hand at
the wrist
• Hyperextension – Moving head upward, toward back or hand toward upper
arm
• Dorsiflexion – bending foot upward, toward the shin
• Plantar Flexion – bending foot downward, toward the heel
• Abduction – Moving a leg away from midline, horizontally
• Adduction – Returning leg from horizontal position back to midline
• Rotation – twisting head from side to side
• Circumduction – moving finger in a circular motion without moving hand
• Supination – palms facing anteriorly
• Pronation – palms facing posteriorly
• Eversion – Pushing foot away from body laterally
• Inversion – Pushing foot laterally toward body (medially)
• Protraction – Pushing chin forward
• Retraction – Pulling chin back
• Elevation – Raising, Shrugging shoulders
• Depression – lowering, drooping shoulders
Gliding
Flexion
Supination vs. Pronation
Supination:
Palm faces upward
Pronation:
Palm faces downward
Extension, Hyperextension, and Flexion
Another example: raising and lowering of hand, without moving arm
Dorsiflexion vs. Plantar flexion
Abduction, Adduction, and Circumduction
Rotation
Inversion vs. Eversion
Protraction vs. Retraction
Elevation vs. Depression
Another example: Shrugging and relaxing of shoulders
Opposition
Examples of Synovial Joints
I. Shoulder Joint – Includes the glenoid
cavity of the Scapula and the head of the
humerus. It is a Ball-and socket joint.
– The joint capsule is attached to the
circumference of the glenoid cavity of the
scapula and the anatomical neck of the
humerus
– The joint capsule is reinforced by several
ligaments and tendons of muscles to create a
rotator cuff which supports the shoulder joint
Ligaments of the Shoulder Joint
Acomion process
1. Coracohumeral –
connects the
coracoid process of
the scapula to the
greater tubercle of
the humerus
Greater
tubercle of
humerus
Coracoid process
Coracohumeral Ligament
MADE UP OF CONNECTIVE TISSUE
2. Glenohumeral Ligament
• These 3 bands of
ligament fibers extend
from the edge of the
glenoid cavity of the
scapula to the lesser
tubercle and the
anatomical head of the
humerus
Acromion Process
Clavicle
Coracoid process
Glenohumeral Ligament
MADE UP OF CONNECTIVE TISSUE
3. Transverse Humeral Ligament
Acomion process
• Connects the
greater and
lesser
tubercles of
the humerus
Greater
tubercle of
humerus
Coracoid process
Lesser Tubercle of humerus
Transverse Humeral Ligament
MADE UP OF CONNECTIVE TISSUE
4. Glenoid Labrum
Joint Capsule
• Attaches along the
circumference of the
glenoid cavity of the
scapula and forms a
cup-like shape with a
free rim
Glenoid Labrum
MADE OF FIBROCARTILAGE
Glenoid cavity
Bursae
• There are several bursae associated with
the shoulder joint. The major ones are:
– Subscapular bursa
– Subdeltoid bursa
– Subacromial bursa
– Subcoracoid bursa
II. Elbow Joint
Has 2 articulations:
• The hinge joint between the trochlea of the
humerus and the trochlear notch of the
ulna
• The gliding joint between the capitulum of
the humerus and the fovea on the head of
the radius
A joint capsule encloses the joint and it is
reinforced by ulnar and radial ligaments
and muscle fibers form the brachialis
muscle
The Elbow Joint
Capitulum
Trochlea
Trochlear notch
Ligaments of the Elbow Joint
1.
Ulnar Collateral Ligament
- Located in the medial wall of the
joint capsule
- thick band of dense connective
tissue
- anterior portion of the ligament
joins the medial epicondyle of the
humerus to the medial margin of the
coronoid process of the ulna
- The posterior portion of the
ligament joins the medial epicondyle
of the humerus to the olecranon
process of the ulna
Coronoid
process of ulna
Olecranon
process of ulna
Medial epicondyle
2. Radial Collateral Ligament
• Located in the lateral wall of
the elbow joint capsule
• Fibrous band that extends
between the lateral
epicondyle of the humerus
and the annular ligament of
the radius
– The annular ligament of the
radius joins the edge of the
trochlear notch of the ulna
and envelopes the head of
the radius
Annular ligament of the radius
Types of Movement at the Elbow
• The humerus and the ulna are a hinge
joint and can only allow flexion and
extension.
• The Radius moves freely inside the
annular ligament - this allows the
pronation and supination of the hand.
Bursa of the elbow
The Hip Joint
• Ball-and-socket joint – head of femur into
acetabulum of coxa
• Heavy, cylindrical joint capsule surrounds
the neck of the femur with the edge of the
acetabulum.
• The joint capsule is reinforced by
ligaments such as the pubofemoral
ligament
Hip Joint Capsule
Ligaments of the Hip Joint
1. Ligamentum Capitis
(ligamentum teres femoris)
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•
•
Attaches the pit in the femur
head (fovea capitis) to the
inside of the acetabulum of the
coxa
Carries blood vessels to the
head of the femur
Not very essential in holding
the joint together – not known
for strength
2. Acetabular Labrum
• Horse-shoe shaped ring of fibrocartilage
• Attaches to the edge of the acetabulum
and makes it deeper
• Encloses head of femur and holds it in
place
• Remember the glenoid labrum? Similar
setup to that
3. Iliofemoral Ligament
• Strongest ligament in
the body!
• Y-shaped band of
fibers
• Connect the anterior
inferior iliac spine of
the coxa to the bony
line between the
greater and lesser
trochanters of the
femur
4. Pubofemoral ligament
• Joins the superior
portion of the
pubis and the
iliofemoral
ligament
5. Ischiofemoral Ligament
• Connects the
ischium behind
the acetabulum
and joins the
fibers of the joint
capsule
Iliofemoral Ligament
Bursa
Pubofemoral Ligament
Knee Joint
• Largest and most complex synovial joint
• Medial and lateral condyles of the femur’s distal
end articulate with the medial and lateral
condyles of the proximal end of the tibia
• Femur also articulates with the patella
• Knee is a joint with multiple movements
– hinge joint - flexion and extension
– Condyloid - allows some rotation (between femur and
tibia)
– and a gliding joint (between femur and patella)
• Joint Capsule – relatively thin, but strengthened
by ligaments and tendons
Ligaments of the Knee Joint
1. Patellar Ligament
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•
The fibers of this
ligament are fused with
the fibers of a tendon
(from the thigh muscle
quadriceps femoris)
Strong flat band that
extends from the edge
of the patella, to the
tibial tuberosity
Patellar
Ligament
2. Oblique Popliteal
• Connects the lateral
condyle of the femur to
the edge of the head of
the tibia (posterior side of
knee)
Oblique Popliteal Ligament
3. Arcuate Popliteal Ligament
• Y-shaped
ligament that
extends from the
lateral condyle of
femur to the
head of the fibula
Arcuate Popliteal
Ligament
4. Tibial(medial) Collateral Ligament
•
Broad, flat ligament
that extends from the
medial epicondyle of
the femur to the medial
condyle of the tibia
5. Fibular (Lateral)
Collateral Ligament
• Extends between
lateral epicondyle of
femur to head of
fibula
THE END