classification of joints and characteristics of each type joint

JOINT
When two or more bones or cartilages come in
contact with each other an articulation or a joint is
formed.

• The study of joints is known as ARTHROLOGY (G.
Arthron = joint).
• The joints vary considerably in their structure and
function.

OBJECTIVE
CLASSIFICATION OF JOINTS
A: STRUCTURE
• FIBROUS JOINTS
• CARTILAGINOUS JOINTS
• SYNOVIAL JOINTS
B: DEVELOPMENT
C: FUNCTION

CLASSIFICATION OF JOINTS:
The joints could be classified on the basis of
• STRUCTURE
• DEVELOPMENT
• FUNCTION

• All joints are MESODERMAL in origin.
• The mesodermal element intervening between the
developing bones and cartilages is differentiated into
various structural components of a joint like joint
capsule, synovial membrane, ligaments, etc.

The joints show varied degree of freedom of
movements, i.e.
• Immovable
• Slightly moveable
• Freely moveable
according to the functional need of a particular joint.

CLASSIFICATION ON THE BASIS OF
STRUCTURE
• A) FIBROUS JOINTS
(Fibrous; Fixed, Immovable; skull)
• B) CARTILAGINOUS JOINTS (Cartilaginous;
slightly movable; vertebral)
• C) SYNOVIAL JOINTS
(Movable; limb)

A- FIBROUS JOINTS
• In these joints the union is due to dense fibrous
tissue.
• They are usually fixed, immovable and mainly limited
to the skull.

Subdivided into three major groups depending upon
the location.
I. SUTURES
II. GOMPHOSIS (Peg and Socket Joint)
III. SYNDESMOSIS

I. SUTURES
Features:
These are the joints of skull bones.
• They are immovable and fixed.
• The union is affected by sutural ligament.

• In the vault of the skull the veins of sutural
ligaments communicate with Diploic veins and
Intracranial venous sinuses.
• Sutures are the sites of active bone growth.
• They show gradual ossification from within
outwards, which commences at the age of twenty
and finishes in old age.
• The process of obliteration of a suture is called
SYNOSTOSIS.

VARIETIES OF SUTURES
There are following varieties of sutures depending
upon :
• The shape of articulating surfaces.
• The mode of fusion of articulating bones.

1-Serrate Sutures
Example:
• Sagittal suture
between two
parietal bones.
• Here the shape
of articulating
surfaces is saw
like.

2. Denticulate suture
Example:
• Lambdoid suture
present between
parietal and occipital
bones.
• The shape of
articulating surfaces is
tooth-like.
• Here the two bones
are more firmly united
as compared with the
serrate sutures.

3. Squamous sutures
Example:
• Temporo-parietal suture
present between temporal
and parietal bones.
• Here the two articulating
bones OVERLAP each other
and are bevelled
reciprocally, i.e., one bone
internally and the other
externally.

4. Limbous suture
• It is a slight modification of squamous suture. Here
the bevelled surfaces may be mutually serrated or
ridged.
Example:
• Modified Temporo-parietal suture.

5. Plane Sutures
Examples:
i) Suture between
horizontal plates of two
palatine bones (Interpalatine
suture).
ii) Palato-maxillary suture.
iii) Zygomatico-palatine
suture.
Here the interlocking surfaces
are slightly rough and irregular.
Pure plane surfaces are seldom
found. They can resist extreme
torsional forces

6. Wedge and groove sutures
(Schindylesis)
Example:
• Vomero-sphenoid suture
— the suture between
vomer bone and rostrum
of sphenoid bone.
• Here a ridged-bone fits
into the groove present
on a neighbouring bone.

II. GOMPHOSIS (Peg and Socket
Joint) :
• It is a specialized fibrous joint in
which the teeth fit into their
sockets situated in the maxilla and
mandible (i.e., upper and lower
jaws).
• The ligament which connects the
tooth with the socket or alveolus is
called PERIODONTAL LIGAMENT.
• It provides an independent and
firm suspension for each tooth.

III SYNDESMOSIS:
• It is a type of fibrous joint
in which the two bones are
united with each other by
INTEROSSEOUS
LIGAMENTS.
• In this joint a slight degree
of movements could be
observed which is due to
twisting or stretching of an
interosseous ligament.

This ligament never shows signs of ossification.
Examples:
i)Inferior tibio-fibular joint.
ii) Old sacro-iliac joint (it is a synovial joint which is
converted into syndesmosis in older age).
iii)Coracoclavicular joint.
iv)Some joints between the vertebrae (i.e., joints
between vertebral arches).
v) Interosseous membranes of fore-arm and leg
which connect:
a. Radius with ulna
b. Tibia with fibula

classification of joints and characteristics of each type joint

B- CARTILAGINOUS JOINTS
• In these joints the bones are united by a cartilage.
• They are usually slightly movable and are found in
those places where stability and strength is required
instead of free movements.

• The opposed bony surfaces are firmly bound together
in order to minimize the risk of dislocations, which
may produce serious effects in these places.
• They are mainly limited to the axial skeleton, e.g.,
vertebral column.

They are subdivided into two major groups on the
basis of morphology and function:
I.PRIMARY CARTILAGINOUS JOINTS
(SYNCHONDROSES)
II. SECONDARY CARTILAGINOUS JOINTS (SYMPHYSES)

PRIMARY CARTILAGINOUS JOINTS
(SYNCHONDROSES)
• These are the joints seen mainly in
developing appendicular bones.
• The bony ends and the shaft remain
united with each other by a plate of
HYALINE CARTILAGE. This
cartilaginous plate is known as
EPIPHYSEAL PLATE.
• These joints are temporary because
at the age of 18-20 years the
epiphyseal cartilage is ossified.
• They are completely immovable.

Examples:
• Joints between the ends and shaft of growing long
bones.
• Neurocentral joints of vertebrae.
• Spheno-occipital synchondrosis.
• 1st sternocostal joint.
• Petrobasilar synchondrosis.

II. SECONDARY CARTILAGINOUS JOINTS
(SYMPHYSES).
•Mainly seen in axial bones.
•Formed by WHITE FIBRO-CARTILAGE
which connects the articular surfaces
covered by hyaline cartilage.
•These joints are permanent.

•Slightly movable and mobility
depends upon sufficient amount of
white-fibro cartilage.
•Frequently a cavity is seen which is
not lined by synovial membrane. This
cavity contains tissue fluid.

Examples:
• Public symphysis.

• Manubriostemal joint.
In early life it is
primary but in later life
it becomes secondary
due to conversion of
hyaline cartilage into
white-fibro cartilage.
• Joints between the
bodies of vertebrae.

C- SYNOVIAL JOINTS
• Seen in all vertebrates and show modifications
according to functional needs.
• All synovial joints possess a definite joint cavity lined
by synovial membrane and filled with a lubricating-
synovial fluid.

CHARACTERISTICS
• The bony articular surface are
covered by articular cartilage
and are not attached to each
other.
• The bony articular surfaces are
connected with each other by
tubular fibrous capsule (articular
capsule).
• The fibrous capsule is lined by
mesothelial membrane called
synovial membrane. This
membrane does not cover the
articular cartilage covering the
articular bony ends.

• Between the articular bones a specific joint cavity is
present.
• The joint cavity is filled with synovial fluid secreted by
the synovial membrane.
• The joint capsule is strengthened by the presence of
accessory ligament.
• The joint cavity may be divided partially or completely
by an articular disc composed of white-fibro cartilage.
• Different types of movements are always possible.

SYNOVIAL JOINTS CLASSIFICATION
can be classified according
to
A)- DEPENDING UPON THE
SHAPE OF ARTICULATING
SURFACES :
1. Homomorphic : When
the two articulating
surfaces are plane ,the
synovial joint is called
homomorphic, e.g.
i) Plane joint
(Intermetatarsal joints).
ii) Saddle joint
(Carpometacarpal joint of
thumb).

2. Hetromorphic :
When there is varied
appearance of two articulating
surfaces, then the synovial joint
is called hetromorphic, e.g.,
i) Ball & Socket Joint
(shoulder and hip joints).
ii) Condyloid joint
(Temporomandibular joint and
knee joint.
iii) Ellipsoid joint (Radiocarpal
joint).

B) DEPENDING UPON COMPLEXITY OF
ORGANIZATION:
1. Simple: When only two bones are participating, the joint is
called simple joint, e.g.,
i) Acromio-clavicular joint. ii) Shoulder joint.
2. Compound: These are formed by participation of more than
two bones, e.g.,
i) Elbow joint ii)Knee joint.
3. Complex: When intra articular discs or menisci are present,
the joint is called complex, e.g.,
i) Knee joint. ii) Temporomandibular join.

C) DEPENDING UPON AXIS OF MOVEMENT:
1. Uniaxial: In these joints movements take place on
one axis only, i.e., on transverse or longitudinal axis,
e.g., Elbow joint.
2. Biaxial: In these joints movements take place on
two axes, i.e.,
i) Transverse axis,
ii) Longitudinal axis, e.g., Wrist Joint.
3. Polyaxial : In these joints movements take place on
more than two axis, e.g.,
i) Shoulder joint
ii) Hip joint

D) DEPENDING UPON THE TYPES OF MOVEMENTS:
1. Gliding: e.g., plane joint (Intermetatarsal joints).
2. Angular: e.g., Condyloid joint (Temporo-
mandibular joint; knee joint). ,
3. Rotatory: e.g., Pivot joint (Superior radio-ulnar
joint).
4. Circumductory : e.g., Ball and socket joint
(shoulder joint and hip joint).

E) ARCHITECTURAL OR STRUCTURAL CLASSIFICATION:
7 verities have been recognized:
1. Plane joints: These are
formed by the apposition of
fairly flat articular surface,
e.g.,
i) Intermetatarsal joints.
ii) Some intercarpal joints.

2. Hinge joints:
They roughly resemble the
hinges of a door, where the
articulating surface are so
moulded that they restrict
the to-and-fro movements
to one plane, i.e., they are
uni-axial.
The sides of the joint are
typically provided with
strong collateral ligaments,
e.g.
i) Elbow joint
ii) Interphalangeal joints

3. Pivot joints:
• These are uni-axial joints (in
which movements take place
around the longitudinal axis).
• They are composed of pivot
surrounded by an osseo-
ligamentous ring.
• Movement is restricted to a
rotation around a longitudinal
axis passing through the centre
of the pivot, e.g.,
i) Proximal radio ulnar joint.
ii) Atlanto-axial joint.

• The pivot may habitually rotate within the ring as in
case of Proximal radioulnar joint in which the head of
the radius rotates within a ring formed by the annular
ligament and radial notch of ulna.
• Conversely the ring may rotate around the pivot as in
the articulation between the dens of the axis and ring
formed by anterior arch of the atlas and its transverse
ligament, i.e., Atlantoaxial joint, the ring rotates
around the pivot, i.e., odontoid process of axis or 2nd
cervical vertebra.

4.Condylar or condyloid Joints
Here two condyles (male
surfaces) are received into two
concave (female surfaces)
cavities. It allows the principal
movement occurring in one
plane, but a limited amount of
rotation is possible about a
second axis set at 90° to the first
one, e.g.,
i) Temporo-mandibular joint
ii) Knee joint

5.Ellipsoid joints :
• These are biaxial joints formed by
reception of an oval, convex male
surface into an elliptical female
concavity.
• Primary movements are possible
about two axes situated at right
angles, e.g., Flexion and extension
and abduction & adduction.
• These movements may be
combined as a movement of
circumduction.
• There is little appreciable rotation
around the third axis, as this is
prevented by overall shape of
articular surfaces, e.g.,
i) Radiocarpal joint
ii) Metacarpophalengeal joints.

6-Saddle joints (Sellar Joints):
These are biaxial joints which are formed by reception of concavo-
convex opposing surfaces.
Primary movements occur in two planes at right angles to each
other but because of the articular geometry, these are
accompanied by a degree of axial rotation of moving bones, e.g.,
(i) Carpometacarpal joint of thumb
(ii) Ankle joint.
(iii) Calcaneocuboid joint.

7. Ball and socket joints (Spheroidal joints):
They are polyaxial joints and are formed by reception
of globular head (male surface) into a cup like
concavity or socket (female surface).
All types of movements are possible, e.g.,
i) Shoulder joint
ii) Hip joint

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classification of joints and characteristics of each type joint

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