This document provides an overview of arthrology (the study of joints). It defines joints as the junction between two or more bones/cartilages and classifies them based on function and structure. The functional classification includes synarthrosis (immovable), amphiarthrosis (slightly movable), and diarthrosis (freely movable). The structural classification includes fibrous, cartilaginous, and synovial joints. Synovial joints are further classified based on the shape of the articular surfaces into plane, hinge, pivot, condylar, ellipsoid, saddle, and ball and socket joints. The key components of synovial joints are also described.

1. ARTHROLOGY
Dr. Seetharama Mithanthaya
Professor,
Dept. of Rachana Sharira
J S Ayurveda Mithanthaya

2. • Introduction
• In general joint is a site where two things join.
However in anatomy, the joint is a junction
between two or more bone/cartilage.
• Few related terms related to joints are arthron
(G), from which terms like arthrology, arthritis,
etc are derived, articulatio (L) from which the
term articulation is derived

3. Definition
The joint site, where two or more bone come
together whether or not there is movement
between them.
These joints may be between bone to bone or
between bone to cartilage. The design of joint in
the human body varies from simple to complex.
Simple joints have stability as a primary function.
Complex joints usually have mobility as a primary
function. However, most joints have to serve a
duel action.

4. Classification of joints
Joints can be classified based on the function and
structure.
Functional classification
Joints are of three types based on their degree of
mobility, they are as follows –
Synarthrosis – Immovable joints, e.g. – cranial sutures
Amphiarthrosis – Slightly movable joints, e.g. – secondary
cartilaginous joint
Diarthrosis – Freely movable joints, e.g. – shoulder joint

5. Structural classification
Based on the type of connecting structure between
articulating bone the joint is of three types.
Fibrous joint
Cartilaginous joint
Synovial joint
The structural classification will be discussed in
detail as it is most commonly followed in clinical
practice.

6. • Fibrous joint
• In this a fibrous connective tissue connects
adjacent bone and form joint. These joints are
either immovable or may produce very slight
degree of movement.
• The fibrous joints are of three types – sutures,
syndesmoses, and gomphoses.

7. Based on shape of bone end
Sutura serrata
Serrate margin
Saw edge – process of one bone fit in to other
eg: Sagital suture
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Dept of Shareera Rachana
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Types of suture

8. Sutura denticulata (dentate)
Tooth like process (narrow process & broad end)
Tooth like process of the 2 bones fit each other.
Eg: articulation between mastoid part of temporal bone
& occipital bone.
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9. Sutura limbosa:
Similar to sqamous suture.
Overlapping margin are ridged
eg:suture between the parietal and frontal bones
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10. Sutura squamosa:
Bones articulate by bevelled margin.
Margin overlap each other.
eg: sqamous part of temporal bone & parietal bone
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11. Sutura plana (Sutura harmonia):-
• Simple apposition
• Adjoining surface are plane
eg: horizontal part of palatine bone & palatal
process of maxilla.
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12. Schindylesis/wedge & a grove joint:
A bony wedge fit into a grove of other bone.
Eg: articulation between the rostrum of sphenoid & the
fissure between ala of the vomer.
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13. Syndesmoses
Joined directly by an Interosseous ligament/ a fibrous
cord/ an apponeurotic membrane.
Usually allow small amount of movement.
Eg: tibiofibular Syndesmoses, middle radioulnar joint
Union of tibia & fibula by means of
Interosseous membrane (uniting shaft)
ant. Interosseous tibiofibular ligament. (uniting distal end of
bone)
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14. Gomphoses joint
Bony components are adapted to each other like a peg in
a hole.
Eg: Only Gomphoses joint in the human body is between
tooth & either maxilla or mandible.
the cavity in mandible/maxilla & root of tooth being
connected by periodontal ligament which contain
gingival fiber, horizontal fiber (Sharpey's fiber).
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15. Cartilaginous joint
The cartilaginous joints are those in which the
adjacent bones are connected by means of
hyaline or fibro-cartilage. These are of two
types-
a) Primary cartilaginous joint (Synchondroses)
b) Secondary cartilaginous joint (Symphyses)

16. a) Primary cartilaginous joint (Synchondroses) –
The bones are united by hyaline cartilage.
These joints are immovable and strong. These
joints are temporary as after certain age the
cartilaginous plate get ossified and replaced
by bone.
E.g. – Joint between epiphysis and diaphysis of
growing long bone, first costosternal joint.

17. a) Primary cartilaginous joint
(Synchondroses) – The bones are united
by hyaline cartilage. These joints are
immovable and strong. These joints are
temporary as after certain age the
cartilaginous plate get ossified and
replaced by bone.
E.g. – Joint between epiphysis and
diaphysis of growing long bone, first
costosternal joint.
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Bone
Bone
Hyaline cartilage

18. b) Secondary cartilaginous joint (symphyses) – Articular
surface are covered by a thin layer of hyaline cartilage
and united by a disc of fibro-cartilage. These joints are
permanent and persist throughout life. The
symphyseal joints permit some degree of movement
due to elastic fibrocartilage. E.g. – symphysis pubis,
intervertebral joint between vertebral bodies.

19. Bone Bone
Hyaline cartilage
Fibrous cartilage
cartilage

20. Difference between primary and
secondary cartilaginous joint
Primary cartilaginous
joint
Secondary cartilaginous
joint
Articular
structure
Articular surface
connected by hyaline
cartilge
Articular surface covered
by hyaline cartilage and
connected by fibrocartilage
Mobility Immovable Slightly movable
Location Rarely in the midline Always in the midline
Ossification Ossifies and cartilage
Disappears with age
Do not Ossifies and
cartilage do not disappear

21. Synovial joint
The synovial joints are most
common and most evolved
variety of joints with
maximum degree of
mobility. In synovial joints
the articular surface of the
adjacent bone are
separated by joint cavity
and margins of articular
surface are connected by
capsular ligament.

22. Characteristic features of synovial joints
• Articular surfaces are covered by hyaline
cartilage, which is avascular, elastic and devoid
of nerve supply.
• Between the articular surfaces there is a cavity
filled with synovial fluid, called articular cavity.
• The cavity is lined by fibrous capsule known as
articular capsule.
• Cavity may be completely or incompletely
subdivided into chambers by articular discs or
meniscus.

23. • Articular capsule is richly supplied by nerve,
and is sensitive to stretch, this prevent sprain
of joint due to over stretch. This is called
watch-dog action of capsule.
• The wall cavity of the cavity is lined by
synovial membrane except articular surface.
• Cells of synovial membrane secrete a slimy
viscous fluid called synovial /synovial fluid
which lubricates the joint cavity including
articular surface and provides slippery surface
for free movement.

24. Components of synovial joints
• Following are the essential components of a
synovial joint
• Articular surface – surface of bone which
involve in the formation of joint, e.g. head of
femur, glenoid cavity of scapula.
• Capsular ligament / Fibrous capsule – It
completely covers the joint and enclose the
joint cavity. This ligament stabilizes the joint,
resist dislocation, and permits free movement.

25. Ligaments – These are thickened band of
collagen fiber. The ligaments stabilize the joint
and permit movement in a particular plane
and prevent unwanted movement in other
plane. Tear in the ligament is known as sprain,
which leads to pain and swelling in the joint.

26. Synovial membrane – A thin vascular membrane
lining the walls of joint cavity except articular
surface. Synovial fluid secreted by this
membrane lubricates the articular surface and
provide free movements of joint.

27. • Articular cartilage – It is made up of hyaline
cartilage. It resists compression and provides
smooth friction free movement.
• Articular disc / meniscus – These are fibro-
cartilaginous pads placed between the articular
surfaces, these pads divides the joint concavity
into two compartments, increase the concavity of
articular surface, acts as a ligament, by providing
cushioning effect they prevents wear and tear of
articular cartilage e.g. knee joint, temporo-
madibular joint, acromio-clavicular joint.

28. • Bursae – These are synovial fluid filled sacs of
connective tissue, found near synovial joints.
They commonly found between muscle and
bone, tendon and bone, skin and bone or skin
and tendon. The bursae reduce the friction
between two moving structures, and they
provide cushioning effect.
• Fatty pads (Haversin glands) – The pad of fat
placed between synovial membrane and
fibrous capsule or bone, they provide enough
cushion. e.g. infra-patellar pad of fat.

30. Classification of synovial joints
Based on shape of articular surface
Based on shape of articular surface the synovial
joints are of seven type they are as follows
Plane joint
Hinge joint
Pivot joint
Condylar joint
Ellipsoid joint
Saddle joint
Ball and socket joint

31. Plane joints – It is a joint formed by flat articular
surfaces. These joints permit gliding movement, e.g.
intercarpal joints, intermetacarpal joints, joints
between articular processes of adjacent, etc.

32. Hinge/Ginglymus joints – The joints having pulley
shaped articular surface, here the movement is
permitted in one plane around transverse axis like a
hinge of a bone and the other movements are
prevented by the strong collateral ligament.
Example – elbow joint, elbow joint, interphalangeal
joint.

33. Pivot joint/trochoid joints - The shape articular
surface of one bone is rounded, pivot (peg) like
which fits into the ostio-ligamentus ring. These
permit a rotation movement around a vertical
axis. Example – superior radio-ulnar joint, atlanto-
axial joint.

34. Condylar joint – The joint in
which the distinct convex
condyles of one bone
articulates with the
reciprocally concave
articular surface of other
bone. The movement is
permitted in two directions
(biaxial) where one is
around the transverse axis
and other around a vertical
axis. Example knee joint,
temporo-mandibular joint.

35. Ellipsoidal joints – The joint is formed by fitting of elliptical
convex surface of one bone in to reciprocally concave
surface of other bone. Ellipsoid joints show movement in
two directions where flexion and extension around
transverse axis and adduction and abduction around
anteroposterior axis. Circumduction is produced by the
combination of above movements. Example – radio-carpal
joint, metacarpo-phalangeal joint, atlanto-occipital joint.

36. 6.Saddle Joints
-Bi-axial joints
-An articular surface of one
bone fits into the saddle-
shaped surface of another
bone.
- Ex- Carpometacarpal
joint.

37. • Ball and socket/spheroidal joints – Rounded
glob like articular surface of one bone fits into
cup shaped socket of other bone. Example –
hip joint, shoulder joint.

38. Based on planes of movement
Based on the planes of movement the joints are of three
types, uniaxial joints, biaxial joints, and multiaxial
joints.
Uniaxial joints – In these joints the movement occurs
around a single axis along only one plane. Example –
elbow joint, interphalangeal joint, atlanto-axial joint.
Biaxial joint – In these joints movements occur around
two axes in two different planes. Example – knee joint,
radia-carpal joint, sterno-clavicular joint, temporo-
mandibullar joint.
Multiaxial joint – In these joints movements occur around
indefinite number of axes in three different planes.
Example – shoulder joint, hip joint.

39. Based on number of articulating bones
Based on the number of articulating surface the
joints are of two types
Simple joint
Compound joint
Simple joint – Only two articular surfaces involve in
the formation of joint, e.g. inter-phalangeal joint.
Compound joint – More than two bones involve
and enclose within a single capsule, e.g. elbow
joint, ankle joint.

40. Complex joint – A joint in which the joint cavity
is divided completely or incompletely into two
parts by an intra-articular disc, e.g. knee joint,
temporo-mandibular joint.

41. Blood supply of synovial joints
The joints get their blood supply from the
periarticular network of arteries which
surround the joint. These vessels supply
capsule, synovial membrane, and epiphysis.
Articular cartilages are avascular where as
ligaments and fibrous capsule are poorly
supplied by blood.

42. Nerve supply of synovial joints
There are three types of nerves fibres, sensory
nerve fibers conveying pain, sensory nerve
fibers conveying proprioceptive sensation, and
autonomic fibers which has vasomotor effect.
The capsule is innervated by ruffini’s corpuscles
encapsulated nerve endings which are
sensitive to proprioceptive sensation (position
of joint sense) and also supplied by the nerve
fibers with free nerve endings which are
sensitive to pain.

43. • Ligaments are supplied by pain sensitive free
nerve endings.
• Synovial membrane is supplied by autonomic
nerve fibers which are vasomotor in function.
• Articular cartilages have no nerve supply and
insensitive.
• Articular discs are supplied by nerve only on its
margin.
• Hilton’s law – Nerve supplying the joint also
supply the muscles which regulate movements of
that joint and the skin over joint.