joints

1. JOINTS
Chapter 9

2. Arthrology
• Bones are too rigid to bend. Flexible
connective tissues from joints and permit
movement.
• A joint, also called articulation is a point
of contact.
• The scientific study of joints is called
arthrology.
• The study of the motion of the human body
is called kinesiology.

3. Joint Classification
• Structurally joints are classified as
following:
– Fibrous joints : the bones are held together by
fibrous connective tissue that is rich in collagen
fibers. No synovial cavity.
– Cartilaginous joints: the bones are held
together by cartilage. No synovial cavity.
– Synovial joints: the bones forming the joint
have a synovial cavity and are united by dense
irregular connective tissue.

4. Joint Classification
• Functionally, joints are classified as one of
the following:
– Synarthrosis: an immovable joint.
– Amphiarthrosis: a slightly movable joint.
– Diarthrosis: a freely movable joint. All
diarthroses are synovial joints.

5. Fibrous Joints
• These are joints that lack a synovial cavity.
They permit little or no movement.
– Sutures: thin layer of dense connective issue.
Unites bones of the skull. Because a suture is
immovable, it is functionally classified as a
synarthrosis. Some sutures are replaced by
bone in the adult. Such a suture is called
synostosis.

6. Fibrous Joints
– Syndesmoses: there is a greater distance
between the bones and more fibrous connective
tissue. The tissue is either arranged as a bundle
(ligament) or as a sheet (interosseus
membrane). Example tibia/fibula. Because it
permits slight movement, a syndesmosis is
classified functionally as an amphiarthrosis.

7. Fibrous Joints
• Gomphoses- this is a type of fibrous joint
in which a cone-shaped peg fits into a
socket. The only example are the
articulations of the roots of the teeth with
the sockets of the alveolar processes of the
maxillae and mandible. The dense fibrous
connective tissue is called the periodonatal
ligament. This is functionally classified as
a synarthrosis.

8. Cartilaginous Joints
• This also lacks a synovial cavity and
permits little or no movement.
– Synchondroses: here the connecting material is
hyaline cartilage. An example is the epiphyseal
plate that connects the epiphysis and diaphysis
of a growing bone. Another example is the joint
between the first rib and manubrium of the
sternum.

9. Cartilaginous Joints
• Symphyses: here the ends of the
articulating bones are covered with hyaline
cartilage but the bones are connected by a
broad flat disc of fibrocartilage. Examples:
pubic symphysis, junction of the
manubrium and sternum, intervertebral
joints. Functionally, this is an
amphiarthrosis, a slightly movable joint.

10. Synovial Joints
• These have a space called a synovial cavity
between the articulating bones. Classified
functionally as diarthroses.
– The bones at synovial joint are covered by an
articular cartilage. Consists of two layers, an
outer fibrous capsule and an inner synovial
membrane.
– Fibrous capsule-ligaments
– Synovial membrane-areolar connective tissue
with elastic fibers. Adipose tissue-articular fat

11. Synovial Joints
• Synovial fluid: the synovial membrane
secretes this. Consists of hyaluronic acid
and interstitial fluid filtered from blood
plasma. Reduces friction by lubricating the
joint. Supplies nutrients and removes
metabolic wastes. Contains phagocytic
cells. Benefits of a “warm up” before
exercise is that it stimulates the production
and secretion of synovial fluid.

12. Synovial Joints
• Accessory ligaments and articular discs:
• Nerve and Blood Supply: contain many
nerve endings. Convey information to the
brain and spinal cord. Arteries penetrate the
ligaments and articular capsule to deliver
oxygen and nutrients. Veins remove carbon
dioxide and wastes from the joints. The
articulating portions receive nourishment
from the fluid. Rest by blood capillaries.

13. Types of Synovial Joints
• Planar joints- the articulating surfaces are
flat or slightly curved. Example are
intercarpal joints, intertarsal joints,
sternoclavicular joints, acromioclavicular
joints, sternocostal joints, vertebrocostal
joints.
• Hinge Joints-the convex surface of one fits
into the concave surface of another. Eg.
Knee, elbow, ankle, interphalangeal.

14. Types of Synovial Joints
• Pivot Joints-here the rounded or pointed surface
of one bone articulates with a ring formed partly
by another bone and partly by a ligament. This is
monaxial. Examples atlanto-axial joint, radioulnar
joint:turns palm anteriorly and posteriorly.
• Condyloid Joints-also called ellipsoidal joint.
The convex oval-shaped projection of one fits into
the oval-shaped depression of another. Eg. Wrist
and metacarpophalangeal joints. Biaxial.

15. Types of Synovial Joints
• Saddle Joints-here the articular surface of
one bone is saddle-shaped and the articular
surface of the other fits into the “saddle”.
Eg. Carpometacarpal joint. Biaxial.
• Ball-and-Socket Joints- this consists of the
ball-like surface of one bone fitting into a
cuplike depression of another bone. Egs.
Shoulder and hip joints. Multiaxial.

16. Bursae and Tendon Sheaths
• Bursae: saclike structures that reduce
friction. Located in the shoulder and knee
joints. Found between skin and bone,
tendons and bones, muscles and bones,
ligaments and bones.
• Tendon Sheaths: tubelike bursae that wrap
around tendons. Found at the wrist, ankle,
fingers and toes.

17. Types of Movements
• Gliding:this consists of side-to-side and
back-and-forth movements.
• Angular movements: there is an increase
or decrease in the angle between
articulating movements. Includes flexion,
extension, lateral flexion, hyperextension.

18. Types of Movements
• Abduction: this is the movement of a bone
away from the midline.
• Adduction: this is the movement of bone
toward the midline.
• Circumduction: this is the movement of
the distal end of a body part in a circle.

19. Types of Movements
• Rotation: a bone revolves around its own
longitudinal axis. Pivot and ball-and-socket
joints permit rotation. Medial (internal)
rotation and lateral (external) rotation.
• Special movements: elevation, depression,
protraction, retraction, inversion, eversion,
dorsiflexion, plantar flexion, supination,
pronation, opposition.

20. Factors affecting ROM at
Synovial Joints
• Structure or shape of the articulating bones
• Strength and tension of ligaments.
• Arrangement and tension of muscles
• Apposition of soft parts
• Hormones
• Disuse

21. Aging and Joints
• Decreased production of synovial fluid
• Articular cartilage becomes thinner with
age, ligaments shortens and lose flexibility.
• Genetic factors
• Males commonly develop degenerative
changes in the vertebral column-hunched.
• Osteoarthritis-occurs over age 70.