The Joints

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The Joints
What is a joint?
A site where two or more bones come together,
whether or not movement occurs between them, is
called a Joint
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Articulation Means pertaining to the joint
e.g. articular surface of the bone, articular
artery, articular nerve etc.
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Classification of the Joints
Joints are classified according to the tissues
that lie between the bones
They are

1. Fibrous
2. Synovial
3. Cartilaginous

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Sutures of the skull
1- Fibrous Joint
The articulating surfaces of the bones are joined
by fibrous tissue, and thus very little movement
is possible. The sutures of the vault of the
skull and the inferior tibiofibular joints are
examples of fibrous joints.
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There are 3 subtypes of fibrous joints
1.Suture Bones are held together by a thin
layer of dense fibrous tissue and also by
interlocking projections of the bones. The
connecting fibers holding bones together are
short. This type of joint occurs only in the
skull cranial sutures
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2. Syndesmoses Bones are held together by a
cord or sheet of dense fibrous connective tissue.
The connecting fibers holding bones together are
long. The tibia/fibula joint and the interosseous
membrane connecting the radius and ulna along
their length, are syndesmosis.
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3.Gomphosis It is a peg-in-socket fibrous
joint.The only examples are the articulations of
teeth (the peg) with their alveolar sockets in
the mandible or the maxillae. The thin fibrous
membrane that hold teeth inside their alveolar
sockets is called the periodontal ligament.
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2- Cartilaginous Joint
In cartilaginous joints the bones are united with
each other by cartilage. There is NO JOINT
CAVITY.
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• There are two subtypes of
• cartilaginous joints
• Primary cartilaginous joints (synchondroses)
• A plate of hyaline cartilage connects the bones
  at the joint. Only hyaline cartilage is involved,
  not moveable. An example is the cartilaginous
  epiphyseal plate which separates the epiphysis
  from the diaphysis in long bones during growth.
  These joints are immoveable (synarthroses) and
  are replaced by bone in the adult.

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2. Secondary cartilaginous joints (symphyses)
It involves both hyaline and fibrocartilage. The
articular surface of each bone is covered with a
thin layer of hyaline cartilage, and
fibrocartilage unites these two layers. Limited
movement is permitted at such joints, depending
on the thickness of the fibrocartilage pad which
can be compressed or stretched.
Two important examples are the pubic symphysis
and the intervertebral discs.
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3-Synovial Joint
Characterized by The articular surfaces of the
bones are covered by a thin layer of hyaline
cartilage separated by a joint cavity This
arrangement permits a great degree of freedom of
movement Synovial membrane lines the joint
cavity that produces the synovial fluid Joint
cavity is enclosed by a double layered membrane
the articular capsule Synovial joints are
reinforced by a number of ligaments
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Synovial joints are classified according to the
shape of the articulating surfaces which, in
turn, determines the range of movement permitted
They can be classified into 7 major categories
1. Plane (gliding) In plane joints, the apposed
articular surfaces are flat or almost flat, and
this permits the bones to slide on one another.
Examples of these joints are the sternoclavicular
and acromioclavicular joints the joints are
nonaxial
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2. Hinge Hinge joints resemble the hinge on a
door, so that flexion and extension movements are
possible. Examples of these joints are the
elbow, knee, and ankle joints
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3. Pivot In pivot joints, a central bony pivot
is surrounded by a bonyligamentous ring, and
rotation is the only movement possible. The
atlantoaxial and superior radioulnar joints are
good examples. Since the only rotation is
allowed, the Joints are uniaxial.
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4. Condyloid Condyloid joints have two distinct
convex surfaces that articulate with two concave
surfaces. The movements of flexion, extension,
abduction, and adduction are possible together
with a small amount of rotation. The
metacarpophalangeal joints or knuckle joints are
good examples
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5. Saddle In saddle joints, the articular
surfaces are reciprocally concavoconvex and
resemble a saddle on a horse's back. These joints
permit flexion, extension, abduction, adduction,
and rotation. The best example of this type of
joint is the carpometacarpal joint of the thumb
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6- Ellipsoid joints In ellipsoid joints, an
elliptical convex articular surface fits into an
elliptical concave articular surface. The
movements of flexion, extension, abduction, and
adduction can take place, but rotation is
impossible. The wrist joint is a good example.
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7. Ball and socket In ball-and-socket joints, a
ball-shaped head of one bone fits into a
socketlike concavity of another. This arrangement
permits free movements, including flexion,
extension, abduction, adduction, medial rotation,
lateral rotation, and circumduction. The
shoulder and hip joints are good examples of this
type of joint
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Introduction to the nervous system
Classification
Nervous System (NS)
Functional Division
Structural Division
Central NS
Autonomic NS
Somatic NS
Spinal Cord
Brain
Peripheral NS
Sympathetic NS
Parasympathetic NS
12 pairs of Cranial nerves 31 pairs of spinal
nerves
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Nervous system consists of two main cell type a.
Neurons b. Neuroglia (Non neuronal
cells) Neurones Neurons are the functional
structural units of nervous system
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CNS
NERVE Bundle of axons NUCLEUS Collection of
nerve cell bodies in the CNS TRACT Bundle of
nerve fibers connecting nuclei
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PNS
GANGLION Collection of nerve cell bodies in the
PNS CRANIAL NERVES Exit the cranial cavity
through foramina 12 pairs of cranial
nerves.  Olfactory I  Optic II  Oculomotor
III  Trochlear IV  Trigeminal V  Abducens
VI  Facial VII  Auditory (vestibulocochlear)
VIII  Glossopharyngeal IX  Vagus X  Spinal
Accessory XI  Hypoglossal XII
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SPINAL NERVES 31 Pair Exit the vertebral column
through intervertebral foramina
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Autonomic NS
Sympathetic Thoracolumber Division
Parasympathetic Craniosacral Division
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