Transcript 02-Joints_&_Nerves2008-10

What is a joint?
A site where two or more bones come together,
whether or not movement occurs between them,
is called a Joint
Articulation
Means
pertaining to the joint
e.g. articular surface of the bone, articular artery,
articular nerve etc.
Joints are classified according to the
tissues that lie between the bones
They are
1. Fibrous
2. Synovial
3. Cartilaginous
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.
Sutures of the skull
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
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.
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.
2- Cartilaginous Joint
In cartilaginous joints the bones are united with each
other by cartilage.
There is NO JOINT CAVITY.
There are two subtypes of
cartilaginous joints:
1. 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.
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.
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
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
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
3. Pivot
In pivot joints, a central
bony pivot is
surrounded by a bony–
ligamentous 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.
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
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
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.
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
Introduction to the nervous system
Classification
Nervous System (NS)
Functional Division
Structural Division
Central NS
Autonomic NS
Somatic NS
Brain
Spinal Cord
Peripheral NS
Sympathetic NS Parasympathetic NS
12 pairs of Cranial nerves
&
31 pairs of spinal nerves
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
NERVE
Bundle of axons
NUCLEUS
Collection of nerve cell bodies in the CNS
TRACT
Bundle of nerve fibers connecting nuclei
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
SPINAL NERVES
31 Pair
Exit the vertebral
column through
intervertebral foramina
Sympathetic
Thoracolumber Division
Parasympathetic Craniosacral Division