Transcript 2-Week-1-2-121

The union or meeting point of two or more than two
bones or parts of the bones is called as Joint
Articulation
Means
pertaining to the joint
e.g. articular surface of the bone, articular artery, articular nerve
Classification of the Joints
Joints are classified according to the tissues that lie between the bones
Fibrous
Synovial
Cartilaginous
Fibrous Joint
•In fibrous joints the bones are
united by tissue consisting of
collagen fibers which run
between the bones
•Very little movement is
possible
•The degree of movement
depends on the length of the
collagen fibers
•No joint cavity
Sutures
There are three 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.
Cartilaginous Joint
In cartilaginous joints
the bones are united
with each other by
cartilage. Again, 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 obliterated 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.
Synovial Joint
majority of articulations between bones are
synovial joints.
freely moveable joints.
characterized by
PRESENCE OF A closed space or CAVITY
between the bones: the joint cavity (=
synovial cavity).
articulating surfaces are covered by
hyaline cartilage, lubricated by a highly
viscous the synovial fluid secreted by the
synovial membrane which lines the cavity.
to reduces friction. Joint cavity is enclosed
by a double layered synovial membrane &
the articular capsule.
Synovial joints are reinforced by a number
of ligaments. Ligaments are bands of
dense regular connective tissue proper
that connect bones to other bones.
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 six major categories:
1. Plane (gliding)
Opposite bone surfaces are flat or slightly curved.
Only sliding motion in all directions are allowed. Since
there is no bone movement around an axis, the joints
are nonaxial.
2. Hinge
Convex surface of one bone fits smoothly into concave surface
of the second bone. The joints are uniaxial.
3. Pivot
A rounded, or conical surface of one bone is inserted into a ring made
partly of another bone and partly of a ligament.
Since the only movement allowed is the rotation of one bone around
its own axis, the Joints are uniaxial.
4. Ellipsoidal (condyloid)
Oval-shaped surface
fits into an ovalshaped cavity (ellipse
means oval).
The movements
allowed are
flexion/extension,
adduction/abduction
and circumduction but
NO ROTATION. Since
bones can move in
both planes: side to
side and back and
forth movements the
joints are biaxial.
5. Saddle
First bone's articular surface is
concave in one direction and convex
in the other while the second bone is
just the opposite (or one bone is
shaped like a saddle, and the other is
shaped like its rider).
The saddle joint is similar to the
Ellipsoidal Joint but the movements
are freer. The movements allowed
are flexion/extension,
adduction/abduction and
circumduction but NO ROTATION.
Since bones can move in both
planes: side to side and back and
forth movements the joints are
biaxial.
6. Ball and socket
Ball-shaped head fits into a
cup-shaped depression
These joints are the most
freely moving of all synovial
joints. The movements are
allowed in all axes and planes:
flexion/extension,
adduction/abduction,
circumduction and rotation.
These joints are multiaxial.
Introduction to the nervous system
Classification
Nervous System (NS)
Functional Division
Structural Division
Central NS
Autonomic NS
Somatic NS
Brain
Sympathetic NS Parasympathetic NS
Spinal Cord
Peripheral 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) VII
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