A site where two or more bones come together, whether or not movement occurs between them, is called...

A site where two or more bones come together, whether or not movement occurs between them, is called a Joint

What is a joint?

Articulation Means

pertaining to the jointe.g. articular surface of the bone, articular artery, articular nerve etc.

1.Fibrous2.Synovial3.Cartilaginous

Joints are classified according to the tissues that lie between the bones

They are

1- Fibrous JointSutures of the skull

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.

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 JointIn 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.

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

3-Synovial Joint

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. CondyloidCondyloid 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 jointsIn 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

Nervous System (NS)

Peripheral NS

Central NS

Autonomic NS Somatic NS

Sympathetic NS Parasympathetic NS

Brain Spinal Cord

Functional Division

12 pairs of Cranial nerves &

31 pairs of spinal nerves

Structural Division

Classification

Nervous system consists of two main cell typea. Neurons b. Neuroglia (Non neuronal cells)

NeuronesNeurons are the functional structural units of nervous system

NERVEBundle of axons

NUCLEUSCollection of nerve cell bodies in the CNS

TRACTBundle of nerve fibers connecting nuclei

GANGLIONCollection 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