Classification of joints | Types of joint | Function of joints

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  JOINTS

• Joint is a point of contact between bones and cartilage or between bone and teeth.
• the site where more than two bones made to carry out the movement is known as joint or articulation.
• More than hundred type of joint are present in the human body.
• Some joint have no movement ( fibrous) , some have only slight movement (cartilaginous) , and some are freely moveable (synovial)

Asthrology :-

is the science considered concerned with the study of anatomy, function, dysfunction and treatment of joint and articulation.

Classification of joints :-

Joints are classified on the basis of structure and function:-

1- Structural classification of joints

Structural classification is based on the material that hold the join together and whether or not a cavity is present in the joint.

- structurally joints are of three types :-

1.  Fibrous joint - there is no saddle joint and the bones are held together by fibrous joint.
2. Cartilage joint - there is no synovial joint cavity and bones  are held together by cartilage.
3. Synovial joint - there is no synovial cavity and bones are held together by dense irregular connective tissue of an articular capsule and accessory ligament.

Based on structural function joints are following types :-

a). Fibrous joint and fixed joint 

The characteristics feature of fibrous joints are- 

• The joint which joint bones fibrous connective tissue are called fibrous joint.

• Joint cavities absent in the fibrous joint.

•fibrous joints are divided into three types :-

1. Sutures :- the layer of connective tissue is called sutural ligament connects the articulating surfaces.

• It present only in skull and show no movement i.e they are immovable.
• It is divided into subtypes are plane suture, limb suture etc.

2. syndesmoses :- in syndesmoses a greater distance is present between the articulating surfaces.

It contained denser irregular connective tissue than a suture.

Example of sutures include

Inferior tibiofibular joint, tympano stapedisl joint joint.

3. Gomphoses( peg and socket joint) :- 

• these are special type of fibrous joint which are involved in fixing of teeth (peg) in the alveolar socket of of maxilla and mandible.

• the periodontal ligament help in the attachment of the root of tooth to the socket within the alveolus.

b) Cartilage joint  :- 

cartilaginous joint the bone are attached to each other by hyaline cartilage or fibrocartilage.

• These joints are devoid of joint cavity.

The two type of of cartilaginous joints are :- 

i) Synchondroses :- it is a primary carton a joint.

• Bones are joint by a hyaline cartilage.

• Immovable joint

• Most temporary in nature.

ii) dymphyses :-  it is a secondary cartilaginous joint.

• bones are joined by the plates of hyaline cartilage.

• all symphyses occurs in the midline of the body.

c) Synovial joint :-(diarthrodial joint) 

• deserve freely movable joint

• these are highly involved in nature

• these types of joint have a cavity and closed in fibrous capsule.

• aarthi plate of hyaline cartilage covers the articular surfaces.

Types of synovial joint :-

There are six types of synovial joints

1. Ball and socket joint - it is a ball shaped head of one bone fit in a socket line concavity or another.

• it is present in hip joint shoulder joint  etc.

2. Condyloid joint - it have two convex surfaces that articulate two concave surfaces.

• it is present in temporomandibular, metacerpophalongeal.

3. Plane or glinding joint - in plain joint the opposite articular surface are flat or almost flat.

• intercorpal, intertarsal

4.Hinge joint :- hinge joint assemble a hinge on a door so that flexion and extension are possible.

• elbow,  knee , ankle etc.

5. Pivot joint :- Central bony pivot surrounded by bony ligamentous ring and rotation is the only movement possible.

• superior radio ulnar.

6. Saddle joint :- the articular surface are reciprocally concave or convex and assemble a saddle on a horse back.

• first carpometacarpel, sternoclavicolar, calcaneo cuboid.

 Types of joint movement :- 

1. Glinding movement- movement of relatively flat bone surface back and forth and side to side over and one another.

• little changes in the angle between bones.

2. Angular - increase or decrease in the angle between bones.

• flexion - decrease the angle between articulating bones, usually in the sagittal plane 

example band trunk or knee.

• extension - increasing in the the angle between articulating bones usually in sagittal plane.

• abduction - movement of a bone away from the midline usually in the frontal plane.

• adduction - movement of a bone towards the midline usually in the frontal plane.

3.  Rotation -

Movement of a bone around its longitudinal access in the limbs it may be medial or lateral.

4.Circumduction -

Circumduction is a movement of limb and ise in a circular direction i.e 360° 

Joint Articulation - 

joint or articulation present in different parts of the body summarised as:-

• axial skeleton articulation.

• appendicular skeleton articulation.

i) Axial skeleton - include like skull hyoid bone, vertebral column (vertebrae and invertebral disks) and thorax ( ripsand sternum).

ii) The appendicular skeleton -  comprises of pectoral girdle (scapulae and clavicles), upperlimbs (humerus, radius, ulna, carpals, metacarpal andphalanges), pelvic girdle (coxal bone articulating with the sacrum) and lower limbs ( femur, tibia, patalla,etc.)