Anatomy and physiology-9.1 Joints and their classification

Bony joints

The attachment of the first rib to the sternum also becomes a bony joint with age.

Bony joints formed by cartilaginous joints.

The epiphyses and diaphyses of the long bones are joined by cartilaginous joints in childhood and adolescence, and these become bony joints in early adulthood.

Serrate sutures

-These appear as wavy lines along which adjoining bones firmly interlock with each other by their serrated margins. -Serrate sutures are analogous to a dovetail wood joint.

Three kinds of fibrous joints

1. Sutures 2. Gomphoses 3. Syndesmoses

Joints/ Articulations

These link the bones of the skeletal system into a functional whole.

The two types of cartilaginous joints

1. Synchondroses 2. Symphyses

Syndesmosis example

A mobile syndesmosis exists between the shafts of the radius and ulna, which are joined by a broad fibrous interosseous membrane. This permits such movements as pronation and supination of the forearm. A less mobile syndesmosis is the one that binds the distal ends of the tibia and fibula together, side by side.

Skeletal system

A system that supports the body, permits effective movement, and protects the softer organs.

Lap suture example

An example is the squamous suture where the temporal bone meets the sphenoid and parietal bones.

Example of Synchondroses; cartilaginous joints

An example is the temporary joint between the epiphysis and diaphysis of a long bone in a child, formed by the cartilage of the epiphyseal plate. Another is the attachment of the first rib to the sternum by a hyaline costal cartilage.

Classes of joints

Bony, fibrous, cartilaginous, and synovial joints.

Classification of joints

Joints are classified according to the manner in which the adjacent bones are bound to each other.

Lap ( squamous) sutures

These occur where two bones have overlapping beveled edges. On the surface, a lap suture appears as a relatively smooth (nonserrated) line

Syndesmoses (syndesmosis); Fibrous joint

This is a fibrous joint at which two bones are bound by relatively long collagenous fibers. The separation between the bones and length of the fibers give these joints more mobility than a suture or gomphosis has.

Synchondroses (synchondrosis); cartilaginous joints

This is a joint in which the bones are bound by hyaline cartilage.

What is a joint/ articulation?

This is any point where two bones meet.

Plane (butt) sutures

This occur where two bones have straight overlapping edges. The two bone merely border on each other.

How are bony joints formed?

Bony joints can form by ossification of either fibrous or cartilaginous joints. An infant is born with right and left frontal and mandibluar bones, for example, but these soon fuse seamlessly into a single frontal bone and mandible. In old age, some cranial sutures become obliterated by ossification and adjacent cranial bones, such as the parietal bones, fuse.

Symphyses (Symphysis); cartilaginous joints

These are two bones that are joined by fibrocartilage.

Example of plane sutures

This type of joint is represented by the intermaxillary suture in the roof of the mouth.

Gomphosis joint and the teeth

The tooth is held firmly in place by a fibrous periodontal ligament, which consists of collagen fibers that extend from the bone matrix of the jaw into the dental tissue. The periodontal ligament allows the tooth to mend or give a little under the stress of chewing. Along with associated nerve ending, this slight tooth movement allows us to sense how hard we are biting and to sense a particle of food stuck between the teeth.

Less moveable/immobile joints

These joints are able to support the body and protect delicate organs.

Example of serrated sutures

Coronal, Sagittal, and lambdoid sutures that border the parietal bones.

Bones of the cranium

frontal, parietal, occipital, temporal, sphenoid, ethmoid. They must protect the brain and sense organs, but need not allow for movement, they are locked together by immobile joints (sutures).

Cartilaginous joints

This is also called an amphiarthrosis. In these joints, two bones are linked by cartilage.

Joint names

The names of joints is typically derived from the names of the bones involved. For example, the atlanto-occipital joint is where the atlas meets the occipital condyles; Glenohumeral joint - this is where the glenoid cavity of the scapula meets the humerus; Radioulnar joint - this is where the radius meets the ulna.

Classification of sutures

Serrate, lap, and plane sutures.

Fibrous Joints (synarthrosis)

This is a point at which adjacent bones are bound by collagen fibers that emerge from one bone, cross the space between them, and penetrate into the other.

Vertebral column

It is moderately mobile, for it must allow for flexibility of the torso and yet protect the delicate spinal cord and support much of the body's weight.

Sutures; Fibrous joint

Sutures the fibers are very short. Sutures are immobile or only slightly mobile fibrous joints that closely bind the bones of the skull to each other; they occur nowhere else.

Example of symphysis (symphyses)

The pubic symphysis, in which the right and left pubic bones are joined anteriorly by the cartilaginous joints. Another is the joint between the bodies of two vertebrae, United by an intervertebral disc. The surface of each vertebral body is covered with hyaline cartilage. Between the vertebrae, this cartilage becomes infiltrated with collagen bundles to form fibrocartilage. Each intervertebral disc permits only movement between adjacent vertebrae, but the collective effects of all 23 discs gives the spine considerable flexibility.

Properties of moveable joints

These joints such as shoulder, elbow, and knee are; self lubricating, almost frictionless, and able to bear heavy loads and withstand compression.

Bony joints (synostosis)

This is an immobile joint formed when the gap between two bones ossifies and they become, in effect, a single bone.

Arthrology

This is the science or study of joint structure, function, and dysfunction.

Kinesiology

This is the study of musculoskeletal movement. It is a branch of biomechanics. Biomechanics this deals with a broad variety of movements and mechanical processes in the body, including the physics of blood circulation, respiration and hearing.

Gomphoses; Fibrous joint

This refers to its similarity to a nail hammered into wood. It can also described with teeth even though they are not bones. The attachment of a tooth to its socket it is classified as a joint called gomphosis.