THE SKELETAL SYSTEM : INTRODUCTION

Hello my dear friends. Are you excited to know about our bones and it's type??? Without further delay we'll discuss about the " THE SKELETAL SYSTEM". I'm having an YouTube channel named "NURSING ABSTRACT". Where videos are posted in both Tamil and English . kindly have a look on it.

English video:https://youtu.be/TfC8TQUmRMU

Tamil video:https://youtu.be/i--s42ZADOE

                     THE SKELETAL SYSTEM

 The bodily system that consists of bones , their associated cartilages and the joints which works as a support system for your body. 

It gives the body its shape, allow movement, make blood cells , provides protection for organs and stores minerals. 

It forms the cavities  i.e. depressions or hollows which protect some structures and fossae i.e it forms the joints and it gives attachment to the muscles

It is also called as musculoskeletal system.

BONE:

 Bone is a living, growing tissue.

 It is made mostly with collagen. 

 The Collagen is a protein.  It provides a soft framework, where as calcium phosphate is a mineral which adds strength and hardens the bony framework. 

This combination of collagen and calcium makes bone strong and flexible which helps  to withstand the  stress. 

 The skeleton forms the cavity which means hole or hollow depression while fossa is (anatomy) a pit, groove.

TYPES OF BONES:

The human body has 5 types of bones . They are

 long bones,

 short bones,

 flat bones,

 irregular bones, 

sesamoid bones.

 LONG BONES:

The Long bones have a diaphysis (shaft) and two epiphysis (extremities) 

 The diaphysis is composed  of compact bone with a central medullary canal, this central medullary canal is composed of fatty yellow bone marrow.

 The epiphysis consist of an outer covering called  compact bone and spongy or cancellous bone inside.

 The diaphysis and epiphyses are separated by epiphyseal cartilage. and  this will  ossify when the growth is complete.

 Long bones are almost  covered by a vascular membrane i.e. the periosteum which has two layers.

 The outer layer is tough and fibrous, and it also protects the bone underneath.

The inner layer contains osteoblasts and osteoclasts, the cells responsible for bone production and breakdown  and is important in repair and remodelling of the bone

With growth plates (epiphysis) at either end 

The long bones have  a hard outer surface of a compact bone and a spongy inner known a cancellous bone containing bone marrow. 

Both ends of the bone are covered in hyaline cartilage . this  helps to protect the bone and aid in  shock absorption 

The Longest bones in the body are the Femur, Humerus, and Tibia .

 The periosteum covers the entire bone except within joint cavities, allows attachments of tendons and is continuous with the joint capsule. 

Hyaline cartilage replaces periosteum on bone surfaces and that forms the  joints. Thickening of a bone occurs under the periosteum by the deposition of new bone tissue. 

Our long bones are hard, dense bones and it  provides strength, structure, and mobility, it is  found in the upper and lower extremities i.e. the arms and the legs). 

FUNCTIONS OF LONG  BONE:

The femur or the thigh bone is a good example of a long bone. And it allows to walk and supports the skeleton.

 Long bones function is to bear the weight of the body and facilitate movement. 

 In  structural role, these bones  play a crucial role in the production of bone marrow and they contain both yellow bone marrow and red bone marrow, which plays a vital role for the production of blood cells.

SHORT BONES:

Short bones are as wide as they are long and have a primary function is to provide  support and stability with little movement. 

Examples of short bones : the Carpals and the  Tarsals – (the wrist and foot bones). They consist of only a thin layer of compact bone, hard bone with spongy bone on the inside along with relatively large amounts of bone marrow.

The shortest bones in the human body are the ear bones i.e. the malleus, the incus, the stapes.

Compact bone is very hard and strong. Spongy bone is found inside the  bones which are lighter and less dense compared to compact bone. This is because spongy bone is porous. Bone marrow is a soft connective tissue and it produces the red blood cells.

FLAT BONE:

Flat bones are  strong, flat plates of bone and  the main function is to provide protection to the body’s vital organs and serving as a base for muscular attachment. 

The examples of a flat bone are the Scapula (shoulder blade), The Sternum (breastbone), Cranium (skull), ilium (hip bone) Pelvis and Ribs .

 Anterior and posterior surfaces are formed of compact bone because they provide strength and  protection to the center consisting of cancellous (spongy) bone and varying amounts of bone marrow. 

In adults, the highest number of red blood 

      cells are formed in flat bones.

IRREGULAR BONE:

Due to their non-uniform shape, these are bones in the body which do not fall into any other category 

best examples  are the Vertebrae, Sacrum, and Mandible (lower jaw). 

They consists of cancellous bone inside with a thin outer layer of compact bone outside.

 They  have a complex shape, which helps protect the internal organs. For example, the vertebrae, irregular bones of the vertebral column which  protects the spinal cord.

SESAMOID BONE:

Sesamoid bones are usually short round bones, embedded in a tendon. 

The most obvious example of sesamoid bone  is the Patella also called as knee cap which sits within the Patella or Quadriceps tendon. 

Some of the Other examples of sesamoid bones are the Pisiform (smallest of the Carpals) and also the two small bones at the base of the 1st Metatarsal.

 

Sesamoid bones are usually present in a tendon  which passes over a joint to protect the tendon.

It’s purpose is to reinforce and decrease stress on that tendon. 

The slides which I have used in the video are given below.