The Musculoskeletal System

The Musculoskeletal System

The third main body system we will look at is the Musculoskeletal system. This system can be broken down into two smaller sections:-

  1. The Skeletal system - Consisting of the bones.

  2. The Muscular system - Consisting of the muscles and tendons.


The Skeletal System

The diagram below shows some the main bones of the Skeletal system:-

The Skeletal system has two main functions:-

  1. Protection - Bone is a very hard and strong material which is used to protect vulnerable organs of the body (e.g. the Skull protects the Brain).

  2. Movement - By giving the Muscular system a solid point to work from, bones are responsible for all movement of the body.


Composition of Bone

Bone is a living material within the body, constantly changing and growing. Bone consists of both organic and inorganic materials.

Bone is made from living cells and hard minerals such as Calcium. This makes bone a living substance.

A bone heated strongly in an oven becomes brittle. This is because the living cells will have been destroyed.

A bone placed in acid will become rubbery and flexible. This is because the hard minerals will have been removed.

Bone Structure

The diagram below shows the structure of a bone:-

Where :-

  1. Compact bone - Made of tightly packed bone cells, this hard layer is responsible for the bone's strength.

  2. Spongy bone - Made of loosely packed bone cells, this soft layer is responsible for the bone's flexibility.

  3. Bone marrow - Soft tissue filling the core of the bones, this bone marrow is responsible for the production of red blood cells.


Joints of the Body

In order for the body to move, the bones has to move past each other easily. Where bones need to move around each other, the bones are shaped in a special way to allow that movement, in the form of joints.

The diagram below shows the some of the main joint types within the human body:-

Muscular System

To make bones move, they must be attached to a pair of muscles by strong tissue called Tendons. When a muscle contracts, it pulls the bone in that direction. The pair of muscles works in opposition to each other (when one contracts the other relaxes).

For example :-

  1. To bend your arm, your bicep must contract, while your tricep relaxes.

  2. To straighten your arm, your tricep must contract, while your bicep relaxes.

The diagram below shows parts of the Muscular system that allow the arms and legs to move, as well as an example of a tendon:-

Case Study - Robert the Bruce

The two sections of the Musculoskeletal system have a large effect on each other. The bones are pulled and stretched by the muscles, which leaves marks behind. These marks can be used to understand things about a person, even if only their skeleton remains.

An example of this process was performed on the skull of Robert the Bruce.

Robert the Bruce was the King of Scotland from 1306 to 1329. He is most famous for fighting the first war of Scottish Independence against England. His most famous victory was the Battle of Bannockburn near Stirling, where a small Scottish force led by the Bruce fought and defeated a much larger English army.

This campaign ultimately securing Scotland as an independent nation until the two crowns were unified together in 1707. This war was popularised in the the film Braveheart.

The video below shows a documentary on the Battle of Bannockburn:-

In 2016, scientists from the University of Glasgow completed a 3D computer facial reconstruction of Robert the Bruce. The process of facial reconstruction is shown below.

The image below shows a plaster cast of the skull thought to belong to Robert the Bruce:-

By using highly detailed laser scans of this plaster cast, a 3D model of the skull is created as shown below:-

All skulls show markings on them which can be used to identify where muscles and other soft tissues were attached, and as such can be used to develop an image of the tissues over the skull:-

By looking at artwork showing Robert the Bruce, as well as written descriptions, hair and eye colour as well as clothing can then be added to complete the reconstruction:-

The video below shows a news bulletin summarising the facial reconstruction of Robert the Bruce.