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Applied Science Year 1 - Unit 8 Musculoskeletal Disorders
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- PEARSON (PEARSON)
Distinction grade assignment for forensic and criminal investigation/applied science BTEC year 1 biology unit 8 musculoskeletal disorders
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Musculoskeletal DisordersThe human skeleton
The human skeleton is made up of 206 bones that can be classified in terms of shape;
bones can be classified into flat, short, irregular, long and sesamoid. The main
function of flat bones is to protect internal organs - some examples of these are
cranial bones on your skull, the sternum, scapulae and ribs. They can protect our brain,
heart and pelvic organs as these are vital in the functioning of our bodies. Sutural bones
are smaller, softer bones found between bones in the cranium. Short bones provide
stability and some movement, and are located mainly in wrist and ankle joints. Carpals
in wrists and tarsals in ankles are some examples of short bones. Irregular bones are
also mainly for protecting internal organs due to their complex shape; they vary in
structure and side and some examples of irregular bones are the vertebrae and bones in
the pelvis such as the pubis, ilium and ischium. Long bones mainly support weight
and also aid in movement. The appendicular skeleton includes the bones of the
shoulder girdle, the upper limbs, the pelvic girdle, and the lower limbs, and is mainly
where long bones are located. Sesamoid bones are small, round and embedded in
tendons. They protect tendons from stress and wear because they redistribute the
forces throughout the muscle or tendon, therefore increasing weight and impact
tolerance. Other functions of bones include storing and releasing fat, producing
blood cells and storing and releasing minerals.
Bones are made up of a framework of a protein called collagen, and the mineral
calcium phosphate helps the framework be hard and strong. Bones store and release
calcium into parts of the body when it’s needed. Within bones are red and yellow bone
marrow, which are spongy tissues found within the centre of most bones which both
contain stem cells that are specialised for different functions; red bone marrow contains
blood stem cells which may be specialised into platelets, or red and white blood cells.
Yellow bone marrow on the other hand is mostly made of fat, and these stem cells can
become cartilage, fat or bone cells.
Our axial skeleton is composed of the bones in
your head, neck, back and chest (cranial
bones, facial bones, auditory ossicles,
vertebral column), and our appendicular
skeleton is the rest of our bones: the ones that
attach (append) to our axial skeleton. The axial
skeleton is made up of 80 bones and its major
function is to provide support and cushioning
for the brain, spinal cord and other organs in
our body.
Below is a diagram of the human skeleton. Of
the 80 axial bones, 29 are in the head and 51
are in the trunk. Red and yellow bone marrow
are found mainly in long bones such as our
femur, the bone indicated on the diagram to be
in our thigh. As well as the femur, they can also
be found in shoulder blades, hips, skull and flat
bones such as our ribs.
Muscles, ligaments and tendons
Muscles are soft tissues made up of stretchy
fibres that are specialised to perform a number
of functions ranging from eating and breathing
to giving birth. The three types of muscle in our
body are skeletal, cardiac and smooth.
Smooth muscles line the insides of muscles
, such as our bladder, stomach and intestines. They are controlled and contract
involuntarily (we don't have to think about them), and play an important part in both
the male and female reproductive systems,
the urinary system and respiratory system.
They help with digestion and nutrient
collection in the stomach and intestines, and
rids the body of toxins and balances
electrolytes in the urinary system. As the
name suggests, cardiac muscles line the
walls of the heart and are similar to smooth
muscles in that they are controlled
involuntarily; the heart tells them when to
contract. Cardiac muscles aid the heart in
pumping blood that travels through our
cardiovascular system. Unlike smooth and
cardiac muscles, skeletal muscles are
controlled voluntarily, meaning that we tell
them when to move; this works by nerves in
our somatic nervous system sending
impulses to tell them when to move. They
are part of the skeletomuscular system
and are the majority of the muscles in our
body, making up about 30-40%. Skeletal muscles work with bones, tendons and
ligaments and help support the weight of our body whilst helping us move. There are
two types of muscle fibres that make up our muscles: fast twitch and slow twitch.
Fast twitch muscle fibres support quick and powerful movements such as sprinting or
weightlifting, whilst slow twitch muscle fibres are for long endurance activities such
as marathon running. Slow twitch muscle fibres are usually darker in colour because
they need more blood and oxygen due to working aerobically. Fast twitch muscle fibres
work anaerobically, meaning that they require less blood and are therefore lighter in
colour. The key muscle groups are: chest, shoulders, arms, back, abdominal and
legs. Skeletal muscle is made up of thousands of tissue fibres wrapped together by
tissue sheaths. Individual bundles of muscle fibres are called fasciculi and the
outermost connective tissue sheath surrounding the whole muscle is called the
epimysium.
Tendons bind muscle to bone and ligaments bind bone to bone. Tendons may also
attach to muscles and serve more as an air in movement, whilst ligaments are more for
holding structures together and keeping them stable. They’re both fibrous connective
tissues. Muscle contraction is when you hold or pick up something, and muscle relaxation
is when contracted muscles return to their normal state. Muscles stabilise our joints and
connective tissues, maintain our posture and also produce heat to keep our body up to
temperature. Muscles can contract because our muscle fibres contain myosin; the
myosin tightens and shortens when we contract our muscles, and loosens and stretch
out when we relax them. Flexion describes the bending movement that decreases the
angle between the bone and the joint, whilst extension increases the angle.
Adduction is motion away from the body whilst abduction is motion towards the centre of
the body. Circumduction is a combination of the four and is usually performed at ball and
socket joints; it’s the circular movement of a body part. Internal rotation is rotation
towards the axis of the body, and external/lateral rotation is rotation away from the
centre of the body.
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