The Muscular System
Task One
In the human body, there are 21 major muscles.
These are the origin and insertions of all the major muscles:
Task Two
Within the human body, there are three different types of muscle tissue; skeletal muscle, smooth muscle and cardiac muscle.
Skeletal Muscle: The tissue most commonly thought of as muscle is skeletal muscle. Skeletal muscles cover your skeleton, giving your body its shape. They are attached to your skeleton by strong, springy tendons or are directly connected to rough patches of bone. Skeletal muscles are under voluntary control, which means you consciously control what ...
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These are the origin and insertions of all the major muscles:
Task Two
Within the human body, there are three different types of muscle tissue; skeletal muscle, smooth muscle and cardiac muscle.
Skeletal Muscle: The tissue most commonly thought of as muscle is skeletal muscle. Skeletal muscles cover your skeleton, giving your body its shape. They are attached to your skeleton by strong, springy tendons or are directly connected to rough patches of bone. Skeletal muscles are under voluntary control, which means you consciously control what they do. Just about all body movement, from walking to nodding your head, is caused by skeletal muscle contraction. Your skeletal muscles function almost continuously to maintain your posture, making one tiny adjustment after another to keep your body upright. Skeletal muscle is also important for holding your bones in the correct position and prevents your joints from dislocating. Some skeletal muscles in your face are directly attached to your skin. The slightest contraction of one of these muscles changes your facial expression.
Smooth muscle: Smooth muscles are around the body in the form of blood vessels, organs and in the eyes. They work automatically without you being aware of them. Smooth muscles are involved in many 'housekeeping' functions of the body. Its functions include blood flow regulation, mixing food in the stomach, pushing urine through the system and dilating the pupils.
Cardiac muscle: The heart is made of cardiac muscle. This type of muscle only exists in the heart. Unlike other types of muscle, cardiac muscle never gets tired. It is completely autonomous and works constantly without ever pausing to rest. Cardiac muscle contracts to squeeze blood out of your heart, and relaxes to fill your heart with blood.
Within the body, there are also 7 different muscle shapes. These are convergent, parallel, multipennate, unipennate, bipennate circular and fusiform. They all have very different characteristics:
Pennate: Feather like fibres are arranged around a single tendon. Many short fibres produce an increased force, but fatigue quickly.
- Unipennate: fibres are on one side of the tendon.
- Bipennate: fibres are on both sides of the tendon;, an example is the Rectus Femoris
- Multipennate: fibres are placed around a central tendon; an example is the Deltoid muscle.
Fusiform: Strap like fibres are parallel to each other and the tendon. They do not produce as much force as pennate muscles. They contract over great force so are not very strong. An example is the biceps.
Convergent: The base of these muscles is wider than the insertion. Muscle fibres converge on the insertion to maximize muscle contraction. An example is Pectoralis Major.
Circular: Surrounds a body opening, such as the mouth, constricting it when contracted.
Parallel: Fibres run parallel to each other and are sometimes called strap muscles. They are normally long muscles which cause large movements, are not very strong but have good endurance.
Another way to classify the muscles is by the three types of muscle fibre:
- Type I (Slow twitch) – These muscle fatigue slowly. They resist fatigue by having large numbers of mitochondria, dense capillary concentration and high aerobic enzyme activity. They are a red colour due to good blood supply. Sports associated: long distance running, long biking trips etc.
- Type IIb (Fast twitch glycolytic) – These muscles fatigue quickly, but they are capable of producing higher forces. They have fewer mitochondria, low aerobic enzyme activity and few capillaries. They are a white colour due to poor blood supply. Sports associated: sprinting, weightlifting, high jump.
- Type IIa (Fast twitch oxidative glycolytic) - These muscles have similar traits to both Type I and Type IIb fibres. They have more mitochondria than type IIb, higher aerobic enzyme activity than type IIb and denser capillary concentrations. They are a white colour due to poor blood supply. Sports associated: 800m, basketball etc.
Fast twitch fibres may be capable of faster and stronger contractions, but are less capable of generating energy through aerobic pathways and are less efficient at utilising ATP and therefore fatigue quickly. Athletes with large proportions of fast twitch fibres are, therefore, more suited to power or short duration events.
Slow twitch fibres may be capable of producing energy via the aerobic pathways and are less prone to fatigue, but they are less capable of generating strong or quick muscle contractions. Athletes with large proportions of slow twitch fibres are, therefore, more suited to endurance events.