1. The Muscular System
There are three types of muscles in the human body:
Cardiac muscle: a type of involuntary muscle that works automatically. It is only found in the heart and is special because it never rests.
Involuntary muscle: also known as smooth muscle, they are not controlled but they work automatically. They are found in the intestines, blood vessels and urinary organs.
Voluntary muscle: the most common muscle type. These attach to the skeleton and we can control these and move them, using signals from the brain. They help us run, jump, throw and perform all sporting skills.
(GCSE PE: Unit 1.2.2)

2. The Muscles Upper Body muscles: Trapezius Deltoid Latissimus dorsi
There are 11 specific muscles that you need to know.
You will need to know where they are found in the body and what movement they produce.
Upper Body muscles:
Trapezius
Deltoid
Latissimus dorsi
Pectorals
Biceps
Triceps
Abdominals
Lower Body muscles:
Gluteals
Quadriceps
Hamstrings
Gastrocnemius
(GCSE PE: Unit 1.2.2)

3. Upper Body
1) Trapezius
Attached to the back of the neck and the shoulder.
Movement: Extension at the neck
(GCSE PE: Unit 1.2.2)

4. Upper Body
2) Deltoid
Attached to the top of the shoulder and the upper arm.
Movement: Abduction at the shoulder but also used for circumduction.
(GCSE PE: Unit 1.2.2)

5. 3) Latissimus dorsi Upper Body
A sheet of muscle which connects from the lower spine to under the upper arm.
Movement: Adduction of the shoulder (behind the back)
(GCSE PE: Unit 1.2.2)

6. Upper Body
4) Pectorals
Covers the chest. There are two main muscles here: pectoralis major and pectoralis minor.
Movement: Adduction of the shoulder (in front of the body).
(GCSE PE: Unit 1.2.2)

7. 5) Biceps 6) Triceps Upper Body
Attached at the top of the shoulder and the elbow.
Triceps (triceps brachii) allows extension at the elbow. Biceps (biceps brachii) allows flexion at the elbow.
When the arm is extended (straightened), the triceps contracts and the biceps relaxes. When the arm is flexed (bent), the triceps relaxes and the biceps contracts
(GCSE PE: Unit 1.2.2)

8. 7) Abdominals Upper Body
They are found across the front of the stomach.
Movement: Flexion in the tors and the vertebrae column
(GCSE PE: Unit 1.2.2)

9. Lower Body
1) Gluteals
These form the buttocks and attach to the upper leg.
Movement: Extension of the hip joint and rotation of the upper thigh.
(GCSE PE: Unit 1.2.2)

10. 2) Quadriceps Lower Body
Found on the front of the upper leg. They attach at the hip and the knee.
Movement: Extension of the knee.
(GCSE PE: Unit 1.2.2)

11. 3) Hamstrings Lower Body
Found on the back of the upper leg. They attach at the bottom of the buttocks and the back of the knee.
Movement: Flexion of the knee
(GCSE PE: Unit 1.2.2)

12. 4) Gastrocnemius Lower Body
Found on the back of the lower leg. It starts at the back of the knee and extends down to the ankle.
Movement: Extends the ankle (and allows pointing of toes – plantar flexion)
(GCSE PE: Unit 1.2.2)

13. Antagonistic Pairs Agonist/Antagonist Fixator
Muscles are arranged in antagonistic pairs, so when one muscle contracts and pulls, the other relaxes to allow the joint to work
For example; The biceps and triceps are arranged in an antagonistic pair to allow movement in the forearm.
Agonist/Antagonist
In these pairs, there is always an agonist and an antagonist. The agonist muscle is the contracting muscle and the antagonist is the relaxing muscle.
For example, when we extend our lower arm, the triceps contract (so it is the agonist) and the bicep relaxes (so it is the antagonist).
When we flex our lower arm, this muscles switch roles. The biceps contracts (so becomes the agonist) and the triceps relax (so they become the antagonist).
Fixator
This is a muscle that works alongside an antagonistic pair to stabilise the origin of the agonist.
For example, the trapezius helps stabilise the origin of the biceps and triceps.