Major Muscles of the Body

This lesson covers the 12 major muscles as required by the Edexcel GCSE PE specification (1PE0 — Topic 1: Applied Anatomy and Physiology). You need to be able to identify and locate each muscle, understand its function, and relate it to sporting movements. The Edexcel specification includes specific muscles that differ from other exam boards — notably external obliques (not "abdominals") and pectoralis major.

---

The 12 Edexcel Required Muscles

Muscle	Location	Primary Action
Deltoid	Shoulder (covering the shoulder joint)	Abduction, flexion, and extension of the shoulder
Biceps	Front of the upper arm	Flexion of the elbow
Triceps	Back of the upper arm	Extension of the elbow
Pectoralis major	Chest	Adduction and flexion of the shoulder
Latissimus dorsi	Mid/lower back (large, flat muscle)	Adduction and extension of the shoulder
External obliques	Sides of the abdomen	Rotation and lateral flexion of the trunk
Hip flexors	Front of the hip (crossing from the pelvis to the femur)	Flexion of the hip
Gluteus maximus	Buttocks	Extension of the hip
Quadriceps	Front of the thigh (group of 4 muscles)	Extension of the knee
Hamstrings	Back of the thigh (group of 3 muscles)	Flexion of the knee
Gastrocnemius	Back of the lower leg (calf)	Plantarflexion of the ankle
Tibialis anterior	Front of the lower leg (shin)	Dorsiflexion of the ankle

Exam Tip: The Edexcel specification uses the term external obliques — NOT "abdominals" or "rectus abdominis". If a question asks about muscles involved in trunk rotation, use the term "external obliques." Similarly, Edexcel specifies pectoralis major rather than just "pectorals." Be precise with your terminology.

---

Upper Body Muscles in Detail

Deltoid

The deltoid is the large, triangular muscle that covers the shoulder joint. It has three parts (anterior, middle, and posterior) but for GCSE PE you treat it as one muscle.

• Action: Abduction of the shoulder (raising the arm out to the side), as well as flexion and extension.
• Sporting examples: Raising the arm to throw in a netball shoulder pass; lifting the arm to serve in tennis; performing a lateral raise in the gym.

Biceps

The biceps brachii is located on the front of the upper arm, between the shoulder and the elbow.

• Action: Flexion of the elbow (bending the arm).
• Sporting examples: Pulling back the bowstring in archery; performing an upward block in martial arts; pulling up on a climbing wall.

Triceps

The triceps brachii is located on the back of the upper arm, opposite the biceps.

• Action: Extension of the elbow (straightening the arm).
• Sporting examples: Pushing up from a press-up position; throwing a javelin (the arm straightens during release); a chest pass in netball or basketball.

Pectoralis Major

The pectoralis major (often called the "pecs") is the large, fan-shaped muscle covering the front of the chest.

• Action: Adduction and flexion of the shoulder — pulling the arm across the body and forward.
• Sporting examples: A forehand drive in tennis (pulling the arm across the body); a chest pass in basketball; a swimming front-crawl arm pull; performing a bench press.

graph TD
    A["Upper Body Muscles"] --> B["Deltoid — shoulder"]
    A --> C["Biceps — front of upper arm"]
    A --> D["Triceps — back of upper arm"]
    A --> E["Pectoralis major — chest"]
    A --> F["Latissimus dorsi — back"]

    style A fill:#4a90d9,color:#fff
    style B fill:#e67e22,color:#fff
    style C fill:#e67e22,color:#fff
    style D fill:#e67e22,color:#fff
    style E fill:#e67e22,color:#fff
    style F fill:#e67e22,color:#fff

Latissimus Dorsi

The latissimus dorsi (often called the "lats") is a large, flat muscle that covers the mid and lower back.

• Action: Adduction and extension of the shoulder — pulling the arm down and back towards the body.
• Sporting examples: A swimming butterfly stroke (pulling the arms down through the water); a pull-up; performing a lat pulldown in the gym; rowing (pulling the oar towards the body).

---

Core Muscles

External Obliques

The external obliques are located on the sides of the abdomen, running diagonally from the ribs to the pelvis.

• Action: Rotation and lateral flexion (side bending) of the trunk.
• Sporting examples: A golf swing (rotating the trunk); throwing a discus (trunk rotation provides power); a side-step in football; performing a twisting sit-up.

Exam Tip: Remember — Edexcel uses the term external obliques, not "abdominals." If you write "abdominals" or "abs" in the exam, you may not receive the mark. Always use the correct Edexcel terminology.

---

Lower Body Muscles in Detail

Hip Flexors

The hip flexors are a group of muscles at the front of the hip, crossing from the pelvis to the top of the femur (the iliopsoas is the primary hip flexor).