Year 7 Health & Physical Education · Movement and Physical Activity · 9m read

The Body in Motion — Muscles, Bones and Joints

Ever wonder why you can twist your ankle but not your elbow? Your skeleton, muscles and joints form an incredible team: bones provide structure and protection, muscles pull on them to create movement, and joints act as hinges. Learning how these three parts work together helps you understand everything from sports injuries to why your PE teacher tells you to warm up first.

Learning objective: Describe the musculoskeletal system and explain how muscles, bones and joints work together during movement.

By the end of this lesson you can:

• I name the major bones and muscle groups.
• I explain the roles of tendons, ligaments and cartilage.
• I describe three types of joints and their movement range.

The musculoskeletal system

THE SKELETAL SYSTEM:
206 bones in the adult human body (babies have ~270 — some fuse together).
Functions: SUPPORT (structure), PROTECTION (skull protects brain, ribs protect organs),
MOVEMENT (lever system), MINERAL STORAGE (calcium, phosphorus), BLOOD CELL PRODUCTION (bone marrow).
MAJOR BONE GROUPS:
Skull → Spine (vertebrae) → Ribcage (ribs + sternum) → Shoulder (scapula, clavicle) →
Arm (humerus, radius, ulna) → Hip (pelvis) → Leg (femur, tibia, fibula) → Foot.

CONNECTIVE TISSUE:
LIGAMENT: bone → bone. Stabilises joints. Tough, slightly elastic.
TENDON: muscle → bone. Transmits muscle force. Very strong, less elastic.
CARTILAGE: covers bone ends in joints. Reduces friction. Doesn't have blood supply → slow to heal.

JOINTS — three types:
IMMOVABLE (fibrous): skull sutures. No movement.
SLIGHTLY MOVABLE (cartilaginous): vertebrae. Limited movement (allows bending).
FREELY MOVABLE (synovial): most body joints. Filled with synovial fluid (lubrication).
Types of synovial joints:
BALL AND SOCKET (hip, shoulder): movement in ALL directions.
HINGE (knee, elbow): bending in ONE plane only.
PIVOT (neck C1-C2): rotation only.
GLIDING (wrist): small sliding movements.

THE MUSCULAR SYSTEM:
SKELETAL muscle: voluntary control. Attached to bones by tendons. Creates movement.
SMOOTH muscle: involuntary. In organs (stomach, blood vessels).
CARDIAC muscle: involuntary. Only in the heart.
ANTAGONISTIC PAIRS: muscles work in pairs. One CONTRACTS (agonist), the other RELAXES (antagonist).
Bicep curls: bicep (agonist contracts) → elbow flexes. Tricep (antagonist relaxes).

Body as a robot arm. Think of your arm as a robot arm. Bones = rigid metal rods. Joints = hinges and pivots. Muscles = motors that pull cables (tendons). Ligaments = bolts holding the hinges together. The robot can only move as well as each component is maintained.

Key musculoskeletal facts

• Muscles only PULL: Muscles can only contract (shorten) — they cannot push. To extend a joint, a different muscle on the other side pulls.
• Tendons ≠ Ligaments: TENDON = muscle to bone. LIGAMENT = bone to bone. "Sprained ankle" = ligament damage. "Achilles tendon" = calf muscle to heel bone.
• Cartilage repairs slowly: Cartilage has no direct blood supply → very slow to heal when damaged. This is why knee injuries in sport can be career-altering.

Quick reference

| Part | Job |
|---|---|
| Bones | Support, protect, levers |
| Muscles | Pull bones to move |
| Joints | Where bones meet |
| Tendons | Muscle to bone |
| Ligaments | Bone to bone |
| Muscle pairs | Biceps bends elbow, triceps straightens it |

Worked example (Easy)

When you perform a bicep curl, which muscles are contracting and which are relaxing?

1. Identify the movement. Bicep curl = elbow flexion (bending).
2. Agonist. The BICEP muscle is contracting (shortening) — pulling the forearm toward the upper arm.
3. Antagonist. The TRICEP muscle is relaxing (lengthening) — allowing the movement to occur.

Answer: Bicep contracts (agonist). Tricep relaxes (antagonist).

Worked example (Hard)

Apply advanced understanding of the body in motion — muscles, bones and joints to a challenging real-world scenario. Demonstrate systematic analysis using key concepts from this topic.

1. Analyse the context. Identify the key principles of the body in motion — muscles, bones and joints that are relevant. Consider what specific knowledge is needed to address this scenario.
2. Apply specific knowledge. Use precise health and physical education terminology to analyse the situation. Show how concepts interact and build upon each other.
3. Evaluate implications. Consider the broader significance. How does this analysis connect to other aspects of health pe?
4. Form a conclusion. Synthesise your analysis into a well-reasoned conclusion supported by specific evidence and terminology.

Answer: Analysis demonstrates deep understanding of the body in motion — muscles, bones and joints with specific terminology, systematic reasoning, and real-world application.

Common mistakes

• Providing surface-level responses without depth Students state facts about the body in motion — muscles, bones and joints without explaining underlying mechanisms, reasoning, or significance. Fix: Always explain WHY and HOW, not just WHAT. In health and PE assessments, depth of explanation distinguishes high-achieving responses from basic recall.
• Not using precise health and physical education terminology Students use everyday language when specific terms would demonstrate stronger understanding. Fix: Build and use a vocabulary of key terms for this topic. Precise terminology shows understanding and earns higher marks in health and PE assessments.

The Body in Motion — Muscles, Bones and Joints — connecting to the bigger picture

Understanding the body in motion — muscles, bones and joints extends beyond this single topic — it connects to broader themes across health pe and other disciplines. Recognising these connections transforms isolated knowledge into an integrated framework that supports deeper analysis and creative problem-solving.

In professional practice, experts use conceptual frameworks — organised structures of related ideas — to approach new problems efficiently. They don't recall every fact; they activate connections between concepts that help them identify what's relevant. This is why the most effective study approach is not memorising more facts, but building richer connections between the facts you already know.

Active learning strategies that build these connections include: relating new concepts to personal experience, comparing ideas across different topics, applying knowledge to unfamiliar scenarios, and teaching concepts to others. Each of these forces you to process information more deeply than passive reading or highlighting. The goal is to develop the kind of flexible understanding that allows you to analyse any question about the body in motion — muscles, bones and joints — even ones you haven't seen before — by drawing on a network of connected ideas.

Practice questions

1. What connects muscle to bone?

   1. Ligament
   2. Cartilage
   3. Tendon
   4. Synovial fluid

   (1 marks)

2. Compare the range of movement at the shoulder joint vs the knee joint. Explain why they differ.

   (2 marks)

Summary

• Name the major bones and muscle groups.
• Explain the roles of tendons, ligaments and cartilage.
• Describe three types of joints and their movement range.