Antagonistic muscles, joints and diversity of movement
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Flip to reveal answersWhy must skeletal muscles work in antagonistic pairs?
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Question
Why must skeletal muscles work in antagonistic pairs?
Answer
A muscle can only **pull (contract)**, not push — so a **second muscle** pulling the opposite way is needed to **reverse** the movement.
Question
In an antagonistic pair, what is happening to the two muscles during a movement?
Answer
One muscle **contracts (pulls)** while its **antagonist relaxes** (and is stretched); they **swap** to reverse the movement.
Question
What do the biceps and triceps each do at the elbow?
Answer
**Biceps flexes** (bends) the elbow; **triceps extends** (straightens) it. They are an **antagonistic pair**.
Question
Give the roles of three parts of a synovial joint.
Answer
**Cartilage** reduces friction on the bone ends; **synovial fluid** lubricates; **ligaments** hold bones together and **stabilise** the joint.
Question
Hinge joint vs ball-and-socket joint?
Answer
**Hinge** (elbow, knee) moves in **one plane**; **ball-and-socket** (hip, shoulder) moves in **many directions** and can rotate.
Question
How does the skeleton act as a lever?
Answer
Bones are **levers** that turn about a **joint (pivot)**, so a muscle's pull is converted into a **larger, controlled movement** of the limb.
Question
Tendon vs ligament?
Answer
A **tendon** joins **muscle to bone**; a **ligament** joins **bone to bone**.
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Topic 2.8 hub
Muscle and motility
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