biology

Myotome

Myotome is a biology topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Myotome rather than just read about it. In short: A myotome is the group of muscles that a single spinal nerve innervates. Similarly a dermatome is an area of skin that a single nerve innervates with sensory fibers.

Key takeaways

Myotome belongs to biology; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Myotome to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Myotome from memory before moving on to harder problems.

Reference excerpt

A myotome is the group of muscles that a single spinal nerve innervates. Similarly a dermatome is an area of skin that a single nerve innervates with sensory fibers. Myotomes are separated by myosepta (singular: myoseptum). In vertebrate embryonic development, a myotome is the part of a somite that develops into muscle.

Structure The anatomical term myotome which describes the muscles served by a spinal nerve root, is also used in embryology to describe that part of the somite which develops into the muscles. In anatomy the myotome is the motor equivalent of a dermatome.

Function Each muscle in the body is supplied by one or more levels or segments of the spinal cord and by their corresponding spinal nerves. A group of muscles innervated by the motor fibres of a single nerve root is known as a myotome.

List of myotomes Myotome distributions of the upper and lower extremity are as follows;

C1/C2: neck flexion/extension C3: Lateral Neck Flexion C4: shoulder elevation C5: Shoulder abduction C6: Elbow flexion/Wrist Extension C7: Elbow extension/Wrist flexion C8: Thumb extension T1: Finger Abduction & Adduction L1/L2: Hip Flexion L3: Knee extension L4: Ankle dorsi-flexion L5: Great toe extension S1: Hip extension/Ankle plantar-flexion/ankle eversion S2: Knee flexion S3–S4: anal wink

Clinical significance In humans myotome testing can be an integral part of neurological examination as each nerve root coming from the spinal cord supplies a specific group of muscles. Testing of myotomes, in the form of isometric resisted muscle testing, provides the clinician with information about the level in the spine where a lesion may be present. During myotome testing, the clinician is looking for muscle weakness of a particular group of muscles. Results may indicate lesion to the spinal cord nerve root, or intervertebral disc herniation pressing on the spinal nerve roots.

References

Further reading Neurology Textbook, edited by Professor L. Sokolva, M.D., D.Sc. 2012, ISBN 9789663824260

External links Embryology at UNSW Notes/skmus7 Embryology at UNSW Notes/week3_6 mslimb-009—Embryo Images at University of North Carolina

Illustrations

Worked examples

Example 1 — a first encounter with Myotome

Start with the simplest possible case. Write down what Myotome claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Myotome before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Myotome ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Myotome

In research: Myotome appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Myotome in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Myotome is common in secondary-school and first-year university syllabi. It links to neighbouring topics Neurology, so understanding it makes those chapters shorter.
In everyday life: Look for Myotome outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Myotome in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Myotome means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Myotome out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Myotome in simple terms?

A myotome is the group of muscles that a single spinal nerve innervates. Similarly a dermatome is an area of skin that a single nerve innervates with sensory fibers.

Why does Myotome matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Myotome?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Myotome.