Human Anatomy & Physiology (Human Body Systems)

Unit 1: Unit 1: Identity (Tissues, Bones, Muscles)HBS 1.2Human Body Systems: muscular system

Identify origin and insertion

Tell a muscle's origin (on the bone that stays put) from its insertion (on the bone that moves).

Builds on (2 levels back)inferred · high confidence

Muscles attach to bones: Muscles connect to two bones; you must know they bridge a joint before you can label which end is which.
Joints let bones move: A muscle moves one bone relative to another across a joint, so you need the idea of a movable joint first.

Prerequisites are inferred: pending teacher review.

Re-learn the skill with worked practice and clear examples.

The origin is the muscle's attachment on the bone that stays relatively still, and the insertion is the attachment on the bone that moves. When the muscle contracts, the insertion is pulled toward the origin.

Step 1: Define both ends

Origin = the attachment on the more stationary bone (it tends to stay put). Insertion = the attachment on the bone that moves toward the origin when the muscle shortens.

Step 2: Use a test

Ask: which bone moves when this muscle contracts? That moving bone holds the insertion. The bone that stays put holds the origin.

Step 3: Watch the trap

Both attachments are real and on real bones: the difference is which bone moves, not which attachment is bigger. The same muscle keeps the same origin and insertion even if you change position.

Practice

A muscle runs from the shoulder blade to a forearm bone. When it contracts, the shoulder blade stays in place and the forearm lifts. Where is the muscle's insertion?

Approved

A simple two-bone diagram. An upper bone is fixed to a wall on the left and stays still. A lower bone is hinged at a joint and shown lifting. A muscle band connects the upper bone to the lower bone. The two attachment points are marked A (on the still upper bone) and B (on the moving lower bone), without saying which is origin or insertion.

A.At point A, on the shoulder blade (the bone that stays still)
B.At point B, on the forearm bone (the bone that moves)
C.There is no insertion; both ends are origins
D.At the joint between the two bones

Show the worked solution ▾

Answer: B. At point B, on the forearm bone (the bone that moves)

Step 1: Find the moving bone: The forearm lifts, so the lower bone (point B) is the one that moves.
Step 2: Match to the definition: The insertion is on the bone that moves, so the insertion is point B on the forearm bone.

Why it's right: The forearm bone moves when the muscle contracts, and the insertion is defined as the attachment on the moving bone.

Why the others miss:

A: Point A is on the still bone: that is the origin, not the insertion.
C: Every muscle has one origin and one insertion; both ends are not origins.
D: The insertion is a bone attachment, not the joint itself.

Aligned to HBS 1.2: origin and insertion · reading level ~grade 9

Where you'd see this

Reading a muscle chart: the origin and insertion columns tell a trainer exactly which bone will move when that muscle is worked.

Careers that use this

Athletic Trainer: Knows a muscle's insertion to predict which joint will move, so they target the right muscle for an injured motion.

Video library

Watch: Identify origin and insertion

Origins, Insertions, Actions and Innervations Explained | Corporis

Corporis · ~6 min

Guided notes

Fill these in as you work through the lesson.

Big idea: Every muscle attaches to two bones; the origin is on the bone that stays relatively still, and the insertion is on the bone that moves toward the origin.

Key terms: write the meaning

Origin (the more stationary end):
Insertion (the end that moves):
Joint (where two bones meet):
Contraction (the muscle shortening):

The rule

When a muscle contracts, the insertion is pulled toward the , so the origin sits on the bone that stays and the insertion sits on the bone that moves.

Check yourself

When you bend your elbow, your forearm moves toward your shoulder. Which bone holds the origin and which holds the insertion of that muscle?
Why does naming the 'more stationary bone' matter for finding the origin?
If a muscle crosses a joint, why does only one of the two bones usually move?

Work one example

A muscle runs from the shoulder blade (which stays put) to a bone in the forearm (which lifts). Label which attachment is the origin and which is the insertion, and explain how you decided.