Week 9 — Count the Skeleton, Read the Joints: A Skeleton Report — Traditional alternative (no AI)

Instructors: publish this instead of the adaptive version if you prefer, and unpublish or delete the adaptive one.

Assignment 8 of the term — add the skeleton up from its regions, read the limbs and joints from the anatomical position, and explain a joint's trade in plain words for someone new to anatomy and physiology.

This week you learned the skeleton's two divisions, the axial skeleton by region, the limbs and the girdles that attach them, how to classify a joint by structure and by function, the parts of a synovial joint, and the trade between moving freely and holding firm. Week 1 gave you the anatomical position and the medial and lateral pair, and Week 7 showed you a single long bone; this week those ideas place every bone and every joint. In this assignment you work four short problems, interpret each one, and explain a joint's trade to someone who has never studied anatomy and physiology. This week's lecture tutorial, quiz, discussion, and A&P Lab & Inquiry practise the same ideas from other angles.

The task

This week's shared dataset is Dataset F, the skeleton counts: canonical counts, not measured data. An adult skeleton has 206 bones, 80 axial and 126 appendicular. The axial skeleton is the skull (22 bones), the associated bones (the hyoid and six ossicles, 7 bones), the vertebral column (26 bones), and the thoracic cage (25 bones). Each limb has 30 bones, and the girdles that attach the limbs count with the appendicular skeleton.

Work these four problems, showing your arithmetic:

1. The skull has 22 bones, the associated bones number 7, the vertebral column has 26 bones, and the thoracic cage has 25 bones. How many bones make up the axial skeleton?
2. The appendicular skeleton has 126 bones, and each of the 4 limbs has 30 bones. How many bones belong to the girdles?
3. The vertebral column has 7 cervical vertebrae, 12 thoracic vertebrae, and 5 lumbar vertebrae above the sacrum. How many separate vertebrae sit above the sacrum?
4. The thoracic cage holds 12 pairs of ribs, with 2 ribs in each pair, and 1 sternum. How many bones make up the thoracic cage?

Beside each answer, add one brief interpretation:

• Problem 1: name the four axial regions in the sum, and explain why the six ossicles and the hyoid are counted apart from the skull's 22 while the scapula is not in this total at all.
• Problem 2: name the six girdle bones and explain why they count as appendicular even though they sit on the trunk, and then, reading from the anatomical position, name the forearm bone on the thumb side and the leg bone that bears the body's weight.
• Problem 3: give the three regions in order from the top down and tie the thoracic count to the rib pairs, and then classify the joint at an intervertebral disc and the joint at a skull suture by structure.
• Problem 4: name the rib groups and explain why the floating ribs are not a third group beside the true and false ribs, and then name the part of a synovial joint that secretes synovial fluid and the rule that links every synovial joint to its functional class.

Explain it to a non-expert

A friend who recently joined a climbing gym asks why a shoulder can slip out of place more easily than a hip, when both are ball joints. Write a 3–5 sentence message that explains what a ball-and-socket joint is, how the shoulder's socket differs from the hip's, and what each one trades for what. Name one limit, for example that this is a picture of how the joints are built and not advice about anyone's shoulder. Put any technical term in everyday words. More than one good message is possible.

For a different, ungraded example, imagine a friend who asks why an elbow only bends one way. Model answer: "Your elbow is a hinge joint, a joint built to bend and straighten in one direction, like a door on its hinges. When you bend it, the angle between your upper arm and forearm gets smaller, and that move is called flexion; straightening it again is extension. The shape of the bones where they meet lets them swing in one plane and not twist freely. That is why the elbow is steady for carrying a bag, but it cannot circle the way a shoulder can. This explains how the joint is built, not why any one elbow might hurt."

Use that pattern for the message to your friend, with your own wording and evidence.

Show your arithmetic. A reader should be able to rebuild every number you report from the values given, without guessing which values you used or which operation you chose.

Deliverables

Submit a single report containing:

• the four answers, each with the arithmetic shown and the brief interpretation the task names for that problem;
• your message to your friend, explaining what a ball-and-socket joint is, how the shoulder's socket differs from the hip's, what each one trades, and one limit; and
• a one-line restatement of the values you used, so your results are reproducible.

Keep it to roughly one page.

Choose how you show it. Present your report as written text, or as a recorded audio or video explanation of about three minutes with a transcript, or as a labeled sketch of the skeleton sorted into its regions with a short note. Every form is graded by the same scoring criteria. Submit in any accessible file type or as a link; a recorded response may be submitted as audio or video with a transcript, or as text.

How you'll be graded

The full analytic rubric is attached to this assignment in Canvas.

Academic integrity and AI use

This version is designed to be completed without AI: do the computations, the interpretations, and the writing yourself, without a chatbot or other AI tool. You may use a calculator or a spreadsheet for the arithmetic. Submitting AI-generated work as your own, or copying another student's work, is an integrity violation under the course policy.

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