Time To Read
Date Last Modified
The Skeletal System · Chapter 2 of 7
October 1985, age 10: the Presidential Fitness mile. She finishes, and by evening the fronts of both shins are hot, red and swollen, sore “in the bone”. “Out of shape — run more.” This chapter builds the bone as an organ: four shapes, the long bone end to end, the flat-bone sandwich, and the periosteum — the living wrapper with the vessels and nerves that let a shin burn after a mile.
The question you will answer
Bone the tissue was Chapter 1. Bone the organ has a shape, ends, a shaft, a cavity, two wrappers and a blood supply that enters through holes you can see on a dry femurThigh bone; longest and strongest bone in the body; has a large round head and prominent trochanters. Which of those parts has nerves — and what does exertion do to an already inflamed one?
Opener · The Mile · about 1¾ minutes
The opener is the same narrated animation you will watch in Scene 1.
Watch the opener first. It sets the question; the chapter answers it.
1
Read the chart
Patient chart · Stina
October 1985 · age 10 · the fitness-test mile
Oct 1985 · 10
Presidential Fitness mile on the cinder track. Finishes near the back. By evening both shins hot, red, swollen and tender along the front — “sore in the bone, not the muscle.” A fever that night. Clears in three days.
The skinThe body’s largest organ, providing protection and regulation.
Sharp-edged red plaques over the anteriorThe front of the body or toward the front when standing in the anatomical position. shins and ankle — Module 5 read them as erysipelas-like erythemaRedness of the skin due to increased blood flow, often caused by heat, infection, or inflammation., FMF’s one pathognomonic rash.
The coach
“Out of shape. Run more.” No visit.
Told
Nothing. It happened again the next spring after field day.
Chart clues this module: 5 · The spots · 6 · this chapter
Before you go on · your prediction
Hot, red, swollen shins by the evening after a mile, “sore in the bone”, gone in three days. The best first reading is…
Open the one you lean toward. Nothing is recorded and nothing is revealed — you come back to it at the end.
Shin splints — muscle and tendon pulling on the bone after unaccustomed running
Ask whether shin splints come with redness, heat and a fever, and whether they clear in three days.
A skin infection on both shins that happened to start on race day
Ask whether cellulitis arrives on both legs at once after exertion and leaves without antibiotics.
An inflamed periosteum and the skin over it, unmasked by the blood flow of exertion
Ask what the periosteum contains, what exertion does to bone blood flow, and what a sharp-edged red plaque on a shin means in a child with fevers.
From Stina’s diary
2
The story
Three short movements: the case, the anatomyThe study of the structure of the human body. and physiologyThe study of how the body functions., then the tie back to Stina. Each links to the scene where you’ll see it move.
I · The mile
The Presidential Fitness mile was run on the cinder track in October 1985, four laps, a coach with a stopwatch at the line. Stina finished near the back, which the coach noted, and went home with legs that felt wrong in a way she could not name. By supper the fronts of both shins were hot, red and swollen, and sore in a place she insisted was the bone and not the muscle. There was a fever that night. In three days it was gone. The coach, told, said she was out of shape and should run more; nobody at home thought a red leg after a run was a doctor’s problem. Module 5 has already read the skin side of that evening: sharply bordered, hot, tender plaques over the anterior shin and ankle, triggered by exertion, clearing in forty-eight to seventy-two hours — erysipelas-like erythema, the one skin sign that is pathognomonic of FMF, in a child nobody was going to test for it. This chapter reads what was under the skin. ‘Sore in the bone’ was a good observation. The question is what, in a bone, can be sore.
See it move: Scene 1 · The Mile · Scene 5 · The Wrapper That Can Feel
II · Shapes, ends and a shaft
Bones come in four shapes. Short bones are cubes — the wrist and ankle. Flat bones are thin plates — skull, sternumFlat bone forming the center of the chest; anchor for ribs and clavicles. Appears as a vertical dagg, ribsCurved bones forming the rib cage; articulate with thoracic vertebrae and most with the sternum.. Irregular bones are everything else — vertebrae, the hip. Long bones — fingers, limbs, the tibiaShinbone; large, weight-bearing medial bone of the lower leg. under her shin — are longer than they are wide and have a standard anatomy. Each end is an epiphysisThe expanded ends of a long bone.: compact boneDense, strong bone tissue forming the outer layer of bones. outside, spongy boneA porous bone tissue found inside bones, providing lightweight support. inside, capped with articular cartilageSmooth hyaline cartilage covering joint surfaces to reduce friction. where it meets a neighbor. The shaft is the diaphysisThe shaft of a long bone.: a thick collar of compact bone around a medullary cavityThe hollow space inside bones that contains bone marrow. that holds yellow marrow in an adult. Between end and shaft, in a child, is the epiphyseal plateA growth plate in developing bones made of cartilage. — cartilageA flexible connective tissue found in joints, the ear, nose, and rib cage. Cartilage can be of three, open, still growing; in an adult it has become the epiphyseal lineA remnant of the epiphyseal plate, marking where growth stopped., closed, all compact bone, visible on an X-ray as a faint seam. The site’s femur diagram and the dry bone on the bench show one more thing: holes. Nutrient foramina, where the arteriesBlood vessels that carry oxygenated blood away from the heart (except pulmonary arteries, which carr go in.
See it move: Scene 2 · Four Shapes · Scene 3 · The Long Bone, End to End
III · The wrapper that can feel
A flat bone is a sandwich: two plates of compact bone with spongy bone — the diploëThe spongy bone layer sandwiched between compact bone in flat bones. — between them, its trabeculae holding red marrowBone marrow that produces blood cells.; a skull is light and hard because of it. Every bone, whatever its shape, is wrapped. Outside, the periosteum has two layers: an outer fibrous layer of dense irregular connective tissue, and an inner osteogenic layer of osteoblasts, osteoclasts and the stem cellsThe basic structural and functional units of life. that make them. Inside, lining the cavity and every trabeculaThe lattice-like structures in spongy bone that support stress distribution., the endosteumA thin connective tissue lining the marrow cavity. does the same job in a single thin sheet — the site calls it a fishnet. The periosteum is pinned to the bone by perforating fibers of collagenA structural protein in the dermis that provides strength and elasticity., and it carries the blood vessels and nerves. Vessels enter through nutrient foramina, run as perforating canals through the compact bone and connect to the central canalsA hollow canal in an osteon containing blood vessels and nerves. of the osteonsThe structural unit of compact bone, consisting of concentric lamellae around a central canal. (Chapter 3). Nerves travel with them, and the periosteum itself is densely innervated — it is the periosteum that hurts when a shin is kicked. Under the thin skinSkin found on most of the body, lacking a stratum lucidum. of the anterior tibia the periosteum is a few millimeters down. Exertion sends blood to bone. If the periosteum and the small vessels it shares with the skin above are already primed by IL-1β, a mile delivers the surge to exactly the place she pointed to: sore in the bone, hot on the skin, over the tibia and nowhere else.
See it move: Scene 4 · The Sandwich · Scene 5 · The Wrapper That Can Feel
3
Watch · explore · think · check
5 scenes. Each one has a short animation or a slide, something to explore, a true/false spot-check of your thinking, and a quick check. Every scene gives you an evidence card for your board.
How to read the scenes
- Animation (dark teal) — a short animated explainer, one idea each
- Slide (dark teal) — a still to study: a micrograph, a diagram or a map
- Explore (purple) — something to push on while you watch
- Game (purple) — a quick challenge
- Think (gold) — reason it out, then spot-check yourself with a few true/false questions; not graded
- Check (gold) — a quick H5P that scores itself
Scene 1 of 5
The Mile
Four laps, a stopwatch, and two shins that were hot by supper.
Animation · in production · 1 min 50 s
The Mile
The cinder track from above, four laps counted. Home: the shins drawn as two red plaques with sharp edges over the tibia, a thermometer. A section A cut or slice of the body or an organ for study. through the shin: skin, a thin fat layer, periosteum, bone — the vessels the skin and periosteum share lighting up with the run. Three days; the red fades. Spring: it happens again. Caption: “sore in the bone” was the right address.
Prefer the full lecture? Bone Macro-anatomy (original video on the site)
Explore
Where exactly does it hurt?
A leg map, a slice through the shin and an exertion slider. Find the address before the overlay, follow it down to the nerves, then decide what a mile does to a wrapper that is already inflamed.
Text description of this explore
A field-test look in five steps. Step 1: a leg map shows the front of both lower legs, skin see-through over the tibia and fibula, and the back of one leg with the calf. Five lettered zones on her right leg: A, the front of the shin over the tibia’s flat front face; B, the inner edge of the shin, lower third; C, the outer front of the leg beside the tibia; D, the front of the ankle; E, the calf. For each, choose what her story puts there (her pain and a plaque; a plaque in the chart; or neither) and what lies under the skin there (bone, close beneath; muscle, then bone; or tendons, then bone). After you commit, sharp-edged red plaques cover the front of both shins and both ankles, and a purple dashed line marks the inner edge of the lower shin, where shin splints usually hurt. Step 2: follow a line straight back from where she pointed and put five layers in the order the line first meets them: skin, subcutaneous fat, periosteum, compact bone, muscle. Step 3: a slice across the middle of her right shin, front at the top: skin and fat, the tibia close under the skin at the front and inner side, the fibula and three blocks of muscle beside and behind it. Choose which layer’s nerves she was reporting (periosteum; the bone mineral; the skin; or the muscle beside the bone). After you commit, a dotted line traces the periosteum’s nerve net. Step 4: set blood flow to bone (rest, a walk, a jog, half a mile, a mile) and her small vessels (quiet, or primed by IL-1β), predict what happens (nothing new; a warm flush that fades within the hour; heat, swelling and pain that outlast the run by hours; or a crack in the tibia), then run it. A plot shows pain and heat at the shin from the run through day 5 and a readout gives the peak, the fever and the time back to baseline (teaching model). Step 5: four features of her October 1985 (both legs at once; a fever that night; a sharp edge; gone in three days without treatment). For each, choose whether it argues against shin splints, against cellulitis, against both, or against neither. After you commit, a table fills in each feature for shin splints, cellulitis and erysipelas-like erythema.
Think · not graded
Shin splints are pain in the muscle–tendon attachment to the tibia; cellulitis is an infected skin; her plaques were sharp-edged, bilateral, febrile, exertion-triggered and gone in three days. Which tissue was the mile actually loading, which structure in it can hurt, and what did the coach’s reading assume?
Spot-check your thinking: true or false?
Check · Multiple Choice
Why can the front of the shin be “sore in the bone” after a hard run?
Evidence card 1
Add it to your evidence board
Bilateral, febrile, sharp-edged, exertion-triggered, three days — not shin splints, not infection; a periosteum and a skin that share small vessels and a cytokine.
Scene 2 of 5
Four Shapes
Cube, plate, oddment, column — and why only one of them has a shaft.
Slide · in production
Bones by Shape
Shape predicts structure: only long bones have a shaft and a cavity; flat bones are a sandwich; short and irregular bones are spongy cores in a compact shell.
Prefer the full lecture? Bone Macro-anatomy (original video on the site)
Game
Sort the skeleton
Twelve bones on the site’s skeleton. Sort each by shape before the key, predict which shapes are hollow, then find her address on the tibia.
Text description of this game
A sorting-desk game in three steps. Step 1: the site’s front-view skeleton with twelve numbered badges in the margins, each pointing to one bone: 1, a carpal at the wrist; 2, the talus at the ankle; 3, the parietal on the side of the skull’s roof; 4, the sternum; 5, a rib; 6, the scapula at the shoulder; 7, the femur; 8, the tibia; 9, a phalanx of a finger; 10, a lumbar vertebra; 11, the hip bone; 12, the patella. For each, choose long, short, flat, irregular or sesamoid. After you commit, the badges color by class: long 7, 8, 9; short 1, 2; flat 3, 4, 5, 6; irregular 10, 11 (the hip can also be called flat); sesamoid 12. Step 2: six tiles, one per class (long: the femur; long and tiny: a phalanx; short: a carpal; flat: the parietal; irregular: a vertebra; sesamoid: the patella), each with an outline whose cut face is hidden. Predict whether each has a medullary cavity, a spongy core in a compact shell, or compact plates around diploë. After you commit, each cut face is drawn: the femur and the phalanx with a shaft cavity of yellow marrow; the carpal, vertebra and patella with a compact shell around spongy bone (red marrow in the vertebra); the parietal as two compact plates with red-marrow diploë between. Step 3: her right tibia and fibula, front view, with four lettered spots: A, the wide upper end at the knee; B, the tibial tuberosity below the knee; C, the front of the shaft; D, the knob of the inner ankle. Choose where her shins hurt and what part of the bone’s anatomy lies closest to the skin there. After you commit, a red band marks C and an inset shows the shaft cut across, the periosteum a few millimeters under the skin.
Think · not graded
A vertebra and a femur are both bones, but one has a shaft with a marrow cavity and one does not. Work out what shape has to do with structure, and why the tibia — long, subcutaneous along its front — is the bone a fitness-test rash picks.
Spot-check your thinking: true or false?
Check · Drag the Words
Sort each bone into its shape class.
Evidence card 2
Add it to your evidence board
The tibia: a long bone whose anterior border lies under skin and a thin periosteum — the one place on a leg where “in the bone” is a few millimeters from the surface.
Scene 3 of 5
The Long Bone, End to End
Epiphysis, diaphysis, cavity, cartilage cap — and a plate that is still open at ten.
Animation · in production · 1 min 45 s
The Long Bone, End to End
A femur splits lengthwise. Labels drop in: epiphysis (compact shell, spongy core, articular cartilage cap), diaphysis (compact collar, medullary cavity, yellow marrow), metaphysis between them. A ten-year-old’s femur beside an adult’s: the plate, cartilage, open; the line, bone, closed. An X-ray of each. Caption: her plates were open in 1985 — and the pain did not close with them.
Prefer the full lecture? Bone Macro-anatomy (original video on the site)
Explore
Label the femur
A blueprint of an adult femur with ten label slots, then a knee you can age from 10 to 25. Watch the plates close, and test the promise “she’ll outgrow it.”
Text description of this explore
A blueprint look in five steps. Step 1: a drawing of an adult femur cut lengthwise on a dark blue grid, with ten numbered label slots joined by leader lines: 1, a pale blue cap on the head; 2, the red spaces in the spongy bone of the head; 3, the cream wall of the shaft; 4, a bracket beside the shaft; 5, a brown line crossing the lower end above the knuckles; 6, the pale spongy bone of the lower end; 7, a bracket across the hollow of the shaft; 8, a pink layer on the outside of the shaft, peeled back in a flap; 9, the yellow fat in the hollow; 10, a bracket beside the lower end. Choose a label for each from: articular cartilage, compact bone, diaphysis, epiphysis, epiphyseal line, epiphyseal plate, medullary cavity, periosteum, red marrow, spongy bone, yellow marrow. Answers: 1 articular cartilage, 2 red marrow, 3 compact bone, 4 diaphysis, 5 epiphyseal line, 6 spongy bone, 7 medullary cavity, 8 periosteum, 9 yellow marrow, 10 epiphysis. Step 2: an age slider from 10 to 25 (1985 to 2000) sets a knee: the lower femur and upper tibia with a pink periosteum along both shafts. Predict whether the plate above the knee is thick and busy, thinning, or a line, then run it: the plates appear (thick blue bands at 10 to 12, thinner at 13 to 15, brown lines from 16), a teaching growth curve for a girl appears beside the knee (5.5 cm a year at 10, peaking at 7.5 at 11, zero from 16), and a readout gives her age, the plate, growth in length and the periosteum, which never changes. Step 3: a timeline from 1975 to 2000; choose the year her plates closed (1985; 1991; 1993 to 1996; or 2000). After you commit, 1991 is marked, at 16, beside OpenStax’s general ranges (length growth ends at 16 to 18; the line by about 18 to 21). Step 4: choose what “she’ll outgrow it” would require to be true. Step 5: the claim “when her plates close, her shins will stop hurting”; for five pieces of evidence, choose whether each refutes it, supports it, or leaves it open.
Think · not graded
“She’ll outgrow it” is a prediction about the epiphyseal plate: when growthAn increase in size and number of cells. stops, the pain stops. Say what the plate is, when it closes, and which structure the mile actually inflamed — and then whether the prediction was ever about the right part.
Spot-check your thinking: true or false?
Check · Fill in the Blanks
Name the parts of a long bone.
Evidence card 3
Add it to your evidence board
Open plates at ten mean a growing skeleton — and a reason the words “outgrow it” sounded plausible to everyone who said them.
Scene 4 of 5
The Sandwich
Two plates of compact bone with a spongy filling — why a skull is light, hard and full of red marrow.
Slide · in production
Flat Bones and the Diploë
A plate of spongy bone between two plates of compact bone: strong, light, and a blood factory for life.
Prefer the full lecture? Spongy and Compact Bone (original video on the site) · histology page: The Lattice
Explore
Build a skull plate
Three layers to stack, six linings and fillings to find, a hammer to drop, and a skeleton to mark. Build the skull’s sandwich, then ask why it is still a blood factory.
Text description of this explore
A dessert-counter look in five steps. Step 1: three empty slots of a flat bone, scalp side at the top: top slot (the outer face), middle slot, bottom slot (the inner face, toward the brain). For each, choose compact bone, spongy bone or hyaline cartilage, and what it gives the plate (a hard, stiff face; lightness and room for red marrow; or growth in length). After you commit, the slots fill: outer table of compact bone, diploë of spongy bone with red marrow, inner table of compact bone. Step 2: a close-up of the sandwich in section: a thin sheet on the top face, the upper compact band, a middle layer of pale struts edged in teal with red marrow in the gaps, the lower compact band, and a thin sheet on the bottom face. Six numbered slots: 1, the top sheet; 2, the upper compact band; 3, a teal strut edge; 4, the middle of a strut; 5, a red gap; 6, the bottom sheet. Label each from: periosteum, compact bone, endosteum, spongy bone (a trabecula), red marrow, medullary cavity. Answers: 1 periosteum, 2 compact bone, 3 endosteum, 4 spongy bone, 5 red marrow, 6 periosteum; no slot is a medullary cavity. Step 3: three plates of the same thickness under a hammer: compact alone, spongy alone, the sandwich. For each, predict the result (holds; the outer table cracks while the inner holds; or crushes) and its weight (heaviest, in between, lightest). After you commit (teaching model, compact alone = 100): compact alone weighs 100 with stiffness 100 and holds; spongy alone weighs 33 with stiffness 10 and crushes; the sandwich weighs 60 with stiffness 81, its outer table cracking and its inner table holding. Step 4: eight bones of an adult; sort each into still a red-marrow site or mostly yellow marrow by adulthood: sternum, hip bone at the iliac crest, skull vault, vertebral bodies, ribs, head of the femur (red); shaft of the femur, finger bones (yellow). After you commit, red patches mark the adult red-marrow sites on the site’s skeleton. Step 5: choose why a bone-marrow biopsy goes into the back of the hip.
Think · not graded
A skull needs to be hard, light and a blood factory. Explain how the sandwich delivers all three, and why a long bone solves the same problem with a shaft and a cavity instead.
Spot-check your thinking: true or false?
Check · Multiple Choice
What is the diploë, and which bones have one?
Evidence card 4
Add it to your evidence board
Red marrow in the diploë and the pelvis is the factory Module 14 will visit — the skeleton as an organ of the blood.
Scene 5 of 5
The Wrapper That Can Feel
Periosteum, endosteum, nutrient foramina, perforating canals — and the nerves that ride with the vessels.
Animation · in production · 2 min
The Wrapper That Can Feel
A long bone peeled: the outer fibrous periosteum lifts; under it the osteogenic layer with its cells; perforating fibers pin it down. A nutrient artery dives through a foramen, runs a perforating canalCanals that connect central canals, allowing blood flow between osteons. across the compact bone and joins the central canals. Nerves ride beside it; the periosteum is dense with them. Then the shin: skin, a few millimeters, periosteum — the vessels the two share drawn once, inflamed, and the run sending blood through them. Caption: the wrapper is the part that feels. Terms: perforating (Sharpey’s) fibers pin the periosteum; nutrient artery, foramen, perforating canal.
Prefer the full lecture? Bone Macro-anatomy (original video on the site)
Explore
Trace the blood in
A fitter’s map of one long bone. Trace the supply from an artery to a buried cell, find the layers that can build bone, map the nerves, then decide why a run marks the shin and not the calf.
Text description of this explore
A fitter’s-map look in five steps. Step 1: a section through the wall of a long bone’s shaft, outside at the top: a thin periosteum; compact bone with two osteons lying lengthwise, each with a central canal; a perforating canal crossing the bone from the cavity up to the osteons and a short one from the periosteum; the nutrient foramen on the surface with a nutrient canal running slantwise through the bone into the medullary cavity, which is lined by the endosteum and filled with yellow marrow. A dashed circle on one central canal is enlarged below as one osteon cut across: a central canal, rings of lacunae joined by canaliculi, and one osteocyte. Six tiles name the stops: nutrient foramen, medullary cavity, perforating canal, central canal, canaliculi, osteocyte. Give each its number on the route from an artery outside the bone to the buried cell (1st to 6th) and choose what reaches it there (blood, inside a vessel; or tissue fluid only). After you commit, the route is drawn in red: 1, in through the nutrient foramen and its canal; 2, branching along the medullary cavity; 3, back out into the compact bone through the perforating canal; 4, along the central canal, where a capillary is the last vessel; then a dotted blue line of tissue fluid runs, 5, through the canaliculi from lacuna to lacuna to, 6, the osteocyte. A dashed periosteal vessel enters the short perforating canal from outside. Step 2: a slab of the shaft wall, outside at the top, with five lettered parts: A, the outermost sheet of wavy collagen; B, a crowded row of cells against the bone; C, a single row of flat cells lining the marrow cavity and a trabecula; D, collagen threads running from A down into the bone; E, cells buried in lacunae in the compact bone. Name each (fibrous layer of the periosteum; osteogenic layer of the periosteum; endosteum; perforating fibers; osteocytes) and choose whether it holds osteogenic cells. After you commit, the names appear and B and C are outlined in green: the two places with osteogenic cells. Step 3: the upper end and shaft of a long bone cut lengthwise: a cartilage cap on the joint surface, spongy bone in the end, compact walls with central canals around a marrow cavity, and the periosteum outside. Five lettered places: A, the periosteum; B, a central canal; C, the matrix between canals; D, the marrow; E, the articular cartilage. For each, choose a dense net of nerves, sparse nerves riding with the vessels, or no nerves. After you commit, gold sensory nerves are drawn: a dense mesh along the periosteum, one thin nerve beside the vessel in each central canal and in the marrow, and none in the matrix or the cartilage. Step 4: four events at the shin: a kick from a soccer cleat; her mile in October 1985, on small vessels primed by IL-1β; a stress fracture in a runner who doubled her mileage; a classmate’s mile on quiet vessels. For each, choose how it feels (sharp at once, easing within the hour; building for hours after the run, hot and swollen, gone in about three days; a pinpoint ache that grows run after run over weeks; nothing at the bone) and what comes with it (perhaps a bruise; redness, heat and a fever; tenderness on one spot of bone with no redness or fever; nothing at the skin). After you commit, a plot of pain against time from one minute to eight weeks draws the four as a teaching model: a spike that fades within the hour, a hump that peaks that evening and is gone by day 3, an ache that climbs from the second week, and a flat line. Step 5: three columns from the skin down to bone: the front of the shin and the inner ankle (skin, a thin band of fat, the periosteum and bone, a few millimeters down) and the calf (skin, fat, several centimeters of muscle, then periosteum and bone). A classmate says that because a run sends the most blood to the calf muscles, the plaque should have flared over the calf if the run caused it. Choose: refute, because the flow is only the trigger and the plaque needs primed small vessels shared by the skin and a periosteum a few millimeters below; support, because the shoe rubbed the front of the shin and ankle; support, because calf skin is too thick for redness to show; or refute, because the calf gets less blood than the bone. After you commit, red small vessels link skin and periosteum over the shin and ankle, which carry a plaque, while over the calf the skin’s vessels sit far from the periosteum, an arrow marks most of the run’s extra flow going into the muscle, and the skin stays clear.
Think · not graded
The periosteum is dense with nerves and shares its small vessels with the skin above it on the shin. Put those two facts together with “exertion raises bone blood flow” and “IL-1β primes small-vessel endothelium” (Module 5), and explain a hot, sore shin by supper — and why it clears in three days.
Spot-check your thinking: true or false?
Check · Fill in the Blanks
The two layers of the periosteum, the lining inside, and the way the vessels get in.
Evidence card 5
Add it to your evidence board
The periosteum hurt, the skin over it flushed, both on the shin, both after exertion, both with a fever — one small-vessel network, one cytokine, one address.
4
Your evidence board
Every scene gave you an evidence card, and the chart adds more. Sort each card into the column it supports: An inflamed periosteum and skin, unmasked by exertion, Neither on its own, or Shin splints or deconditioning. Some cards can honestly go in more than one place — that’s allowed, and the feedback tells you which cards decide the case.
5
Your verdict
Time to decide. Look back at your bet, then build your verdict from statements that hold up — no writing needed.
Look back at your prediction
Hot, red, swollen shins with a fever the evening after a mile, gone in three days — the reading that fits best is…
Find the one you chose at the top. Does the evidence support it, refute it, or revise it?
- Shin splints — muscle and tendon pulling on the bone after unaccustomed running
- A skin infection on both shins that happened to start on race day
- An inflamed periosteum and the skin over it, unmasked by the blood flow of exertion
Build your verdict · no writing
Choose the statement that holds in each set. The ones you keep become your argument.
6
The finding
Finding · the mile
Sore in the Bone
October 1985, age 10: hot, red, sharp-edged, swollen shins with a fever the evening after the fitness-test mile, “in the bone”, gone in three days, back after field day. Chart entry: the periosteum is the innervated, vascular wrapper of a living organ; exertion sends blood to it; a periosteum and a skin sharing small vessels primed by IL-1β light up together over the one bone that lies under the skin. Held open: what the architecture under that wrapper is built to carry — and what standing on concrete does to it.
Next · Chapter 3
Pillars and Trusses
A new town, a school with concrete floors, and feet and shins that hurt by the end of every day. Under the periosteum, compact bone is pillars and spongy bone is trusses — and each is built for a different kind of load.
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All pages for Module 6 — The Skeletal System
6.0 Module Overview
6.1 Growing Pains
6.2 The Fitness Test
6.3 Pillars and Trusses
6.4 She’ll Grow Out of It
6.5 The Joint That Swelled With the Fever
6.6 Five Percent a Week
6.7 Broken, Mended, Read Whole
6.8 Conclusion and Assessment
6.9 The Evidence Behind the Case
All Modules
- Anatomical Language, Membranes & Homeostasis
- Just Enough Chemistry
- The Cell & Its Transport
- Making Cells & Proteins
- The Integumentary System
- The Skeletal System
- The Muscular System
- Nervous Tissue & the Senses
- The Spinal Cord
- The Brain & the Blood–Brain Barrier
- The Autonomic Nervous System
- Special Senses (in developmentThe process of growth and differentiation.)
- The Endocrine System
- Blood
- The Heart
- Blood Vessels
- The Digestive System
- The Respiratory System
- The Urinary System
- Fluids, Electrolytes & Acid–Base Balance
- The Reproductive System
- The Immune System
List of terms
- femur
- skin
- anterior
- erythema
- anatomy
- physiology
- sternum
- ribs
- tibia
- epiphysis
- compact bone
- spongy bone
- articular cartilage
- diaphysis
- medullary cavity
- epiphyseal plate
- cartilage
- epiphyseal line
- arteries
- diploë
- red marrow
- cells
- trabecula
- endosteum
- collagen
- central canals
- osteons
- thin skin
- section
- growth
- perforating canal
- development