How Many Bones Are in the Human Body? The Count That Changes as You Grow
A typical adult has 206 bones, though the real number varies slightly from person to person because small accessory and sesamoid bones are common.…
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Blog Category
Body & Anatomy
Clear explainers on how the body works, organ by organ and system by system. Knowing the anatomy makes symptoms, scan reports and treatment plans far easier to follow when you talk with your doctor.
Why Do Your Ears Pop? Pressure, Altitude and the Tube That Fixes It
Ears pop when the eustachian tube, a narrow passage connecting the middle ear to the back of the nose, briefly opens and equalizes air…
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The Dominant Eye Test: Find Yours in 30 Seconds (and Why It Matters)
To find your dominant eye, stretch both arms out and overlap your hands to form a small triangle. With both eyes open, center a…
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Why Do We Cry? The Three Kinds of Tears and What Each Is For
Humans cry for three different reasons, and each produces a distinct tear. Basal tears constantly coat and protect the eye, reflex tears flush out…
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How Long Does Food Stay in Your Stomach? A Timed Tour of Digestion
A typical mixed meal stays in the stomach for roughly two to five hours before emptying into the small intestine, about half of…
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How Many Valves the Heart Has, and What They Do
The human heart has four valves: the tricuspid, pulmonary, mitral, and aortic valves. Each is a set of thin tissue flaps that opens to…
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Why Rabies Causes a Fear of Water: Hydrophobia Explained and Why Prevention Matters
Rabies causes hydrophobia because the virus damages the brainstem centers that coordinate swallowing. When a person tries to drink, the throat and breathing muscles…
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Are Yawns Really Contagious? What Mirror Neurons Have to Do With It
Yes, for many people, yawns are genuinely contagious. In laboratory studies, roughly half to two-thirds of adults yawn after watching, hearing, or even reading about…
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How Fast Do Fingernails Grow? The Speed of You, Measured
Fingernails grow about 3 to 3.5 millimeters per month, roughly 0.1 millimeter a day, or close to 1 millimeter a week. A completely…
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The Popliteal Fossa: What Sits Behind the Knee and What Swells There
The popliteal fossa is the diamond-shaped hollow behind the knee, framed by the hamstring tendons above and the two heads of the calf muscle…
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The MTP Joint: The Big-Toe Joint Behind Bunions and Turf Toe
The MTP (metatarsophalangeal) joint is where each long metatarsal bone of the foot meets the base of a toe. The first MTP joint, at…
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Metacarpal Bones: The Hand Fractures Surgeons See Most
Metacarpals are the five long bones of the palm, linking the wrist to the fingers, and they account for roughly a third of all…
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The Sacral Region: The Base of the Spine and the Pain That Starts There
The sacral region is the base of the spine: the sacrum, a triangular bone formed by five vertebrae (S1–S5) that fuse in early adulthood.…
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How Many Ribs Do Humans Have? The Anatomy and the Myths
Nearly all humans, women and men alike, have 24 ribs, arranged in 12 pairs. The idea that men have one fewer rib…
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The Sagittal Plane: How Doctors Describe Movement and Imaging Slices
The sagittal plane is a vertical plane that divides the body into left and right portions. Movements within it travel forward and backward, …
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The Solar Plexus: What It Actually Is (and Why a Blow There Winds You)
The solar plexus, known medically as the celiac plexus, is a dense network of nerves in the upper abdomen behind the stomach, roughly where…
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The Mediastinum: The Crowded Space in the Middle of Your Chest
The mediastinum is the central compartment of the chest, sitting between the two lungs and stretching from the breastbone back to the spine. It…
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Dorsum of the Foot: The Top of the Foot and What Pain There Usually Means
The dorsum of the foot is its top surface: the side you see when you look down, opposite the sole (the plantar side).…
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