Synarthosis vs. Synovia: Blame a Swiss Physician

Every once in a while, I get to dig into anatomy and physiology. While I'm not super great at remembering specifics, I have always been a "word nerd," relying on my knowledge of prefixes, word roots, and suffixes to work out what a strange word means. Usually, this works really well.

And then I got to the words "synarthrosis" and "synovial" and my usual strategies flew out the window:

Synarthrosis, noun: "an immovable articulation in which the bones are united by intervening fibrous connective tissues."

Synovial fluid, noun: "a transparent viscid lubricating fluid secreted by a membrane of an articulation, bursa, or tendon sheath;" synovia, noun: "a lubricating fluid resembling the white of an egg."

A synarthrosis or synarthrotic joint, which is held together by fibrous connective tissues and is relatively immovable, does not have a membrane that secretes synovial fluid. However, synovial joints, which do have synovial fluid and are freely movable, are considered diarthrotic.

In my frustration, I reached out to a college friend of mine ("L.B.," below) who teaches Latin, by essentially asking, "Why are these words like this???"

L.B.: "Why are they so similar?"

B.I.: "Yeah, so, in anatomy and physiology, we have synovial joints -- a synovial cavity and membrane that secrete synovial fluid, right? But we can also classify joints by how movable they are. Synarthrotic joints have little to no movement, amphiarthrotic have some movement, diarthrotic are fully movable."

L.B.: "It's what happens when a random Swiss dude [arbitrarily] makes up words by mashing Latin and Greek together (synovial)."

B.I.: *laugh-emoji-with-tears*

L.B.: "Synarthrotic is Greek. Syn means 'with,' the artho part is 'joint.' Syn is a Greek prefix but scientists don't care about that so it's also new Latin to mean 'with' and ova is 'eggs' and it's egg-like in color.

"But I was only partially joking... 'Mid 18th century: from modern Latin synovia, probably formed arbitrarily by Paracelsus.' Whereas the other is from the 1500s as a [first] use and developed in the anatomy community naturally."

B.I.: "gdi, Paracelsus."

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"Paracelsus (c. 1493 – 24 September 1541), born Theophrastus von Hohenheim (full name Philippus Aureolus Theophrastus Bombastus von Hohenheim), was a Swiss physician, alchemist, lay theologian, and philosopher of the German Renaissance.

He was a pioneer in several aspects of the 'medical revolution' of the Renaissance, emphasizing the value of observation in combination with received wisdom. He is credited as the 'father of toxicology'." -- Wikipedia, accessed 4/18/2025.

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So, just to recap:

• Synarthrotic Joints -- Typically immovable & fibrous, such as the sutures between cranial bones.
• Amphiarthrotic Joints -- Slightly movable & cartilaginous, such as the pubic symphysis and the joints between vertebral bodies.
• Diarthrotic Joints -- Freely movable within a synovial capsule filled with synovial fluid, such as your shoulder, knee, and hip joints.

... gdi, Paracelsus.

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