25 Days of Skeletal Facts: Day 25 – The Sphenoid

Sphenoid (yellow) in situ

Happy Christmas everyone! Today I wanted to focus on my favorite bone, the sphenoid. Honestly, I like the look of confusion and maybe slight horror people have when I tell them it is the bone behind their eyes. The sphenoid is an unpaired bone of the the neurocranium (see yesterday’s post and the image to the left) and its foramena (holes through the bone) transmit many important blood vessels and branches of cranial nerves from the brain to different areas of the head. The word sphenoid is derived from the Greek sphenoeides meaning wedge. Most students I have worked with see a butterfly or a bat when looking at a disarticulated sphenoid.

The sphenoid is also the resting place for the pituitary gland, which sits in the sella turcica (see image below), or the ‘Turkish saddle’. Hormones from this gland help regulate a variety of essential processes related to growth, energy, sexual activity, and metabolism to name a few. If pituitary tumors get too large they can actually start to erode the bone. Bioarchaeological research has also indicated that the greater wing of the sphenoid may be diagnostic for cases of scurvy, caused by a severe deficiency in vitamin C (Ortner & Putschar 1985). For more on scurvy, see the post A Pirate’s Life for Me: The Bioarchaeology of Scurvy. Advanced stages of scurvy can appear as new bone formations, spicules, and abnormal porosity on the bones of the skull, especially if it appears on more than one of the following elements: the orbits, mandible, maxilla, hard palate, parietals, the occipital, and the sphenoid.

Sphenoid with labeled features

That’s a wrap on my favorite bone, the sphenoid. Thank you so much for joining me in a celebration of winter cheer meets skeletal anatomy. I hope that you learned something new and now have some fun facts to share with family and friends this holiday season.

Happy Hanukkah, Christmas, Kwanzaa, Festivus, Winter Solstice and anything and everything else you celebrate!


The Sphenoid Bone. TeachMe Anatomy Series. 2020

Skeletal manifestations of infantile scurvy. Brickley & Ives. American Journal of Physical Anthropology. 2007

Identification of pathological conditions in human skeletal remains. Ortner & Putschar. Smithsonian Institution Press. 1985

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