anatomy · section one
the skeleton
206 bones · 237 joints
Point at the drawing, or search for a bone by any name you know it by. Choosing one marks it in ink and turns everything it joins onto green, because a bone on its own tells you almost nothing — what it does is decided by what it is attached to.
green marks what it joins onto
“atlas (c1). one of them.”
axial skeleton · spine
Atlas (C1)
Atlas · one of them · also called C1, first neck bone, first cervical vertebra
It carries the whole weight of the head and lets you nod yes, because the base of the skull rests in two shallow cups on its upper surface. You cannot feel the ring itself, but press into the soft hollow just below and in front of the bony bump behind your ear and the hard nub you meet is the tip of its side wing.
it has no body and no disc above or below it - that missing block became the peg of the axis beneath
what it joins onto
- atlanto-occipital jointsynovial condylar (egg-in-cup)nodding - tips the head forward and back to say yes
- median atlanto-axial jointsynovial pivotpivot - turns the head left and right to say no
- lateral atlanto-axial jointssynovial planegliding - carries the head round as it turns
62 entries, 206 bones