sphenic

Sphenic is an adjective derived from the Greek sphen-, meaning wedge-shaped. The term is used in different disciplines to describe wedge-like forms or structures associated with the sphenoid bone of the skull, a central wedge-shaped bone at the base of the skull.

In anatomy, the sphenoid bone is a central, butterfly- or wedge-shaped bone located at the skull base; the adjective sphenic can be used to describe features relating to this bone, though the more common term is sphenoid.

In number theory, sphenic numbers are positive integers that are the product of three distinct prime numbers. Equivalently, n = p q r with p, q, r primes and all different. Such numbers are squarefree and have exactly eight positive divisors. The sequence begins with 30 (2 × 3 × 5), 42 (2 × 3 × 7), 66 (2 × 3 × 11), 70 (2 × 5 × 7), and continues with other products of three distinct primes.

See also sphenoid bone; sphenic numbers.