Side view of skull. Mastoid process shown in red.
|Latin||processus mastoideus ossis temporalis|
|Anatomical terms of bone|
The mastoid process is a conical prominence projecting from the undersurface of the mastoid portion of the temporal bone. It is located just behind the external acoustic meatus, and lateral to the styloid process.
This part of the skull projects from the temporal bone and is roughly pyramidal or conical in shape. It is also filled with cavities called "air cells".
Variation in humans
Its size and form vary somewhat; it is larger in the male than in the female.
The mastoid process is absent or rudimentary in the neonatal skull. It forms postnatally, as the sternocleidomastoid muscle develops and pulls on the bone.
One important role for this bone is as a point of attachment for several muscles - the splenius capitis, longissimus capitis, digastric posterior belly, and sternocleidomastoid. These muscles are one reason the mastoid process tends to be larger in men, because men have bigger muscles as a general rule and thus require larger points of attachment.
The term “mastoid” is derived from the Greek word for “breast,” a reference to the shape of this bone.
- This article uses anatomical terminology; for an overview, see anatomical terminology.
Base of skull. Mastoid process labeled at middle left.
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- lesson5 at The Anatomy Lesson by Wesley Norman (Georgetown University)