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.
The mastoid process projects from the temporal bone in the skull and is roughly pyramidal or conical in shape. It is also filled with cavities called "air cells" known as sinuses. On the medial side of the mastoid process is a deep groove, the mastoid notch (also known as the digastric fossa), for the attachment of the digastric muscle.
Variation in humans
Its size and form vary somewhat; it is larger in the male than in the female.
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 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.
Base of skull. Mastoid process labeled at middle left.
|Wikimedia Commons has media related to Mastoid process.|
- lesson5 at The Anatomy Lesson by Wesley Norman (Georgetown University)
- Diagram - #5 (source here)
- Anatomy diagram: 34257.000-1 at Roche Lexicon - illustrated navigator, Elsevier