Mastoid process

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Mastoid process
Mastoid process - lateral view.png
Side view of skull. Mastoid process shown in red.
Mastoid process
Latin processus mastoideus ossis temporalis
TA A02.1.06.004
FMA 52872
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, for the attachment of the digastric muscle.

Variation in humans[edit]

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 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.

See also[edit]

This article uses anatomical terminology; for an overview, see Anatomical terminology.

Additional Images[edit]


This article incorporates text in the public domain from the 20th edition of Gray's Anatomy (1918)

External links[edit]