Mastoid Process
Definition
The conical projection inferior to the external auditory meatus on the temporal bone. Attachment for sternocleidomastoid and splenius capitis muscles. Scored 1 (small, female) to 5 (large, male) on the Walker scale; the highest individual discriminating trait.
- Sex dimorphism indicator
- Males show larger, longer, more rugged mastoid processes; females show smaller, smoother ones
- Walker scale scoring
- Ranges from 1 (small, female) to 5 (large, male); rated as the highest individual discriminating trait for skeletal sex estimation
- Anatomical location
- Conical projection on the temporal bone, posterior and inferior to the external auditory meatus
Common questions
Why is the mastoid process useful for determining biological sex?+
The mastoid process shows clear sexual dimorphism. In males it is larger, longer and more rugged due to greater muscle attachment and bone robustness. In females it is smaller and smoother. According to the Walker scale used in forensic anthropology, this is one of the highest individual discriminating traits for sex estimation from the skull.
Where exactly is the mastoid process located?+
The mastoid process is a conical projection on the temporal bone positioned behind and below the ear (inferior to the external auditory meatus). It's easily palpable on a living person as a bony bump behind the ear.
What muscles attach to the mastoid process?+
Two major muscles attach here: the sternocleidomastoid and the splenius capitis. These muscles control head and neck movement. The size and robustness of the mastoid process reflects the strength demands placed on these muscle attachments, which is why it varies by sex.
Related terms
- Glabella
- The midline prominence on the frontal bone between the superciliary arches. Scored 1 (flat, female) to 5 (highly prominent, male). Correlated with...
- Biological Profile
- The four-part osteological description of an unidentified individual: sex, age range, population affinity (ancestry), and estimated stature. The profile constrains the pool...
- Cranial Robusticity
- The overall size and prominence of bony surface features on the skull, reflecting body size and musculature. Males are on average more...
- Epiphyseal Fusion
- The obliteration of the cartilaginous growth plate and bony union of the epiphysis with the diaphysis. Fusion sequence and timing form the...
- FORDISC
- Forensic Discriminant Computer program, developed by Ousley and Jantz at the University of Tennessee Knoxville. Performs discriminant-function analysis on user-supplied craniometric measurements...
- Forensic Anthropology
- The laboratory and scene-side discipline concerned with the analysis of skeletal and decomposed remains to establish biological profile, manner of death, trauma,...
- Gonial Angle
- The angle at the posterior inferior corner of the mandible (gonion) where the ramus meets the body. Males: more acute and everted;...
- Gustafson Method
- Dental ageing method based on six progressive changes in a single tooth: attrition, periodontosis, secondary dentine, cementum apposition, root resorption and root...
- Haversian System (Osteon)
- Cylindrical structural unit of compact bone with a central Haversian canal, concentric lamellae and osteocytes in lacunae; pattern and canal density differ...
- Mental Eminence
- The bony chin prominence of the mandible. Scored 1 (slight, triangular, female) to 5 (pronounced, squared, male). Used both in cranial scoring...
- Nuchal Crest
- The raised area on the posterior occiput at the attachment of the nuchal muscles (trapezius, semispinalis capitis). Scored 1 (smooth, female) to...
- Regression Formula
- Linear equation of the form Stature = a + b × bone length (in cm), used to estimate living stature from a...
Explained in these topics
- Sex Estimation from the Skull and MandibleThe conical projection inferior to the external auditory meatus on the temporal bone. Attachment for sternocleidomastoid and splenius capitis muscles. Scored 1...
- Skeletal Remains: Species, Sex, Age, Stature and IdentificationConical projection behind the ear on the temporal bone; larger, longer and more rugged in males, smaller and smoother in females.