It refers to the posterior view of the skull, that is convex upwards and on sides and flat below.
Bones
- Posterior part of parietal bones (superiorly on each side).
- Upper/squamous part of occipital bone (inferiorly).
- Mastoid part of the temporal bone (inferiorly on each side).
Sutures
- Lambdoid suture: It runs sideways and downward between the occipital bone and the two parietal bones.
- Occipitomastoid suture: It is present between the occipital bone and mastoid part of the temporal bone.
- Parietomastoid suture: It lies between the parietal bone and mastoid part of the temporal bone.
- Posterior part of sagittal suture.
Important Features
- External occipital protuberance: Median prominence in lower part of the occipital bone, about midway between lambda and foramen magnum. It marks the junction of the head and neck
- Inion: Most prominent point of external occipital protuberance.
- Occipital point: Median point located a little above the inion, it is the point farthest from the glabella.
- Superior nuchal lines: Curved bony ridges passing laterally from the protuberance.
- Inferior nuchal line: Curved bony ridges passing laterally from middle of the external occipital crest
- Highest nuchal lines: Present in some cases, these are faint bony ridges situated about 1 cm above the superior nuchal lines. They begin from the upper part of external occipital protuberance and are more arched than superior nuchal lines.
- Mastoid foramen: Present on the mastoid part of the temporal bone at or near the occipitomastoid suture. It transmits an emissary vein and meningeal branch of the occipital artery.
- Interparietal bone (inca bone): It is a large triangular bone occasionally present at the apex of the squamous part of occipital bone. It represents the membranous part of the occipital bone that has failed to fuse with the rest of the bone.
- Lambda, Parietal foramina and Obelion
References
- BD Chaurasia's Human Anatomy Volume 3 (Head & Neck), Eighth edition, CBS Publishers and Distributors Pvt Ltd
- Textbook of Anatomy Head, Neck, and Brain (Volume III), Vishram Singh
- Image Source: Wikimedia Commons. Author: MAKY.OREL. This file is made available under the Creative Commons CC0 1.0 Universal Public Domain Dedication.
*This article is an excerpt from the above mentioned sources and Medical Sutras does not make any ownership or affiliation claims.