Inion
Encyclopedia
The inion is the most prominent projection of the occipital bone
at the posterioinferior (lower rear) part of the skull
. The ligamentum nuchae
and trapezius muscle
attach to it.
The term external occipital protuberance (protuberantia occipitalis externa) is sometimes used as a synonym
, but more precisely the term "inion" refers to the highest point of the external occipital protuberance
.
Occipital bone
The occipital bone, a saucer-shaped membrane bone situated at the back and lower part of the cranium, is trapezoidal in shape and curved on itself...
at the posterioinferior (lower rear) part of the skull
Human skull
The human skull is a bony structure, skeleton, that is in the human head and which supports the structures of the face and forms a cavity for the brain.In humans, the adult skull is normally made up of 22 bones...
. The ligamentum nuchae
Nuchal ligament
The paxwax or nuchal ligament is a fibrous membrane, which, in the neck, represents the supraspinal ligaments of the lower vertebræ...
and trapezius muscle
Trapezius muscle
In human anatomy, the trapezius is a large superficial muscle that extends longitudinally from the occipital bone to the lower thoracic vertebrae and laterally to the spine of the scapula...
attach to it.
The term external occipital protuberance (protuberantia occipitalis externa) is sometimes used as a synonym
Synonym
Synonyms are different words with almost identical or similar meanings. Words that are synonyms are said to be synonymous, and the state of being a synonym is called synonymy. The word comes from Ancient Greek syn and onoma . The words car and automobile are synonyms...
, but more precisely the term "inion" refers to the highest point of the external occipital protuberance
External occipital protuberance
Near the middle of the occipital squama is the external occipital protuberance, and extending lateralward from it on either side is the superior nuchal line, and above this the faintly marked highest nuchal line.It is less pronounced in females....
.