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Craniometric points (in alphabetical order)




The ANS corresponds to the anterior nasal spine. At the level of ANS is situated another craniometric point, called acanthion, which is the most forward point of the anterior nasal spine.



The asterion is located at the confluence point of the lambdoid, parietomastoid and the occipitomastoid suture.

Morphometric studies

In adults it is ± 20 mm distant from the internal acoustic meatus, ± 31 mm from the posterior clinoid process, ± 34 mm from the dorsum sellae, ± 19 mm from the jugular foramen, ± 23 mm from the hypoglossal canal, ± 28 mm from the zygomatic root, ± 22 from the Henle's spine, ± 15 mm from the mastoid process, and ± 36 mm from the external occipital protuberance.

Relationship with anatomical structures

The right asterion is located below (14%), in correspondence (85%) and above (less than 1%) the junction of transverse and sigmoid sinuses. The left asterion is located below (8%), in correspondence (88%) and above (4%) the junction of transverse and sigmoid sinuses.



Basion corresponds to the anterior margin of the Foramen Magnum at midline. It is the attachment point of the apical ligament at the level of craniovertebral junction. The distance between the basion and the Sellar Point varies by gender, in particular, it is higher in males.

Relationship with anatomical structures

The basion and the opisthion serve as Landmarks to localise cerebellar tonsils. In particular the inferior margin of cerebellar tonsils is located immediately above the virtual line joining the basion and the opisthion (McRae line).



The bregma is the craniometric point located at the junction of the coronal and the sagittal sutures.

Relationship with anatomical structures

The bregma is 5 cm distant to the SRP (Superior Rolandic Point), which identifies the superior end of the central fissure.
In infants, the bregma corresponds to the anterior (or bregmatic) fontanelle. The anterior fontanelle is a membranous structure which ossifies within 4-26 months of life. The clinical evaluation of infants must always include palpation of the anterior fontanelle: a depressed fontanelle indicates dehydration, a tense fontanelle indicates an intracranial hypertension.



The dacryon is located at the anterior and the superior angle of the lacrimal bone, at the junction of the frontal bone.

Morphometric studies

The line joining the right and the left dacryon corresponds to the interorbital distance, ± 25 mm in male, ± 28 mm in female. The dacryon is a landmark for the localization of the posterior and the anterior ethmoidal artery: it is ± 21 mm distant from the anterior ethmoidal foramen and ± 34 mm from the posterior ethmoidal foramen.



The eurion is located at the central point of the parietal eminence. The distance between the right and the left eurion corresponds to the biparietal diameter. The ratio between the biparietal diameter, multiplied by 100, and the distance between the glabella and opisthocranion (anteroposterior diameter) defines the cephalic index.



Glabella is located in the flat area between the superciliary arches.



The gonion is located at the apex of the jaw angle. It can be used for the localization of the MMN (Marginal Mandibular Nerve), that runs along the inferior margin of the jaw: the gonion is ± 0.75 mm above the MMN.



Inion is the craniometric point which corresponds to the external occipital protuberance.

Relationship with anatomical structures

The external occipital protuberance in turn corresponds intracranially to the internal occipital protuberance, which identifies the endinion, another craniometric point. The endinion is located at the level of sinuses confluence (superior sagittal sinus, rectus sinus, occipital sinus and transverse sinus).

Morphometric studies

The distance between the inion and the opisthocranion is ± 2 cm, whereas the distance between the inion and the inferior nucal line is ± 13 mm.



Lambda is located at the junction of the saggital the lambdoid sutures. In infants it corresponds to the posterior (or lambdoid) fontanelle. The lambda can be used as a landmark to identify the cuneus.

Morphometric studies

The distance between the lambda and the Opisthocranion is ± 3 cm.



The menton corresponds to the lower point of the mental tuberosity.



The nasion is located at the midpoint of the nasofrontal suture.

Morphometric studies

The distance between the nasion and the tuberculum sellae and between the nasion and the inion are used as morphologic index of the human skull base during the development. The minimum distance between the nasion and the anterior cranial fossa, in adults, is between 13 mm and 20 mm, while the minimum distance between nasion and the frontal sinus, in adults, is between 2 mm and 10 mm.



Obelion is located on the sagittal suture at the level of parietal foramens.



The ophryon is a craniometric point located at the level of the forehead at the midline. It corresponds to the minimum distance between the point where the inferior and the superior temporal lines are closest and the midline.



Opisthion corresponds to the posterior margin of the Foramen Magnum at midline. It is used to define the Occipital Angle. The opisthion identifies the level of the cervico-medullary junction.

Relationship with anatomical structures

Furthermore, the basion and the opisthion can be used as Landmark to localise the cerebellar tonsils. In particular, the inferior margin of cerebellar tonsils is located immediately above the virtual line joining the basion and the opisthion (McRae line)



Opisthocranion corresponds to the most posterior point of the occipital bone. Frequently it is located at level of the superior occipital squama and only rarely it corresponds to the external occipital protuberance. Opisthocranion is also defined as the most distant point, on the cranial vault, from the Glabella.

Morphometric studies

This distance defines the maximum skull diameter and in adults it is ± 180 mm. The opisthocranion is ± 3 cm distant to the Lambda. It is used as a landmark to localise the calcarine fissure.



The PNS corresponds to the posterior nasal spine. It is formed by the union, at midline, of two medial protrusions localized at the level of the posterior edge of the horizontal plates of palatine bones.



The pogonion corresponds to the most forward point of the mental tuberosity. The pogonion is one of the landmarks used for identification of the Holdaway's H angle, which is the angle between a line from the pogonion to the nasion and a line from the pogonion to the most forward point of the upper lip (in adults ± 10°).



From greek poròs, “passage”. The porion is located at the highest and most external point of the external acoustic meatus. It is a landmark for the frontotemporal branch of the facial nerve.

Morphometric studies

In particular, the frontotemporal branch of the facial nerve in adults is ± 12 mm distant from the porion along both the supraorbitomeatal line (SOML) and the infraorbitomeatal line (IOML).

Relationship with anatomical structures

The porion corresponds intracranially to the posterior branch of the middle meningeal artery (MMA).



Prosthion is located at the most forward point of the maxillary alveolar process, at the midline.



From greek pteròn, “wing”. It corresponds to the area where the large sphenoid wing articulates with the parietal bone, the frontal bone and the squamous part of temporal bone. It is H-shaped. There are four morphological types of pterion: sphenoparietal, frontotemporal, starry and epipteric.

Morphometric studies

Morphometric studies show that its location in adults is ± 40 mm distant from the midpoint of the zygomatic arc, ± 31 mm from the frontozygomatic suture and ± 78 mm from the glabella.

Relationship with anatomical structures

The midpoint of the pterion corresponds to the superior branch of the middle meningeal artery (MMA) in 68% of cases, while in a smaller percentage of cases the midpoint of the pterion is located anterior to this branch. The pterion corresponds intracranially to the lateral (Sylvian) fissure.


Sellar Point

The sellar point corresponds to the geometric centre of the sella turcica.



Staphylion is the craniometric point located at the midpoint of the hard palate, just before the PNS.



The stefanion is the intersection point between the coronal suture and the superior temporal line.



Vertex is the highest craniometric point, at the midline, from the Frankfurt plane.

Relationship with anatomical structures

The topographic relation between the vertex and the parietal lobe changes during the development. Unlike the adulthood, in childhood the parietal lobe is located posterior to the vertex. The vertex, the coronal suture and the lambdoid suture can be used as landmarks to assess the number, the localization and the dimension of tributaries veins of the SSS (Superior Sagittal Sinus), in order to reduce possible complications related to neurosurgical interhemispheric approaches. The average number of tributary veins to the SSS before the CS (Coronal Suture) is 3, between the CS and the Vertex is 3, and between the Vertex and the LS (Lambdoid Suture) is 2, with no significant differences between left and right.

Morphometric studies

The diameter of veins before the CS is ± 2.5 mm, between the CS and the Vertex is ± 3.0 mm, between the Vertex and the LS is ± 2.5 mm, and between the LS and the confluence of sinuses is ± 2 mm.




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Federico Nicolosi, MD

University of Milan
"Spedali Civili" Hospital Brescia (Italy)
Scientific Team - UpSurgeOn


Edoardo Agosti, MS

Medical Student 
University of Brescia (Italy) 
Scientific Team UpSurgeOn