Cranial landmarks are osseous features that can be observed on the external aspect of the skull as various formations, such as elevations and depressions. Most of these landmarks are formed at sites where several sutures intersect.

The skull presents with the following cranial landmarks:

Bregma - a midline bony landmark that is formed on the anterior aspect of the calvaria; it is found at the intersection of the coronal suture and sagittal suture (between the frontal bone and both parietal bones); it represents the site of the frontal (anterior) fontanelle;
Lambda - another midline bony landmark that is formed at the convergence between the sagittal suture and lambdoid suture (between the occipital bone and both parietal bones); it represents the site where once the occipital (posterior) fontanelle was located;
Vertex - the highest bony landmark of the skull; it can be defined as a single midline landmark that is found on the top of the calvaria between the bregma and lambda, almost at the midpoint of the sagittal suture;
Obelion - formed at the intersection of the sagittal suture and an imaginary line that connects both parietal foramina; it represents the site at which the fusion and ossification of the sagittal suture has started;
Pterion - a bilateral landmark seen on the lateral sides of the skull and found at the anterior end of the squamous suture; it appears as an H-shaped formation and represents the junction of four bones (the greater wing of the sphenoid, squamous part of the temporal bone, frontal bone and parietal bone); It is formed by the intersection of the sphenofrontal suture, coronal suture, sphenoparietal suture, sphenosquamous suture, and squamous suture; this is clinically relevant landmark due to the many junctions; also, it is a weak spot of the skull and prone to fractures; directly underneath it is the middle meningeal artery (branch of the maxillary artery), and trauma to the pterion can rupture it, causing epidural hematoma; in neurosurgery, this landmark is a common approach to the middle cranial fossa;
Asterion - found on the posteroinferior part of the skull at the junction of the parietomastoid suture, occipitomastoid suture, and lambdoid suture (junction site between the temporal, parietal, and occipital bones); additionally, it represents the site of the closed mastoid fontanelle; it is found at the posterior end of the parietomastoid suture;
Porion - a paired point that is found on the lateral aspect of the skull; it represents the most lateral part of the superior margin of the external auditory meatus;
Glabella - a small midline elevation above the nasal bones between both superciliary arches; it is the most prominent point of the forehead;
Dacryon - a point of intersection of the lacrimomaxillary suture, frontolacrimal suture, and frontomaxillary suture; it is found on the medial wall of the bony orbit and can also be defined as the midpoint at which the frontal bone, maxilla, and lacrimal bone meet;
Nasion - a midline bony depression between both orbits below the glabella; it is the site at which the frontal and both nasal bones meet;
Nasospinale - the lowest point on the inferior border of the anterior nasal aperture; it is found at the anterior nasal spine;
Prosthion - the most anterior point that is found on the alveolar arches of the maxillae between the central incisors.

All these cranial landmarks primarily serve as surgical landmarks and craniometric points in radiology, neurosurgery, and anthropology. Additionally, cranial landmarks are used in forensic medicine.

Unlock with Premium

Cranial landmarks (part 1)