Lateral View of Skull

Lateral view of the skull:

This section discusses the osteology of the lateral part of the calvaria, facial skeleton and the mandible.

The lateral portion of Calvaria begins anteriorly with the frontal bone, the paired parietal and temporal bone and ending posteriorly at the occipital bone. The frontal bone articulates with the parietal bone at the Coronal Suture and parietal bone in turn articulates with the occipital bone posteriorly at the Lambdoid Suture. Coming below, the Greater wing of the sphenoid bone articulates anteriorly with the frontal bone, superiorly with the parietal bone (sphenoparietal suture), posteriorly with the squamous part of the temporal bone (sphenosquamous suture). This area is also referred to as the Pterion and is site of numerous clinically important facts.

The squamous part of the temporal bone is attached superiorly to the parietal bone via squamous suture and posteriorly with the occipital bone via occipitomastoid suture. The mastoid process is a visible protuberance of the temporal bone, behind the external acoustic meatus and provides attachment site for several muscle.

Laterally the visible part of the Facial skeleton is formed by the nasal bones, the maxilla (discussed in previous section) and the zygomatic bone. The zygomatic bone is an irregular shaped bone that contributes –medially- in the formation of the inferio-lateral part of the orbital rim. Laterally the temporal process of the zygomatic bone arches out and meets posteriorly with the zygomatic process of the temporal bone to for the zygomatic arch. The zygomatic arch encloses the temporal fossa and below the infra-temporal fossa. The zygomaticofacial foramen can be usually seen on the body of the zygomatic bone along with the zygomaticotemporal foramen.

Now let’s briefly review some of the important bones i.e. the temporal bone and the mandible.

The Temporal bone:

  

It is and irregular shaped bone with many parts and forms most of the lateral wall of the Calvaria. Briefly it has squamous, tympanic, petro-mastoid parts.

·         The squamous part of the temporal bone is the large flat surface above the zygomatic arch that is visible in the lateral view of the skull. It is attached anteriorly to the greater wing of the sphenoid bone through sphenosquamous suture. And superiorly with the parietal bone through squamous suture.

·         The tympanic part can be seen below the zygomatic arch. It houses the external acoustic meatus. The styloid process can be seen behind the tympanic part of the temporal bone as small bony projections.

·         The petro-mastoid part is usually separated into two, the petrous part and the mastoid part. The mastoid part is the posterior most region of the temporal bone. Superiorly it articulates with the parietal bone (parietomastoid suture) and posteriorly with the occipital bone (occipitomastoid suture). Point where these two sutures meet the lambdoid suture is called Asterion. Inferiorly, the mastoid process is a large bony projection that provides attachment site for many muscles. The Petrous part of the temporal bone will be discussed in detail when we will look at the skull inferiorly. On the underside of the temporal bone –adjacent to styloid process- are numerous foramen for facial and hypoglossal nerve, external carotid artery and internal jugular vein.

·         The zygomatic process of the temporal bone forms most of the zygomatic arch. On its underside is a curved depression for the articulation of the condyle of the mandible at the temporomandibular joint. The zygomatic arch encloses the temporal fossa and the infra-temporal fossa.