[The temporal periosteum: anatomical study and surgical implications]

Could mastication modify the shape of the orbit? A scannographic study in humans

PURPOSE

Since prehistory, changes of the facial skeleton have been related to the modification of diet. More recent studies have shown changes in the morphology of the mandible and maxilla due to variations of strain during mastication. The temporal muscle (TM) is a strong masticatory muscle, with its insertions extending through the temporal fossa. Our objective is to observe the relations between the TM and the lateral orbital wall (LOW) which could indicate an influence of mastication on the shape of the LOW.

METHODS

We conducted a retrospective study using 100 CT scans. The length of the lateral orbital wall (LLOW), the angle between LOW and the medial orbital wall (MOW), the cross-sectional areas of LOW and of the TMs were measured on both sides of each CT scan. The correlation between TMs and other three parameters was studied by Pearson correlations.

RESULTS

A correlation was found between TMs and LOWs, a lower with LLOW, and a very weak and negative correlation between LOW/MOW angle.

CONCLUSIONS

Anatomical knowledge about TM and investigation of masticatory strains lead us to think that mastication have minimal effect on the morphology of the LOW, only on the frontal process of zygomatic. This may explain, in part, why the LOW is the strongest wall of the orbit.

[Orbital fractures in children]

The aim of this article is to review data concerning paediatric orbital fractures. These fractures exhibit strong specificities because they occur in a growing face. Due to the craniofacial growing pattern and the peumatization of paranasal sinuses, there are differences in the anatomical location of orbital fracture with the age: before the age of seven they are mostly orbital roof and after seven they involve the orbital floor. The clinical diagnosis is confirmed with a computed tomography scan (CT scan), gold standard for the imaging in the orbital fractures. The magnetic resonance imaging (MRI) offers a better soft-tissue depiction and is useful when clinical data are not consistent with CT scan findings. The orbital fractures in children are rarely operated. In emergency the main surgical indications are the trap-door fracture involving the ocular muscles and the compressive haematomas. We hypothesize that the periosteum more likely than the bony structure is involved in the responsible trap-door fractures: the thickness and the elasticity of the periosteum leads to reposition the floor or the medial wall of the orbit to its initial position.