Accessory occipital bone sutures
The occipital bone has complex development, it ossifies from six centers. The foramen magnum is surrounded by four ossification centers. On each side are the exoccipitals, ventrally located is the basoccipital and dorsally, the supraoccipital center contains the midline occipital fissure which can sometimes persist antenatally. This pattern of development can therefore give rise to numerous accessory sutures that could be mistaken for fractures especially with plain film evaluation alone.
It`s important to know these anatomic informations mainly on the head trauma image studies in children, where colud be difficult make the difference of non-depressed skull fractures and an accessory sutures.
Radiographic differentiation of skull fracture and accessory suture
Accessory sutures usually:
- Make a "zig-zag" pattern with interdigitations;
- Have sclerotic borders similar to major calvarial sutures;
- Are often present on both sides and are fairly symmetric especially in the parietal bones. Occipital accessory sutures can be complex and multiple but are also frequently bilateral.
Simple non-depressed skull fractures usually:
- Have sharp lucencies with non-sclerotic edges;
- Widening as it approaches the suture or there is associated diastasis of the adjacent synchodrosis or suture;
- Can cross suture lines or extend from one major suture to another (in high impact fractures);
- Have a soft tissue swelling or hematoma associated. (However, absence of subgaleal hematoma or swelling does not entirely rule out a fracture especially if the injury is remote or imaging was performed several days after the trauma).
Synonyms & Alternative Spellings
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|Occipital ossification centers||✓|