Figure 4.
Hypoplasia of the left superior oblique muscle and an absence of the left fourth cranial nerve. Coronal T2-weighted orbital image showing that the left superior oblique muscle (red arrow) is smaller than the right (yellow arrow), suggesting hypoplasia (A). A high-resolution image shows that the right fourth cranial nerve (arrow) is well-identified; however, the left fourth cranial nerve is not visible (B).