Morphological analysis and morphometry of the occipital condyle and its relationship to the foramen magnum, jugular foramen, and hypoglossal canal: implications for craniovertebral junction surgery

Abstract

Anatomical knowledge of the occipital condyle (OC) and its relationships to surrounding structures is important for avoiding injury during craniovertebral junction (CVJ) surgeries. This study was conducted to evaluate the morphology and morphometry of OC and its relationship to foramen magnum, jugular foramen (JF), and hypoglossal canal (HC). Morphometric parameters including length, width, height, and distances from the OC to surrounding structures were measured. The oval-like condyle was the most common OC shape, representing for 33.0% of all samples. The mean length, width and height of OC were 21.3±2.4, 10.5±1.4, and 7.4±1.1 mm, respectively. Moreover, OC was classified into three types based on its length. The most common OC length in both sexes was moderate length or type II (62.5%). The mean distance between anterior tips and posterior tips of OC to basion, and opisthion were 11.5±1.4, 39.1±3.3, 25.2±2.2, and 27.4±2.7 mm, respectively. The location of intracranial orifice of HC was commonly found related to middle 1/3 of OC in 45.0%. JF was related to the anterior 2/3 of OC in 81.0%, the anterior 1/3 of OC in 12.5%, and the entire OC length in 6.5%. These morphological analysis and morphometric data should be taken into consideration before performing surgical operation to avoid CVJ instability and neurovascular structure injury.

Morphological analysis of the jugular foramen in dry human skulls in northeastern Brazil

“…The difference on the right and left sizes of the IJV is noticed in the human embryo at 8 weeks post conception, due to the variation of the development of the right and left brachiocephalic veins [ 10 , 22 , 26 , 27 ]. It has been noted that the right foramen is frequently larger than the left [ 6 , 22 , 28 ], fact that was confirmed in this study ( P =0.001). This may occur due to the superior sagittal sinus that could drain into the right transverse sinus [ 2 , 10 , 22 ].…”

“…The JF is an important structure at this region since it is a primary pathway for venous outflow from the skull and is a passageway for nerve structures of the peripheral nervous system through the base of the skull [ 3 ]. The following structures pass through the JF: the distal sigmoid sinus (SS), that continues as jugular bulb and the internal jugular vein (IJV), the inferior petrosal sinus, the meningeal branches of pharyngeal and ascending occipital arteries, besides the cranial nerves glossopharyngeal (CN IX), vagus (CN X) and accessory (CN XI) [ 2 , 4 - 6 ].…”

“…There is currently a lack of agreement regarding the subdivision of compartments within the JF [ 4 - 8 ]. But historically, this foramen has divided into the 2 compartments, the anteromedial pars nervosa and posterolateral pars venosa, divided by the intrajugular process [ 3 , 4 , 7 , 9 - 12 ].…”