We compare, on left and right side of human skulls, the length of Whitnall's tubercle as a relevant landmark and anchor point for the lateral retinaculum. Twenty human skulls were used in this study. A caliper was used to measure the length of Whitnall's tubercle, the distance from Whitnall's tubercle to the frontozygomatic suture and the height of the orbit. An overall mean for these three parameters was calculated using the data obtained. There were no significant differences between left and the right sides. The combined mean length of Whitnall's tubercle was 4.9 mm ± 23%. The combined mean distance from the frontozygomatic suture was 7.8 mm ± 25%. The orbital height was found to be the measurement with the highest congruence between the two sides having a combined mean of 32.3 mm ± 7%. Although 6 out of 20 skulls were found to have no tubercle, five out of twenty skulls had a tubercle only on one side. Even though human skulls develop from bilateral symmetric osteogenesis, surgeons should always be aware of possible asymmetry and possible absence of Whitnall's tubercle between sides or among individuals. The frontozygomatic suture was found to be a useful landmark in identifying the position of Whitnall's tubercle in the majority of specimens. Such information will be useful in realigning the lateral retinaculum following surgery.

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The nature, function, and anatomy of the heart have been extensively studied since 3500 B.C. Greek and Egyptian science developed a basic understanding of the heart, although this was primarily related to religious beliefs. During the Hippocratic era, Hippocrates and his colleagues developed a more scientific and less religious understanding of the cardiovascular system. The post-Hippocratic era was characterized by more advanced descriptions of the location, structure, and function of the heart. The Alexandrian, Roman, Medieval Islamic, and European eras included turning points in the history of cardiac anatomy. Subsequently, after the structure and function of the heart were established, its connection with the lungs was investigated. Description of the pulmonary circulation was followed by the discovery of the conductive system and innervation of the heart.

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The clinical implications of these various studies lie in the importance of the innervation patterns for the mechanism of spinal pain. Immunohistochemical studies have provided further evidence regarding the nature of the innervation of the spine.