Reasonable classical concepts in human lower limb anatomy from the viewpoint of the primitive persistent sciatic artery and twisting human lower limb

Abstract

Summary:The main aim of this review is (1) to introduce the two previous studies we published human lower limb anatomy based on the conventional macroscopic anatomical criteria with hazardous recognition of this description, (2) to activate the discussion whether the limb homology exists, and (3) to contribute to future study filling the gap between the gross anatomy and embryology.One of the topics we discussed was the human persistent sciatic artery. To date, numerous human cases of persistent sciatic artery have been reported in which the anomalous artery was present in the posterior compartment of the thigh alongside the sciatic nerve. As one of the important criteria for assessing the human primitive sciatic artery, its ventral arterial position with respect to the sciatic nerve is reasonable based on the initial positional relationship between ventral arterial and dorsal nervous systems and comparative anatomical findings. We also discuss ways of considering the topography of muscles of the lower limb and their innervations compared to those of the upper limb. We propose a schema of the complex anatomical characteristics of the lower limb based on the vertebrate body plan. According to this reasonable schema, the twisted anatomy of the lower limb can be understood more easily.These two main ideas discussed in this paper will be useful for further understanding of the anatomy of the lower limb and as a first step for future. We hope that the future study in lower limb will be further developed by both viewpoints of the classical gross anatomy and recent embryology.

An artery accompanying the sciatic nerve (arteria comitans nervi ischiadici) and the position of the hip joint: a comparative histological study using chick, mouse, and human foetal specimens

“…Usually, the femoral artery replaces the main arterial trunk by joining the popliteal artery. The sciatic artery in birds and reptiles runs anteriorly to the sciatic nerve [13,17]. Although many reports have referred to the "persistent sciatic artery" (see Introduction), the sciatic artery proper seems to be very rare in adults (4 out of 1724 cadavers, 0.23%) [20] when it is defined as running a course anterior to the sciatic nerve in the thigh.…”

“…Moreover, vascular surgeons have recently drawn attention to aneurysms of this accompanying artery as a cause of leg pain or paralysis, such reports [6,18,22,25,34] having increased significantly in number since the year 2000. Kawashima and Sasaki [17] considered that most of these reported arteries were not a true remnant of the primitive sciatic artery, but rather a secondarily developed collateral branch, because of its course running posterior to the sciatic nerve. Does the foetal sciatic nerve have an accompanying space that would favour secondary development of a longitudinal artery?…”

“…Thus, the sciatic artery as well as the femoral artery may be able to take a short-cut course from the pelvis to the knee without running along the extended aspect. According to Kawashima and Sasaki [17], unlike the longitudinal artery accompanying the human sciatic nerve (the so-called persistent sciatic artery; see the paragraph above), the sciatic artery in birds and reptiles runs along the anterior side of the sciatic nerve. People may consider that the difference in the arterial origin connects with that in the arterial course.…”

Human fetal topographical anatomy of the femoral triangle in relation with change in the hip joint position.

“…In spite of the fetal hip joint position, some Japanese anatomists have hypothesized that a long axis of the dermatomes and myotomes (segmental nerve supplying areas) in the human lower extremity is twisted or rotated "medially" at the hip joint (Aizawa, 1992;Ogoshi et al, 2001;Kodama, 2000;Kawashima and Sasaki, 2010). According to their understanding, not only the femoral nerve branches but also the iliofemoral ligament in adults suggests the twisting or rotation in the "fetal period".…”

Novel femoral artery terminology: From complex to simple or toward more complex?

“…Embryologically, both the SFA and DFA originate from the anterior (secondary) arterial channel, eventually replacing the posterior primitive artery (sciatic artery) at the level of the thigh by joining the popliteal artery. The femoral artery and its branches are distributed to the anterior/extensor femoral muscles, together with the ventral divisions of the lumbosacral plexus; this disposition is even more evident in avian and reptilian species in which the principal artery to the lower limb is the sciatic artery (Kawashima and Sasaki, 2010).…”