The Achilles tendon (AT) consists of fascicles that originate from the medial head of the gastrocnemius (MG), lateral head of the gastrocnemius (LG), and soleus muscle (Sol). These fascicles are reported to have a twisted structure. However, there is no consensus as to the degree of torsion. The purpose of this study was to investigate the twisted structure of the AT at the level of fascicles that originate from the MG, LG, and Sol, and elucidate the morphological characteristics. Gross anatomical study of 60 Japanese cadavers (111 legs) was used. The AT fascicles originated from the MG, LG, and Sol were fused while twisting among themselves. There were three classification types depending on the degree of torsion. Further fine separation of each fascicle revealed MG ran fairly parallel in all types, whereas LG and Sol, particularly of the extreme type, were inserted onto the calcaneal tuberosity with strong torsion. In addition, the sites of Sol torsion were 3-5 cm proximal to the calcaneal insertion of the AT. These findings provide promising basic data to elucidate the functional role of the twisted structure and mechanisms for the occurrence of AT injury and other conditions.
Findings on the twisting structure and insertional location of the AT on the calcaneal tuberosity are inconsistent. Therefore, to obtain a better understanding of the mechanisms underlying insertional Achilles tendinopathy, clarification of the anatomy of the twisting structure and location of the AT insertion onto the calcaneal tuberosity is important. The purpose of this study was to reveal the twisted structure of the AT and the location of its insertion onto the calcaneal tuberosity using Japanese cadavers. The study was conducted using 132 legs from 74 cadavers (mean age at death, 78.3 ± 11.1 years; 87 sides from men, 45 from women). Only soleus (Sol) attached to the deep layer of the calcaneal tuberosity was classified as least twist (Type I), both the lateral head of the gastrocnemius (LG) and Sol attached to the deep layer of the calcaneal tuberosity were classified as moderate twist (Type II), and only LG attached to the deep layer of the calcaneal tuberosity was classified as extreme twist (Type III). The Achilles tendon insertion onto the calcaneal tuberosity was classified as a superior, middle or inferior facet. Twist structure was Type I (least) in 31 legs (24%), Type II (moderate) in 87 legs (67%), and Type III (extreme) in 12 legs (9%). A comparison between males and females revealed that among men, 20 legs (24%) were Type I, 57 legs (67%) Type II, and eight legs (9%) Type III. Among women, 11 legs (24%) were Type I, 30 legs (67%) Type II, and four legs (9%) Type III. No significant differences were apparent between sexes. The fascicles of the Achilles tendon attach mainly in the middle facet. Anterior fibers of the Achilles tendon, where insertional Achilles tendinopathy is most likely, are Sol in Type I, LG and Sol in Type II, and LG only in Type III. This suggests the possibility that a different strain is produced in the anterior fibers of the Achilles tendon (calcaneal side) where insertional Achilles tendinopathy is most likely to occur in each type. We look forward to elucidating the mechanisms generating insertional Achilles tendinopathy in future biomedical studies based on the present results.
Seventy-one Caucasian orbits (36 right, 35 left) were studied by dissection. The diameter of the ophthalmic a. (2 mm from the origin) was 1.54 +/- 0.04 mm (male) and 1.31 +/- 0.05 mm (female). In individual cases, there were no significant differences in vessel diameter between the right and left sides but, differences in vessel diameter between males and females were more commonly observed in the arteries which leave the orbit (extraorbital group), the individual vessels having a larger diameter in males. The incidence of the ophthalmic a. passing in the orbit medially under the optic n. was 18.6%. The lacrimal a. was observed to arise from the ophthalmic a. in only 82.5% of the cases examined, 15.9% of the cases showed the origin to be at the anastomotic branch of the middle meningeal.
The main osseous landmarks of the border area between the infratemporal fossa and the para- and retro pharyngeal space are the sphenoidal spine and the pterygoid and styloid processes, and the styloid vagina. These landmarks, as well as some vascular anomalies, were studied in order to illustrate the variable anatomy, which is encountered in the surgical lateral transzygomatic infratemporal fossa approach. Hundred well-preserved human skull bases were examined. The deep infratemporal fossa was dissected into 54 halves of fixed cadaveric head and neck specimens of both sexes. Dry skull specimens of New and Old World monkeys, skulls of rodents, herbivora and carnivora, and computed tomograms of the head of Macaca fuscata Japonica, were also studied. In 91 of the human skull bases, the sphenoidal spine was prominent and well developed. In three skulls, the spine was absent. In four specimens, however, the spine was not sphenoidal but a part of the temporal bone, occurring in the form of a process, which emanated from the styloid vagina. In two further cases, there was unilaterally a duplicated spine; the anterior part represented a regular sphenoidal spine, while the posterior part constituted a part of the vagina of the styloid process. A complete osseous bar, arch or lamina-connecting the posterior border of the lateral lamina of the pterygoid process and the sphenoidal spine-existed in six of the human dry skulls. In ten of the human skulls examined, the breadth of the lateral lamina of the pterygoid process was greater than 10 mm; thus, the so-called pterygospinous (ps) and the pterygostyloid gates-of significance where surgical approaches are concerned-were less than 10 mm in width. Fibrous or muscular connections were also found in some cadaveric specimens between the posterior border of the lateral lamina of the pterygoid process and the sphenoidal spine: a ps ligament existed in 11 cases (20.4%) and a ps muscle in 5 cases (9.2 %), in 3 of which it inserted into both the medial wall capsule and the articular disc of the temporo-mandibular joint. Among the cadaveric specimens exhibiting ps structures was one in which an osseous ps bar occurred together with a ps muscle; in two cases a strong ps ligament was observed together with a ps muscle. The distribution pattern of the mandibular nerve was affected by the positioning of the ps bar, ligament and muscle when the latter were present. The existence of a wide ps bar was noted in all the skulls of herbivora, rodentia, carnivora, and Old World monkeys that were examined, but never in those of the New World monkeys; it is likely that, in the human, this ps bar represents a phylogenetic remnant. In the human dry skull specimens and cadaveric material, the ps ligament was found to be a reinforcement of the interpterygoid fascia, and the ps muscle to be a third head of the lateral pterygoid muscle. In two cases, the internal carotid artery exhibited a significant elongation and space-consuming tortuosity (so-called coiling behavior) in the depth of the infratemporal...
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