Relationship between attachment site of tibialis anterior muscle and shape of tibia: anatomical study of cadavers.

BACKGROUND: Tibialis anterior (TA) muscle is the largest dorsiflexor of the ankle joint and plays an important role during gait movement. However, descriptions of the TA attachment site are inconsistent even among major anatomy textbooks, and its origin, especially the attachment site for the tibia, has not been reported in detail. This study is the first experimental attempt to investigate the origin of the TA in detail, paying particular attention to the relationship with the shape of the tibia, including sex differences. METHODS: Forty legs (20 males, 20 females) from twenty Japanese cadavers were examined. Gross anatomical examination of the TA's attachment site to the tibia and the tibia's shape was performed. RESULTS: The location of the distal end of the TA's attachment on tibia was significantly more distal in males than in females (p < 0.01). The anterior border of the tibia had a gentle S-like curve, with a medially convex curve in the proximal region and a laterally convex curve in the distal region in frontal plane. The most protruding point of the distal curve of the anterior border located significantly more proximal in females than in males (p = 0.02). CONCLUSIONS: There were sex differences in the distal end of the attachment site on tibia of the TA and the shape of the tibia. Consequently, the variations in the attachment site of TA were considered to provide for differences in function of TA. In males, the TA may enable advantageous power exertion, whereas in females it may work efficiently for dorsiflexion of ankle, respectively. Sex differences in TA's attachment site and the shape of the tibia may be involved in gait movement as well as frequency of lower leg disorders such as chronic exertional compartment syndrome.

Transverse ligament of the elbow joint: an anatomic study of cadavers.

BACKGROUND: The medial collateral ligament of the elbow joint consists of the anterior oblique ligament (AOL), posterior oblique ligament (POL), and transverse ligament (TL). This study aimed to clarify the structure of the TL, with a focus on the continuity between the TL and AOL. METHODS: A total of 42 cadavers (18 males, 24 females) were dissected at Aichi Medical University between 2016 and 2018. Cases of elbow deformity or atrophy were excluded, and 60 elbows (15 males, 15 females) were dissected to assess the fibers of both the TL and AOL using a stereomicroscope. RESULTS: The TL could be detected in all elbows and always continued to the AOL. The TL was classified into 2 types. The TLs continuing to the distal half of the AOL (type I) were observed in 44 elbows (73.3%), whereas the TLs continuing to the entire AOL (type II) were found in 16 elbows (26.7%). Type II TLs were significantly more frequently observed in the elbows of females than in those of males (P = .041). Stereomicroscopic observation revealed that the TL fibers entered perpendicularly to the distal half of the AOL in both types. CONCLUSIONS: The TL frequently continues to the distal half of the AOL, but rarely continues to the entire AOL. The TLs continuing to the entire AOL were more frequently detected in the elbows of females than in those of males. The TL possibly contributes to medial elbow stability via its continuity to the AOL.