The talus bone, calcaneus, and navicular bone are considered the proximal row of tarsal bones. The navicular bone in humans is one of the tarsal bones, found in the foot. Four major glands are the preorbital, forehead, tarsal, and metatarsal glands. This connection maintains proper alignment between the metatarsal and the tarsal bones. Its tibial and tarsal lengths indicate a leaping ability similar to bonobos. Inversion occurs at the subtalar joint and transverse tarsal joint. Below its tendon, the tendons of the long flexors pass through the tarsal canal. It inactivates the superior tarsal muscle which produces ptosis. The second tarsal segment is lobed, extending distally below the third tarsal segment. The talar shelf is typically involved in subtalar or talocalcaneal tarsal coalition. Common causes include trauma, varicose veins, neuropathy and space-occupying anomalies within the tarsal tunnel. On the underside of the tarsal segments there frequently are pulvillus-like organs or plantulae. It is adjoined by the superior tarsal muscle. It has long limbs, and the male has tarsal spurs. Meanwhile, females measure in wing chord, in tail length and tarsal length.