Astragalus

Astragalus is a large genus of about 3,000 species of herbs and small shrubs, belonging to the legume family Fabaceae and the subfamily Faboideae. It is the largest genus of plants in terms of described species. The genus is native to temperate regions of the Northern Hemisphere. Common names include milkvetch (most species), locoweed (in North America, some species) and goat's-thorn (A. gummifer, A. tragacanthus). Some pale-flowered vetches are similar in appearance, but vetches are more vine-like.

Ecology

Astragalus species are used as food plants by the larvae of some Lepidoptera species including many case-bearing moths of the genus Coleophora: C. cartilaginella, C. colutella, C. euryaula, and C. onobrychiella feed exclusively on Astragalus, C. astragalella and C. gallipennella feed exclusively on the species Astragalus glycyphyllos, and C. hippodromica is limited to Astragalus gombo.

Traditional uses

The natural gum tragacanth is made from several species of Astragalus occurring in the Middle East, including A. adscendens, A. gummifer, A. brachycalyx, and A. tragacanthus. Also Astragalus propinquus (syn. A. membranaceus) has a history of use as a herbal medicine used in systems of traditional Chinese medicine and Persian medicine. In traditional Chinese medicine A. membranaceus has been used to reinforce qi and strengthen the superficial resistance, and promote the discharge of pus and the growth of new tissue.

Talus bone

The talus bone (/ˈteɪləs/; Latin for ankle), astragalus /əˈstræɡələs/, or ankle bone is one of the group of foot bones known as the tarsus. The tarsus forms the lower part of the ankle joint through its articulations with the lateral and medial malleoli of the two bones of the lower leg, the tibia and fibula. Within the tarsus, it articulates with the calcaneus below and navicular in front within the talocalcaneonavicular joint. Through these articulations, it transmits the entire weight of the body to the foot.

The second largest of the tarsal bones, it is also one of the bones in the human body with the highest percentage of its surface area covered by articular cartilage. Additionally, it is also unusual in that it has a retrograde blood supply, i.e. arterial blood enters the bone at the distal end.

In humans, no muscles attach to the talus, unlike most bones, and its position therefore depends on the position of the neighbouring bones.

Structure

Though irregular in shape, the talus can be subdivided into three parts.