History of phalanges
Etymology
The term phalanx or phalanges refers to an ancient Greek army formation in which soldiers stand side by side, several rows deep, like an arrangement of fingers or toes. In animals
Most land mammals including humans have a 2-3-3-3-3 formula in both the hands (or paws) and feet. Primitive reptiles usually had the formula 2-3-4-4-5, and this pattern, with some modification, remained in many later reptiles and in the mammal-like reptiles. The phalangeal formula in the flippers of cetaceans (marine mammals) varies widely due to hyperphalangy (the increase in number of phalanx bones in the digits). In humpback whales, for example, the phalangeal formula is 0/2/7/7/3; in pilot whales the formula is 1/10/7/2/1.In vertebrates, proximal phalanges have a similar placement in the corresponding limbs, be they paw, wing or fin. In many species, they are the longest and thickest phalanx ("finger" bone). The middle phalanx also a corresponding place in their limbs, whether they be paw, wing, hoof or fin. The distal phalanges are cone-shaped in most mammals, including most primates, but relatively wide and flat in humans. Primates
The morphology of the distal phalanges of human thumbs closely reflects an adaptation for a refined precision grip with pad-to-pad contact. This has traditionally been associated with the advent of stone tool-making.
Pulmonary alveolar microlithiasis (PAM) is a rare, inherited disorder of lung phosphate balance that is associated with small stone formation in the airspaces of the lung. Mutations in the gene SLC34A2 result in loss of a key sodium, phosphate co-transporter (called Npt2b), known to be expressed in distal alveolar type II cells, as well as in the mammary gland, and to a lesser extent in intestine, kidney, skin, prostate and testes. As the disease progresses, the lung fields become progressively more dense (white) on the chest xray, and low oxygen level, lung inflammation and fibrosis, elevated pressures in the lung blood vessels, and respiratory failure ensue, usually in middle age. The clinical course of PAM can be highly variable, with some patients remaining asymptomatic for decades, and others progressing more rapidly. There is no effective treatment, and the mechanisms of stone formation, inflammation and scarring are not known. Signs and symptoms
Patients typically have no symptoms until the third or fourth decade of life. In most cases, the disease is discovered incidentally on routine chest Xray. The most common symptoms include the following:
dyspnea
dry cough
chest pain
sporadic hemoptysis
asthenia
pneumothoraces

Genetics
PAM is hereditary and another involved family member can be identified in 36% to 61% of cases. Impaired activity of the SLC34A2 gene is responsible for PAM.The SLC34A2 gene encodes a membrane protein that is expressed primarily in the apical portions of alveolar type II cells and is the most abundant phosphate carrier in the lungs.