THE UPPER EXTREMITY: Congenital absence of clavicle--Elevation of scapula--Winged scapula--Congenital paralytic deformities of shoulder--Deformities of elbow--Club-hand--Deformities of wrist--Madelung's deformity--Deformities of fingers--Dupuytren's contraction--Polydactylism. The surgery of the extremities is so largely concerned with the correction of deformities that it is necessary at the outset to refer briefly to some points relating to the time and mode of origin of these. 1. _Congenital deformities_--that is, those which originate _in utero_ and are present at birth--are comparatively common and may be due to a variety of causes. Some result from errors of development--for example, supernumerary fingers or toes, and deficiencies in the bones of the leg or forearm. A larger number are to be attributed to a persistent abnormal attitude of the fœtus, usually associated with want of room in the uterus--for example, the common form of club-foot and congenital dislocation of the hip. Less frequently amniotic bands so constrict the digits or the limbs as to produce distortion, or even to sever the distal part--_intra-uterine amputation_. Lastly, certain diseases of the fœtus, and particularly such as affect the skeleton--for example, achondroplasia--cause congenital deformities. 2. _Deformities originating during birth_ are all traceable to the effects of injuries sustained in the course of a difficult labour. Examples of these are: wry-neck resulting from rupture of the sterno-mastoid; lesions of the shoulder-joint and brachial plexus due to hyper-extension of the arm; a spastic condition of the lower limbs--Little's disease--resulting from tearing of blood vessels on the surface of the brain with hæmorrhage and interference with the function of the cortical motor area. 3. _Deformities acquired after birth_ arise from widely different causes, of which diseases of bone, including rickets, diseases of joints, and affections of the nervous system attended with paralysis, are amongst the commonest. Other deformities are produced by unsuitable clothing, such as a tight corset, or ill-fitting shoes distorting the toes, prolonged standing in growing subjects overstraining the mechanism of the foot and giving rise to the common form of flat-foot. The part played by the palsies of children in the surgical affections of the extremities necessitates a short description of their more important features.