284 THE SKELETON. 



in an antero-posterior direction, when the fracture occurs from direct force, or by compression 

 laterally, when the acetabula are pressed together, and the bone gives way in the same place 

 from indirect violence. Occasionally the fracture may be double, occurring on both sides of the 

 body. It is in these cases that injury to the contained viscera is liable to take place : the urethra, 

 the bladder, the rectum, the vagina in the female, the small intestines, and even the uterus, 

 have all been lacerated by a displaced fragment. Fractures of the acetabulum are occasionally 

 met with : either a portion of the rim may be broken off, or a fracture may take place through 

 the bottom of the cavity, and the head of the femur driven inward and project into the pelvic 

 cavity. Separation of the Y-shaped cartilage at the bottom of the acetabulum may also occur 

 in the young subject, separating the bone into its three anatomical portions. 



The sacrum is occasionally, but rarely, broken by direct violence i. e. blows, kicks, or falls 

 on the part. The lesion may be complicated with injury to the nerves of the sacral plexus, 

 leading to paralysis and loss of sensation in the lower extremity, or to incontinence of faeces 

 from paralysis of the sphincter ani. 



The pelvic bones often undergo important deformity in rickets, the effect of which in the 

 adult woman may interfere seriously with childbearing. In consequence of the yielding nature 

 of the bones, the acetabula become approximated, the symphysis is pushed forward, and the 

 antero-posterior diameter lessened. In osteo-malacia also great deformity may occur, the pelvis 

 becoming beak-shaped. The promontory of the sacrum is pushed forward by the weight of the 

 body, and the sides of the pelvis are approximated by the pressure of the two thigh-bones : this 

 gives to the pelvis the peculiar deformity which is characteristic of this disease. 



THE THIGH. 

 The Femur, or Thigh-Bone. 



The Femur (femur, the thigh) is the longest, 1 largest, and strongest bone in 

 the skeleton, and almost perfectly cylindrical in the greater part of its extent. In 

 the erect posture it is not vertical, being separated from its fellow above by a 

 considerable interval, which corresponds to the entire breadth of the pelvis, but 

 inclining gradually downward and inward, so as to approach its fellow toward 

 its lower part, for the purpose of bringing the knee-joint near the line of gravity 

 of the body. The degree of this inclination varies in different persons, and is 

 greater in the female than the male, on account of the greater breadth of the 

 pelvis. The femur, like other long bones, is divisible into a shaft and two 

 extremities. 



The Upper Extremity presents for examination a head, a neck, and the great 

 and lesser trochanters. 



The head, which is globular, and forms rather more than a hemisphere, is 

 directed upward, inward, and a little forward, the greater part of its convexity 

 being above and in front. Its surface is smooth, coated with cartilage in the 

 recent state, except at a little behind and below its centre, where is an ovoid 

 depression, for the attachment of the ligamentum teres. The neck is a flattened 

 pyramidal process of bone which, connects the bead with the shaft. It varies in 

 length and obliquity at various periods of life and under different circumstances. 

 The angle is widest in infancy, and becomes lessened during growth, so that at 

 puberty it forms a gentle curve from the axis of the shaft. In the adult it forms 

 an angle of about 130 with the shaft, but varies in inverse proportion to the 

 development of the pelvis and the stature. In consequence of the prominence of 

 the hips and widening of the pelvis in the female, the neck of the thigh-bone forms 

 more nearly a right angle with the shaft than it does in man. It has been stated 

 that the angle diminishes in old age and the direction of the neck becomes 

 horizontal, but this statement is founded on insufficient evidence. Sir George 

 Humphry states that the angle decreases during the period of growth, but after 

 full growth has been attained it does not usually undergo any change, even in old 

 age. He further states that the angle varies considerably, in different persons of 

 the same age. It is smaller in short than in long bones, and when the pelvis 

 is wide. 2 The neck is flattened from before backward, contracted in the middle, 

 and broader at its outer extremity, where it is connected with the shaft, than at 

 its summit, where it is attached to the head. The vertical diameter of the outer 



1 In a man six feet high it measures eighteen inches one-fourth of the whple body. 



2 Journal of Anatomy and Physiology. 



