At the inferior angle of the base of the cervix femoris, and on the internal and posterior part, we notice a short conical process, trochanter minor, (processes interior feinoris,) attached to the bone by its base, its apex directed downwards, inwards, and backwards, smooth on its whole surface. This process affords insertion to the tendon of the psoas and iliacus muscles.
In the male adult, the axis of the bead and neck of the femur passes downwards, outwards, and slightly backwards, and forms an obtuse angle with the shaft, an angle of about 135 degrees. In the female this angle is somewhat smaller, and approaches more nearly to a right angle, which contributes with the greater lateral dimensions of the pelvis, to increase the distance of the trochanters of opposite sides from each other, and to cause that projection of these processes which forms a peculiarity of the female form. In early age, when the neck of the femur is imperfectly developed, the angle between the neck and shaft is not defined ; in the earliest condition the connexion of the head and shaft very much resembles the permanent condition of the corresponding parts in the humerus ; as the neck becomes developed, the angle is ren dered apparent, at first, however, little removed from a right angle, but subsequently it in creases up to the adult period ; after that time we often find that the neck of the bone dimi nishes in its dimensions, and the angle is con sequently altered, so as to approximate to a right angle.
The following may be given as the mean measurements of the different parts of the neck of the femur. In the centre it measures about one inch, its posterior surface about fifteen lines, its inferior edge about twenty lines, and its superior about eleven lines ; its vertical diameter, in its most contracted part, is about seventeen lines, and its antero-posterior about ten.
The shaft of the femur forms a slight curve from above downwards, convex anteriorly and concave posteriorly, the excavation thus formed behind being filled up by the powerful muscles on the back of the thigh. It presents the appearance as if it had been twisted, like that which we have noticed in the humerus, the inferior extremity being twisted inwards, the superior in the contrary direction. Cru
veilhier remarks, that this curvature of torsion is in relation with the disposition of the femoral artery, which in its spiral course passes from the anterior to the posterior surface of the bone.
In the greater part of its extent the shaft of the femur is prismatic ; at the superior extre mity it is expanded laterally and flattened ; at the inferior it is likewise very considerably ex panded.
The anterior surface of the shaft is smooth and rounded ; at the upper part it is a little rough this surface is covered completely by the triceps extensor muscle. The posterior surface is divided along the middle into two, which are inclined, the one forwards and in wards, the other forwards and outwards ; the external surface is covered by the vastus exter nus, the internal by the vastus internus. In the middle, separating these two surfaces, is a rough ridge, linea aspen:, which occupies two fifths of the shaft of the bone about its middle, but is bifurcated above and below. Superiorly the bifurcation takes place about the termina tion of the superior fifth ; two lines proceed, the external, rough and prominent, to the great trochanter ; the internal, rather indistinct, to the lesser trochanter. The external line gives in sertion to the vastus externus, the adductor magnus, and the glutceus maximus; the pecti nreus and the vastus internus are inserted into the internal line. Inferiorly, the bifurcation takes place at a point corresponding to the commencement of the two inferior fifths ; each line proceeds down to the corresponding con dyle, and a triangular space is thus enclosed, the base of which is formed by the posterior extremities of the condyles, and the apex is at the point of bifurcation of the linea aspera. This space, which presents a smooth surface, slightly concave in both the vertical and trans verse directions, forms the floor of the popliteal region. The external line, from the inferior bifurcation, is more prominent than the inter nal, and gives insertion to the vastus externus and to the short head of the biceps. The in ternal is very faint superiorly where the femoral artery passes over it, and inferiorly the vastus internus and the adductor magnus are inserted into it.