DESCRIPTIVE AND SURGICAL ANATOMY

THE LOWER EXTREMITY

The Lower Extremities, two in number, are connected with the inferior part of the trunk. They are divided into three parts, the thigh, the leg, and the foot, which correspond to the arm, the forearm, and hand in the upper extremity.

The thigh is formed of a single bone, the femur.

THE FEMUR

The Femur is the longest, largest, and heaviest bone in the skeleton, and almost perfectly cylindrical in the greater part of its extent. In the erect position of the body it is not vertical, but presents a general curvature in the longitudinal direction, which renders the bone convex in front and slightly concave behind; it also gradually inclines from above down­wards and inwards, approaching its fellow towards its lower part, but separated from it above by a very considerable in­terval which corresponds to the entire breadth of the pelvis. The degree of this inclination varies in different persons, and is greater in the female than in the male. The femur, like other long bones, is divisible into a shaft and two extremi­ties.

The Upper Extremity presents for ex­amination a head, neck, and the greater and lesser trochanters.

The head, which is globular, and forms rather more than a hemisphere, is directed upwards, inwards, and a little forwards, the greater part of its convexity being above and in front. Its surface is smooth, coated with cartilage in the recent state, and presents a little behind and below its centre a rough depression, for the attachment of the ligamentum teres. The neck is a flattened pyramidal pro­cess of bone, which connects the head with the shaft. It varies in length and obliquity at various periods of life, and under different circumstances. In the adult male, it forms an obtuse angle with the shaft, being directed upwards, in­wards, and a little forwards. In the female, it approaches more'nearly a right angle. Occasionally, in very old subjects, and more especially in those greatly de­bilitated, its direction becomes horizontal* so that the head sinks below the level of the trochanter, and its length diminishes to such a degree, that the head becomes almost contiguous with the shaft. The neck, is flattened from before backwards, 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. It is much broader in the vertical than in the ante­rior posterior diameter, on account of the greater amount of resistance required in sustaining the weight of the trunk. Its anterior surface, narrower than the posterior, is perforated by numerous vascular foramina. Its posterior surface is smooth, broader, and more concave than the anterior, and receives towards its outer side the attachment of the capsular ligament of the hip. Its superior border is short and thick, bounded externally by the great trochanter, and its surface perforated by large foramina. Its inferior border, long and narrow, curves a little backwards, to terminate at the lesser trochanter.

The Greater Trochanter is a large irregular quadrilateral eminence, situated at the outer side of the neck, at its junction with the upper part of the shaft. It is directed a little outwards and backwards, and rises less high than the head. It presents for examination two surfaces and four borders.

Its external surface, quadrilateral in form, is broad, rough, convex, and marked by a prominent diagonal line, which extends from the posterior superior to the anterior inferior angle: this line serves for the attachment of the tendon of the Gluteus medius. Above the line is a triangular surface, sometimes rough for part of the tendon of the same muscle, sometimes smooth for the interposition of a bursa between that tendon and the bone. Below and behind the diagonal line is a smooth triangular surface, over which the tendon of the Gluteus maximus muscle plays, a bursa being interposed. The internal surface is of much less extent than the external, and presents at its base a deep depression, the digital or trochan-teric fossa, for the attachment of the tendon of the Obturator externus muscle.

The superior border is free; it is thick and irregular, and marked by im­pressions for the attachment of the Pyriformis behind, the Obturator internus and Gemelli in front. The inferior border is placed at the point of junction of the trochanter with the outer surface of the shaft; it is rough, prominent, slightly curved, and gives attachment to the upper part of the Vastus externus muscle. The anterior border is prominent, somewhat irregular, as well as the surface of bone immediately below it; it affords attachment by its outer part to the Gluteus minimus. The posterior border is very prominent, and appears as a free rounded edge, which forms the back part of the digital fossa.

 

Femur

The Lesser Trochanter is a conical eminence, which varies in size in different subjects; it is situated at the lower and back part of the base of the neck. Its base is triangular, and connected with the adjacent parts of the bone by three well-marked borders: of these the superior is continuous with the lower border of the neck; the posterior, with the posterior intertrochanteric line; and the inferior with the middle bifurcation of the linea aspera. Its summit, which is directed inwards and backwards, is rough, and gives insertion to the tendon of the Psoas magnus. The Iliacus is inserted into the shaft below the lesser trochanter, be­tween the Vastus internus in front, and the Pectineus behind. A well marked prominence, but of variable size, situated at the upper and front part of the neck, at its junction with the great trochanter, is called the tubercle of the femur; it is the point of meeting of three muscles, the Gluteus minimus exter­nally, the Vastus externus below, and the tendon of the Obturator internus and Gemelli above. Running obliquely downwards and inwards from the tubercle is the spiral line of the femur, or anterior intertrochanteric line; it winds around the inner side of the shaft, below the lesser trochanter, and terminates in the linea aspera, about two inches below this eminence. Its upper half is rough, and affords attachment to the capsular ligament of the hip joint; its lower half is less promi­nent and gives attachment to the upper part of the Vastus internus. The posterior inter-trochanteric line is very prominent, and runs from the summit of the great trochanter downwards and inwards to the upper and back part of the lesser tro­chanter. Its upper half forms the posterior border of the great trochanter. A well-marked eminence commences about the centre of the posterior inter-trochan-teric line, and passes vertically down­wards for about two inches along the back part of the shaft: it is called the linea quadrati, and gives attachment to the Quadratus femoris, and a few fibres of the Adductor magnus muscles.

The Shaft, almost perfectly cylindrical in form, is a little broader above than in the centre, and somewhat flattened from before backwards below. It is curved from before backwards, smooth and convex in front, and strengthened behind by a pro­minent longitudinal ridge, the linea aspera. It presents for examination three borders separating three surfaces. Of the three borders, one, the linea aspera, is posterior, the other two are placed laterally.

The linea aspera is a prominent longitudinal ridge or crest, presenting on the middle third of the bone an external lip, an internal lip, and a rough inter­mediate space. A little above the centre of the shaft, this crest divides into three lines; the most external one becomes very rough, and is continued almost ver­tically upwards to the base of the great trochanter; the middle one, the least dis­tinct, is continued to the base of the trochanter minor; and the internal one is lost above in the spiral line of the femur. Below, the linea aspera divides into two bifurcations, which enclose be­tween them a triangular space (the po­pliteal space), upon which rests the popliteal artery. Of these two bifurca-cations, the outer branch is the most prominent, and descends to the summit of the outer condyle. The inner branch is less marked, presents a broad and shallow groove for the passage of the femoral artery, and terminates at a small tubercle at the summit of the internal condyle.

To the inner lip of the linea aspera, its whole length, is attached the Vastus interims; and to the whole length of the outer lip the Vastus externus. The Adductor magnus is also attached to the 5 whole length of the linea aspera, being ' connected with the outer lip above, and ' the inner lip below. Between the Vastus externus and the Adductor magnus are attached two muscles, viz., the Gluteus maximus above, and the short head of the Biceps below. Between the Adductor magnus and the Vastus internus four muscles are attached: the Iliacus and Pectineus above (the latter to the middle division of the upper bifurcation); below these, the Adductor brevis and Adductor longus. The linea aspera is perforated a little below its centre by the nutritious canal, which is directed obliquely from below upwards.

Femur

The two lateral borders of the femur are only very slightly marked, the external extending from the anterior inferior angle of the great trochanter to the anterior extremity of the external condyle; the internal passes from the spiral line, at a point opposite the trochanter minor, to the anterior extremity of the internal condyle. The internal border marks the limit of attachment of the Cru-raeus muscle internally.

The anterior surface includes that portion of the shaft which is situated be­tween the two lateral borders. It is smooth, convex, broader above and below than in the centre, slightly twisted, so that its upper part is directed forwards and a little outwards, its lower part forwards and a little inwards. The upper three-fourths of this surface serve for the attachment of the Cruraeus; the lower fourth is separated from this muscle by the intervention of the synovial membrane of the knee-joint, and affords attachment to the Sub-cruraeus to a small extent. The external surface includes the portion of bone between the external border and the outer lip of the linea aspera; it is continuous above with the outer surface of the great trochanter, below with the outer surface of the external condyle: to its upper three-fourths is attached the outer portion of the Crurseus muscle. The internal surface includes the portion of bone between the internal border and the inner lip of the linea aspera; it is continuous above with the lower border of the neck, below with the inner side of the internal condyle: it is covered by the Vastus internus muscle.

The Lower Extremity, larger than the upper, is of a cuboid form, flattened from before backwards, and divided by an interval presenting a smooth depression in front, and a notch of considerable size behind, into two large eminences, the condyles. The interval is called the inter-condyloid notch. The external con­dyle is the most prominent anteriorly, and is the broadest both in the antero-posterior and transverse diameters. The internal condyle is the narrowest, longest, and most prominent internally. This difference in the length of the two condyles depends upon the obliquity of the thigh-bones, in consequence of their separation above at the articulation with the pelvis. If the femur is held in this oblique position, the surfaces of the two condyles will be seen to be nearly hori­zontal. The two condyles are joined together anteriorly, and form a smooth trochlear surface, the external border of which is more prominent, and ascends higher than the internal one. This surface articulates with the patella. It pre­sents a median groove, which extends downwards and backwards to the inter-condyloid notch; and two lateral convexities, of which the external is the broader, more prominent, and prolonged farther upwards upon the front of the outer condyle. The inter-condyloid notch lodges the crucial ligaments; it is bounded laterally by the opposed surfaces of the two condyles, and in front by the lower end of the shaft.

Outer Condyle. The outer surface of the external condyle presents, a little behind its centre, an eminence, the outer tuberosity; it is less convex and pro­minent than the inner tuberosity, and gives attachment to the external lateral ligament of the knee. Immediately beneath it is a groove, which commences at a depression a little behind the centre of the lower border of this surface: the depression is for the tendon of origin of the Popliteus muscle; the groove in which this tendon is contained is smooth, covered with cartilage in the recent state, and runs upwards and backwards to the posterior extremity of the condyle, The inner surface of the outer condyle forms one of the lateral boundaries of the inter-condyloid notch, and gives attachment, by its posterior part, to the anterior crucial ligament. The inferior surface is convex, smooth, and broader than that of the internal condyle. The posterior extremity is convex and smooth: just

above the articular surface is a depression, for the tendon of the outer head of the Gastrocnemius.

Inner Condyle. The inner surface of the inner condyle presents a convex eminence, the inner tuberosity, rough, for the attachment of the internal lateral ligament. Above this tuberosity, at the termination of the inner bifurcation of the linea aspera, is a tubercle, for the insertion of the tendon of the Adductor magnus; and behind and beneath the tubercle a depression, for the tendon of the inner head of the Gastrocnemius. The outer side of the inner condyle forms one of the lateral boundaries of the inter-condyloid notch, and gives attachment, by its anterior part, to the posterior crucial ligament. Its inferior or articular surface is con­vex, and presents a less extensive surface than the external condyle.

Structure. Like that of the other cylindrical bones, the linea aspera is com­posed of a very dense, ivory-like, compact tissue.

Articulations. With three bones; the os innominatum, tibia, and patella.

Development. The femur is developed by five centres; one for the shaft, one for each extre­mity, and one for each trochanter. Of all the long bones, it is the first to show traces of ossification: this fi rst commences in the shaft, at about the fifth week of foetal life, the centre s of ossification in the epiphyses appe ar-ing in the following order. First, in the lower end of the bone, at the ninth month of foetal life; from this the condyles and tuberosities are formed; in the head, at the end of the first year after birth; in the great trochanter, during the fourth year; and in the lesser trochanter, between the thirteenth and four­teenth. The order in which the epiphyses are joined to the shaft, is the direct reverse of their appear­ance; their junction does not com­mence until after puberty, the lesser trochanter being first joined, then the greater, then the head, and, lastly, the inferior extremity (the first in which ossification com­menced), which is not united until the twentieth year.

Attachment oj Muscles, lo the great trochanter, the liluteus meouus, minimus, Pyriformis, Obturator internus, Obturator externus, Gemellus superior, Gemellus inferior, and Quadratus femoris. To the lesser trochanter, the Psoas magnus, and the Iliacus below it. To the shaft, its posterior surface, the Vastus externus, Gluteus maximus, short head of the Biceps, Vastus internus, Adductor magnus, Pectineus, Adductor brevis, and Adductor longus; to its anterior surface, the Crurasus and Sub-crureus. To the condyles, the Gastrocnemius, Plantaris, and Popliteus.

THE LEG

The Leg consists of three bones: the Patella, a large sesamoid bone, placed in front of the knee, analogous to the olecranon process of the ulna; and the Tibia and Fibula.

THE PATELLA

The Patella is a small, flat, triangular bone, situated at the anterior part of the knee-joint. It resembles the sesamoid bones, from being developed in the tendon of the Quadriceps extensor; but, in relation with the tibia, it may be regarded as analogous to the olecranon process of the ulna, which occasionally exists as a sepa­rate piece, connected to the shaft of that bone by a continuation of the tendon of the Triceps muscle. It presents an anterior and posterior surface, three borders, a base, and an apex. of nutrient vessels, and marked by numerous rough, ' longitudinal striae. This surface is covered, in the recent state, by an expansion from the tendon of the Quadriceps extensor, separated from the integument by a synovial bursa, and gives attachment below to the ligamentum patellae. The posterior surface presents a smooth, oval-shaped, articular surface, covered with car­tilage in the recent state, and divided into two facets by a vertical ridge, which descends from the superior to­wards the inferior angle of the bone. The ridge cor­responds to the groove on the trochlear surface of the femur, and the two facets to the articular surfaces of the two condyles; the outer facet, for articulation with the outer condyle, being the broader and deeper, serves to indicate the leg to which the bone belongs. This surface presents, inferiorly, a rough, convex, non-arti­cular depression, the lower half of which gives attach­ment to the ligamentum patellae; the upper half being separated from the head of the tibia by adipose tissue.

Patella

Its superior and lateral borders give attachment to the tendon of the Quadriceps extensor; to the superior border, that portion of the tendon which is derived from the Bectus and Crurseus muscles; and to the lateral borders, the portion derived from the external and in­ternal Vasti muscles.

The anterior surface is convex, perforated by small apertures, for the passage

The base, or superior border, is thick, directed upwards, and cut obliquely at the expense of its outer surface; it receives the attachment, as already mentioned, of part of the Quadriceps extensor tendon.

The apex is pointed, and gives attachment to the ligamentum patellae.

Structure. It consists of loose cancellous tissue, covered by a thin compact lamina.

Development. By a single centre, which makes its appearance, according to Beclard, about the third year. In two instances, I have seen this bone cartilagi­nous throughout, at a much later period (six years). More rarely, the bone is developed by two centres, placed side by side.

Articulations. With the two condyles of the femur.

Attachment of Muscles. Four muscles are attached to the patella, viz., the Bectus, Cruraeus, Vastus internus, and Vastus externus. The tendons of these muscles joined at their insertion, constitute the Quadriceps extensor cruris.  NEXT PAGE