the lower part of the adductor magnus close to the linea aspera, and has already been seen in the popliteal space lying upon the popliteal artery.

The Gracilis is a long, strap-like muscle, which is situated along the inner aspect of the thigh and knee. It springs by a thin tendon from the lower half of the body of the pubis, close to the symphysis, and also from the upper half of the pubic arch. It ends in a slender, rounded tendon which inclines forwards below the knee, and then expands to find insertion into the upper part of the inner surface of the tibia, under cover of the tendon of the sartorius, and at a higher level than the insertion of the semitendinosus. A synovial bursa separates the expanded tendon of the gracilis from the internal lateral ligament of the knee-joint, and is prolonged above it, so as to intervene between it and the tendon of the sartorius.

The Adductor Magnus is one of the most powerful muscles of the thigh. It forms a flat fleshy mass, which springs from the anterior surface of the entire length of the pubic arch, and from the lower part of the tuberosity of the ischium. The fibres which arise from the pubic arch spread out as they approach the back of the femur. The upper fibres are nearly horizontal in their direction; below this they descend with increasing degrees of obliquity. They are inserted into the posterior surface of the femur, immediately internal to the gluteal ridge, into the linea aspera, and into a small portion of the upper part of the internal supracondyloid ridge. The fibres which take origin from the ischial tuberosity descend almost vertically and form the thick inner border of the muscle. In the lower third of the thigh they end in a strong, rounded tendon, which is inserted into the adductor tubercle on the inner tuberosity of the femur. This tendon is further attached to the femur by the internal intermuscular septum which stretches between it and the internal supracondyloid line. Close to the linea aspera the dissector will notice that fibrous arches are formed in connection with the insertion of the adductor magnus for the passage of the perforating

arteries. The opening through which the femoral artery enters the popliteal space lies in series with these. It is a gap between the two portions of the muscle, and is situated in the lower third of the thigh.

The adductor magnus has a double nerve supply. Behind, it is supplied by branches from the great sciatic, whilst in front it receives the greater part of the posterior division of the obturator.

Dissection. The adductor magnus should now be detached from its origin, in order that the obturator externus muscle and the obturator artery may be more fully examined.

Obturator Externus-Obturator Artery.-The obturator externus is a flat, fan-shaped muscle, which is placed over the front of the thyroid foramen of the innominate bone. It springs from the inner half of the membrane which closes the foramen, and also from the inner and lower part of its bony margin. It proceeds backwards and outwards below the neck of the femur and the capsular ligament of the hip-joint, and ends in a stout tendon which obtains insertion into the digital fossa at the root of the great trochanter. This tendon has already been noticed in the dissection of the gluteal region.

The obturator artery (arteria obturatoria) appears in the thigh through the upper part of the thyroid foramen of the innominate bone. It at once divides into two terminal branches, which diverge from each other, and form an arterial circle upon the thyroid membrane, under cover of the obturator externus. This muscle must therefore be detached in order that these vessels may be followed. Both branches give twigs to the neighbouring muscles, whilst the outer branch (i.e., the branch which runs round the outer side of the foramen (sends an articular twig through the cotyloid notch of the acetabulum into the hipjoint. When the joint is opened this twig may be followed, in a well-injected subject, along the ligamentum teres into the head of the femur.

Psoas and Iliacus.-These muscles arise within the

abdomen and enter the thigh behind Poupart's ligament. A tendon appears on the outer side of the psoas, and into this the fibres of the iliacus are for the most part inserted. The conjoined tendon of the ilio-psoas is implanted into the small trochanter of the femur, but a certain proportion of the fleshy fibres of the iliacus obtain direct insertion into the shaft of the femur below and in front of that prominence.

Dissection.-Divide the femoral vessels, and the anterior crural nerve, about an inch below Poupart's ligament, and having tied them together with twine throw them downwards. Now cut through the sartorius and the rectus femoris about two inches from their origin and turn them aside. The tendon of the ilio-psoas must next be detached from its insertion and the muscle thrown upwards. This will expose the anterior surface of the capsule of the hip-joint. An intervening bursal sac will also be displayed. Open this and ascertain its extent by introducing the finger. It facilitates the play of the ilio-psoas upon the front of the hip-joint, and in some rare cases it will be found to be directly continuous with the synovial membrane of this articulation through an aperture in the capsular ligament. The intimate connection which exists between the capsule of the hip-joint and the tendon of the gluteus minimus, the reflected head of the rectus femoris, and the deep layer of the ilio-tibial band, should be noticed. Lastly, reflect the tensor fasciæ femoris, and carefully clean the capsule of the hip-joint.

HIP-JOINT (ARTICULATIO COXA)

It is necessary that the hip-joint be studied at this stage, as the further dissection of the limb can only be satisfactorily carried out after its removal from the trunk.

The hip-joint is the most perfect example of an enarthrodial or ball and socket joint in the body. It does not allow so free a range of movement as that which takes place at the shoulder-joint, but what it loses in this respect it gains in strength and stability. Its great strength and security depend: (1) upon the depth of the cotyloid cavity and the thorough manner in which the head of the femur is received into it; (2) upon the tension and power of the ligaments; (3) upon the length and oblique direction of the neck of the femur; and (4) upon atmospheric pressure,

The Ligaments in connection with the hip-joint are:

1. Capsular.

3. Cotyloid.

2. Ligamentum teres.

4. Transverse.

The capsular ligament and the ligamentum teres are attached to both bones entering into the construction of the joint. The transverse and the cotyloid ligaments are connected with the acetabular cavity; the former partially fills up the notch or deficiency in its inferior part, whilst the latter surrounds its circumference in a ring-like fashion, and serves to still further deepen it.

Capsular Ligament (capsula articularis)-This is exceedingly strong, and surrounds the joint on all sides. Superiorly, it is attached around the acetabulum; above and behind, directly to the innominate bone, just outside the rim of the cavity; in front, to the outer aspect of the cotyloid ligament; and below, to the transverse ligament. Inferiorly, it clasps the neck of the femur. In front, it is attached to the whole length of the anterior intertrochanteric line, and to the root of the great trochanter. This attachment is very firm and strong. Behind and below, it falls short of the posterior intertrochanteric line. by about half an inch, and it presents a weak attachment to the posterior and inferior surfaces of the neck of the femur.

If the capsule of the hip-joint has been carefully cleaned it will be seen that the fibres which compose it run in two different directions. The majority pass in a longitudinal direction from one bone to the other; others, however, may be observed to take a more or less transverse or circular course. The latter are only seen to advantage on the posterior aspect of the capsule, whilst the longitudinal fibres are massed on the front of the joint. Certain thickened portions of the capsule, with more or less distinct attachments, are described as the accessory ligaments of the joint. These are:

1. Ilio-femoral.

2. Pubo-femoral.

3. Ischio-capsular.
4. The zonular band,

The ilio-femoral band (ligamentum iliofemorale) is placed over the front of the articulation, and constitutes the thickest and most powerful part of the capsule. It springs from the anterior inferior spine of the ilium, and from a depressed surface on the bone immediately to the outer side of this. As it proceeds downwards in the capsule, it divides into two limbs, which diverge slightly from each other. The outer portion is implanted into the upper part of the anterior intertrochanteric line, close to the

ilio-femoral band.

FIG. 53. The ilio-femoral band isolated from the remainder

great trochanter; the inner portion, longer and almost vertical in direction, descends to find attachment into the lower end of the anterior intertrochanteric line. The interval between these two diverging parts of this ligament is occupied by a thinner portion of the capsule. The ilio-femoral band is sometimes called the Y-shaped ligament,