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and extension (occurring at the carpo-metacarpal, metacarpo-phalangeal, and inter-phalangea joints); abduction and adduction, together with circumduction (occurring at the carpo-metacarpal joint).

The muscles and their respective actions are given in the following table :

Flexion.

{

Opponens pollicis (carpo-metacarpal
joint)
(carpo-metacarpal and
metacarpo-phalangeal

Extension.

Abductor pollicis (carpo-metacarpal
longus
joint)
Extensor pollicis (carpo-metacarpal and
metacarpo-phalan-
geal joint)
Extensor pollicis longus (all joints)

Flexor brevis
Adductor
Abductor brevis joint)
Flexor pollicis longus (all joints)

Adduction.

Adductor of the thumb
Flexor pollicis brevis
Opponens pollicis
First dorsal interosseous

brevis

Abduction.

Abductor pollicis brevis
Extensors of the thumb

Circumduction-a combination of the above muscles.

The characteristic features of the movements of the upper limb are their range and refinement. The hand, in addition to its intrinsic powers, can be moved through a wide range and in several planes by the muscles acting on the wrist and radio-ulnar joints; this range is increased by the fore and aft movements at the elbow-joint, and the extensive movements of which the shoulder and clavicular joints are capable. The result is that the hand can be brought into a position to cover and guard any portion of the body. The precision and refinement of movement is made possible by the coordinate movements of the various muscles acting upon the several joints, so that actions can be performed (as raising the food to the mouth) in which all the articulations of the limb are brought into play; while others (such as writing) are possible by movements at the joints of the wrist and fingers along with fixation of the elbow-joint.

THE LOWER LIMB.

FASCIÆ AND MUSCLES OF THE THIGH.

AND BUTTOCK.

FASCIÆ.

The superficial fascia of the thigh and buttock is continuous above with the fascia of the abdomen and back, medially with that of the perineum, and distally with that of the leg. It presents noticeable features in the buttock and groin.

In the buttock the superficial fascia is of considerable thickness, and is usually loaded with fat, whereby it assists in forming the contour of the buttock and the fold of the nates.

In the groin it is divisible into two layers: a superficial fatty layer, continuous with a similar layer on the anterior surface of the abdominal wall above, and over the perineum medially, and a deeper membranous layer, which is attached above to the medial half of the inguinal ligament, and to the deep fascia of the thigh just distal to the lateral half of that ligament. Medially it is attached to the pubic arch, and below the level of the femoral triangle it blends inseparably with the superficial fatty layer. The separation of these two layers of the superficial fascia is occasioned by the presence between them of the inguinal and superficial subinguinal lymph glands, the great saphenous vein and its tributaries, and some small arteries. The attachment of the deeper layer of the fascia to the pubic arch and the inguinal ligament cuts off the superficial tissues of the thigh from the perineum and the abdominal wall, and prevents the passage into the thigh of fluid collected in the perineum or beneath the fascia of the abdominal wall.

The deep fascia or fascia lata forms a tubular investment for the muscles and vessels of the thigh and buttock. It is firmly attached above to the iliac crest, the sacro-tuberous ligament, the ischium, the pubic arch, the pubic symphysis and crest, and the inguinal ligament. In the distal part of the thigh it forms the intermuscular septa; and in relation to the knee, it is continuous with the deep fascia of the leg, gains attachment to the patella, the condyles of the tibia and the head of the fibula, and forms the collateral ligaments of the patella.

On the front of the thigh the deep fascia is thick and strong. It is pierced by numerous openings for vessels and nerves, the most important of which is the fossa ovalis (O.T. saphenous opening) for the passage of the great saphenous vein. A femoral

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FIG. 358. SUPERFICIAL ANATOMY OF THE LEFT GROIN.

hernia passes through this opening to reach the groin and anterior abdominal wall. It is an oval opening, of variable size, situated just distal to the medial half of the inguinal ligament, and immediately anterior to the femoral vessels. It is covered by the superficial fascia, and by a special layer of fascia, the fascia cribrosa, a thin perforated lamina attached to the margins of the opening. The lateral edge of the opening (margo falciformis) is formed by the margin of the iliac portion of the fascia lata, which is attached above to the iliac crest and the inguinal ligament; the medial edge is formed by the fascia pectinea which is continued proximally, behind the femoral sheath, over the adductor longus and pectineus muscles to the ilio-pectineal line and the capsule of the hip-joint. These two layers of the fascia lata are continuous at the distal concave margin of the fossa ovalis, forming its As they pass proximally towards the pelvis they occupy different

inferior cornu.

planes, the iliac portion being in front of the sheath of the femoral vessels, while the pectineal fascia is behind it. The superior cornu of the fossa ovalis, placed in front of the sheath, is derived solely from the iliac portion of the fascia lata. It forms a strong triangular band of fascia known as the falciform margin, attached above to the medial half of the inguinal ligament. It has an important share in directing the course of a femoral hernia upwards on to the abdominal wall.

On the medial side of the thigh the fascia lata is thin where it covers the adductor muscles. At the knee it is associated with the tendons of the vasti muscles, and forms the collateral ligaments of the patella, attached to the borders of the patella and to the condyles of the tibia. On the lateral side of the thigh it

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FIG. 359.-THE DISSECTION OF THE LEFT INGUINAL CANAL.

forms the tractus iliotibialis-a broad thick layer of fascia which is attached above to the iliac crest, and receives the insertions of the tensor fascia latæ, and part of the gluteus maximus muscles; its distal attachment is to the capsule of the kneejoint and the lateral condyle of the tibia. A strong band of fascia continued proximally from the ilio-tibial tract, beneath the tensor fascia latæ muscle, joins the tendon of origin of the rectus femoris and the capsule of the hip-joint.

On either side of the thigh above the knee an intermuscular septum is formed. The lateral intermuscular septum extends medially from the ilio-tibial tract to the lateral epicondylic line and linea aspera of the femur, and gives attachment to the vastus lateralis and vastus intermedius anteriorly, and the short head of the biceps posteriorly. The medial intermuscular septum in the distal third of the thigh is associated with, and to a large extent represented by, the tendon of insertion of the adductor magnus muscle. It is also related to the fascia which envelops the

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adductor muscles, and forms the sheaths for the sartorius and gracilis muscles. In the middle third of the thigh the fascia under the sartorius is greatly thickened by transverse fibres and binds together the vastus medialis and adductor longus and adductor magnus muscles. This layer of fascia roofs over the femoral vessels in their course through adductor canal (Hunter's).

The fascia lata of the buttock is thick anteriorly where it covers and gives origin to the gluteus medius, thinner posteriorly over the gluteus maximus, at the upper border of which it splits to enclose the muscle. It is thickened over the greater trochanter, where it forms the insertion of the greater part of the latter muscle.

On the posterior surface of the thigh and over the popliteal fossa the fascia is strengthened by transverse fibres derived from the hamstring muscles. The popliteal fascia forming the roof of the popliteal fossa is specially thick, and is usually pierced by the small saphenous vein.

Aft

Femoral Sheath. This is a conical membranous investment, derived from the fascial lining of the abdominal cavity, the fascia transversalis in front and the fascia iliaca behind, prolonged along the femoral vessels in their passage behind the inguinal ligament into the femoral triangle. The sheath is about an inch and a half in length, and is divided into three compartments-a lateral space for the artery, an intermediate space for the vein, and a medial channel containing lymph vessels and fat, and named the femoral canal. This canal is the passage through which a femoral hernia enters the thigh. Its proximal limit is the femoral ring, bounded anteriorly by the inguinal ligament, posteriorly by the origin of the pectineus muscle from the pubis, medially by the ligamentum lacunare (Gimbernati), and laterally by the femoral vein. In front of it the fascia transversalis forming the sheath is thickened to form the deep femoral arch. The part of the inguinal ligament in front of the ring is called the superficial femoral arch. The inferior epigastric artery separates the ring from the abdominal inguinal ring. The canal ordinarily contains fat which is continuous above with the extra-peritoneal tissue. The ring is filled by a plug of fat or a lymph gland, constituting the femoral septum.

The femoral canal ends behind the fossa ovalis, covered by the fascia cribrosa, while the falciform margin crosses over it and conceals its proximal portion. The course of a femoral hernia is determined by this band. The hernia descends through the femoral ring, pushing the femoral septum before it; after passing through the femoral canal, it is directed forwards through the fossa ovalis. The anterior part of the hernia being pressed upon and retarded by the femoral arches, and by the falciform margin, the posterior part pushes onwards, hooks round the falciform margin, and is directed upwards over the inguinal ligament. The coverings of a femoral hernia, in addition to peritoneum and extra-peritoneal tissue (femoral septum), are femoral sheath, fascia cribrosa, superficial fascia, and skin.

MUSCLES OF THE THIGH AND BUTTOCK.

The muscles of the thigh and buttock are divisible into four main groups by their situation, action, and nerve-supply. On the anterior surface of the thigh are the quadriceps femoris, the sartorius, ilio-psoas, and pectineus muscles; on the medial side of the thigh are the adductor muscles; in the region of the buttock are the glutei and rotators of the hip-joint; and on the posterior aspect of the thigh are the hamstring muscles.

THE MUSCLES ON THE ANTERIOR ASPECT OF THE THIGH.

The chief muscle on the anterior aspect of the thigh is the quadriceps femoris, which occupies the space between the tensor fascia latæ and ilio-tibial tract laterally, and the sartorius medially. The sartorius crosses the thigh obliquely; it separates the quadriceps femoris from the adductor muscles; it forms in the proximal third of the thigh the lateral boundary of the femoral triangle, and in

Ilio-tibial tract

GRACILIS

ADDUCTOR
MAGNUS

VASTUS
LATERALIS

RECTUS FEMORIS

the middle third of the thigh, the roof of adductor canal (Hunter's). The ilio-psoas, passing into the thigh beneath the inguinal ligament, assists, along with the pectineus and adductor muscles, in forming the floor of the femoral triangle.

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Nerve-Supply.-The sartorius is supplied by two sets of nerves associated with the two intermediate cutaneous branches of the femoral nerve (L. 2. 3.). "the Actions. The sartorius, tailor's muscle," is a flexor of the hip RECTUS FEMORIS and knee joints. It also everts the thigh and assists in medial rotation of the tibia.

M. Sartorius.-The sartorius, a long strap-like muscle, arises from the superior anterior spine of the ilium and half of the margin of the notch below it (Fig. 360).

It passes distally in the thigh, across the medial side of the knee, and is inserted, by aponeurotic fibres, into the medial surface of the body of the tibia just distal to the medial condyle, and by its borders into fascial expansions which join the capsule and the tibial collateral ligament of the knee-joint, and the fascia lata of the leg (Fig. 363, p. 408).

The sartorius is superficial in its whole extent. Its proximal third forms the lateral boundary of the femoral triangle; its middle third forms the roof of the adductor canal; and its distal third, in contact with the medial side of the knee, is separated from the tendon of the gracilis muscle by the saphenous nerve and the saphenous branch of the arteria genu suprema. A bursa lies beneath the tendon at its insertion.

TENDON OF

LIGAMENTUM
PATELLA

FIG. 360.-THE MUSCLES OF THE ANTERIOR ASPECT OF
THE RIGHT THIGH.

M. Quadriceps Femoris.The quadriceps femoris is composed of four muscles-the rectus femoris, vastus lateralis, vastus intermedius, and vastus medialis.

The rectus femoris is superficial except at its origin, which is covered by the glutæi, sartorius, and tensor fascia latæ muscles. The vasti lie on either side of the rectus muscle, the vastus lateralis being partially concealed

by the tensor fascia latæ and ilio-tibial tract, the vastus medialis by the sartorius

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