=M. biceps femoris= (Fig. 68, _t_, page 117).--A very large flat muscle
covering about two-thirds of the lateral side of the thigh.
_Origin_ (Fig. 90, 2).--From the ventral surface of the tuberosity of
the ischium by tendon- and muscle-fibres. The fibres diverge, and near
the knee the mass has spread out, ending in a fascia. The dorsal border
of the muscle and the common fascia are continuous dorsad with the
superficial fascia of the thigh and with the tendon of the
caudofemoralis (Fig. 68, _s_). Ventrad it is continuous with the
superficial fascia of the shank.
_Insertion_ into rather more than the proximal one-third of the dorsal
border of the tibia along its lateral margin and into the lateral margin
of the patella. In passing over the knee-joint it is closely united to
the underlying ligaments and tendons.
_Relations._--Outer surface with the superficial fascia and with a few
of the most caudal fibres of the cutaneus maximus (Fig. 62, _b_, page
94). Cranial (or dorsal) edge with the caudofemoralis (Fig. 68, _s_) and
the vastus lateralis (Fig. 90, _d_). Caudal border with the
semitendinosus (Fig. 68, _u_) and a mass of fat. Inner surface with the
caudofemoralis (Fig. 68, _s_), the tenuissimus (Fig. 90, _g_), the
obturator internus (Fig. 90, _e_), the quadratus femoris (Fig. 90, _f_),
the semitendinosus (Fig. 68, _u_), the semimembranosus (Fig. 90, _i_),
the adductor femoris (Fig. 90, _h_), the great sciatic nerve (Fig. 163,
_a_), and distad with the following muscles of the lower leg: the
tibialis anterior (Fig. 90, _n_), the extensor longus digitorum (Fig.
90, _p_), the peroneus longus (Fig. 90, _q_), and the lateral head of
the gastrocnemius (Fig. 90, _m_).
_Action._--Abductor of the thigh, and flexor of the shank.
=M. tenuissimus= or =M. abductor cruris= (Fig. 90, _g_).--A very slender
muscle, only three or four millimeters wide.
_Origin_ from the tip of the transverse process of the second caudal
vertebra, in common with the caudofemoralis (Fig. 68, _s_) or gluteus
maximus. It passes obliquely beneath the biceps femoris (Fig. 68, _t_)
distad and ventrad, to the distal end of the ventral border of that
muscle. Here it becomes continuous with the ventral border of the
biceps, ending in a continuation of the same fascia into which the
biceps is inserted.
_Relations_.--Outer surface with the caudofemoralis (Fig. 68, _s_) and
the biceps femoris (Fig. 68, _t_); distad with the integument. Inner
surface with the obturator internus (Fig. 90, _e_), quadratus femoris
(_f_), semitendinosus (_j_), adductor femoris (_h_), semimembranosus
(_i_), and distad with the muscles of the lower leg.
=M. caudofemoralis= (=parameralis=, Strauss-Durckheim) (Fig. 68, _s_,
page 117).
_Origin_ by a flat tendon from the transverse processes of the second
and third caudal vertebræ. The muscle forms a flat band which passes
distad along the middle of the lateral side of the thigh over the pelvis
and caudad of the great trochanter. At the middle of the thigh it ends
in a very thin tendon. The tendon passes distad along the medial surface
of the biceps femoris (Fig. 68, _t_), pierces the fascia lata near the
knee, and passes to its
_Insertion_ into the middle of the lateral border of the patella.
_Relations._--Outer surface with the superficial fascia and a few fibres
of the cutaneus maximus; distad with the biceps femoris (Fig. 68, _t_).
Cranial border with the gluteus maximus; caudal border with the biceps
femoris. Inner surface with the tenuissimus (Fig. 90, _g_), the gluteus
maximus, the abductor caudæ internus, and with the obturator internus
(Fig. 90, _e_); distad with the vastus lateralis.
_Action._--Abducts the thigh and helps to extend the shank.
=M. semitendinosus= (Fig. 90, _j_).--A long slender muscle on the
ventral (caudal) border of the thigh, between the semimembranosus (_i_)
and the biceps femoris (Fig. 68, _t_).
_Origin_ from the apex of the tuberosity of the ischium beneath the
origin of the biceps femoris. The muscle passes to the medial side of
the shank and ends in a thin but strong tendon (Fig. 92, _i′_) about
five millimeters broad. The tendon curves proximad and passes beneath
the gracilis tendon (Fig. 91, _b_) to its
_Insertion_ into the crest (dorsal border) of the tibia one or two
centimeters from its proximal end.
_Relations._--Lateral surface with the biceps femoris (Fig. 68, _t_),
the integument, a mass of fat, and distad with the gastrocnemius (Fig.
92, _j_) and popliteus (Fig. 92, _k_). Caudal surface with the
integument. Medial surface with the semimembranosus (Fig. 90, _i_) and
distad with the integument of the lower leg.
_Action._--Flexor of the shank.
=M. semimembranosus= (Figs. 90 and 91, _i_; Fig. 92, _h_).--A thick
prismatic muscle lying along the ventral (or caudal) side of the thigh
between the semitendinosus (_j_) and the gracilis (Fig. 91, _b_).
_Origin_ by short tendon-fibres from the caudal border of the tuberosity
and the ramus of the ischium. The muscle mass is divided throughout most
of its length into two portions (Fig. 92, _h_ and _h′_), one of which
(_h′_) lies laterad and caudad of the other. The two portions pass to
the medial side of the knee. The caudal portion (_h′_) ends in a strong
flat tendon five millimeters broad, the
_Insertion_ of which is into the medial surface of the femur on the
medial epicondyle, at the middle of its distal border and into the
adjacent medial surface of the tibia behind the lateral ligament.
The dorsal part has its _insertion_ into the distal one and one-half to
two centimeters of the ridge which is continued from the medial
epicondyle of the femur onto the shaft; and into the sesamoid bone of
the medial epicondyle.
_Relations._--Lateral surface with the semitendinosus (Fig. 90, _j_),
the biceps femoris (Fig. 68, _t_), and distad with a small part of the
adductor femoris (Fig. 92, _g_), and with the gastrocnemius (Fig. 92,
_j_). Medial surface with the gracilis (Fig. 91, _b_) and distad with
the sartorius (Fig. 91, _a_). Cranial (or dorsal) border at the origin
with the quadratus femoris (Fig. 90, _f_); for the remainder of its
length with the adductor femoris (Fig. 90, _h_). Caudal border with the
integument proximad.
_Action._--Extensor of the thigh.
[Illustration: FIG. 91.--MUSCLES ON THE MEDIAL SIDE OF THE LEG.
_a_, M. sartorius; _b_, M. gracilis; _c_, M. iliopsoas; _d_, M. rectus
femoris; _e_, M. vastus medialis; _f_, M. pectineus; _g_, M. adductor
longus; _h_, M. adductor femoris; _i_, M. semimembranosus; _j_, M.
semitendinosus; _k_, medial head of M. gastrocnemius; _l_, M.
plantaris; _m_, M. flexor longus hallucis (_m′_, its tendon); _n_, M.
flexor longus digitorum; (_n′_, its tendon); _o_, M. tibialis
posterior; _p_, M. tibialis anterior; _q_, M. interosseus of second
digit. 1, patella; 2, calcaneus; 3, medial malleolus; 4, second
metatarsal; 5, transverse ligament of the lower leg.]
=M. sartorius= (Fig. 91, _a_; Fig. 68, _q_).--A large flat muscle along
the medial side of the thigh near its cranial (dorsal) border.
_Origin_ from the ventral half of the crest of the ilium and from the
medial half of its ventral border craniad of the auricular impression.
The caudal third of the origin is by a thin tendon, the rest by fleshy
fibres.
_Insertion_ on a long S-shaped line which begins on the dorsal border of
the tibial shaft about two centimeters from its proximal end, passes
thence to the middle of the proximal end of the medial surface of the
tibia, thence across the ligaments of the knee-joint and the medial
surface of the medial epicondyle to the patella, crosses the patella
obliquely to the middle of its proximal end, and may be continued for
some distance proximad along the middle line on the fascia.
_Relations._--Medial surface with the integument and proximad with the
internal oblique muscle (Fig. 68, _p_). Lateral (inner) surface with the
tensor fasciæ latæ (Fig. 68, _r_), the vastus lateralis (Fig. 90, _d_),
the superficial fascia, the vastus medialis (Fig. 92, _c_), the rectus
femoris (Fig. 92, _b_), and the distal end of the semimembranosus (Fig.
92, _h′_).
_Action._--Adducts and rotates the femur and extends the tibia.
=M. gracilis= (Fig. 91, _b_).--The gracilis is a flat, thin,
subcutaneous muscle occupying the ventral half of the medial surface of
the thigh.
_Origin_ by a strong tendon from the caudal three-fourths of the
symphysis of the ischium and pubis. The tendon may extend caudad of the
symphysis in the middle line to the level of the tuberosity of the
ischium. For about its first centimeter the tendon is common to the two
muscles of opposite sides and gives origin on two sides to the fibres of
the adductor femoris. The common tendon divides into two which pass
laterad, each ending in a convex border from which the muscle-fibres
spring.
_Insertion._--It ends in a thin aponeurosis, part of which is continuous
with that of the sartorius. The aponeurosis is finally inserted into the
medial surface of the tibia near its proximal end, while distally it is
continuous with the fascia.
_Relations._--Outer (medial) surface with the integument. Inner
(lateral) surface with the semimembranosus (Fig. 91, _i_) and the
adductor femoris (Fig. 91, _h_).
_Action._--Adducts the leg and draws it caudad.
=M. adductor femoris= (magnus et brevis) (Fig. 92, _g_; Fig. 90,
_h_).--The adductor femoris lies between the semimembranosus (Fig. 92,
_h_) and the femur. Its proximal part is covered by the semimembranosus,
while its distal part lies outside of it.
_Origin_ by muscle-fibres from the rami of the pubis and the ischium
along the whole of the length of the symphysis; from the ramus of the
ischium between the symphysis and the tuberosity, and from the tendon of
origin common to the two gracilis muscles.
_Insertion_ into nearly the whole of the ventral surface of the shaft of
the femur. The area begins at the base of the great trochanter opposite
the proximal end and the insertion area of the gluteus maximus. It
extends thence distad along the caudal border of the surface as an area
about one millimeter wide. At the junction of the first and second
thirds of the shaft the area expands and occupies the whole of the
ventral surface of the bone, ending at the intercondyloid fossa.
_Relations._--Lateral surface with the biceps (Fig. 68, _t_), the great
sciatic nerve (Fig. 163, _a_), the tenuissimus (Fig. 90, _g_), and the
semimembranosus (Fig. 92, _h_); dorsolateral border in contact with the
vastus lateralis (Fig. 92, _c_). Dorsal surface with the quadratus
femoris (Fig. 90, _f_) and obturator externus (Fig. 90, _e_). Caudal
surface with the semimembranosus (Fig. 92, _h_). Medial surface with the
gracilis (Fig. 91, _b_), adductor longus (Fig. 92, _f_), pectineus (Fig.
92, _e_), vastus medialis (Fig. 92, _c_), and distad with the medial
head of the gastrocnemius (Fig. 92, _j_).
_Action._--An extensor of the thigh.
=M. adductor longus= (Fig. 91, _g_; Fig. 92, _f_).--A thin muscle which
covers the dorsal half of the medial surface of the adductor femoris
(Fig. 92, _g_).
_Origin_ by muscle-fibres from the median three-fourths of the cranial
border of the pubis, the line of origin forming a medial continuation of
that of the pectineus (Fig. 92, _e_).
_Insertion_ by a thin aponeurosis into the external linea aspera of the
femur along the second and third fifths of the bone.
_Relations._--With its medial or cranial surface the adductor longus
forms part of the boundary of a depression among the muscles at the
proximal end of the medial side of the leg. This depression is called
the iliopectineal fossa; it contains the femoral vein and artery and
saphenous nerve imbedded in fat (Fig. 127). The medial edge of the
adductor longus is in relation with the integument; the lateral edge
with the pectineus (Fig. 92, _e_). Inner or caudal surface with the
adductor femoris (Fig. 92, _g_).
_Action._--Adductor of the thigh.
[Illustration: FIG. 92.--SECOND LAYER OF MUSCLES ON THE MEDIAL SIDE OF
THE THIGH.
_a_, M. tensor fasciæ latæ; _a′_, fascia lata; _b_, M. rectus femoris;
_c_, M. vastus medialis; _d_, M. iliopsoas (cut); _e_, M. pectineus;
_f_, M. adductor longus; _g_, M. adductor femoris; _h_, _h′_, M.
semimembranosus; _i_, M. semitendinosus (_i′_, its tendon); _j_,
medial head of M. gastrocnemius; _k_, M. popliteus; _l_, M. flexor
longus digitorum. 1, patellar ligament; 2, ligamentum collaterale
tibiale.]
=M. pectineus= (Fig. 92, _e_).--A flat band of fibres closely united
with the adductor longus (_f_), of which it appears to be a lateral
continuation.
_Origin_ by fleshy fibres from the lateral one-fourth of the cranial
border of the pubis. The muscle passes over the smooth outer surface of
the pubis between its origin area and the acetabulum, crosses the
iliopsoas (_d_) obliquely and has its
_Insertion_ by muscle-fibres into an elongated area (five millimeters in
length) on the shaft of the femur just distad of the lesser trochanter
and between the insertion of the adductor femoris (_g_) and that of the
vastus medialis (_c_).
_Relations._--The cranial edge forms part of the floor of the
iliopectineal fossa. Lateral surface in relation with the iliopsoas
(_d_) and vastus medialis (_c_); medial surface with the adductor longus
(_f_) and adductor femoris (_g_).
_Action._--Adductor of the thigh.
=M. quadriceps femoris.=--The quadriceps femoris is a very powerful
extensor muscle on the front of the thigh. It consists of four muscles
which unite to form the great extensor of the shank. It is inserted into
the patella and through it, by the ligamentum patellæ, into the tibia.
It may be compared to the triceps brachii. The parts are:
(1) =M. rectus femoris= (Fig. 92, _b_; Fig. 90, _c_).
_Origin_ by strong tendon from an elongated triangular area which has
its base at the acetabulum and its apex about five to seven millimeters
craniad of the acetabulum, along the ventral border of the ilium. The
area is between that for the capsularis and that for the iliopsoas. The
muscle is flat near its origin, but soon becomes a triangular prismatic
mass which is united to the dorsal border of the vastus lateralis (Fig.
90, _d_) at the junction of the middle and last thirds of the thigh.
_Insertion_ into the oblique area on the outer surface of the patella
near its proximal border in connection with the vastus lateralis.
_Relations._--Outer or lateral surface at the origin with the gluteus
minimus, the edge of the capsularis, the gluteus medius (Fig. 90, _b_),
and farther distad with the vastus lateralis (Fig. 90, _d_). Medial
surface with the tensor fasciæ latæ (Fig. 92, _a_), sartorius (Fig. 90,
_a_), and vastus medialis (Fig. 92, _c_). Inner (caudal) surface with
the vastus intermedius.
(2) =M. vastus lateralis= (Fig. 90, _d_).--A flat triangular prismatic
mass joined distally to the preceding. It covers the dorsal part of the
lateral surface of the thigh.
_Origin_ from a triangular area on the dorsal and lateral surfaces of
the shaft and the great trochanter of the femur. The base of the area is
at the great trochanter, and its apex is at the junction of the second
and third fifths of the shaft on the linea aspera. The linea aspera
forms the ventral boundary of the triangle, while its dorsal boundary is
formed by a line drawn from its apex to the dorsomedial angle of the
great trochanter. The mass unites with the rectus femoris (_c_) by its
dorsal border at the junction of the middle and distal thirds of the
thigh.
_Insertion_ into the oblique area on the outer surface of the patella
near its lateral border in connection with the rectus femoris.
(3) =M. vastus medialis= (Fig. 92, _c_) lies on the medial side of the
thigh.
_Origin_ by fleshy fibres over a diamond-shaped area on the shaft of the
femur lying between the medial branch of the linea aspera and the area
for the vastus lateralis. Proximad the area is bounded by the spiral
line, and distad it is bounded by a line parallel to the spiral line and
having its proximal end at about the junction of the first and second
thirds of the bone. The muscle forms a triangular, prismatic mass. It
ends in a thin aponeurosis which is continuous dorsad with the border of
the rectus femoris (Fig. 92, _b_), and ventrad sometimes with the tendon
of the gracilis (Fig. 91, _b_).
_Insertion_ into the medial border of the patella and the ligamentum
patellæ. The insertion may extend onto the head of the tibia.
The adjacent surfaces of the vastus lateralis and the vastus medialis
are connected over their distal thirds by an aponeurosis which passes
transversely beneath the rectus femoris. The distal end of the
aponeurosis is inserted into the proximal border of the patella. Its
proximal end receives the insertion of some muscle-fibres which form a
part of the vastus medialis as here described. This mass of fibres is
described by Strauss-Durckheim as the =crural= muscle. Sometimes the
transverse aponeurosis is continuous with only one of the two vasti and
sometimes with neither, so that the insertion of the crural of
Strauss-Durckheim becomes more or less independent.
_Relations_ of the vastus medialis.--Outer (medial) surface with the
sartorius (Fig. 91, _a_) and the structures in the iliopectineal fossa.
Cranial (or dorsal) surface with the rectus femoris (Fig. 92, _b_) and
vastus intermedius. Caudal (ventral) surface with the pectineus (Fig.
92, _e_), adductor longus (Fig. 92, _f_), adductor femoris (Fig. 92,
_g_), and semimembranosus (Fig. 92, _h_).
(4) =M. vastus intermedius.=--A flat mass of muscle which lies beneath
the rectus femoris.
_Origin_ from nearly the whole of the dorsal surface of the shaft of the
femur between the areas for the vastus medialis and vastus lateralis.
The area of origin extends distad to an oblique line the middle of which
is about one and one-half centimeters from the patellar surface, the
lateral border of the area being longer than the medial border.
_Insertion_ by muscle-fibres into the capsule of the joint. The central
fibres are inserted about one centimeter proximad of the patella, while
the lateral mass passes to the level of the proximal end.
_Relations._--Outer surface with the rectus femoris (Fig. 92, _b_);
borders with the vastus medialis (Fig. 92, _c_) and vastus lateralis
(Fig. 90, _d_); inner surface with the femur.
_Action._--The quadriceps extensor is an extensor of the shank. The
vastus intermedius acting separately is a tensor of the capsule of the
knee-joint.