=Fascia of the Thigh.=--After the removal of the superficial fascia with
its fat and blood-vessels, there is seen a strong glistening fascia, the
=fascia lata= (Fig. 68, _z_, page 117), covering the vastus lateralis
muscle over the dorsal half of the thigh. Ventrally it dips between the
vastus lateralis and the biceps femoris and, becoming gradually thinner,
is lost on the surface of the former muscle. Passing over the dorsal
border of the thigh, it extends beneath the sartorius and is attached to
the dorsal border of the vastus medialis. Toward its distal end the
fascia is continuous with the tendon of the biceps femoris and dorsad
with the border of the sartorius muscle, while between these points it
is united with the tendon of the vastus lateralis; it thus gains
insertion into the patella. At its proximal end the fascia receives the
insertion of the tensor fasciæ latæ (Fig. 68, _r_).
=M. tensor fasciæ latæ= (Fig. 68, _r_, page 117; Fig. 92, _a_).--The
tensor fasciæ latæ is a thick triangular muscle which may be recognized
by its insertion into the proximal end of the fascia lata (Fig. 68, _z_;
Fig. 92, _a′_).
_Origin_ by fleshy fibres as a thick triangular prism from the outer
margin of the ventral border of the ilium craniad of the auricular
impression and from the fascia covering the ventral border of the
gluteus medius (Fig. 90, _b_) over its cranial half. The caudal border
of the muscle may be continuous with the cranial border of the gluteus
maximus. The muscle spreads out in a fan-like manner, covering the
proximal third of the dorsal surface of the thigh. The cranial fibres
pass farther distad than the others.
_Insertion_ into the fascia lata (Fig. 68, _z_) along an irregular line
which begins caudad at the base of the great trochanter and ends on the
cranial side of the thigh at the junction of the first and second
thirds.
_Relations._--Outer surface with the cutaneus maximus (Fig. 62, _b_,
page 94) and craniad with the sartorius (Fig. 68, _q_). Cranial border
with the sartorius (_q_); caudodorsal border with the gluteus medius
(Fig. 90, _b_). Inner surface with the gluteus medius, the rectus
femoris (Fig. 92, _b_), and the vastus lateralis (Fig. 90, _d_).
_Action_ indicated by the name. It also assists the quadriceps femoris
in extending the leg.
=M. gluteus maximus.=--The gluteus maximus is a rather small
quadrangular muscle in the angle between the gluteus medius (Fig. 90,
_b_) and the caudal vertebræ.
_Origin_ (Fig. 163, 3, page 401) by fleshy fibres from the tips of the
transverse processes of the last sacral and the first caudal vertebræ,
from the fascia covering the spinous muscles dorsad of the transverse
processes of these vertebræ, and from the fascia covering the gluteus
medius. The muscle passes laterad and slightly caudad to its
_Insertion_ by tendon and muscle-fibres into a tubercle on the caudal
side of the great trochanter at the middle of its distal end, and for a
few millimeters into the ridge which continues distad from this
tubercle.
_Relations._--Outer surface with the caudofemoralis (Fig. 68, _s_, page
117), the superficial fascia, and a few fibres of the cutaneus maximus.
Inner surface with the abductor caudæ internus, the tenuissimus (Fig.
90, _g_), the great sciatic nerve (Fig. 163, _a_), the obturator
internus (Fig. 90, _e_), the gluteus medius (Fig. 90, _b_), the gemellus
superior, and the pyriformis (Fig. 163, 7). Cranial border with the
gluteus medius and the tensor fasciæ latæ. Caudal border with the
caudofemoralis (Fig. 68, _s_).
_Action._--Abducts the thigh.
=M. gluteus medius= (Fig. 90, _b_).--The gluteus medius is a very large
triangular muscle which connects the ilium and the sacrum with the great
trochanter (1).
_Origin_ by fleshy fibres (1) from the superficial sacral fascia; (2)
from the lateral surface of the fascia which covers the surface of the
supraspinous extensor muscles of the tail; (3) from the fascia
intervening between it and the tensor fasciæ latæ; (4) by tendon fibres
from the dorsal half of the crest of the ilium and its dorsal border,
and the dorsal half of the lateral surface craniad of the auricular
impression; and (5) from the tips of the transverse processes of the
last sacral and the first caudal vertebræ. The fibres converge to a
strong internal tendon.
_Insertion_ into the proximal end of the great trochanter.
_Relations._--Outer surface with the gluteus maximus and tensor fasciæ
latæ, and between these with the strong fascia lying beneath the
cutaneus maximus muscle. Inner surface with the gluteus minimus, the
pyriformis, and the gemellus superior. Cranial border with the tensor
fasciæ latæ. Caudal border with the gluteus maximus.
_Action._--Abducts the thigh.
=M. pyriformis= (Fig. 163, 7).--The pyriformis is a triangular muscle
covered by the gluteus maximus and the gluteus medius (Fig. 90, _b_) and
overlying the gemellus superior (Fig. 163, 6).
_Origin_ by fleshy fibres from the tips of the transverse processes of
the last two sacral and the first caudal vertebræ. The muscle passes
laterad through the great sciatic notch to its
_Insertion_ by a flat tendon into an elongated area on the proximal
border of the great trochanter just outside (caudad) of the insertion of
the gemellus superior.
_Relations._--Outer surface with the gluteus medius (Fig. 90, _b_) and
the gluteus maximus. Inner surface with the gemellus superior (Fig. 163,
6), the great sciatic nerve (Fig. 163, _a_), and the flexor caudæ longus
(Fig. 68, _x_).
_Action._--Abductor of the thigh.
=M. gemellus superior= (Fig. 163, 6).--The gemellus superior is a
triangular muscle lying beneath the pyriformis (Fig. 163, 7). It is
broader than the pyriformis, so that it projects beyond its borders both
caudad and craniad. It is closely united craniad with the gluteus
minimus, so that the limits of the two are definable only with
difficulty. Its caudal border is closely united to the gemellus
inferior.
_Origin_ by fleshy fibres from an elongated area on the dorsal border of
the ilium and ischium. The area is narrowed craniad. It does not quite
reach the posterior inferior iliac spine in the one direction nor the
spine of the ischium in the other direction. The fibres converge to a
strong tendon the
_Insertion_ of which is into a triangular area dorsad of the tip of the
great trochanter.
_Relations._--Outer surface with the gluteus medius (Fig. 90, _b_), the
pyriformis (Fig. 163, 7), the great sciatic nerve (Fig. 163, _a_), and
the gluteus maximus. Inner surface with the ilium, ischium, the
capsularis, the caudal edge of the gluteus minimus (Fig. 163, 5), and
the cranial edge of the obturator internus (Fig. 90, _e_).
_Action._--Rotates the femur and abducts it so as to carry the foot
outward.
=M. gluteus minimus= (Fig. 163, 5).--The gluteus minimus is a long
triangular muscle beneath the middle of the gluteus medius (Fig. 90,
_b_) and with its caudal border against or covering the cranial border
of the gemellus superior (Fig. 163, 6), to which it is frequently
closely united.
_Origin_ from the ventral half of the ilium, from near its cranial end
to a point midway between the posterior iliac spine and the spine of the
ischium. The muscle ends in a strong flat tendon.
_Insertion_ into an oval facet at the base of the dorsal surface of the
great trochanter on its lateral side.
_Relations._--Outer surface with the gluteus medius (Fig. 90, _b_) and
at the caudal border with the gemellus superior (Fig. 163, 6). Inner
surface with the capsularis and rectus femoris (Fig. 92, _b_).
_Action._--Rotates the femur so as to carry the foot out.
=M. capsularis= (gluteus quartus, or epimeralis).--The capsularis is a
small flat bundle of muscle-fibres which lies obliquely beneath the
gluteus minimus (Fig. 163, 5) and gemellus superior (6) on the lateral
or outer surface of the ilium.
_Origin_ by fleshy fibres from the surface of the ilium over a
triangular area between the origin of the rectus femoris (Fig. 92, _b_)
ventrad, the gemellus superior (Fig. 163, 6) dorsad, and of the gluteus
minimus (Fig. 163, 5) craniad and the acetabulum caudad. The muscle
passes over the smooth surface of the ilium and the pubis ventrad of the
acetabulum and then over the capsule of the joint.
_Insertion_ by fleshy fibres for about one centimeter in the middle line
on the dorsal surface of the femur distad of the great trochanter.
_Relations._--Outer surface with the gluteus minimus (Fig. 163, 5), the
gemellus superior (6), and the vastus lateralis (Fig. 90, _d_). Inner
surface with the ilium, the rectus femoris (Fig. 92, _b_), the capsule
of the joint, and the vastus medialis (Fig. 92, _c_).
_Action._--Rotates the thigh so as to carry the foot inward, hence
antagonizes the iliopsoas.
=M. gemellus inferior.=--The gemellus inferior is a flat triangular
muscle situated just caudad of the gemellus superior and beneath the
obturator internus (Fig. 90, _e_), so that it is seen on reflecting the
latter
_Origin_ from the dorsal one-half of the whole lateral surface of the
ischium between the ischial spine and the ischial tuberosity. The fibres
converge toward its insertion. The inner surface of the muscle is
covered by a strong tendon.
_Insertion_ into the inner surface of the tendon of the obturator
internus (Fig. 90, _e_) by tendon- and muscle-fibres. Some of the
muscle-fibres are inserted into the capsule of the joint.
_Relations._--Outer surface with the obturator internus (Fig. 90, _e_).
Medial surface with the ischium. Caudal border with the quadratus
femoris (Fig. 90, _f_). Cranial border with the gemellus superior.
_Action._--Abductor of the thigh. The muscle may be considered as a
separate head of the obturator internus (Fig. 90, _e_).
=M. quadratus femoris= (Fig. 90, _f_).--The quadratus femoris is a short
thick muscle connecting the ischial tuberosity (2) and the proximal end
of the femur. It lies just caudad of the obturator internus (_e_)
beneath the proximal end of the biceps femoris (Fig. 68, _t_).
The _origin_ is by fleshy fibres from a considerable triangular area on
the lateral surface of the ischium near the tuberosity. The area lies
between the origin areas of the gemellus inferior, biceps,
semimembranosus, and the obturator externus.
_Insertion_ into the distal two-thirds of the ventral border of the
great trochanter and about half the adjacent surface of the lesser
trochanter.
_Relations._--Outer surface with the tenuissimus (Fig. 90, _g_), the
biceps (Fig. 68, _t_), the semitendinosus (Fig. 90, _j_), and the great
sciatic nerve (Fig. 163, _a_). Caudal border with the semimembranosus
(Fig. 90, _i_). Ventral border with the adductor femoris (Fig. 90, _h_);
dorsal border with the obturator internus (Fig. 90, _e_) and gemellus
inferior.
_Action._--Extensor of the thigh and rotator of the femur so as to carry
the foot inward.
=M. obturator externus.=--The obturator externus is a flat triangular
muscle beneath the adductor femoris (Fig. 92, _g_).
_Origin_ by fleshy fibres from the median lip of the obturator foramen
and from both dorsal and ventral surfaces of the rami of the pubis and
ischium adjacent to the lip. Also from the outer surface of the ramus of
the ischium as far as the area for the quadratus femoris (Fig. 90, _f_).
The fibres converge to a strong flat tendon.
[Illustration: FIG. 90.--MUSCLES ON THE LATERAL SIDE OF THE LEG, AFTER
REMOVAL OF THE MUSCLES SHOWN IN FIG. 68 (BICEPS, TENSOR FASCIÆ LATÆ,
CAUDOFEMORALIS, AND GLUTEUS MAXIMUS).
_a_, M. sartorius; _b_, M. gluteus medius; _c_, M. rectus femoris;
_d_, M. vastus lateralis; _e_, M. obturator internus; _f_, M.
quadratus femoris; _g_, M. tenuissimus; _h_, M. adductor femoris; _i_,
M. semimembranosus; _j_, M. semitendinosus; _k_, M. vastus
intermedius; _l_, M. plantaris; _m, m′, m″_, M. gastrocnemius, outer
head (_m_, part from the external sesamoid bone; _m′_, from the
plantaris; _m″_, from the superficial fascia); _n_, M. tibialis
anterior; _o_, M. soleus; _p_, M. extensor longus digitorum; _q_, M.
peroneus longus; _r_, M. peroneus tertius (_r′_, its tendon); _s_, M.
peroneus brevis; _t_, tendon of Achilles; _u_, M. extensor brevis
digitorum. 1, great trochanter of femur; 2, tuberosity of ischium,
with cut origin of M. biceps femoris; 3, patella; 4, calcaneus; 5,
transverse ligaments; 6, lateral malleolus.]
_Insertion_ into the proximal portion of the bottom of the trochanteric
fossa.
_Relations._--Ventral surface with the adductor femoris (Fig. 92, _g_).
Dorsal surface with the pubis and ischium. Caudal border with the
quadratus femoris (Fig. 90, _f_).
_Action._--Assists the iliopsoas.
B. MUSCLES ON THE MEDIAL SURFACE OF THE HIP.--=M. obturator internus=
(Fig. 90, _e_).--The obturator internus appears as a triangular muscle
caudad of the gemellus superior.
_Origin_ by numerous small separate heads from the dorsal surface of the
ramus of the ischium along its symphysis and following its medial border
from the symphysis nearly to the tuberosity. The fibres form a flat
muscle which narrows and passes through the lesser sciatic notch, turns
ventrad and ends in a strong flat tendon whose
_Insertion_ is into the bottom of the trochanteric fossa of the femur.
The tendon is continued proximad on the inner surface of the muscle and
forms a smooth firm surface by which the muscle glides over the dorsal
border of the ischium. Into the inner surface of this tendon near its
insertion the tendon of the gemellus inferior is inserted.
_Relations._--Medial surface within the pelvis with a mass of fat
separating it from the pelvic organs. Dorsal or outer surface with the
biceps femoris, the tenuissimus, the caudofemoralis, and the great
sciatic nerve. Inner surface with the ischium and the great sciatic
nerve. Caudal (or ventral) border with the quadratus femoris.
_Action._--Abductor of the thigh.
=M. iliopsoas= (Fig. 162, 8; Fig. 91, _c_).--The iliopsoas (equivalent
to the human psoas and iliacus) is a conical muscle emerging from the
abdominal cavity onto the medial surface of the femur.
_Origin._--(_a_) The portion corresponding to the human psoas (Fig. 162,
8) arises by ten vertebral heads. The first five of these come from the
five cranial tendons of origin of the psoas minor (Fig. 162, 9); the
sixth from a tendinous expansion which passes from the tendon of the
first head over the ventral longitudinal muscles to the transverse
process of the fifth lumbar vertebra. The seventh, eighth, ninth, and
tenth heads arise by fleshy fibres from the ventral surfaces of the
centra of the last four lumbar vertebræ.
(_b_) The portion corresponding to the human iliacus arises by fleshy
fibres from the ventral border of the ilium, from opposite the auricular
impression to the iliopectineal eminence. The portions of the muscle all
converge to form a conical mass which ends in a strong tendon lying on
its outer surface.
_Insertion_ by tendon and fleshy fibres into the apex of the lesser
trochanter of the femur.
_Relations._--Dorsal surface with the quadratus lumborum (with which
this muscle is partly united), the rectus femoris (Fig. 91, _d_), and,
by the iliac head, with the gluteus minimus. Ventral and medial surface
with the psoas minor (Fig. 162, 9) and the peritoneum. Lateral edge with
the transversus abdominis (Fig. 162, 4).
_Action_.--Rotates the thigh so as to carry the foot out; also flexes
the thigh.