D. J. (Daniel John) Cunningham.

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the distal part of the trochanter major, and to the proximal
part of the body of the femur; (7) the proximal part of the
adductor magnus, immediately distal to the quadratus femoris;
(8, 9, and 10) the biceps femoris, the semitendinosus and the
semimembranosus (hamstrings), springing from the tuberosity
of the ischium. In addition to the above-mentioned muscles
the dissector should note (n) that the proximal part of the
vastus lateralis is under cover of the tendinous insertion of the
glutaeus maximus, distal to the lateral part of the trochanter
major, and (12 and 13) that the lower and medial part of
the glutaeus maximus, which forms the posterior boundary
of the ischio-rectal fossa, is separated by a pad of fat from
the levator ani and the coccygeus muscles, which form the
medial wall of the fossa.

The vessels and nerves under cover of the glutaeus maximus
are also numerous ; they are :

(1) Issuing between the adjacent borders of the glutaeus
medius and piriformis and passing into the deep surface of
the glutaeus maximus, superficial branches of the superior gluteal
artery. The trunk from which the branches spring, and the
superior gluteal nerve, which accompanies it, can be seen if
the borders of the muscles are separated.

(2) In the interval between the lower border of the piri-
formis and the upper border of the superior gemellus two
arteries and six nerves emerge through the greater sciatic
foramen into the buttock, viz. :

A . fi. Arteria glutaea inferior.

ies ' \2. Arteria pudenda interna.

1. Nervus glutseus inferior.

2. Nervus cutaneus femoris posterior.

3. Nervus ischiadicus.

4. Nervus pudendus.

Nerve to the obturator internus.
Nerve to the quadratus femoris.

(3) In the interval between the gemellus inferior and the
quadratus femoris, the ascending terminal branch of the medial

femoral circumflex artery will be seen.

(4) At the distal border of the quadratus femoris the trans-
verse terminal branch of the medial femoral circumflex artery passes
backwards to the hamstring muscles ; and the first perforating

i 19 c



Nerves,



296 THE INFERIOR EXTREMITY

branch of the profunda artery pierces the adductor magnus
close to the distal part of the gluteal tuberosity of the femur.

Nervus Glutaeus Inferior. The inferior gluteal nerve is
the nerve of supply to the glutaeus maximus. It springs
from the sacral plexus, and enters the gluteal region through
the lower part of the great sciatic foramen. When the
glutaeus maximus was reflected the nerve was seen breaking
up into numerous twigs which entered the deep surface of
the muscle.

Arteria G-lutaea Inferior (O.T. Sciatic). The inferior
gluteal artery, a branch of the hypogastric artery (O.T. in-
ternal iliac), issues from the pelvis, through the great sciatic
foramen, below the piriformis muscle, and proceeds distally,
with the sciatic nerve, under cover of the glutaeus maximus,
in the hollow between the greater trochanter and the ischial
tuberosity. At the lower border of the glutaeus maximus it
is continued, as a fine cutaneous twig, to the posterior aspect
of the thigh, in company with the posterior cutaneous nerve.
It gives off numerous branches in the gluteal region. Of
these the large muscular offsets to the glutaeus maximus, and
the cutaneous twigs that accompany the branches of the
posterior cutaneous nerve of the thigh which turn round the
distal border of that muscle, have been already studied. The
following three branches remain to be examined : ( i ) the
coccygeal branch, which passes medially between the sacro-
tuberous and sacro-spinous ligaments to reach the integument
and fascia in the region of the coccyx; a number of twigs
derived from this branch have been previously noticed piercing
the sacro- tuberous ligament and ending in the glutaeus
maximus ; (2) arteria comitans nervi ischiadici, a minute artery,
which runs distally on the sciatic nerve and finally penetrates
into its substance ; (3) the artery to the quadratus femoris,
which accompanies the nerve to that muscle ; it will be found
lying on the hip bone under cover of the sciatic nerve.

In a well-injected body the anastomosis between the
inferior gluteal artery, the two terminal branches of the
medial circumflex artery, and the first perforating artery may
be made out.

Nervus Cutaneus Femoris Posterior (O.T. Small Sciatic
Nerve). The posterior cutaneous nerve of the thigh arises,
within the pelvis, from the sacral plexus. After escaping
through the greater sciatic foramen it extends distally, with the



GLUTEAL REGION



297



inferior gluteal artery, under cover of the glutseus maximus.
From the inferior border of the glutaeus maximus it proceeds
distally, on the back of the thigh, immediately subjacent to
the deep fascia. It will afterwards be traced to the posterior
aspect of the calf of the leg.

In the gluteal region it gives off several cutaneous branches,



LIV



LV



To piriformis



To piriformis



,, Lumbo-sacral trunk

Superior gluteal nerve

Inferior gluteal nerve



Nerve to quadratus femoris
Nerve to obturator internus




Sciatic nerve



.Common

roneal nerve



'Sciatic nerve



X Tibial nerve

Post. cut. N. of thigh (O. T. small sciatic)
Perineal N. and dorsal N. of penis \ Pudendal
Inferior haemorrlioidal nerve / nerve

Perforating cutaneous nerve

-Y '

Nerves to levator ani
Coccygeal branches

FIG. 131. Diagram of Sacral Plexus.

viz. (i) inferior nerves of the buttock, which wind round
the inferior border of the glutaeus maximus to supply a
limited area of the skin of the buttock; (2) a few twigs to
the skin to the medial region of the thigh ; and (3) the
perineal branches, of which one is known as the long perineal
nerve (O.T. long pudendal). This branch turns medially, round
the origin of the hamstring muscles, to reach the perineum.



298 THE INFERIOR EXTREMITY

Nervus Ischiadicus (O.T. Great Sciatic Nerve). The sciatic
nerve, the largest nerve in the body, comes from the sacral
plexus, and enters the gluteal region through the lower part
of the great sciatic foramen. At first it has the form of a
flattened band, but soon it becomes oval or round, as seen in
section. Covered by the glutaeus maximus, the sciatic nerve
traverses the gluteal region in the interval between the greater
trochanter of the femur and the tuberosity of the ischium.
From above downwards it lies on the body of the ischium
and the nerve to the quadratus femoris, the tendon of the
obturator internus with the two gemelli muscles, the quadratus
femoris, and the adductor magnus. The nerves to one or
more of the hamstring muscles issue from the main trunk
near the lower border of the glutaeus maximus.

The sciatic nerve frequently escapes from the pelvis in the form of two
trunks (the two divisions into which it normally divides in the thigh, viz.,
the tibial and the common peroneal) which enclose between them a portion
of the piriformis muscle.

Arteria Pudenda Interna, Nervus Pudendus (O.T. Internal
Pudic), and the Nerve to the Obturator Internus. The
internal pudendal artery, the pudendal nerve and the nerve
to the obturator internus muscle are exposed, in the present
dissection, only in a very short part of their extent. They all
emerge from the greater sciatic foramen and cross the spine
of the ischium or the adjacent part of the sacro-spinous
ligament ; then they enter the lesser sciatic foramen and pass
out of view. The nerve to the obturator internus is placed
most laterally. It lies on the base of the ischial spine, and
furnishes a twig to the gemellus superior. The internal
pudendal artery -, with a companion vein on each side, crosses
the tip of the spine. The pudendal nerve is placed most
medially, and lies on the sacro-spinous ligament, close to its
attachment to the spine. In some cases, however, the
pudendal" nerve unites in a plexiform manner with the
nerve to the obturator internus, so that the whole, or a part,
of it may lie lateral to the pudendal vessels.

Small Lateral Rotator Muscles of the Thigh. Under this
heading are included the piriformis, the obturator internus,
and the two gemelli, the quadratus femoris, and the obturator
externus. They all lie directly under cover of the glutaeus
maximus in the greater part of their extent, except the
obturator externus which lies deep (anterior) to the quadratus



GLUTEAL REGION 299

femoris, and cannot be properly seen from behind until that
muscle has been reflected ; they are all inserted into, or in the
neighbourhood of, the greater trochanter of the femur, and
they are applied to the posterior surface of the capsule of
the hip joint. The first five are lateral rotators of the thigh,
when the hip joint is extended, but they become abductors
when the joint is flexed. The obturator externus is a lateral
rotator in both positions.

M. Piriformis. The piriformis arises within the pelvis
from the three middle pieces of the sacrum, and slightly from
the upper margin of the great sciatic notch of the hip bone.
The sacral origin cannot be seen at present, but the iliac
origin should be made out. After it has passed through
the great sciatic foramen, the muscle is directed downwards,
laterally, and forwards. Its fleshy belly rapidly tapers and it
ends in a rounded tendon, which crosses superficial to the
common tendon of the obturator internus and gemelli, and
is inserted into a small impression on the highest part of the
greater trochanter of the femur (Fig. 1 1 7, p. 262). It is closely
adherent to the subjacent obturator tendon for some distance.
The piriformis is supplied by branches from the first and
second sacral nerves.

Mm. Obturator Internus et Gemelli. These muscles,
together, constitute a tricipital muscle with one large intra-
pelvic belly (obturator internus), and two small extra-pelvic
bellies (gemellus superior and inferior). The common tendon
is inserted into an impression on the upper part of the
greater trochanter of the femur, immediately posterior to and
below the insertion of the piriformis (Fig. 117, p. 262).

The gemellus superior arises from the spine of the ischium,
at the upper margin of the small sciatic notch. Its fibres
pass laterally, along the superior border of the tendon of the
obturator internus, and are inserted obliquely into that tendon.

The gemellus inferior arises from the tuberosity of the
ischium, at the lower margin of the lesser sciatic notch, and
is inserted into the lower border of the obturator tendon, in
a similar manner to the gemellus superior. Close to their
origins the gemelli meet under cover of the obturator tendon,
and form a fleshy bed on which the tendon lies ; near the
trochanter the fibres of the gemelli overlap the obturator
tendon, and tend to cover its superficial surface.

The tendon of the obturator internus has already been



300 THE INFERIOR EXTREMITY

divided and the peculiarities of its deep surface have been
examined (see p. 293).

M. Quadratus Femoris. The quadratus femoris lies
between the gemellus inferior and the adductor magnus. It
arises from the lateral border of the ischial tuberosity, and
proceeds horizontally to gain insertion into the quadrate
tubercle, and into a line which extends distally from it, on
the back of the femur, for about two inches (Figs. 121, 122).

Dissection. The nerve to the quadratus femoris should now
be traced to its termination. It lies deep to the two gemelli,
the obturator internus, and the quadratus femoris. The obtu-
rator internus has already been divided. Now divide the two
gemelli muscles, lateral to the nerve. Raise the medial parts
and follow the nerve behind them. As the inferior gemellus
is approached secure the twig which the nerve supplies to it.
Lastly, divide the flat quadratus femoris, midway between the
tuberosity of the ischium and the femur and throw the two parts
aside. When the dissection is completed not only is the whole
length of the nerve to the quadratus femoris exposed, but also a
considerable portion of the posterior aspect of the capsule of the
hip joint is laid bare ; further, part of the obturator externus
muscle, the termination of the medial circumflex artery, and
the insertion of the ilio-psoas are brought into view. The
exposed posterior part of the capsule of the hip joint consists
largely of circularly arranged fibres.

Nerve to the Quadratus Femoris. The small nerve to
the quadratus femoris runs distally on the hip bone and
passes successively anterior to the following structures : the
sciatic nerve, the gemellus superior, the tendon of the obturator
internus, the gemellus inferior. It gives the nerve of supply
to the gemellus inferior and a twig to the hip joint, and ends
by sinking into the deep surface of the quadratus femoris.

M. Obturator Externus. The terminal part of the obturator
externus muscle can now be seen winding round the neck of
the femur. It ends in a rounded tendon which is implanted
into the fossa trochanterica of the femur (Fig. 122, p. 271).
Its origin has already been examined (p. 277).

Arteria Circumflexa Femoris Medialis. The medial cir-
cumflex artery comes to an end at the proximal border of
the adductor magnus by dividing into its ascending and trans-
verse terminal branches. The ascending branch runs obliquely
upwards and laterally, anterior to the quadratus femoris
and upon the posterior surface of the obturator externus.
Its terminal twigs ramify in the neighbourhood of the
trochanteric fossa, where they anastomose with twigs from



GLUTEAL REGION 301

the inferior and superior gluteal arteries. The transverse
branch passes posteriorly, between the quadratus femoris and
the adductor magnus, and enters the hamstring muscles. It
anastomoses with the terminal twig of the middle division of
the lateral circumflex artery, which, in a well-injected subject,
will be noticed appearing from amidst the fibres of the proximal
part of the vastus lateralis. An arterial circle is thus com-
pleted, around the proximal part of the femur; it com-
municates proximally with the inferior gluteal artery and
distally with the first perforating artery. This series of in-
osculations is sometimes spoken of as the crucial anastomosis
of the thigh.

The dissector has now examined all the structures in the
gluteal region which lie below the level of the piriformis.
He should, in the next place, turn his attention to that
portion of the dissection which lies above the level of
that muscle. There he will find several structures which lie
in close relation to the dorsum ilii. These are the glutaeus
medius, the glutaeus minimus, and the tensor fasciae latae,
together with the blood-vessels and nerve which supply them,
viz., the superior gluteal artery and vein, and the superior
gluteal nerve.

The posterior part of the glutaeus medius muscle was
covered by the glutaeus maximus. Its anterior border is
overlapped by the tensor fasciae latae, and the intermediate
area is invested by the dense fascial layer already referred to.

Dissection. Remove the fascia from the superficial surface
of the glutaeus medius and pull the tensor fasciae latae forward.

M. Glutseus Medius. The glutaeus medius arises from
that part of the dorsum ilii which is bounded above by the
posterior curved line and the anterior four-fifths of the crest of
the ilium, and below by the anterior gluteal line (Fig. 128,
p. 286); it derives fibres also from the strong fascia which
covers it. The fibres converge to form a flattened band,
partly fleshy and partly tendinous, which is inserted into an
oblique line on the lateral aspect of the greater trochanter
of the femur, and into the surface immediately above it.
The glutaeus medius muscle is supplied by the superior gluteal
nerve. As a whole the muscle is an abductor of the thigh,
but its anterior fibres can rotate the thigh medially, and the
posterior fibres can rotate it laterally,



302 THE INFERIOR EXTREMITY

Dissection. The glutaeus medius must now be reflected.
Keep the tensor fasciae pulled well forward. Insert the fingers
between the posterior borders of the glutaeus medius and minimus,
and separate the muscles, from behind forwards, to their anterior
margins, which were exposed and defined in the dissection of the
anterior part of the thigh (see p. 249). Then divide the medius
two inches above the trochanter major. Turn the lower part
towards the trochanter, into which it is inserted, and the upper
part towards its origin from the ilium. As the lower part of
the muscle is reflected to its insertion into the oblique line on
the lateral surface of the trochanter major, a small bursa will
be displayed between the muscle and the upper and anterior
part of the lateral surface of the trochanter. When the upper
part of the muscle is raised, towards its origin, the branches of
the superior gluteal vessels and the superior gluteal nerve, which
lie between the glutseus medius and minimus, will be exposed ;
they must be carefully cleaned and preserved, except the smaller
twigs which enter the deep surface of the glutaeus medius which
may be cut if they interfere with the reflection of the muscle.
As the branches of the artery and nerve are followed the super-
ficial surface of the glutaeus minimus must be cleaned.

Nervus Glutaeus Superior. After emerging from the
pelvis, through the greater sciatic foramen, the superior
gluteal nerve turns forward, between the glutseus medius and
minimus, and immediately divides into an upper and a lower
branch. The upper branch follows the upper border of the
glutseus minimus and it gives branches to the glutseus medius.
The lower branch of the nerve crosses the middle of the
glutseus minimus with the lower branch of the superior
gluteal artery. It supplies branches to both the glutseus
medius and minimus, then passes between the anterior
borders of those two muscles and ends in the tensor fascise
latse.

Arteria Glutaea Superior. The superior gluteal artery is
a large vessel which springs from the hypogastric artery and
escapes from the pelvis, through the upper part of the great
sciatic foramen, above the level of the piriformis.

Immediately after its exit, it divides into a superficial and
a deep division. The superficial division has been already
seen during the reflection of the glutseus maximus. Its
branches are distributed to the deep surface of that muscle.

The deep division bifurcates, close to its origin, into a
superior and an inferior branch, which run forwards between
the glutseus medius and minimus. The superior branch
follows accurately the anterior gluteal line on the dorsum ilii,
and, at the anterior superior spine, terminates by anastomos-
ing with the superficial and deep circumflex iliac arteries,



GLUTEAL REGION 303

and with the ascending branch of the lateral femoral circum-
flex artery. The latter has already been noticed passing
proximally under cover of the tensor fasciae latae. The
inferior branch runs forwards across the middle of the glutseus
minimus, with the inferior branch of the superior gluteal
nerve. It supplies the two gluteal muscles between which it
lies and the tensor fasciae latae. It gives twigs to the hip
joint, and others of its branches anastomose with twigs of the
ascending branch of the lateral femoral circumflex artery.

M. G-lutseus Minimus. The glutaeus minimus muscle arises
from the broad area on the dorsum ilii, which is included
between the anterior and inferior curved lines (Fig. 1 28, p. 286).
The muscular fibres pass gradually into an aponeurotic tendon,
which covers the superficial surface of the distal part of the
muscle. The tendon, as it passes distally, narrows into a flat-
tened band, which is inserted into a special impression on the
lower and lateral part of the anterior aspect of the greater
trochanter of the femur (Figs. 117, 118, p. 262). It is
intimately connected, near its insertion, with the capsule of the
hip joint, and it is separated from the upper and anterior part
of the trochanter major by a small bursa. The glutaeus
minimus is supplied by the superior gluteal nerve. Its actions
are the same as those of the glutaeus medius (see p. 301).

Dissection. After the superior gluteal vessels and nerve
have been studied the glutaeus minimus must be reflected.
Detach it from its origin and turn it downwards.

Parts under Cover of the Glutaeus Minimus. As the

glutseus minimus is reflected three structures are displayed :
(i) part of the capsule of the hip joint; (2) the reflected
tendon of the rectus femoris ; and (3) the bursa between the
tendon of the glutaeus minimus and the upper part of the
anterior aspect of the greater trochanter. The bursa should
be opened in order that its extent may be examined.

At this stage the dissector should examine not only the
part of the capsule of the hip joint exposed by the reflection
of the glutaeus minimus, but also the parts exposed by the
reflection of the quadratus femoris (see p. 300), and the obtu-
rator internus (see p. 293); collectively they are the upper and
posterior portions. They are all loosely attached to the
back and upper part of the neck of the femur, about a
finger's breadth medial to the trochanter, but they are firmly



304 THE INFERIOR EXTREMITY

attached to the acetabular rim. Many of the fibres of the
posterior part of the capsule run circularly round the neck
of the femur. Others run parallel with the neck, at right
angles to the circular fibres, and in the lower part of the
capsule, which is covered by the obturator externus, is a
band of fibres, the ischio-capsular band, which runs upwards
and laterally parallel with the course of the obturator
externus.

The reflected tendon of the rectus femoris is attached to
the floor of a groove situated immediately above the upper
part of the margin of the acetabulum, and is there embedded
in the superficial fibres of the capsule which must be removed,
to expose it, by cutting through them parallel with the
direction of the tendon.



FOSSA POPLITEA (POPLITEAL SPACE).

The popliteal fossa should be dissected, if possible, before
the posterior region of the thigh is disturbed, in order that
its contents may be examined before the medial and lateral
boundaries of its proximal portion are displaced from their
positions. During the dissection the following structures
will be met with :

1. Superficial fascia.

2. The small saphenous vein.

3. The posterior cutaneous nerve of the thigh.

4. Popliteal fascia.

Biceps femoris.



Gastrocnemius.
Plantaris.

6. The tibial and common peroneal nerves and their branches.

7. The popliteal artery and vein and their branches and tributaries.

8. A few lymph glands.

9. A slender branch from the obturator nerve.
10. The popliteus muscle.

Surface Anatomy. The area of the popliteal fossa is
popularly called the ham. It is situated in the posterior
region of the knee, and it lies behind the distal third of the
femur, the knee joint, and the proximal fifth of the tibia.
It appears as a hollow when the knee joint is flexed, but
forms a slight prominence when the joint is fully extended,



POPLITEAL FOSSA 305

In the sides of the area, about the middle of its length,
the condyles of the femur are easily distinguished ; distal to
them lie the condyles of the tibia. The head of the fibula is
posterior and a little distal to the most projecting part of the
lateral condyle of the tibia.

The tendons which form the medial and lateral boundaries
of the proximal part of the popliteal fossa are the tendons of
the hamstring muscles ; the biceps femoris on the lateral side
and the semitendinosus and semimembranosus on the medial
side. They can be seen in both the extended and flexed
positions of the knee, but they are most obvious when the
knee is flexed. When the knee is flexed and deep pressure
is made in the middle of the hollow between the hamstring
tendons, the (injected) popliteal artery can be distinguished,
and in the living subject the pulsations of the artery can be
felt. The biceps tendon should be followed to its insertion
into the head of the fibula whilst the knee is flexed, then the
knee should be extended. When that has been done and
pressure is made immediately above the head of the fibula,
at the anterior border of the biceps tendon, the proximal
part of the cord-like fibular collateral ligament of the knee
joint may be distinguished, whilst, on the medial side of the
posterior border of the biceps tendon, the common peroneal
nerve can be felt. When a little care is exercised the nerve
can be rotated against the posterior part of the lateral
condyle of the femur, but palpation of the nerve is more



Online LibraryD. J. (Daniel John) CunninghamCunningham's manual of practical anatomy (Volume 1) → online text (page 30 of 44)