Download Gluteal Region, Posterior Thigh, and Popliteal Fossa

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Gluteal Region, Posterior Thigh, and Popliteal Fossa
I.
Surface anatomy of the gluteal region
A. observe or palpate theses structures
1. the iliac crest
2. posterior superior iliac spine and dimple over it at the level of S3
3. natal cleft, 3rd sacral spine, tip of coccyx
4. gluteal fold, ischial tuberosity, and sacrotuberous ligament
a. the gluteal fold does not follow the border of the gluteus maximus
II.
Cutaneous innervation over the gluteal region
A. superior cluneal nerves
1. from the posterior rami of L1, 2, & 3
2. supplies the upper buttocks
B. middle cluneal nerves
1. from the posterior primary rami of S1, 2, 3
2. supplies the medial buttocks
C. inferior cluneal nerves
1. branches from the posterior femoral cutaneous nerve and anterior primary
rami of S1, 2, & 3
2. supplies the lower buttocks
III.
Fascia of the gluteal region
A. superficial fascia is a bit thicker and tougher than in other areas of the body
B. deep fascia
1. encloses the gluteus maximus and tensor fascia lata muscles between
two layers
2. very tough above the gluteus maximus where it is superficial to the gluteus
medius, also giving partial origin for the gluteus medius
IV.
Muscles of the gluteal region
A. the four largest muscles in this area are sometimes referred to as the gluteal
muscles since all are innervated by the gluteal nerves
1. gluteus maximus muscle
a. origin is from the back of the pelvis, erector spinae tendon, and
sacrotuberous ligament
b. inserts into the iliotibial tract and gluteal tuberosity of the femur
c. innervated by the inferior gluteal nerve (L5, S1 & 2)
d. extends and laterally rotates the thigh at the hip
2. tensor fascia lata muscle
a. arises from the anterior part of the crest of the ilium
b. inserts into the iliotibial tract and lateral condyle of the tibia
c. innervated by the superior gluteal nerve (L4 & 5, S1)
d. flexes and medially rotates the thigh at the hip and helps stabilize both
hip and knee joints
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3. gluteus medius muscle
a. arises below the iliac crest and between the anterior and posterior gluteal
lines
b. inserts on the greater trochanter of the femur
c. innervated by the superior gluteal nerve
d. it is a strong abductor and medial rotator of the thigh
4. gluteus minimus muscle
a. arises from the ilium beneath the gluteus medius
b. inserts on the greater trochanter of the femur
c. innervated by the superior gluteal nerve
d. it is a strong abductor of the thigh at the hip and medially rotates the thigh
B. The following are group of small muscles known as the small lateral rotators of
the hip that lie deep to the gluteus maximus
1. piriformis muscle
a. arises from the front of the sacrum inside the pelvis and passes through the
greater sciatic notch
b. inserts on the greater trochanter of the femur
c. innervated by branches of S1 & 2
d. it is a lateral rotator of the thigh at the hip
2. obturator internus muscle
a. arises from inside the pelvis off the obturator membrane and part of the
bone forming the obturator foramen
b. it then goes through the lesser sciatic notch, makes a 90O turn, then
c. inserts on the greater trochanter of the femur
d. innervated by the nerve to the obturator internus - L5, S1 & 2
e. it is a lateral rotator of the thigh at the hip
3. superior and inferior gemelli muscles
a. arise from the superior and inferior margins of the lesser sciatic notch,
respectively
b. insert on the tendon of the obturator internus muscle
c. innervation
(1) superior gemellus - nerve to the obturator internus - L5, S1 & 2
(2) inferior gemellus - nerve to the quadratus femoris - L4 & 5, S1
d. aid in lateral rotation of the thigh
4. quadratus femoris muscle
a. arises from the lateral side of the ischial tuberosity
b. inserts on the intertrochanteric crests of the femur
c. innervated by the nerve to the quadratus femoris - L4 & 5, S1
d. it laterally rotates the thigh
C. the small lateral rotators of the hip lie in a plane with the gluteus minimus
above and the adductor magnus below
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V.
Nerves that are in the gluteal region are branches of the sacral plexus. All of the
branches pass through the greater sciatic foramen.
A. superior gluteal nerve (posterior branches of L4, & 5, S1)
1. it emerges from the greater sciatic foramen above the piriformis muscle
accompanied with the superior gluteal vessels
2. it supplies the gluteus medius, gluteus minimus, and tensor fascia lata muscles
B. inferior gluteal nerve (posterior branches of L5, S1, & 2)
1. it appears below the piriformis muscle
2. it supplies the gluteus maximus muscle
3. it is accompanied by the inferior gluteal vessels
C. posterior femoral cutaneous nerve (anterior branches of S2 & 3; posterior
branches of S1 & 2)
1. it emerges under the piriformis muscle
2. it is superficial to the long head of the biceps femoris muscle
3. it gives off the inferior cluneal nerves and the perineal branch
4. continues down the back of the thigh under the deep fascia as far down as the
popliteal fossa
D. sciatic nerve - consists of two nerves
1. the tibial nerve: anterior branches of L4, 5 and S1, 2, 3
2. the common peroneal nerve: posterior branches of L4, 5 and S1, 2
3. it appears under the piriformis muscle with the posterior femoral cutaneous
nerve and the inferior gluteal artery
4. crosses the gemelli, obturator internus, and quadratus femoris muscles just
lateral to the ischial tuberosity at a position 1/3 the distance between it and the
greater tuberosity of the femur.
E. pudendal nerve (anterior branches of S2, 3, &4)
1. it crosses the sacrospinous ligament and re-enters the pelvis through the
lesser sciatic foramen
2. lateral to the nerve are the internal pudendal vessels
F. nerve to the obturator internus muscle (anterior portion of L5, S1 &2)
1. it appears lateral to the internal pudendal vessels
2. supplies the superior gemellus muscle
3. then, it enters the pelvis through the lesser sciatic foramen to supply the
obturator internus muscle
G. nerve to the quadratus femoris muscle (anterior branches of L4 & 5, S1)
1. lateral to the nerve to the obturator internus but passes deep to the surface of
gemelli and obturator internus muscles to reach the anterior surface of the
quadratus femoris muscle
2. innervates the inferior gemellus muscle along its way, as well as the hip joint
H. nerve to the piriformis muscle (posterior branches of S1 & 2)
1. it is given off in the pelvis and never appears in the gluteal region
I. nerves to the pelvic diaphragm (levator ani & coccygeus muscles) (anterior
branches of S3 &4)
1. given off in the pelvis and never seen in the gluteal region
J. pelvic splanchnic nerves (preganglionic parasympathetic) (S2, 3, 4) in pelvis
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V.
Blood vessels in the gluteal region
A. superior gluteal vessels appear above the piriformis muscle in company with
the superior gluteal nerve - a branch of the posterior part of internal iliac artery
B. inferior gluteal vessels appear below the piriformis muscle with the inferior
gluteal nerve - a branch of the anterior part of internal iliac artery
C. medial femoral circumflex vessels appear between the quadratus femoris and
adductor magnus muscles, near the hamstrings - usually off deep femoral artery
D. first perforating vessels (off deep femoral artery) pierce the adductor magnus
adjacent to the linea aspera
E. lateral femoral circumflex artery appear above the neck of the femur and
lateral to the shaft below the greater trochanter - off the deep femoral artery
F. all of the above vessels anastomose
1. the latter four vessels form the cruciate anastomosis
VII.
The posterior compartment of the thigh contains the hamstring muscles that insert
on the tibia and fibula: they extend the thigh at the hip and flex the leg at the knee
A. semimembranous muscle
1. arises from the ischial tuberosity
2. inserts on the medial condyle of the tibia
3. at its insertion, it sends collagen fibers up and across the back of the knee
joint to form the oblique popliteal ligament plus a sheet of fibers over the
popliteus muscle
4. the upper half of the muscle is aponeurotic
5. innervated by the tibial division of the sciatic nerve (L5 - S2)
B. semitendinous muscle
1. arises from the ischial tuberosity with the long head of the biceps femoris
muscle
2. inserts on the anteromedial aspect of the tibia below the medial condyle of the
tibia below the sartorius and gracilis muscles to help form the pes anserinus
3. the lower half of the muscle is tendinous
4. innervated by the tibial division of the sciatic nerve (L5 - S2)
C. biceps femoris muscle
1. long head arises with the semitendinous muscle from the ischial tuberosity
2. short head arises from the linea aspera and lateral intermuscular septum
3. the two heads merge and insert on the upper end of the fibula
4. long head innervated by the tibial division of the sciatic nerve (S1 - 3)
5. short head innervated by the peroneal division of the sciatic nerve (L5- S2)
D. hamstring muscles - innervated by unlike portions of the sciatic nerve
1. arising from the ischial tuberosity are innervated by tibial portion
2. arising from the linea aspera of femur is innervated by peroneal portion
E. blood supply to the posterior compartment muscles
1. medial femoral circumflex artery
2. deep femoral artery
3. perforating vessels
4. lower parts of the muscles are served by the popliteal vessels
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VIII.
The popliteal fossa contains the terminal branches of the sciatic nerve, the popliteal
vessels and their branches, a few lymph nodes, and fat. It is diamond shaped.
A. boundaries of the popliteal fossa
1. superiorly & medial - the semimembranous and semitendinous muscles
2. superiorly & lateral - the biceps femoris muscles
3. inferiorly (medial & lateral) - the two heads of the gastrocnemius muscle
4. roof - deep fascia (fascia lata)
5. floor - popliteal surface of femur, back of knee joint, and popliteus muscle
a. above the level of the tibia and between the muscular boundaries is
the opening to the popliteal fossa
b. the fossa extends downward and deep to the gastrocnemius muscle
B. contents of the popliteal fossa
1. tibial nerve traverses the vertical midline of the fossa and gives off branches
to the plantaris and the two heads of the gastrocnemius muscles
a. it gives rise to the medial sural nerve - a cutaneous nerve that supplies an
area in the upper middle area of the posterior leg
2. common peroneal nerve lies just under cover of the medial border of the
biceps femoris muscle
a. it give rise to the lateral sural nerve - a cutaneous nerve that supplies the
upper lateral part of the leg
b. the medial and lateral sural nerves usually merge to form the sural
nerve - a cutaneous nerve of the lower lateral half of the posterior leg
3. popliteal vessels enter the deep portion of the fossa through the adductor
magnus muscle with the popliteal artery being near the popliteal surface of
the femur. The popliteal vein is superficial to the artery at the heads of the
gastrocnemius as it crosses the artery from its medial to lateral side then
passes through the adductor hiatus to become the femoral vein.
4. muscular branches are given to the adjacent muscles in addition to the
following named branches branches of the popliteal artery
a. medial and lateral superior genicular vessels go immediately above the
corresponding condyles of the femur and right on the bone
b. lateral inferior genicular vessels travel horizontally to pass under the
collateral ligament of the knee joint
c. medial inferior genicular vessels parallel the upper border of the
popliteus muscle to pass between the medial collateral ligament and tibia
d. middle genicular vessels directly enter the knee joint
e. popliteal vessels divide distally into anterior and posterior tibial vessels