326
UNIT TWO
thigh, continuing to its insertion as a long, cordlike tendon.
It fl exes and rotates the leg medially and extends the thigh
(see f
g. 9.39).
The
semimembranosus
(sem
e-mem
brah-no-sus) is
the third hamstring muscle and is the most medially located
muscle in the back oF the thigh. It connects the ischium to
the tibia and fl exes and rotates the leg medially and extends
the thigh (see f
g. 9.39).
Strenuous running or kicking motions can tear the tendinous attach-
ments of the hamstring muscles to the ischial tuberosity. Internal
bleeding from damaged blood vessels that supply the muscles usually
occurs with this painful injury, commonly called “pulled hamstrings.”
Flexors
As its name implies, the
biceps femoris
(bi
seps Fem
or-is) has
two heads, one attached to the ischium and the other attached
to the Femur. This muscle passes along the back oF the thigh
on the lateral side and connects to the proximal ends oF the
f bula and tibia. The biceps Femoris is one oF the hamstring
muscles, and its tendon (hamstring) can be Felt as a lateral
ridge behind the knee. This muscle fl exes and rotates the leg
laterally and extends the thigh (see f gs. 9.38 and 9.39).
The
semitendinosus
(sem
e-ten
˘-no-sus) is another
hamstring muscle. It is a long, bandlike muscle on the back
oF the thigh toward the medial side, connecting the ischium
to the proximal end oF the tibia. The semitendinosus is so
named because it becomes tendinous in the middle oF the
Adductor magnus
Gracilis
Semitendinosus
Semimembranosus
Semimembranosus
Sartorius
Gastrocnemius
Gluteus medius
Gluteus maximus
Vastus lateralis
covered by fascia
Biceps femoris
Biceps femoris
(short head)
Semitendinosus
Biceps femoris
(long head)
(a)
(b)
(c)
FIGURE 9.39
Muscles of the thigh and leg. (
a
) Muscles of the posterior right thigh. (
b
and
c
) Isolated views of muscles that F
ex the leg at the knee.
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