- The document provides information about the anatomy of the posterior compartment of the thigh, including the hamstring muscles (biceps femoris, semitendinosus, and semimembranosus) and the sciatic nerve. - It describes the origin, insertion, nerve supply, and actions of the hamstring muscles. It also details the course and branches of the sciatic nerve as it passes through the pelvis, gluteal region and thigh. - Safe sites for intramuscular injection are discussed to avoid injury to the sciatic nerve and blood vessels in the region. Causes and effects of sciatic nerve injury are also summarized.

1. ‫الرحيم‬ ‫الرحمن‬ ‫هللا‬ ‫بسم‬
Dr. Mohammed Gebba
Anatomy & Embryology Department
Faculty Of Medicine, Merit University

2. By the end of this lecture student should be able to:
-Recognize the anatomy of the posterior compartment
of the thigh.
-Describe the anatomy of the Sciatic nerve.
Objectives

3. Posterior compartment of Thigh:
-Muscles: (Origin – Insertion – Nerve supply – Muscle action)
-Biceps femoris
-Semitendinosus
-Semimembranosus
Nerves:
Sciatic nerve
Contents

4. - Origin
- Insertion
- Nerve supply
- Muscle action
Muscles
of the
posterior
compartment

5. - Origin
- Insertion
- Nerve supply
- Muscle action
Hamstring Muscles

6. The most lateral of the
hamstring muscles.
Biceps femoris

7. -It forms long cord like tendon.
-It is medial to the biceps femories
and lies on the semimembranosus.
Semitendinosus

8. It is deep to the semitendinosus.
Semimembranosus

9. 1 2
Hamstring Muscles
Origin

10. Linea aspra
1-Superolateral part of the 1
upper area of the ischial
tuberosity.
2-Inferomedial part of the
upper area of the ischial
tuberosity.
Hamstring Muscles
Origin
2

11. 1
2
1-Semimembranosus
2-Long head of biceps
&Semitendinosus
Short head of biceps
Lateral lip of
the linea aspra and
lateral supracondylar
line
Hamstring Muscles
Origin

12. Hamstring Muscles
Insertion

13. Head of the fibula
(Lateral surface)
Upper part of
the medial
surface of the
tibia
Hamstring Muscles
Insertion
Groove on the
Back of
medial tibial
condyle

14. Semimembranosus:
Groove on the
medial tibial
condyle
Semitendinosus:
Upper part of the
medial surface of
the tibia
Biceps
femoris:
Head of
the fibula
Hamstring Muscles
Insertion

15. Biceps femoris
- Origin
- Insertion
Head of the fibula
Long head
Inferomedial
part of the upper area
of the ischial tuberosity
Short head
linea aspra
and lateral
supracondylar
line

16. Upper part of the
medial surface of
the tibia
Inferomedial
part of the upper area
of the ischial tuberosity
-Origin
-Insertion
Semitendinosus

17. Semimembranosus
- Origin
- Insertion
Groove on the
medial tibial condyle
Superolateral part of
the upper area of the
ischial tuberosity

18. Long head of
biceps femoris
Semitendinosus
Semimembranosus
Tibial nerve
Sciatic nerve
Short head of
biceps femoris
Common
Peroneal
(fibular) nerve
Hamstring Muscles
Nerve supply

19. at
All Flex the leg
the knee joint
All Extend
the thigh at
the hip joint
Muscle action
Hamstring Muscles

20. Semitendinosus & membranosus
Medially rotates the leg at the knee
Biceps femoris
laterally rotates the leg at the knee
Hamstring Muscles
Muscle action

21. Semitendinosus & membranosus
Medially rotates the leg at the knee
Biceps femoris
laterally rotates the leg at the knee
Hamstring Muscles
Muscle action

22. Origin Insertion Nerve
supply
Muscle action
Biceps femoris Short head:
linea aspra and
lateral
supracondylar
line
Long head:
Inferomedial
part of the upper
area of the ischial
tuberosity
Head of the fibula
Sciatic
(Tibial &
common
Peroneal
(fibular)
nerves)
-Flexes the leg at
the knee joint
-Extends the thigh
at the hip joint
-Laterally rotates
leg at the knee
Semitendinosus Inferomedial
part of the upper
area of the ischial
tuberosity
Upper part of the
medial surface of
the tibia
Sciatic
(Tibial
nerve)
-Flexes the leg at
the knee joint
-Extends the thigh
at the hip joint
-Medially rotates
the leg at the knee
Semimembranosus Superolateral
part of the upper
area of the ischial
tuberosity
Groove on the
medial tibial
condyle
Muscles of the posterior compartment

23. It ends at the middle of
the back of the leg
It enters the back of
the thigh.
Posterior
cutaneous
nerve of thigh
Sciatic n.
In the gluteal region it lies
medial to the sciatic nerve.
Course
Posterior cutaneous nerve of the thigh

24. Posterior
cutaneous
nerve of
thigh
Course
Posterior cutaneous nerve of the thigh
It enters the back of
the thigh
It ends at the middle of
the back of the leg
In the gluteal region it lies
medial to the sciatic nerve.

25. Innervates the
skin at the back
of thigh and the
upper leg.
Gluteal branches: to the
skin over the gluteal fold.
Branches
Posterior cutaneous
nerve of the thigh

26. Origin
Course
Branches
Sciatic nerve
The largest nerve
in the body
(in diameter)

27. Sciatic Nerve
L4
L5
S1
S2
S3
Sciatic nerve
Origin:
Lumbosacral plexus
(L4,5, S1,2,3)

28. Origin:
Lumbosacral plexus
(L4,5, S1,2,3)
Sciatic nerve

29. Pelvis
Greater sciatic foramen
Gluteal region
Back of the thigh
Course
Sciatic nerve

30. In the pelvis
It originates in the pelvis
It passes through the
greater sciatic foramen
inferior to the
piriformis muscle to
enter the gluteal
region.
Course Sciatic nerve Anterior View

31. It passes through the
greater sciatic foramen
inferior to the piriformis
muscle to enter the
gluteal region.
In the gluteal region
Course Posterior View
Sciatic nerve

32. and back of thigh
In the gluteal region
Sciatic nerve
In the back of the
thigh it lies on
adductor magnus
and it is crossed by
long head of biceps
femoris muscle.
At the lower border of
quadratus femoris it enters
the back of the thigh.
In the gluteal region
it lies deep to the
gluteus maximus at
the mid point
between the greater
trochanter and the
ischial tuberosity.
It crosses the obturator
internus, 2 gemelli and
quadratus femoris.
Sciatic nerve Course

33. and back of thigh
It ends proximal to
the knee by dividing
into the tibial and
common fibular
(peroneal) nerves
Tibial n.
Common
fibular n.
In the gluteal region
Sciatic nerve

34. In the gluteal region
and back of thigh
Gluteus maximus
Obturator internus & 2 gemelli
Qudratus femoris
Adductor magnus
Sciatic nerve

35. -All muscles of the
back of the thigh.
-Hamstring part of
adductor magnus.
-All muscles of the
leg and foot.
Branches
-Skin on the
lateral side of
the leg.
-Skin on the
lateral side,
dorsal surface
and sole of
foot.
Sciatic nerve

36. Origin
-From the lumbosacral plexus (L4,5,S1,2,3)
Course -It originates in the pelvis.
-It passes through the greater sciatic foramen inferior to the piriformis
muscle to enters the gluteal region.
-In the gluteal region it lies deep to the gluteus maximus at the mid point
between the greater trochanter and the ischial tuberosity.
-It crosses the obturator internus, 2gemelli and quadratus femoris.
-At the lower border of quadratus femoris it enters the back of the thigh
-In the back of the thigh it lies on adductor magnus and it is crossed by
long head of biceps femoris muscle.
-It ends proximal to the knee by dividing into the tibial and common
fibular (peroneal) nerves.
Branches
-All muscles of the back of the thigh.
-Hamstring part of adductor magnus.
-All muscles of the leg and foot.
-Skin on the lateral side of the leg .
-Skin on the lateral side, dorsal surface and sole of foot.
Sciatic nerve

37. -The anterior corner of the upper lateral
(outer) quadrant.
-It is the safe site for intramuscular injection
to avoid injury for the sciatic nerve and
blood vessels in the region.
Intramuscular injection

38. Sciatica

39. Causes:
-Disc prolapse.
-Hip dislocation.
-Misplaced injection.
-Entrapment by piriformis
muscle (Piriform syndrome).
Sciatic nerve injury
The effect:
-Paralysis for the hamstring
muscles, all muscles of the leg
& foot.
-Sensory loss in the skin area
supplied by the sciatic nerve.

41. Gray's Anatomy for Students, 3rd Ed.With STUDENT
CONSULT Online Access Drake, Vogl & Mitchell 2014.
ISBN: 978-0-7020-5131-9
Images:
https://www.amazon.com/Grays-Anatomy-Students-Student-Consult/dp/0702051314
https://www.netterimages.com/
https://teachmeanatomy.info/lower-limb
https://www.kenhub.com/en/library/anatomy/regions-of-the-lower-limb
References

42. Thank You