Posterior compartment of the
thigh
Dr. Heba Kalbouneh
Associate Professor of Anatomy and Histology
1-Muscles:
Biceps femoris
Semitendinosus
Semimembranosus
Adductor magnus (hamstring part or ischial part)
2- Blood supply:
Branches of profunda femoris artery
3- Nerve supply:
Sciatic nerve
Posterior compartment of the thigh
Biceps femoris
Semitendinosus
Semimembranosus
Hamstring part of
adductor magnus
The posterior thigh muscles were called “hamstrings” because
butchers used to hang pigs by these muscles outside their shops
In ancient times, the soldiers utilized to slash the rear of the knees of horses of their rivals to be
able to cut the tendons of hamstring muscles, to bring the horse and its rider down. They also
utilized to cut the hamstring tendons of soldiers in order that they couldn’t run. This was referred
to as “hamstringing” the enemy.
All Extend the hip EXCEPT short head of biceps
All Flex the knee EXCEPT adductor magnus
Lateral muscles rotate the knee laterally
Medial muscles rotate the knee medially
Ischial tuberosity
Origin:
All from ischial tuberosity EXCEPT
Short head of biceps femoris from
linea aspera and lateral
supracondylar ridge.
Insertion :
Biceps femoris: head of fibula
Semitendinosus: upper part of
medial surface of the tibia (SGS).
Semimembranosus: medial condyle
of the tibia
Adductor Magnus (Ischial head):
Adductor tubercle of femur
Biceps femoris Long head
Biceps femoris Short head
Origin: two heads
1-Long head: ischial tuberosity
2-Short head: linea aspera, lateral
supracondylar ridge
Insertion: Head of fibula
Nerve supply:
Long head: tibial portion of sciatic
nerve
Short head: common fibular portion
of sciatic nerve
Action: Flexes and laterally rotates
leg at knee joint; long head also
extends thigh at hip joint
Biceps femoris
Origin:
Ischial tuberosity
Where?
Insertion:
Upper part of medial surface of shaft
of tibia (SGS area)
Nerve supply: Tibial portion of
sciatic nerve
Action: Flexes and medially rotates
leg at knee joint; extends thigh at hip
joint
Semitendinosus
Semimembranosus
Origin: Ischial tuberosity, where?
Insertion: Medial condyle of tibia
(posterior surface) Groove for semimembranosus
Nerve supply: Tibial portion of sciatic
nerve
Action: Flexes and medially rotates leg
at knee joint; extends thigh at hip joint
Biceps femoris
Anterior
Posterior
Semitendinosus
Semimembranosus
The ischial tuberosity is covered by gluteus maximus when one
stands. In the sitting position the muscle slips away laterally. To
palpate this bony point, therefore, feel for it uncovered by gluteus
maximus in the flexed position of the hip
Ischial tuberosity
Divided by a transverse ridge into:
An upper quadrangular and a lower triangular
parts
The lower triangular part is divided by a
longitudinal ridge into:
1-Lateral part that gives attachment
to the ischial part of the adductor
magnus
2-Medial part (subcutaneous part)
Covered by connective tissue and bursa
The upper quadrangular part is divided by
an oblique ridge into:
1- Upper Lateral part for the attachment
of semimembranousus
2- Lower Medial for the attachment of
semitendinosus and
long head of biceps Medial Lateral
When sitting, this medial part
supports the body weight
Qu
adra
tus
fem
ori
s
Inferior gemellus
Pay attention to the fact that the muscles of the thigh are designed
To act on the knee joint
For example, quadriceps femoris occupies the anterior compartment of the thigh but its
Main action is to extend the knee joint
The same should be considered for the muscles of the posterior compartment of the thigh
Although they occupy the posterior compartment of the thigh
Their main function is to flex the knee joint
Now think!
Which muscles will rotate the knee joint medially and laterally?
Keep in your mind that when the knee joint is extended medial and
lateral rotation is not possible!
The joint said to be locked
Therefore, we need to unlock the extended (locked) knee joint
A small muscle called popliteus unlocks the knee joint by
rotating the femur on the tibia laterally before any flexion of the knee can take place
Now the joint is unlocked
Only now when the knee joint is semiflexed:
The biceps femoris can act as a lateral rotator of the leg
The semimembranousus and semitendinosus can act as medial rotators of the leg
Sciatic nerve A branch of the sacral plexus
(L4 L5 S1 S2 S3)
Emerges from the pelvis through the
greater sciatic foramen below
piriformis
Is the largest nerve in the body
Consists of the tibial and common
fibular nerves bound together with
fascia.
Commonly terminates in the
lower third of the thigh by
dividing into:
Tibial nerve
(Medial popliteal nerve)
Common fibular nerve
(Lateral popliteal nerve or
Common peroneal nerve)
Surface anatomy of sciatic nerve PSIS
Greater trochanter
Ischial
tuberosity
The greater trochanter of the femur
can be felt about one hand’s width
inferior to the midpoint of the iliac
crest
The ischial tuberosity is palpable
just above the gluteal fold
A branch of the sacral
plexus S1,2,3
Enters the gluteal region
through the lower part of the
greater sciatic foramen below
piriformis
Supplies the skin over the
back of thigh and upper part of
the leg
Posterior Cutaneous Nerve of the Thigh