Sciatic Nerve :
-largest nerve in the body
- about 2cm in diameter
O:L4, L5, S1, S2, and S3 Inside the pelvis
Then leave through greater sciatic Foremen, frequently (usually) below piriformis to appear in gluteal region, descend to reach popliteal fossa. There it divides into 2 terminal branches they are :
Tibial Nerve
Fibular Nerve (Common peroneal nerve).
-at the lower part of the gluteal region it pass between 2 land marks, they are:
1- ischial tuberosity (medial).
2 Greater Trochanter of femur (lateral) there it pass midway between 2 bones that’s why if neck of femur is fractured the nerve could be trapped and injured (sciatic nerve trap).
Sciatic bed (when patient on his face)
-i.e anterior relation of sciatic nerve
-sciatic nerve has the following anterior relations from superior to inferior
Ischial spine
Gemellus superior
Obturator internus muscle
Gemellus inferior
Quadratus femoris
Adductor magnus
Posterior compartment of the thigh
Has the following muscles form lateral to medial
Biceps Femoris
Semitendinosus
Semimembranosus
Hamstring part of adductor magnus
All originated from Ischial tuberosity.
All innervated by sciatic Nerve
All supplied by profunda femoris artery
Most extend thigh at hip joint
Most flex leg at knee Joint
[1]Biceps Femoris
-Long head
O : Ischial tubrosity
-Short head
O: linea aspra of femur
Ins: head of fibula(for both heads)
N.s: sciatic Nerve
Action: long head- Extend the hip
Both heads flex the Knee
[2]Semitendinosus
O: Ischial tuberosity
Ins: SGS area
N.s: sciatic Nerve
Action: extend the hip/ flex the knee
[3]Semimembranosus
O: Ischial tuberosity
Ins: medial condyle of Tibia
Some of its fibers will return back on posterior aspect of knee joint to strengthen it, they are called oblique popliteal ligament
N.s: sciatic nerve
Action; extend the hip/ flex the knee
[4]Hamstring part of ad.magnus
Ac: extend hip
Popliteal fossa :
Diamond shaped
-Behind the knee joint and has:
Borders ( boundaries)
Above and lateral--> biceps femoris
Above and medial--> semitendenous and semimembranosous
Lower and lateral --> lateral head of gastrocnemius.
Lower and medial--> medial head of gastrocnemius.
4 borders____ 4 angles
1-Roof
*Skin
*Superficial fascia
*Small saphenous vein
*Sural nerve
*Deep fascia
2-Contents from superficial to deep
*Sciatic Nerve and branches
*Popliteal vein and tributaries
*Popliteal artery and branches
*Popliteal lymph nodes
*Popliteal pad of fat
3-Floor from superior to inferior
*Popliteal surface of femur
*Capsul of knee joint
*Oblique popliteal ligament
*Popliteus muscle
*Popliteal Muscle
Its function to initiate flexion of knee joint (the key of flexion of knee)
As when start setting, jumping up, and landing ground .
With best dedication to all my friends especially,
Ro2a, Boshra, Bayan, Do3a2, Leen, Samar, Rawan & Dana
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