From back of buttock to back of knee
- separated from anterior compartment by lateral intramuscular septum
- not separated from adductor compartment; adductor magnus is both adductor & flexor.
Cutaneous nerve supply by posterior femoral cutaneous nerve (504)
- this runs down deep to fascia lata, pierces it behind the knee and ends 1/2way down calf.
- Sends its branches through the fascia to posterior thigh skin.
Hamstrings
All arise (at least partly) from ischial tuberosity ¨ tibia or fibula (\ span 2 joints);
- sciatic nerve supplies & runs deep to them (on adductor magnus & short head biceps)
1)
Semimembranosus
(461)
Arises: from lateral ischial tuberosity anterior (ie is deep) to common origin of other two
- a long flat tendon; muscle fibres begin about mid-thigh
Inserts: medial condyle of tibia; three expansions diverge from its insertion (see 476):
- i) passes forwards about medial condyle under tibial collateral lig, separated by a bursa
- ii) passes obliquely up toward lateral femoral condyle as oblique popliteal ligament.
- iii) passes down forming strong fascia overlying popliteus, reaches soleal line of tibia.
A useful landmark in thigh wounds as sciatic nerve lies one fingerbreadth lateral to lateral edge.
2)
Semitendinosus (461)
Arises: in common with biceps femoris, from medial ischial tuberosity.
- fleshy belly diminishes in size becoming a cord on back of semimemb which does opposite.
Inserts: upper subcutaneous border of tibia, posterior to gracilis (472)
3) Biceps femoris (461)
Arises: Long head arises with semitendinosus; short head has long origin from entire linea aspera and upper part of supracondylar line of femur.
Inserts: single tendon; splits around the fibular collateral ligament ¨ head of fibula (472).
- common peroneal nerve lies medial to its tendon in popliteal fossa.
Mainly profunda femorisŐ penetrating branches.
- pierce adductor magnus, also supply subcut tissue and overlying skin.
Inferior gluteal artery supplies upper hamstrings and popliteal the lower.
¨ form a string of anastomosis on back of thigh, highest being the cruciate.
Tibial part of sciatic (L5,S1) except short head biceps (fibular part of sciatic, still L5,S1)
Flex knee, and extend hip if acting from below (eg walking)
- biceps is a lateral rotator, the other two are medial rotators (of the leg)
Knee flexed against resistance, palpate.
Runs down between biceps femoris (deep to it) and adductor magnus
¨ divides at apex of popliteal fossa into tibial & common peroneal components (though division may be much higher).
Surface marking is midway between gr trochanter and ischial tuberosity ¨ apex of popliteal fossa.