The posterior compartment of the thigh is one of the fascial compartments that contains the

knee In humans and other primates, the knee joins the thigh with the leg and consists of two joints: one between the femur and tibia (tibiofemoral joint), and one between the femur and patella (patellofemoral joint). It is the largest joint in the ...

flexors A flexor is a muscle that flexes a joint. In anatomy, flexion (from the Latin verb ''flectere'', to bend) is a joint movement that decreases the angle between the bones that converge at the joint. For example, one’s elbow joint flexes when o ...

and hip

extensors In anatomy, extension is a movement of a joint that increases the angle between two bones or body surfaces at a joint. Extension usually results in straightening of the bones or body surfaces involved. For example, extension is produced by extendin ...

known as the

hamstring muscles In human anatomy, a hamstring () is any one of the three posterior thigh muscles in between the hip and the knee (from medial to lateral: semimembranosus, semitendinosus and biceps femoris). The hamstrings are susceptible to injury. In quadrupeds, ...

, as well as vascular and nervous elements, particularly the

sciatic nerve The sciatic nerve, also called the ischiadic nerve, is a large nerve in humans and other vertebrate animals which is the largest branch of the sacral plexus and runs alongside the hip joint and down the lower limb. It is the longest and widest ...

Structure

The posterior compartment is a fascial compartment bounded by

fascia A fascia (; plural fasciae or fascias; adjective fascial; from Latin: "band") is a band or sheet of connective tissue, primarily collagen, beneath the skin that attaches to, stabilizes, encloses, and separates muscles and other internal organs ...

. It is separated from the anterior compartment by two folds of

deep fascia Deep fascia (or investing fascia) is a fascia, a layer of dense connective tissue that can surround individual muscles and groups of muscles to separate into fascial compartments. This fibrous connective tissue interpenetrates and surrounds the ...

, known as the medial intermuscular septum and the lateral intermuscular septum. The muscles of the posterior compartment of the thigh are the: *

biceps femoris muscle The biceps femoris () is a muscle of the thigh located to the posterior, or back. As its name implies, it has two parts, one of which (the long head) forms part of the hamstrings muscle group. Structure It has two heads of origin: *the ''long h ...

, which consists of a short head and a long head. * semitendinosus muscle * semimembranosus muscle These muscles (or their tendons) apart from the short head of the biceps femoris, are commonly known as the

hamstring In human anatomy, a hamstring () is any one of the three posterior thigh muscles in between the hip and the knee (from medial to lateral: semimembranosus, semitendinosus and biceps femoris). The hamstrings are susceptible to injury. In quadrupe ...

s. The depression at the back of the knee, or ''kneepit'' is the

popliteal fossa The popliteal fossa (also referred to as hough, .html" ;"title="/sup>">/sup> or kneepit in analogy to the cubital fossa) is a shallow depression located at the back of the knee joint. The bones of the popliteal fossa are the femur and the tibia ...

, colloquially called the ''ham''. The tendons of the above muscles can be felt as prominent cords on both sides of the fossa—the biceps femoris tendon on the lateral side and the semimembranosus and semitendinosus tendons on the medial side. The hamstrings flex the knee, and aided by the gluteus maximus, they extend the hip during walking and running. The semitendinosus is named for its unusually long tendon. The semimembranosus is named for the flat shape of its superior attachment.

Innervation

The hamstrings are innervated by the sciatic nerve, specifically by a main branch of it: the

tibial nerve The tibial nerve is a branch of the sciatic nerve. The tibial nerve passes through the popliteal fossa to pass below the arch of soleus. Structure Popliteal fossa The tibial nerve is the larger terminal branch of the sciatic nerve with root val ...

. (The short head of the biceps femoris is innervated by the common fibular nerve). The sciatic nerve runs along the longitudinal axis of the compartment, giving the cited terminal branches close to the superior angle of the popliteal fossa.

Blood supply

The arteries that supply the posterior compartment of the thigh arise from the inferior gluteal and the perforating branches of the

profunda femoris artery The deep artery of the thigh, (profunda femoris artery or deep femoral artery) is a large branch of the femoral artery. It travels more deeply (posteriorly) than the rest of the femoral artery. Structure The deep artery of the thigh branches of ...

, a major collateral branch of the femoral artery and part of the

anterior compartment of thigh The anterior compartment of thigh contains muscles which extend the knee and flex the hip. Structure The anterior compartment is one of the fascial compartments of the thigh that contains groups of muscles together with their nerves and blood s ...

. The femoral artery itself crosses the adductor hiatus to enter the posterior compartment at the level of the popliteal fossa, giving branches that supply the knee. This crossing marks the point in which the vessel changes its name to

popliteal artery The popliteal artery is a deeply placed continuation of the femoral artery opening in the distal portion of the adductor magnus muscle. It courses through the popliteal fossa and ends at the lower border of the popliteus muscle, where it branche ...

Clinical significance

As with any other fascial compartment, the posterior compartment of thigh can develop

compartment syndrome Compartment syndrome is a condition in which increased pressure within one of the body's anatomical compartments results in insufficient blood supply to tissue within that space. There are two main types: acute and chronic. Compartments of the ...

when pressure builds up inside it, reducing the ability of arteries to transport blood to muscles and nerves. In acute cases, this is most frequently a consequence of trauma.

References

External links

* *
knee/muscles/thigh3
at the

Dartmouth Medical School The Geisel School of Medicine at Dartmouth is the graduate medical school of Dartmouth College in Hanover, New Hampshire. The fourth oldest medical school in the United States, it was founded in 1797 by New England physician Nathan Smith. It is o ...