Boundaries and External Landmarks
The posterior region of the thigh has clear anatomical limits:
- Superior boundary: transverse gluteal fold (plica glutea).
- Inferior boundary: circular line drawn 6 cm above the patella.
- Medial boundary: line connecting the pubic symphysis to the medial epicondyle of the femur.
- Lateral boundary: line from the anterior superior iliac spine (spina iliaca anterior superior) to the lateral epicondyle of the femur.
Surface landmarks upon inspection and palpation include the ischial tuberosity (tuber ischiadicum), femoral epicondyles (epicondyli femoris), and the anterior superior iliac spine.
Superficial layers and fasciae
The skin of the region is thin, with varying degrees of hair coverage. The subcutaneous adipose tissue is usually well-developed. It contains branches of cutaneous nerves:
- In the lateral part — branches of the lateral cutaneous nerve of the thigh (n. cutaneus femoris lateralis).
- Posteriorly, at the border of the upper and middle thirds — branches of the posterior cutaneous nerve of the thigh (n. cutaneus femoris posterior).
The fascia lata (fascia lata) sends two important structures deep into the thigh:
- Lateral intermuscular septum (septum intermusculare femoris laterale), separating the anterior and posterior fascial compartments.
- Posterior intermuscular septum (septum intermusculare femoris posterior), which covers the posterior surface of the adductor magnus muscle and separates the posterior compartment from the medial one.
Muscles of the posterior fascial compartment
The posterior fascial compartment (compartimentum femoris posterius) is bounded posteriorly by the fascia lata, laterally by the intermuscular septa, and anteriorly by the femur. All flexor muscles in this compartment, except for the short head of the biceps femoris, originate from the ischial tuberosity.
- Biceps femoris muscle (m. biceps femoris). Lies most laterally. The long head originates from the ischial tuberosity, the short head from the linea aspera (linea aspera) and the lateral septum. The common tendon attaches to the head of the fibula.
- Semitendinosus muscle (m. semitendinosus). Lies superficially on the medial side. Its lower third is occupied by a long tendon which, together with the tendons of the sartorius and gracilis muscles, attaches to the tibial tuberosity, forming the pes anserinus (pes anserinus).
- Semimembranosus muscle (m. semimembranosus). Noticeably wider than the semitendinosus, located anterior and deep to it.
Topography of the sciatic nerve
The projection of the sciatic nerve (n. ischiadicus) is defined by a line from the midpoint between the ischial tuberosity and the greater trochanter to the midpoint of the line connecting the femoral epicondyles. Its point of emergence is located in the angle between the inferior edge of the gluteus maximus muscle and the lateral edge of the biceps femoris muscle.
In the upper third of the thigh, the nerve lies lateral to the tendon of the biceps femoris, directly beneath the fascia lata, covered by the long head of the biceps femoris. Lower down, it runs in the space between the biceps femoris and semimembranosus muscles. Anterior to the nerve is the adductor magnus muscle, covered by the loose posterior septum. Running alongside it is always the thin sciatic nerve artery (a. comitans n. ischiadici). In the lower half of the thigh (frequently higher), the nerve divides into two trunks:
- Tibial nerve (n. tibialis).
- Common fibular nerve (n. fibularis communis).
Blood supply and pathways of infection spread
An important feature of the posterior region of the thigh is that there are no proper main trunk arteries here. The blood supply is provided by branches of the three perforating arteries (aa. perforantes), which arrive from the anterior region of the thigh by perforating the adductor magnus muscle, forming extensive anastomoses with each other.
The cellular space of the posterior compartment actively communicates with adjacent regions, which is of critical importance in purulent processes:
- Superiorly: with the subgluteal space (along the course of the sciatic nerve).
- Inferiorly: with the adipose tissue of the popliteal fossa (along the course of the sciatic nerve).
- Anteriorly: with the anterior compartment of the thigh (along the course of the perforating arteries).
In the lower medial part of the region, beneath the muscles, lies the adductor hiatus (hiatus adductorius). The femoral vessels emerge from it into the popliteal fossa: the vein (v. femoralis) lies superficially and laterally, while the artery (a. femoralis) lies deeper and more medially toward the bone.
Briefly: answers to topical questions
To which anatomical structures do the tendons of the posterior thigh muscles attach?
The tendons of the posterior thigh muscles attach to the bones of the leg, fasciae, and the joint capsule of the knee.
- Biceps femoris muscle (m. biceps femoris) — attaches to the head of the fibula (caput fibulae), partially to the lateral condyle of the tibia and the crural fascia.
- Semitendinosus muscle (m. semitendinosus) — attaches to the tibial tuberosity (tuberositas tibiae) as part of the pes anserinus (pes anserinus), with some fibers blending into the crural fascia.
- Semimembranosus muscle (m. semimembranosus) — splits into three bundles: to the medial condyle of the tibia, into the fascia of the medial head of the gastrocnemius muscle, and to the knee joint capsule (continuing as the oblique popliteal ligament, lig. popliteum obliquum).
Which nerves innervate the flexor muscles of the leg in the posterior compartment of the thigh?
The flexor muscles of the leg in the posterior compartment of the thigh are innervated by branches of the sciatic, tibial, and common fibular nerves.
- Semimembranosus muscle (m. semimembranosus) — innervated by the tibial nerve (n. tibialis).
- Semitendinosus muscle (m. semitendinosus) — innervated by the tibial nerve (n. tibialis).
- Biceps femoris muscle (m. biceps femoris) — the long head receives branches from the tibial (n. tibialis) and sciatic (n. ischiadicus) nerves, whereas the short head is innervated by branches of the common fibular (n. fibularis communis) and sciatic nerves.
Additionally, muscular branches arise directly from the trunk of the sciatic nerve to supply all three muscles.
What branches does the sciatic nerve give off within the posterior region of the thigh?
Within the posterior region of the thigh, the sciatic nerve gives off muscular, articular, and terminal branches.
- Muscular branches — run to the biceps femoris (m. biceps femoris), semitendinosus (m. semitendinosus), semimembranosus (m. semimembranosus), and adductor magnus (m. adductor magnus) muscles.
- Articular branches — go to the hip and knee joints.
- Terminal branches — in the lower half of the thigh (or higher), the nerve divides into two large trunks: the tibial nerve (n. tibialis) and the common fibular nerve (n. fibularis communis).
Which anatomical structures form the walls of the adductor canal (canalis adductorius)?
The walls of the adductor canal are formed by the thigh muscles and the fibrous intermuscular septum.
- Lateral wall — vastus medialis muscle (m. vastus medialis).
- Medial wall — adductor magnus muscle (m. adductor magnus).
- Anterior wall (roof) — vastoadductor membrane or fibrous lamina (septum intermusculare vastoadductoria / lamina vastoadductoria), which spans between the vastus medialis and adductor magnus muscles.
The muscles of the posterior group are easy to remember by their inferior attachment sites: the biceps goes laterally (toward the fibula), while the muscles with the prefix "semi-" (semitendinosus, semimembranosus) run medially (toward the tibia).
Class and exam questions
Where do the muscles of the posterior compartment of the thigh originate?
Except for the short head of the biceps femoris, all muscles of the posterior group originate from a single point — the ischial tuberosity (tuber ischiadicum).
Which vessels supply blood to the posterior fascial compartment?
There are no proper main trunk arteries here. Blood supply is provided by branches of the three perforating arteries (aa. perforantes), which arrive from the anterior compartment of the thigh through the adductor magnus muscle.
Where can an abscess from the posterior compartment of the thigh spread?
The infection can migrate upward into the subgluteal fascial space, downward into the popliteal fossa (along the course of the sciatic nerve), and also into the anterior compartment of the thigh through the gaps of the perforating vessels.
What else to study on this topic
- Formation and structure of the pes anserinus (pes anserinus)
- Syntopy of the vessels at the adductor hiatus (hiatus adductorius)
- Variants of sciatic nerve division in the thigh
- Features of collateral circulation through anastomoses of the perforating arteries
- Topography of the subcutaneous prepatellar bursa
Master the complete topic in the "Topographic Anatomy" course
This is a summary. The course covers everything tested in classes and exams.
- Complete study guide on the "Posterior region of the thigh" and 2,777 more subject pages
- Assignments and quizzes after every topic — just like in a colloquium
- AI tutor answers questions on the topic anytime
- 91 video lessons on the subject
Other topics in the "Lower Limb" section
Free video lessons: topographic anatomyShort lessons with study notes — no registration required.
Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.