Topographical anatomy of lower limb

The borders and layers of the lower limb`s regions

The upper limb is separated from the trunk by: the inguinal ligament anterosuperiorly, the iliac crest posterosuperiorly and a line connecting posterior superior iliac spine with the IV lumbar spinous process.

The lower limb can be divided into following regions:

1. Gluteal region;
2. Femoral region;
3. Knee region;
4. Crural region;
5. Talocrural region;
6. Region of the foot.

1. The gluteal region.

Borders: superior – iliac crest; inferior – gluteal skin fold; external – the line connecting the anterior superior iliac spine with the greater trochanter.

Layers:

1. skin;
2. subcutaneous tissue;
3. superficial fascia;
4. superficial layer of the gluteal fascia (forms a fascial sheath for the gluteus maximus);
5. gluteus maximus;
6. subgluteal space;
7. deep layer of the gluteal fascia;
8. gluteus medius, piriformis, gemelli, obturator internus, quadratus femoris;
9. deep subgluteal space ;
10. gluteus minimus, obturatorius externus ;
11. the proximal end of the femur.

The subgluteal space.

It is between the superficial layer of the gluteal fascia covering the posterior side of the gluteus maximus and deep layer of the gluteal fascia covering the gluteus medius. The space connects with deep fat of the posterior femoral region; with the pelvic fat through foramen infrapiriforme; with fat in ischiorectal fossa through the lesser sciatic foramen; with the medial femoral compartment. The space contains the vessels and nerves passing through foramen infrapiriforme and suprapiriforme (see the table “Topography of limbs’).

The deep subgluteal space is closed because the gluteus medius and minimus lie in common fascial sheath.

2. The femoral region.

Borders: anterosuperior – the inguinal ligament; posterorsuperior – gluteal skin fold; inferior – the line passing about 3 cm above the patella. The femoral region is divided into anterior and posterior by the lines connecting the femoral epicondyles with the anterior superior iliac spine (externally) and pubic symphysis (internally).

Layers of anterior femoral region:

1. skin;
2. subcutaneous tissue;
3. superficial fascia;
4. fascia lata (in the upper part of the thigh, the fascia lata divides into two layers: superficial and deep; superficial layer covers the femoral vessels and nerve from the front side, while the deep one is behinde these vessels and nerve);
5. tensor fasciae latae, the muscles of anterior compartment (quadriceps femoris, sartorius), iliopsoas, the muscles of the medial compartment (pectineus, adductor longus, gracilis);
6. the muscles of the medial compartment (adductor brevis, adductor magnus)

Subcutaneous tissue contains superficial branches of the femoral artery with accompanying veins and inguinal lymph nodes. Superficial layer of the fascia lata is continuous with the inguinal ligament; the deep one gives the iliopectineal arch separating lacuna vasorum and lacuna musculorum. The inner part of the superficial layer of the fascia lata over the femoral vessels is called fascia cribrosa. It is pierced by vessels. If we remove the fascia cribrosa we can see the opening called saphenous hiatus with a thick border called the falciform margin. The saphenous hiatus contains the last part of the long saphenous vein which drains into the femoral vein.

The fascia lata sends three intermuscular septa (medial,lateral and posterior) to attach to the femur. The septa separate femoral muscle compartments. The fascia lata forms separate sheaths for the sartorius, tensor fasciae latae and gracilis, and for the femoral vessels and nerve.

The anterior femoral region contains the lacuna vasorum and musculorum, femoral triangle and adductor canal. The detailed information about them see in the table “Topography of limbs”.

Layers of posterior femoral region:

1. skin;
2. subcutaneous tissue;
3. superficial fascia;
4. fascia lata;
5. muscles of the posterior compartment: biceps femoris, semitendinosus and semimembranosus

In the lower third of the posterior femoral region, the adductor canal opens. The upper part of the sciatic nerve passes  between the fascia lata and biceps femoris; the lower part is between the biceps femoris and semimembranosus.

3.The knee region.

Borders: superior — the line passing horizontally about 3 cm above the patella; inferior — the line passing horizontally about 3 cm below the patella.

The knee region is divided into anterior and posterior by the vertical lines passing through the femoral epicondyles..

Layers of anterior knee region:

1. skin;
2. subcutaneous tissue;
3. superficial fascia;
4. fascia lata (it merges here with the tendons of the femoral muscles and with the ligaments of the knee joint);
5. quadriceps femoris tendon which envelops patella and is continuous with patellar ligament

Subcutaneous tissue contains medially the long saphenous vein with the saphenous nerve; laterally the short saphenous vein.

Layers of posterior knee region:

1. skin ;
2. subcutaneous tissue ;
3. superficial fascia ;
4. fascia lata;
5. popliteal fossa bounded superolaterally by the biceps femoris; superomedially by the semimembranosus; inferolaterally by the lateral head of the gastrocnemius; inferomedially by the medial head of the gastrocnemius. The floor of the fossa is the popliteus, knee joint capsule and femur. The fossa contains superficially the sciatic nerve and its branches (common peroneal nerve and tibial nerve); deep to it is the popliteal vein; deep to the vein is popliteal artery. The vessels and nerves are surrounded by fat. Under the superficial fascia in the popliteal fossa there are superficial lymph nodes; under the fascia lata there are deep lymph nodes.

 

4. The crural region.

Borders: superior – the line passing horizontally about 3 cm below the patella; inferior – the line passing through the bases of the malleoli.

The crural region is divided into anterior and posterior by the lines connecting the femoral condyles with the malleoli.

Layers of anterior crural region:

1. skin;
2. subcutaneous tissue;
3. superficial fascia;
4. crural fascia;
5. tibia (its medial surface is nor covered by muscles), the muscles of the anterior compartment: tibialis anterior, extensor digitorum longus; the muscle of lateral compartment (peroneus longus);
6. the muscle of the anterior compartment (extensor hallucis longus); the muscle of lateral compartment (peroneus brevis)

The subcutaneous tissue contains the long and short saphenous veins and its tributaries, and also cutaneous sural nerves. The crural fascia gives anterior and posterior intermuscular septa which are attached to the fibula and separate the leg into three muscle compartments: anterior; lateral and posterior. The anterior compartment contains the anterior tibial vessels and deep peroneal nerve; the lateral compartment contains the peroneal vessels and superficial peroneal nerve.

The anterior crural region contains the superior musculoperoneal canal (see the table “Topography of limbs”).

 

Layers of posterior crural region:

1. skin;
2. subcutaneous tissue;
3. superficial fascia;
4. crural fascia;
5. superficial muscles of the posterior compartment: gastrocnemius and deep to it soleus (in the lower third of leg they form the calcaneal tendon, under which there is much fat;
6. deep muscles of the posterior compartment: flexor digitorum longus, flexor hallucis longus and tibialis posterior.

The posterior compartment contains the posterior tibial vessels and tibial nerve.

The posterior crural region contains the inferior musculoperoneal canal and cruropopliteal canal (see the table “Topography of limbs”).

5. The talocrural region.

Borders: superior – the line passing through the bases of the malleoli; inferior – the line passing horizontally and connecting the malleoli anteriorly and the line passing through the sole and connecting the malleoli.

The talocrural region is divided into anterior, posterior, medial and lateral.

Layers of anterior talocrural region:

1. skin;
2. subcutaneous tissue;
3. superficial fascia;
4. crural fascia (forms here the superior and inferior extensor retincula);
5. tendons of the anterior crural muscles

In subcutaneous tissue, the long saphenous vein passes in front of the medial malleolus and the branches of the superficial peroneal nerve between the malleoli.

Under the extensor retinacula there are three canals containing the tendons of the anterior crural muscles enclosed in synovial sheaths: medial canal contains the tendon of the tibialis anterior; lateral canal contains the tendon of the extensor digitorum longus; middle canal contains the tendon of the extensor hallucis longus and anterior tibial vessels and deep peroneal nerve.

 

Layers of posterior talocrural region:

1. skin;
2. subcutaneous tissue;
3. superficial fascia;
4. crural fascia enveloping the calcaneal tendon from all sides;
5. fat;
6. tibia

Layers of lateral talocrural region:

1. skin;
2. subcutaneous tissue (there is no subcutaneous tissue over the lateral malleolus)
3. superficial fascia;
4. crural fascia which forms here the superior and inferior peroneal retinacula; under the retinacula, behind the lateral malleolus there is a canal containing the tendons of the peroneus longus and brevis enclosed in a common synovial sheath;
5. lateral malleolus

In subcutaneous tissue behind the lateral malleolus there are the short saphenous vein and its tributaries and sural nerve.

Layers of medial talocrural region:

1. skin;
2. subcutaneous tissue;
3. superficial fascia;
4. crural fascia which forms here the flexor retinaculum; under the retinaculum, behind the medial malleolus there is a canal containing the tendons of the deep posterior crural muscles: anteriorly is the tendon of the tibialis posterior; posteriorly is the tendon of the flexor hallucis longus; between these two is the tendon of the flexor digitorum longus; the canal also contains the posterior tibial vessels and tibial nerve.
5. medial malleolus

6. The region of the foot.

Borders: superiorly, the line passing through the apices of the malleoli.

The region of the foot is divided into dorsal and plantar regions.

Layers of the dorsal region of the foot:

1. skin;
2. subcutaneous tissue;
3. superficial fascia;
4. superficial layer of the dorsal fascia of the foot;
5. tibialis anterior, m. extensor hallucis longus and m. extensor digitorum longus;
6. extensor hallucis brevis and extensor digitorum brevis;
7. deep layer of the dorsal fascia of the foot;
8. metatarsal bones and dorsal interossei.

Subcutaneous fat of the dorsal side contains a venous network which gives rise to the long and short saphenous veins, and the cutaneous branches of the superficial and deep peroneal nerves.

Layers of the plantar region of the foot:

1. skin;
2. subcutaneous tissue;
3. superficial fascia;
4. superficial layer of the plantar fascia of the foot (it thickens in the middle to form the plantar aponeurosis, and sends the septa to the III and IV metatarsal bones, separating three muscle groups in the sole);
5. in the middle of the sole: flexor digitorum brevis, then quadratus plantae, then tendons of the flexor digitorum longus with lumbricals, then tendon of the flexor hallucis longus and then the tendon of the peroneus longus; under the muscles is the deep layer of the plantar fascia of the foot. Under the fascia there are the plantar interossei and metatarsal bones.
6. in the medial muscle group there are the abductor hallucis, flexor hallucis brevis, adductor hallucis; in the lateral muscle group there are abductor digiti minimi, flexor digiti minimi

There are medial and lateral plantar grooves in the sole (see the table «Topography of limbs»)

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