Crus (lower leg)

The lower leg (Latin crus ) is a part of the leg and is located between the knee and foot.

Bone

The lower leg is made up of two bones, the tibia (tibia ) and the fibula ( fibula ). These are the top through a tight joint ( amphiarthrosis ) and below by a band adhesion ( syndesmosis tibiofibularis ) connected to each other. Between them runs a firm, fibrous band structure ( interosseous membrane ).

Adjacent joints

In the joint between the knee and lower leg ( knee ) is a rotary hinge joint, the articular surfaces are located on the condyle of the femur (femur) and the shin and on the back of the kneecap ( patella).

The joint between the lower leg and foot ( ankle ) is also a hinge joint and is formed by the two ankle on the tibia and fibula, and the talus ( astragalus ).

Musculature

The muscles of the lower leg are grouped according to their function and location and divided into four groups as follows:

• The front lower leg muscles consists of the extensors ( extensors ) on the lateral- anterior ( ventero -lateral ) side and
• The peroneal muscles in the area of the fibula on the outer ( lateral ) side.

• The superficial flexors ( flexor ) on the back, which are collectively referred to as the triceps surae and
• The deep flexor muscles in the back.

In quadrupedal mammals lies between the two heads of the gastrocnemius muscle or the superficial flexors of the foot ( flexor digitorum superficialis pedis ).

Boxes, fascia, and compartment syndrome

The entire lower leg is surrounded by a connective tissue skin that Unterschenkelfaszie ( crural fascia ). The individual muscle groups are surrounded by rough and non-stretch fascia and separate. At this separation, the band adhesion between the bone and the deep layer (lamina profunda ) the Unterschenkelfaszie are involved, which separates the deep and superficial flexors of each other.

By separating the muscle groups, so-called muscle compartments arise (also compartments ) in which muscles are combined with of related function. Each compartment is separated by a surrounding Bindegewebshaut of adjacent compartments and forms with its contents an almost completely self-contained space.

According to the muscle groups can be found in the lower leg following boxes:

• The extensor (anterior compartment, sometimes called tibialis anterior Loge )
• The Peronaeusloge ( lateral compartment or Fibularisloge )
• The superficial flexor compartment ( superficial posterior compartment )
• The deep flexor ( deep posterior compartment )

The fascia around the lodges around have the force of compression, limiting swelling. After lower leg injuries, it can also lead to bleeding into a muscle compartment. The coarse connective tissues can not expand, so that the pressure in the box increases greatly. The most important result is a compression of the neurovascular bundle of the lower leg. This can lead to irreparable damage especially the deep and superficial peroneal nerve. As a result, a drop foot developed. This phenomenon is referred to as compartment syndrome. It is usually not at a loss of pulse by clamping the arteries, as damage to the nerves already threatened in the lower leg boxes of 40 mmHg from a pressure. The normal systemic pressure averages around 100 mmHg, so the lower leg arteries remain open when compartment syndrome. If nothing is done fast enough, die adjacent to the nerve from the muscles. In the case of compartment therefore need to act quickly. The lodges of the lower leg should be opened quickly so that the pressure returns to normal. Irreparable damage may consist inter alia in a Funktionsverlusst the nerves and contractures in the scarred muscle tissue.

Even after a strong over- load, for example, in sport at an unusual long-distance running may lead to a compartment syndrome. Also to fixed -term associations can have such an effect.

The symptoms are pain, redness, swelling, loss of function and sensation disorders. If nothing is done fast enough, this will cause irreparable damage. Prophylactic the legs should be elevated in fractures to avoid a compartment syndrome. Particularly common is the damage to the front of the leg extensor lying ( tibialis anterior syndrome). Similar problems there may be in the forearm muscles.

Arteries

In the squat, the popliteal artery divides ( Kniebeugerarterie ) in the

• Anterior tibial artery (anterior tibial artery), in animals as cranial tibial artery called, and the
• Posterior tibial artery ( posterior tibial artery), called with animals caudal tibial artery.

On the anterior tibial artery, the anterior tibial artery returning spring ( recurrent artery tibialis anterior ), which rises again to the knee, and the inner and outer front of the ankle arteries ( anterior medial malleolar artery anterior malleolar artery and lateral ). Finally, she ends up in the artery of the dorsum of the foot ( dorsalis pedis). This walk from the medial tarsal artery and the lateral tarsal artery. A little above the metatarsophalangeal joints form the dorsalis pedis artery and the lateral tarsal artery arcuata. From this the füßrückenseitigen deep metatarsal arteries ( arteries dorsal metatarsal ) go down, the digital lost in the dorsal artery and thus supply the toes with blood.

From the posterior tibial artery, the peroneal artery arises ( peroneal artery ), the inner soles artery ( medial plantar ) and the outer soles artery ( lateral plantar ).

Veins

Superficial veins

In the lower leg is the one the great hidden vein ( " large rose vein", also called " great saphenous vein ," the great saphenous vein, in animals saphenous vein medial ), by the foot of her in front of the medial malleolus, then centered to the shin and finally back central condyle on the inner thigh runs. The vein opens into the groin into the femoral vein ( femoral vein ). The small hidden vein ( " small rose wire " analog, also called " small saphenous vein ", saphenous vein, in animals saphenous vein lateralis) runs behind the lateral malleolus, then back along in mid-calf in the subcutaneous adipose tissue and finally pours into the Kniebeugervene ( popliteal vein ). The small hidden vein is commonly used in dogs and cats for blood sampling or intravenous injection.

Deep vein

In the calf run between the muscles a series of deep veins. They are functionally more important than the superficial veins. They accompany the arteries in the rule and are often as two or three escort vessels built around the arteries. They are divided according to the arteries into the following groups:

• Tibialis posterior group
• Tibialis anterior group
• Peroneal group

Especially the veins of the posterior tibial group are not infrequently affected by deep vein thrombosis.

Bug

In the popliteal fossa, the sciatic nerve ( sciatic nerve ) divides into the common peroneal nerve ( peroneal ) and tibial nerve ( tibial nerve ).

The common peroneal nerve is in turn divided into the deep peroneal nerve ( deep fibular ) and the superficial peroneal nerve ( superficial peroneal nerve ). The tibial nerve divides only on foot.