I really like anatomy and I believe that a good specialist (even if he will only work in the mouth) must have a big variety of different skills as well as knowledge, so I decided to do an additional work, so called preparation. With a student from another group we prepared the left leg. Firstly, we peeled (don't know if it's the right word to use though :D) the skin and took off all the fats from the muscles and other areas. Here you can see the result:
This is the back of the left leg and the musles (starting from the bottom and going up): Biceps Femoris muscle, Semitendinosus muscle, Semimembranosus muscle;
The biceps femoris muscle is lateral in the posterior compartment of thigh and has two heads:
-The long head originates with the semitendinosus muscle from the inferomedial part of the upper area of the ischial tuberosity.
-The short head arises from the lateral lip of the linea aspera on the shalf of the femur
The muscle belly of the long head crosses the posterior thigh obliquely from medial to lateral and is joined by the short head distally. Together, fibers from the two heads form a tendon, which is palpable on the lateral side of the distal thigh. The main part of the tendon inserts into the lateral surface of the head of the fibula. Extensions from the tendon blend with the fibular collateral ligament and with ligaments associated with the lateral side of the knee joint. The biceps femoris flexes the leg at the knee joint. The long head also extends and laterally rotates the hip. When the knee is partly flexed, the biceps femoris can laterally rotate the leg at the knee joint. The long head is innervated by the tibial division of the sciatic nerve and the short head is innervated ny the common fibular division of the sciatic nerve.
The semitendinosus muscle is medial to the biceps femoris muscle in the posterior compartment of thigh. It originates with the long head of the biceps femoris muscle from the inferomedial part of the upper area of the ischial tuberosity. The spindle-shaped muscle belly ends in the lower half of the thigh and forms a long cord-like tendon, which lies on the semimembranosus muscle and descends to the knee. The tendon curves around the medial condyle of the tibia and inserts into the medial surface of the tibia just posterior to the tendons of the gracilis and sartorius muscles. The semitendinosus flexes the leg at the knee joint and extends the thigh at the hip joint. Working with the semimembranosus, it also medially rotates the thigh at the hip joint and medially rotates the leg at the knee joint. The semitendinosus muscle is innervated by the tibial division of the sciatic nerve.
The semimembranosus muscle lies deep to the semitendinosus muscle in the posterior compartment of thigh. It also attached above to the superolateral impression on the ischial tuberosity and below mainly to the groove and adjacent bone on the medial and posterior surfaces of the medial tibial condyle. Expansions from the tendon also insert into and contribute to the formation of ligaments and fascia around the knee joint. The semimembranosus flexes the leg at the knee joint and extends the thigh at the hip joint. Working with the semitendinosus muscle, it medially rotates the thigh at the hip joint and the leg at the knee joint. The semimembranosus muscle is innervated by the tibial division of the sciatic nerve.
The semimembranosus muscle lies deep to the semitendinosus muscle in the posterior compartment of thigh. It also attached above to the superolateral impression on the ischial tuberosity and below mainly to the groove and adjacent bone on the medial and posterior surfaces of the medial tibial condyle. Expansions from the tendon also insert into and contribute to the formation of ligaments and fascia around the knee joint. The semimembranosus flexes the leg at the knee joint and extends the thigh at the hip joint. Working with the semitendinosus muscle, it medially rotates the thigh at the hip joint and the leg at the knee joint. The semimembranosus muscle is innervated by the tibial division of the sciatic nerve.
Nerves of the leg: the posterior cutaneous nerve and the sciatic nerve which divides into to branches 1)The common fibular nerve 2) The tibial nerve
The sciatic nerve is the largest nerve of the body and carries contributions from L4 to S3. It leaves the pelvis through the greater sciatic foramen inferior to the piriformis muscle, enters and passes through the gluteal region and then enters the posterior compartment of the thigh where it divides into two major branches:
1. The common fibular nerve
2. The tibial nerve
Posterior divisions of L4 to S2 are carried in the common fibular part of the nerve and the anterior divisions of L4 to S3 are carried in the tibial part. The sciatic nerve innervates:
- All muscles in the posterior compartment of the thigh
-The part of adductor magnus originating from the ischium
-All muscles in the leg and foot
-Skin on the lateral side of the leg and the lateral side and sole of the foot
The posterior cutaneous nerve of thigh is formed by contributions from S1 to S3 and leaves the pelvic cavity through the greater sciatic foramen inferior to the piriformis muscle. It passes vertically through the gluteal region deep to the gluteus maximus and enters the posterior thigh and innervates:
-A longitudinal band of the skin over the posterior aspect of the thigh that continues into the upper leg
-Skin over the gluteal fold, over the upper medial part of the thigh and in the adjacent regions of the perineum
The popliteal fossa is an important area of transition between the thigh and leg and is the major route by which structures pass from one region to the other. The popliteal fossa is a diamond-shaped space behind the knee joint formed between muscles in the posterior compartments of thigh and leg.
The margins of the upper part of the diamond are formed medially by the distal ends of the semitendinosus and semimembranosus muscles and laterally by the distal end of the biceps femoris muscle;
The margins of the smaller lower part of the space are formed medially by the medial head of the gastrocnemius muscle and laterally by the the plantaris muscle and the lateral head of the gastrocnemius muscle;
The floor of the fossa is formed by the capsule of the knee joint and adjacent surfaces of the femur and tibia, and, more inferiorly, by the popliteus muscle;
The roof is formed by the deep fascia, which is continuous above with tha fascia lata of the thigh and below with deep fascia of the leg.
The major contents of the popliteal fossa are the popliteal artery, the popliteal vein, and the tibial and common fibular nerves
The gastrocnemius muscle
The soleus muscle
The calcaneal tendon (Achilles tendon)
The gastrocnemius muscle is the most superficial of the muscles in the posterior compartment and is one of the largest muscles in the leg. It originates from two heads, one lateral and one medial:
-The medial head is attached to an elongate roughening on the posterior aspect of the distal femur just behind the adductor tubercle and above the articular surface of the medial condyle;
-The lateral head originates from a distinct facet on the upper lateral surface of the lateral femoral condyle where it joins the lateral supracondylar line.
At the knee, the facing margins of the two heads of the gastrocnemius form the lateral and medial borders of the lower end of the popliteal fossa. In the upper leg, the heads of the gastrocnemius combine to form a single elongate muscle belly, which forms much of the soft tissue bulge identified as the calf. In the lower leg, the muscle fibers of the gastrocnemius converge with those of the deeper soleus muscle to form the calcaneal tendon, which attaches to the calcaneus (heel) of the foot. The gastrocnemius plantarflexes the foot at the ankle joint and can also flex the leg at the knee joint. It is innervated by the tibial nerve.
The soleus is a large flat muscle under the gastrocnemius muscle. It is attached to the proximal ends of the fibula and tibia, and to a tendinous ligament, which spans the distance between the two heads of attachment to the fibula and tibia:
-On the proximal end of the fibula, the soleus originates from the posterior aspect of the head and adjacent surface of the neck and upper shaft of the fibula;
-On the tibia, the soleus originates from the soleal line and adjacent medial border;
-The ligament, which spans the distance between the attachments to the tibia and fibula, arches over the popliteal vessels and tibial nerve as they pass from the popliteal fossa into the deep region the posterior compartment of leg
In the lower leg, the soleus muscle narrows to join the calcaneal tendon that attaches to the calcaneus. The soleus muscle, together with the gastrocnemius and plantaris, plantarflexes the foot at the ankle joint. It is innervated by the tibial nerve.
How did you like the anatomy? Have you ever done something like this? Let me now!! ;)
