Identifying Muscles of the Lower Extremities - Anatomy

For this question, we are looking for a muscle that is located in the lateral compartment of the thigh. In addition, this muscle should contract when the thigh is either abducted or medially rotated. The correct answer is the tensor fasciae latae which is the only muscle of the choices that fits these categories.

We are looking for a muscle in the posterior compartment of the thigh. This means that the muscle will be on the back of the leg, between the pelvis and the kneecap. The correct answer is the gracilis muscle, which unlike the other three is located in the anterior compartment of the thigh.

Extensor muscles located in the deep, posterior compartment of the leg are responsible for flexing the toes. In this case, the correct answer is the extensor digitorum longus because it controls the 2nd through 5th digits in the feet. We can infer this by looking at the word "digitorum", meaning digits, as in fingers or toes. The extensor hallucis longus extends the first digit in the lower extremity (hallux) and dorsiflexes the foot. The tibialis anterior is the strongest dorsiflexor of the foot.

The quadriceps tendon is located in the anterior compartment of the thigh. This means we are looking for a muscle that is also located in the anterior compartment of the thigh. There are four muscles that insert via the quadriceps tendon: rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius.

Both the superior gemellus and the obturator internus muscles are innervated by the same nerve. The nerve that innervates the obturator internus is easy to remember because the nerve and the muscle have the same name. That means the obturator internus nerve is the correct answer.

Vastus medialis is most medial (medialis) as well as most distal. Rectus femoris is located most medially to the leg, but not the body, which is what is used as reference when looking at anatomical position. Vastus lateralis (lateral) and Vastus medialis (medial) are also not correct as they do not fit the description of both medical and distal. Finally the sartorius is not part of the quadriceps muscle group.

The hamstring muscle group is responsible for knee flexion. The quadriceps muscle group is responsible for knee extension. The posterior muscle group is not an anatomical muscle group. The biceps muscle group is located in the upper arm, and produces elbow flexion.

Although the gastrocnemius is a large muscle, it is not as involved in walking and running as is the soleus. Rather, it is a powerful plantarflexor of the foot and is more active in jumping and other movements that require powerful plantarflexion. The gracilis muscle is located in the thigh, and is responsible for weak flexion, internal rotation, and adduction of the hip. The plantaris muscle only minimally aids in running and walking and is not present in about 10% of the population. This means the correct answer is the soleus muscle.

The gastrocnemius is one of the muscles that makes up the calf muscles in the leg. The other calf muscle is the soleus, which lies under the gastrocnemius. The gastrocnemius also has two heads which give it a "diamond" shape. There are several layers of different muscles on the soles of the feet. The hamstrings are the group of muscles found on the back of the thigh, with the biceps femoris being the largest. The quadriceps are the muscle group on the front of the thigh, the vastus lateralis is the largest of these.

The largest muscle in the entire body is the Gluteus Maximus which is found in the buttocks. It has the function of keeping the entire body erect by inserting itself in the pelvic bone.

The tensor fascia latae attaches from the anterior superior iliac spine to the iliotibial band.

The soleus is one part of the calf muscle, and is deep to the gastrocnemius. This muscle inserts via the achilles tendon to the calcaneus and allows for plantarflexion of the foot.

The tibial tuberosity is located at the proximal anterior portion of the tibia, and the navicular tuberosity and 1st cuniform are located in the midfoot and are insertion points for medial and lateral muscles of the foot and lower leg.

The muscles that insert to the achilles tendon allow for plantarflexion of the foot, which is created due to shortening of the posterior muscles of the lower leg. Dorsiflexion is created through the anterior muscles of the lower leg. Eversion is created through the lateral muscles, and inversion is created with the medial muscles. Abduction is the motion of moving a body part away from the midline.

The sartorius, semitendinous and gracilis all make up the pes anserine tendon. Vastus medialis, although on the medial aspect of the knee, does not make up this muscle group as it inserts to the tibial tubercle via the patellar tendon.

The iliopsoas muscle is composed of the iliacus and psoas major muscles. It functions as a flexor of the thigh at the hip joint and laterally rotates it. It's also capable of flexing the trunk on the hip as in sitting up from the supine position.

Sartorius, gracilis, semitendinosus make up the pes anserine group whose conjoined tendons insert onto the anteromedial surface of the proximal extremity of the tibia. They flex and medially rotate the leg at the knee joint.

The adductor magnus is innervated by both the sciatic nerve and the obturator nerve.

The tibialis anterior and extensor digitorum longus muscles both dorsiflex the foot at the ankle joint; the tibialis anterior also inverts the foot at the intertarsal joints and the extensor digitorum longus extends the proximal and distal phalanges. The gastrocnemius and soleus muscles are plantarflexors of the foot at the ankle joint. The gastrocnemius also flexes the leg at the knee joint.

The quadriceps femoris group of muscles are the main extensors of the leg at the knee joint. They consist of the rectus femoris, vastus lateralis, vastus intermedius, and vastus medialis muscles. The rectus femoris muscle also flexes the thigh at the hip joint.