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Biarticular muscles are muscles that cross two joints rather than just one, such as the hamstrings which cross both the hip and the knee. The function of these muscles is complex and often depends upon both their anatomy and the activity of other muscles at the joints in question. Their role in movement is poorly understood.
Biarticular muscles cross two joints in series, usually in a limb. The details of the origin (proximal attachment) and insertion (distal attachment) can play a large role in determining muscle function. For instance, the human gastrocnemius technically spans both the knee and ankle joints. However, the origin point of the muscle is so close to the axis of rotation of the knee joint that the muscle's effective lever arm would be very small, especially compared to its large lever arm at the ankle.[ citation needed ] As a result, even though it spans two joints, the strong bias in lever arms allows it to function primarily as an ankle plantar flexor. Other muscles, such as the hamstrings, do not display such biases, so their function is not immediately evident from anatomy alone. Another important concept of biarticular muscles (consider the rectus femoris muscle for this example) is the change in muscle length when motion at the proximal and distal ends of the muscle is happening. For example, in the propulsive phase of a jump, the thigh is extended at the coxal joint, and the shank (lower leg) is extended at the tibiofemoral joint. These joint positions cause the rectus femoris muscle to remain unchanged in net length, because the proximal (Eccentric action) and distal (concentric action) attachments are contradicting one another.
Biarticular muscles can fulfill a range of functions during movement. By contracting isometrically (without changing length), they put the joint into a four-bar linkage, allowing the contraction of muscles at one joint to move the other by a fixed amount. Unlike four-bar linkages in which all elements are bone and angle relationships are fixed by the relative bone lengths, the biarticular muscle can hold the joint at many different lengths, creating a range of four-bar properties as needed.
Biarticular muscles can also transfer mechanical power between distal and proximal joints, though the direction and magnitude of this transfer varies with anatomy, muscle activity level, and joint angles. This is a crucial consideration when analyzing an organism's movement using inverse dynamics.
The leg is the entire lower limb of the human body, including the foot, thigh or sometimes even the hip or buttock region. The major bones of the leg are the femur, tibia, and adjacent fibula.
In human anatomy, a hamstring is any one of the three posterior thigh muscles between the hip and the knee.
In anatomy, the thigh is the area between the hip (pelvis) and the knee. Anatomically, it is part of the lower limb.
The tibia, also known as the shinbone or shankbone, is the larger, stronger, and anterior (frontal) of the two bones in the leg below the knee in vertebrates ; it connects the knee with the ankle. The tibia is found on the medial side of the leg next to the fibula and closer to the median plane. The tibia is connected to the fibula by the interosseous membrane of leg, forming a type of fibrous joint called a syndesmosis with very little movement. The tibia is named for the flute tibia. It is the second largest bone in the human body, after the femur. The leg bones are the strongest long bones as they support the rest of the body.
The fibula or calf bone is a leg bone on the lateral side of the tibia, to which it is connected above and below. It is the smaller of the two bones and, in proportion to its length, the most slender of all the long bones. Its upper extremity is small, placed toward the back of the head of the tibia, below the knee joint and excluded from the formation of this joint. Its lower extremity inclines a little forward, so as to be on a plane anterior to that of the upper end; it projects below the tibia and forms the lateral part of the ankle joint.
The gluteus minimus, or glutæus minimus, the smallest of the three gluteal muscles, is situated immediately beneath the gluteus medius.
The quadriceps femoris muscle is a large muscle group that includes the four prevailing muscles on the front of the thigh. It is the sole extensor muscle of the knee, forming a large fleshy mass which covers the front and sides of the femur. The name derives from Latin four-headed muscle of the femur.
The biceps femoris is a muscle of the thigh located to the posterior, or back. As its name implies, it consists of two heads; the long head is considered part of the hamstring muscle group, while the short head is sometimes excluded from this characterization, as it only causes knee flexion and is activated by a separate nerve.
The vastus medialis is an extensor muscle located medially in the thigh that extends the knee. The vastus medialis is part of the quadriceps muscle group.
The semitendinosus is a long superficial muscle in the back of the thigh. It is so named because it has a very long tendon of insertion. It lies posteromedially in the thigh, superficial to the semimembranosus.
The rectus femoris muscle is one of the four quadriceps muscles of the human body. The others are the vastus medialis, the vastus intermedius, and the vastus lateralis. All four parts of the quadriceps muscle attach to the patella by the quadriceps tendon.
Lombard's paradox describes a paradoxical muscular contraction in humans. When rising to stand from a sitting or squatting position, both the hamstrings and quadriceps contract at the same time, despite them being antagonists to each other.
The lateral circumflex femoral artery is an artery in the upper thigh. It is usually a branch of the profunda femoris artery, and produces three branches. It is mostly distributed to the muscles of the lateral thigh, supplying arterial blood to muscles of the knee extensor group.
The tuberosity of the tibia, tibial tuberosity or tibial tubercle is an elevation on the proximal, anterior aspect of the tibia, just below where the anterior surfaces of the lateral and medial tibial condyles end.
The posterior compartment of the thigh is one of the fascial compartments that contains the knee flexors and hip extensors known as the hamstring muscles, as well as vascular and nervous elements, particularly the sciatic nerve.
Comparative foot morphology involves comparing the form of distal limb structures of a variety of terrestrial vertebrates. Understanding the role that the foot plays for each type of organism must take account of the differences in body type, foot shape, arrangement of structures, loading conditions and other variables. However, similarities also exist among the feet of many different terrestrial vertebrates. The paw of the dog, the hoof of the horse, the manus (forefoot) and pes (hindfoot) of the elephant, and the foot of the human all share some common features of structure, organization and function. Their foot structures function as the load-transmission platform which is essential to balance, standing and types of locomotion.
Terrestrial locomotion by means of a running gait can be accomplished on level surfaces. However, in most outdoor environments an individual will experience terrain undulations requiring uphill running. Similar conditions can be mimicked in a controlled environment on a treadmill also. Additionally, running on inclines is used by runners, both distance and sprinter, to improve cardiovascular conditioning and lower limb strength.
Anatomical terminology is used to uniquely describe aspects of skeletal muscle, cardiac muscle, and smooth muscle such as their actions, structure, size, and location.
A kick is a skill in association football in which a player strikes the ball with their foot. Association football, more commonly referred to as football and also known as soccer, is a sport played world-wide, with up to 265 million people around the world participating on a yearly basis. Kicking is one of the most difficult skills to acquire in football. This skill is also vitally important, as kicking is the way in which passes are made and the primary means by which goals are scored.