Because there is no muscle below the knee/hock to cushion the bones
The patellar reflex employs the sensory and motor nerves in the leg that control the contraction of the quadriceps muscle in response to tapping the patellar tendon just below the knee cap.
The two joints that the sartorius muscle crosses are the hip joint and the knee joint. The muscle originates at the anterior superior iliac spine of the hip bone and inserts at the upper medial surface of the tibia below the knee joint.
The horse's gaskin is part of its hind leg, located between the stifle (knee) and hock joints. It is a muscle group that helps power the horse's movement, particularly in activities like jumping or pushing off the ground.
The muscle primarily responsible for the last 10 degrees of knee extension is the popliteus muscle. It is a small muscle located at the back of the knee joint and helps to unlock the knee by internally rotating the tibia on the femur.
Gastrocnemius muscle
An agonist muscle is a muscle that plays a part in the extension of a muscle. The agonist muscles for a knee extension are the quadriceps and hamstrings.
The flexor would be the hamstring, and gastrocnemius, which bend/flex the knee. The quadriceps, are extensors, which straighten/extend the knee.
The muscle that contracts when the leg is extended at the knee is call the gastrocnemius muscle
Vastus medialis (a tear-shaped muscle right above your knee)
Quadriceps muscle or thigh muscle.
The "calf muscle" is the common name for the gastrocnemius muscle which is located below the knee posteriorly between the popliteal space and Achilles tendon. It functions to plantarflex the ankle.The calf muscle is located on the back of the lower leg, below the knee, between the popliteal space and Achilles tendon. It is made up of two individual muscles, the gastrocnemius and soleus.