The triceps surae consists of two

muscle Skeletal muscles (commonly referred to as muscles) are Organ (biology), organs of the vertebrate muscular system and typically are attached by tendons to bones of a skeleton. The muscle cells of skeletal muscles are much longer than in the other ...

s located at the

calf Calf most often refers to: * Calf (animal), the young of domestic cattle. * Calf (leg), in humans (and other primates), the back portion of the lower leg Calf or calves may also refer to: Biology and animal byproducts *Veal, meat from calves ...

– the two-headed gastrocnemius and the soleus. These muscles both insert into the

calcaneus In humans and many other primates, the calcaneus (; from the Latin ''calcaneus'' or ''calcaneum'', meaning heel) or heel bone is a bone of the tarsus of the foot which constitutes the heel. In some other animals, it is the point of the hock. ...

, the bone of the heel of the human

foot The foot ( : feet) is an anatomical structure found in many vertebrates. It is the terminal portion of a limb which bears weight and allows locomotion. In many animals with feet, the foot is a separate organ at the terminal part of the leg mad ...

, and form the major part of the muscle of the posterior leg, commonly known as the calf muscle.

Structure

The triceps surae is connected to the foot through the

Achilles tendon The Achilles tendon or heel cord, also known as the calcaneal tendon, is a tendon at the back of the lower leg, and is the thickest in the human body. It serves to attach the plantaris, gastrocnemius (calf) and soleus muscles to the calcane ...

, and has 3 heads deriving from the 2 major masses of muscle. * The superficial portion (the gastrocnemius) gives off 2 heads attaching to the base of the

femur The femur (; ), or thigh bone, is the proximal bone of the hindlimb in tetrapod vertebrates. The head of the femur articulates with the acetabulum in the pelvic bone forming the hip joint, while the distal part of the femur articulates wit ...

directly above the

knee In humans and other primates, the knee joins the thigh with the human leg, leg and consists of two joints: one between the femur and tibia (tibiofemoral joint), and one between the femur and patella (patellofemoral joint). It is the largest join ...

. * The deep (profundus) mass of muscle (the soleus) forms the remaining head which attaches to the superior posterior area of the tibia. The triceps surae is innervated by the tibial nerve, specifically, nerve roots L5–S2.

Function

Contraction of the triceps surae induce plantar flexion (sagittal plane) and stabilization of the ankle complex in the transverse plane. Functional activities include primarily movement in the

sagittal plane The sagittal plane (; also known as the longitudinal plane) is an anatomical plane that divides the body into right and left sections. It is perpendicular to the transverse and coronal planes. The plane may be in the center of the body and div ...

, stabilization during locomotion (walking, running), restraining the body from falling and power

jumping Jumping or leaping is a form of locomotion or movement in which an organism or non-living (e.g., robotic) mechanical system propels itself through the air along a ballistic trajectory. Jumping can be distinguished from running, galloping and ...

. By controlling the disequilibrium torque, the triceps surae can affect force through the exchange of potential into

kinetic energy In physics, the kinetic energy of an object is the energy that it possesses due to its motion. It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity. Having gained this energy during its a ...

Clinical significance

Calf strain (torn calf muscle)

A calf strain refers to damage to a muscle or its attaching tendons. A premature return before recovery is achieved will result in a prolonged recovery or incomplete return to baseline prior to injury. Stretches such as alternating calf raises can improve flexibility as well as mobilize legs before running. Calf muscles are a common place for

fasciculation A fasciculation, or muscle twitch, is a spontaneous, involuntary muscle contraction and relaxation, involving fine muscle fibers. They are common, with as many as 70% of people experiencing them. They can be benign, or associated with more seri ...

Additional images

File:Triceps surae - animation.gif, Animation. Gastrocnemius and Soleus are shown in different colors. File:Sobo 1909 303.png, Illustration of the gastrocnemius. File:Sobo 1909 304.png, Illustration of soleus. File:Sobo 1909 579-580.png, Nerves, arteries and veins surround the gastrocnemius and soleus. File:Braus 1921 293.png, Cross section of the lower leg, with triceps surae at back (soleus and gastrocnemius) File:Sobo_1909_720.png, Nerves and blood-vessels overlying the triceps surae File:Medial view of a cadaver dissection of the gastrocnemius–soleus junction - with text.png, Photograph of the gastrocnemius- soleus junction.

Etymology and pronunciation

The term is pronounced . It is from Latin ''caput'' and ''sura'' meaning "three-headed uscleof the calf".