Muscles, Tendons, and Ligaments of the Body
Abdominal Head of Pectoralis Major Muscle
The abdominal head of the pectoralis major muscle is one of three origins for the pectoralis major. It arises from the fascia of the external oblique muscle. Broadly, pectoral is a term relating to the chest, and the pectoralis major is a large, fan-shaped muscle that covers much of the front upper chest. It begins at the breastbone (sternum) and the cartilage of the second to the sixth ribs and is attached to the collarbone (clavicle) to converge on the upper arm bone (humerus) just below the shoulder. Its main use is in moving the arm across the body.
Abductor Digiti Minimi Muscle of Foot
The abductor digiti minimi muscle of foot is a muscle attached to the small toe that serves to pull that toe away from the other toes. It runs from the outer front of the heel bone and along the side of the foot to insert at the proximal phalanx. Generally, abduction refers to movement of a limb away from the central line of the body or of a digit away from the axis of a limb. Muscles, then, that carry out this type of movement are called abductor muscles.
Abductor Hallucis Muscle
The abductor hallucis muscle is one of the hallux muscles. This one serves to move the big toe away from the other toes. The hallux (plural, hallucis) are muscles pertaining to the big toe.
Adductor Brevis Muscle
The adductor brevis muscle arises from the pubic body and finds insertion at the posterior of the femur, in its upper third. The adductor brevis primarily adducts but also helps in lateral rotation of the hip. Generally, adductor muscles move a limb toward the central line of the body or a digit toward the axis of a limb. It comes from the Latin word, adductus, meaning one that draws to.
Adductor Hallucis Muscle
The adductor hallucis muscle is located on sole of the foot. It adducts the big toe, moving it closer to the smaller toes. The muscle separates into two heads: the transverse and oblique heads. The transverse goes over the sole of the foot under all of the smaller toes and the oblique adheres to the big toe's lower bone. The other end of the oblique head attaches to a bone that is in front of the heel.
Adductor Longus Muscle
The adductor longus muscle is a long, triangular muscle that runs from the pubic bone to the femur. It functions to adduct, or move the thigh inward, and assists in flexing and rotating it to the side.
Adductor Magnus Muscle
The adductor magnus muscle is the largest of three adductor muscles arising from the pelvic bones and inserting on the femur. In this case, the adductor magnus is split into two divisions, the adductor portion and hamstring portion. The adductor powerfully adducts the hip, while the hamstring portion of the adductor magnus rotates the leg medially. Generally, adductor muscles move a limb toward the central line of the body or a digit toward the axis of a limb. It comes from the Latin word, adductus, meaning one that draws to.
Calcaneal (Achilles) Tendon
The calcaneal (or Achilles) tendon is the thickest and strongest in the human body and is about 15 cm in length. This tendon connects the calf muscle to the heel bone. It puts a spring in the step and helps one to stand on tiptoe. Unlike the other tendons in the body, though, it has no protective covering and is therefore very vulnerable to inflammation and injury. Even shoes that don't fit correctly can inflame or tear the tendon. The Achilles tendon gets its common name from the Greek warrior, Achilles, who was the son of a sea goddess and of a mortal father. When he was a baby, his mother tried to make him immortal by dipping him in the River Styx. She held him by his heel, which consequently never touched the water, making it his only vulnerable spot. Years later, he died in the Trojan War when his enemy shot him in the heel with an arrow.
Clavicular Head of Pectoralis Major Muscle
The clavicular head of pectoralis major muscle is one of three origins for the pectoralis major. It arises from the clavicle (towards the sternum) and is critical in flexion and rotation of the humerus bone. Broadly, pectoral is a term relating to the chest, and the pectoralis major is a large, fan-shaped muscle that covers much of the front upper chest. It begins at the breastbone (sternum) and the cartilage of the second to the sixth ribs and is attached to the collarbone (clavicle) to converge on the upper arm bone (humerus) just below the shoulder. Its main use is in moving the arm across the body.
Diaphragm
The diaphragm is the dome-shaped sheet of muscle and tendon that serves as the main muscle of respiration and plays a vital role in the breathing process. Also known as the thoracic diaphragm, it serves as an important anatomical landmark that separates the thorax, or chest, from the abdomen. The origins of the diaphragm are found along the lumbar vertebrae of the spine and the inferior border of the ribs and sternum. Openings in the diaphragm allow the esophagus, phrenic and vagus nerves, descending aorta, and inferior vena cava to pass between the thoracic and abdominal cavities. The lungs are enclosed in the thoracic cavity by the rib cage on the front, back, and sides with the diaphragm forming the floor of the cavity. When we inhale, the diaphragm contracts and is drawn inferiorly into the abdominal cavity until it is flat. At the same time, the external intercostal muscles between the ribs elevate the anterior rib cage like the handle of a bucket. The thoracic cavity becomes deeper and larger, drawing in air from the atmosphere. During exhalation, the rib cage drops to its resting position while the diaphragm relaxes and elevates to its dome-shaped position in the thorax. Air within the lungs is forced out of the body as the size of the thoracic cavity decreases. Structurally, the diaphragm consists of two parts: the peripheral muscle and central tendon. The peripheral muscle is made up of many radial muscle fibers — originating on the ribs, sternum, and spine — that converge on the central tendon. The central tendon — a flat aponeurosis made of dense collagen fibers — acts as the tough insertion point of the muscles. When air is drawn into the lungs, the muscles in the diaphragm contract, and pull the central tendon inferiorly into the abdominal cavity. This enlarges the thorax and allows air to inflate the lungs. The peripheral muscle can be further divided by its origins into the sternal, costal, and lumbar regions. The sternal region is made up of two small muscular segments that attach to the posterior aspect of the xiphoid process. The costal region is made up of several wide muscle segments whose origins are found on the internal surface of the inferior six ribs and costal cartilages. The lumbar region has its origins on the lumbar vertebra by way of two pillars of tendon called the musculotendinous crura. These pillars wrap around the aorta as it passes through the diaphragm to form the aortic hiatus. The diaphragm sometimes contracts involuntarily due to certain irritations; these contractions can happen because we eat too quickly, drink carbonated beverages, experience some acid indigestion, or are dealing with a stressful day. If air is inhaled at these times of contraction, the space between the vocal cords at the back of the throat closes suddenly, producing the noise we call hiccups. Short-lived hiccuping episodes are very common. Longer-term hiccups (lasting for days) can occur as well and are usually caused by irritated nerves, though medical attention would be needed in order to rule out other health concerns.
Dorsal Interosseous Muscles of Foot
The dorsal interosseous muscles of the the foot, or dorsal interossei, are a set of four muscles that run along the back of the foot and between the bones of the toes.
Extensor Digitorum Brevis Muscle
The extensor digitorum brevis muscle is located on the foot's top surface. This muscle extends the second through fourth digits.
Extensor Digitorum Longus Muscle
The extensor digitorum longus muscle is situated along the outside of the lower leg, just behind the tibialis anterior. It comes from close to the midline of the tibia and the shaft of the fibula. Its tendon divides into four parts as it passes over the front of the ankle. These parts continue over the surface of the foot and attach to the four smaller toes. The actions of this muscle include dorsiflexion of the foot, eversion of the foot, and extension of the toes.
Extensor Digitorum Longus Tendons
The extensor digitorum longus tendons connect the extensor digitorum longus muscle to the second, third, fourth, and fifth toes at the distal and middle phalanges.
Extensor Hallucis Brevis Muscle
The extensor hallucis brevis muscle arises from the dorsal side of the calcaneous to insert at the big toe's proximal phalanx, serving to help extend the big toe. The hallux (plural, hallucis) are muscles pertaining to the big toe. The extensor hallucis longus are muscles used in extending the toe; the flexor hallucis longus are used in flexing it and moving it to the side.
Extensor Hallucis Longus Muscle
The extensor hallucis longus muscle has its origin in the middle of the fibula, running along the inside of that bone and over the ankle to insert on the distal phalanx. It extends the big toe (straightens it) and assists in the ankle's dorsal flexion. The hallux (plural, hallucis) are muscles pertaining to the big toe. The extensor hallucis longus are muscles used in extending the toe; the flexor hallucis longus are used in flexing it and moving it to the side.
Gluteus Minimus Muscle
The gluteus minimus muscle lies beneath the gluteus medius and is its companion in attachments and functions. Its fibers extend from the ilium to the femur, and they function to move the thigh out and rotate it medially. Both muscles lie beneath the superficial and largest of the posterior thigh muscles, the gluteus maximus.
Gracilis Muscle
The gracilis muscle is a long, strap-like muscle that passes from the pubic bone to the tibia in the lower leg. It functions to adduct the thigh and to flex and rotate the leg medially at the knee.
External Abdominal Oblique Muscle
The external abdominal obliques are a pair of broad, thin, superficial muscles that lie on the lateral sides of the abdominal region of the body. Contraction of these muscles may result in several different actions, but they are best known for their lateral flexion and rotation of the trunk known as a side bend. The external obliques get their name from their position in the abdomen external to the internal abdominal obliques and from the direction of their fibers, which run obliquely (diagonally) across the sides of the abdomen. The external abdominal obliques have their origins along the lateral ribs 5 through 12 and insert into the linea alba of the abdomen, the pubis, and the iliac crest of the hip bones. Their shape is roughly rectangular with the long axis running anterior to posterior along the linea alba. Muscle fibers in the external obliques run medially and inferiorly from the origins to the insertions across the lateral sides of the abdomen and end just lateral to the rectus abdominis muscles. The location and structure of the external abdominal obliques gives them many different possible actions. Contraction of both external obliques together results in the compression of the abdomen (as in sucking in the gut) or the flexion of the trunk (as in performing a crunch or sit-up). Contraction of one of the abdominal obliques results in the lateral flexion and rotation of the trunk on the opposite side; in other words, the left external oblique rotates and flexes the trunk to the right.
Flexor Digiti Minimi Brevis Muscle of Foot
The flexor digiti minimi brevis muscle of the foot is a short muscle on the plantar surface of the foot, running beneath the smallest toe and serving to flex it. A flexor muscle is one that decreases the angle between two bones, as in bending the arm at the elbow.
Flexor Digitorum Brevis Muscle
The flexor digitorum brevis muscle is a relatively large short muscle of the foot, running on its plantar side from the medial aspect of the calcaneous' tuberosity to each of the lesser toes. Generally, a flexor muscle is one that decreases the angle between two bones, as in raising the leg toward the stomach when kicking a football.
Flexor Digitorum Longus Muscle
The flexor digitorum longus muscle extends from the back surface of the tibia to the foot. Its tendon passes along the plantar surface of the foot. There, it divides into four parts that attach to the terminal bones of the four small toes. It assists in plantar flexion of the foot, flexion of the four small toes, and inversion of the foot.
Flexor Digitorum Longus Tendon
The flexor digitorum longus tendon serves the flexor digitorum longus muscle, which extends from the back surface of the tibia to the foot. Its tendon passes along the plantar surface of the foot. There, it divides into four parts that attach to the terminal bones of the four small toes. It assists in plantar flexion of the foot, flexion of the four small toes, and inversion of the foot.
Flexor Hallucis Brevis Muscle
The flexor hallucis brevis muscle can be found in the sole of the foot. It comes from under the cuboid bone's medial portion, the tibialis posterior tendon's prolongation, and the third cuneiform's contiguous part. It has two heads that insert on the lateral and medial sides at the base of the big toe's first phalanx. The flexor hallucis brevis muscle helps with bending down the big toe.
Flexor Hallucis Longus Muscle
The flexor hallucis longus muscle is one of the hallux (plural, hallucis) muscles pertaining to the big toe. It is used in flexing the big toe and moving it to the side. The extensor hallucis longus are muscles used in extending the toe.
Flexor Hallucis Longus Tendon
The flexor hallucis longus tendon attaches the muscle of the flexor hallucis longus to the big toe's terminal phalanx. The flexor hallucis longus muscle is one of the hallux (plural, hallucis) muscles. It is used in flexing the largest, or big, toe and moving it to the side.
Flexor Retinaculum of Foot
The flexor retinaculum of the foot runs (posteriorly, on the inside) between the medial malleolus (network of nerve tissues and muscle around the ankle) and the calcaneus (Achilles tendon) and forms sheaths for tendons passing beneath the foot. There is a corresponding flexor retinaculum in the wrist and palm of the hand.
Lumbrical Muscles of Foot
The four lumbrical muscles of the foot are small skeletal muscles on the foot's plantar surface, extending the lateral toes from the interphalangeal joints and flexing them from the metatarsophalangeal joints. Numbered one through four from the medial side outward, the first and most medial of the lumbrical muscles is somewhat distinct from the other three more lateral muscles, being served by different nerves and arteries among other distinctions. Innervated by the medial plantar nerve (on the most medial of the lumbrical foot muscles) and lateral plantar nerve branches of the tibial nerve, the lumbrical muscles help articulate and curl the lesser toes. They receive their blood supply from the medial and lateral plantar arteries. The lumbricals serve as accessory muscles to the flexor digitorum longus, which runs across the sole of the foot and the medial (tibial) side of the heel. The origin of the first lumbrical muscle is a single head on the medial side of the flexor digitorum longus, while the other three lumbricals each arise from two heads between their respective tendons. All four lumbrical muscles pass along the medial sides of their respective toes to insert into extensor tendons of the extensor digitorum longus on the front of the foot at the proximal phalanges.
Gastrocnemius Muscle (Medial Head)
The gastrocnemius muscle is the most superficial and prominent of the calf muscles. It is made of two muscular regions, the medial head and lateral head, which attach to the medial and lateral sides of the femur. The heads of the gastrocnemius muscle work together to plantarflex the foot at the ankle and to flex the leg at the knee.
Gluteus Maximus Muscle
The gluteus maximus muscle is the strongest muscle in the body and covers a large part of the buttock. It connects the ilium, sacrum, and coccyx to the femur by tissues of the thigh and acts to extend the thigh. The gluteus maximus causes the leg to straighten at the hip when a person walks, runs, or climbs. It is also used to raise the body from a sitting position. It partly covers the gluteus medius muscle, which lies over-top of the gluteus minimus.
Gluteus Medius Muscle
The gluteus medius muscle is partly covered by the gluteus maximus. Its fibers extend from the ilium to the femur, and they function to move the thigh out and rotate it medially. The gluteus minimus lies beneath the gluteus medius and is its companion in attachments and functions.
Iliopsoas Muscle
The iliacus and psoas major muscles of the hip are so closely related in structure and function that they are often referred to as a single muscle, the iliopsoas. While each muscle has its own origin — the iliacus arises from the ilium and the psoas major arises from the lumbar vertebrae — both muscles merge at their midpoint to form a common insertion at the lesser trochanter of the femur. Working together, the muscles of the iliopsoas are the most powerful flexors of the thigh at the hip joint. Flexion of the hip by the iliopsoas is an essential part of many complex motions such as walking and running. The iliopsoas of both legs can also work together to flex the trunk at the hip when other muscles hold the legs steady, as in sitting up from a supine (lying-down) position. The iliopsoas muscles also have the ability to laterally rotate the thigh at the hip. This rotation results in the leg and foot moving so that the patella, or kneecap, points away from the opposite leg.
Iliacus Muscle
The iliacus muscle works with the psoas major as a powerful flexor of the thigh at the hip joint. It joins the psoas in a number of other actions as the iliopsoas. The iliopsoas muscle is frequently regarded as a single muscle, because it is a blending of two muscles, the psoas major and the iliacus.
Iliotibial Tract
The iliotibial tract, also known as the iliotibial band, is a thick strip of connective tissue connecting several muscles in the lateral thigh. It plays an important role in the movement of the thigh by connecting hip muscles to the tibia of the lower leg. Located on the lateral edge of the fascia lata, the iliotibial tract forms a wide sheath of fibrous connective tissue that surrounds the lateral thigh. It arises at its proximal end from the tendons of the tensor fasciae latae and gluteus maximus muscles. From its origin, the iliotibial tract travels along the lateral side of the thigh and across the knee joint, inserting on the lateral epicondyle of the tibia. The iliotibial tract is classified as a deep fascia of the body, surrounding and connecting the muscles of the body to surrounding tissues. Like all other deep fascia, it is made almost exclusively of dense regular connective tissue. Dense regular connective tissue is a form of fibrous connective tissue that is extremely strong, tough, and avascular. It is made almost exclusively of collagen fibers and fibroblast cells, which produce collagen. Collagen is the strongest protein found in nature and is one of the strongest structures in the entire human body. The collagen fibers are arranged in a regular pattern of straight lines, giving the iliotibial tract incredible strength in the direction in which muscle force is applied to it and considerably less strength in other directions. A small number of elastin protein fibers are also found intermingled with the collagen fibers to permit a degree of elasticity in the tissue. Functionally, the iliotibial tract extends the tensor fascia latae muscle into the lower thigh and leg, allowing it to function as an abductor, medial rotator and flexor of the thigh. It also allows the tensor fascia latae and gluteus maximus muscles to support the extension of the knee while standing, walking, running and biking. A common injury to the iliotibial tract is iliotibial band syndrome (ITBS), a condition caused by the friction of the tract moving across the tissues on the lateral side of the thigh. When the knee flexes, the iliotibial band moves posteriorly over the bony ridge of the lateral condyle of the femur. It then passes over the lateral condyle again when it moves anteriorly during knee extension. The repeated flexion and extension involved in long distance running results in the iliotibial band becoming inflamed, irritated and painful. Fortunately, this condition is easily treated with rest, ice, compression and elevation (RICE).
Inferior Extensor Retinaculum
The inferior extensor retinaculum is a sheet of connective tissue that crosses over the front of the ankle in a Y-shape from the outside of the foot toward the arch. The tissue formations in various regions of the ankle are thickened to form such retinacula in sheaths to hold tendons down as they are crossing the front of the ankle.
Inferior Gemellus Muscle
The inferior gemellus muscle arises from the ischial tuberosity and inserts on the medial surface of the greater trochanter of the femur and rotates the thigh outward.
Inguinal Ligament
The inguinal ligament is an important connective tissue structure in the inguinal, or groin, region of the human body. It supports soft tissues in the groin as well as the external abdominal oblique muscle. The inguinal ligament is a narrow band of dense regular fibrous connective tissue in the pelvic region of the body. Its collagen fibers arise from the inferior aponeurosis of the external abdominal oblique and run obliquely across the pelvis. On its superior and lateral end it connects to the anterior iliac spine of the ilium and extends to the pubic tubercle of the pubis bone on its inferior and medial end. The inguinal ligament supports the muscles that run inferior to its fibers, including the iliopsoas and pectineus muscles of the hip. It also supports the nerves and blood vessels of the leg as they pass through the groin, including the femoral artery, femoral vein, and femoral nerve. The support provided by the inguinal ligament is important to maintaining the flexibility of the hip region while allowing vital blood and nerve supply to the leg. A small opening in the muscles and connective tissues of the abdomen — known as the superficial inguinal ring — is located just superior to the inguinal ligament. This opening forms part of the inguinal canal, which permits the spermatic cord in males and the round ligament of the uterus in females to exit the abdominopelvic cavity and pass through the external tissues of the pelvis. The inguinal ligament forms the floor of the inguinal canal and supports the passage of structures through the canal. Inguinal hernias are a complication of the anatomical arrangement of the inguinal canal, especially in males. The spermatic cord requires that the inguinal canal remain open to permit the passage of blood vessels, nerves, and the ductus deferens into the scrotum. Under strenuous contraction of the abdominal muscles, the pressure on the organs of the abdominopelvic cavity can become so great that a segment of the small intestine can be forced through the inguinal canal, resulting in an inguinal hernia. Surgery for this condition may include the grafting of reinforcing mesh material to the inguinal ligament to prevent further herniation.
Internal Abdominal Oblique Muscle
The internal abdominal oblique muscle lies on the sides and front of the abdomen and is the intermediate of the three flat muscles in this area, below the external oblique and above the transverse abdominal muscle. It is broad, thin and irregularly four-sided and occupies the lateral walls of the abdomen, stretching across to the front. Both sides, acting together, flex the vertebral column by drawing the pubis toward the xiphoid process (the smallest of the three parts of the breastbone). One side also bends the vertebral column sideways and rotates it, bringing the shoulder of that side forward. The external abdominal oblique muscle is also irregularly four-sided in form and lies superficial to the internal oblique muscle. Both sides, acting together, flex the vertebral column, drawing cartilage down toward the pubis. One side acts alone bending the vertebral column sideways, rotating it to bring the shoulder of the opposite side forward. Both of the abdominal oblique muscles work to compress abdominal contents, assist in the digestive process and in forced expiration.
Gastrocnemius Muscle (Lateral Head)
The lateral head of the gastrocnemius muscle, together with the medial head, makes up the gastrocnemius muscle that forms part of the calf. It comes from two immovable ends (or heads) located on the femur, one on the side (lateral) and one toward the center (medial). The far end of this muscle joins the strong Achilles tendon, which descends to the heel and attaches to the calcaneus. The gastrocnemius is a powerful plantar flexor of the foot, that aids in pushing the body forward when a person walks or runs. It also works to flex the leg at the knee.
Biceps Femoris Muscle (Short Head)
The short head of biceps femoris muscle originates from a ridge at the middle of the femur to cross the knee and insert on the tibia and fibula. As the name implies, the biceps femoris has two heads, or immovable ends, one attached to the ischium (bone in the pelvis) and the other attached to the femur (thigh bone). The muscle passes along the back of the thigh on the lateral side and connects close to the midline ends of the fibula and tibia (bones in the lower leg). The biceps femoris is one of the hamstring muscles, and its tendon (hamstring) can be felt as a ridge behind the knee. This muscle functions to flex and rotate the leg laterally and to extend the thigh.
Latissimus Dorsi Muscle
The latissimus dorsi muscle, whose name means "broadest muscle of the back," is one of the widest muscles in the human body. Also known as the "lat," it is a very thin triangular muscle that is not used strenuously in common daily activities but is an important muscle in many exercises such as pull-ups, chin-ups, lat pulldowns, and swimming. The latissimus dorsi muscle has its origins along the lumbodorsal fascia of the lower back, arising from the inferior thoracic and lumbar vertebrae, sacrum, iliac crest, and the four most inferior ribs. From its many widespread origins, it runs obliquely, superiorly and laterally through the back and armpits to insert on the posterior side of the humerus of the upper arm. As the latissimus dorsi approaches its insertion point, the many muscular fibers from its many origins merge to a point, giving the muscle a triangular shape. The latissimus dorsi has several different functions, all of which involve movements of the arm. The primary function of the lat is the adduction of the arm, which is often used when performing a pull-up or chin-up or when pulling a heavy object down from a shelf above one's head. Another function of the lat is extension of the arm, as in swinging the arm toward the back. This motion is used when swinging the arms while walking as well as during rowing exercises. Finally, the latissimus dorsi medially rotates the arm, moving the front of the arm towards the body's midline. When performed with a bent elbow, medial rotation of the arm brings the hand towards the chest, like when folding the arms or touching the elbow on the opposite arm.
Biceps Femoris Muscle (Long Head)
The long head of biceps femoris muscle originates from the lower end of the ischium to cross the front of the knee and insert on the tibia and fibula. As the name implies, the biceps femoris has two heads, or immovable ends, one attached to the ischium (bone in the pelvis) and the other attached to the femur (thigh bone). The muscle passes along the back of the thigh on the lateral side and connects close to the midline ends of the fibula and tibia (bones in the lower leg). The biceps femoris is one of the hamstring muscles, and its tendon (hamstring) can be felt as a ridge behind the knee. This muscle functions to flex and rotate the leg laterally and to extend the thigh.
Long Plantar Ligament
The long plantar ligament is in the sole of the foot. The plantar calcaneonavicular ligament joins the navicular bone in the ankle to the calcaneus, or heel bone; the plantar cuboideonavicular ligament joins the navicular bone to the cuboid bone of the ankle. The plantar metatarsal ligaments bind the instep across the sole of the foot.
Oblique Popliteal Ligament
The oblique popliteal ligament connects the lateral condyle of the femur (thighbone) to the margin of the head of the tibia at the knee.
Pectineus Muscle
The pectineus muscle is a flat, quadrangular muscle, situated at the front part of the upper and middle part of the thigh. It arises from the pectin pubis (called the pectineal line) and, to some extent, from the surface of the bone just in front of it. Some fibers also come from the tissue covering the front surface of the muscle itself. The pectineus muscle flexes and moves the thigh toward the body and rotates it toward the center.
Peroneus Brevis Muscle
The peroneus brevis muscle (sometimes called the fibularis brevis muscle) originates from the mid-portion of the shaft of the fibula and inserts on the base of the #5 metatarsal bone. It extends and abducts the foot.
Peroneus Longus Muscle
The peroneus longus muscle, whose name means "long muscle of the fibula" is a major muscle of the lower leg that plantar flexes and everts the foot at the ankle. Also known as the fibularis longus, it is the longest muscle that attaches to the fibula and is used specifically when balancing one's weight on one foot. The peroneus longus muscle has its origin along the lateral edge of the head and proximal shaft of the fibula, just below the styloid process of the fibula. From its origin, it descends along the lateral edge of the leg as a thin strap of muscle in the lateral compartment of the leg. About halfway between the knee and ankle, it tapers to a point and begins to form a long tendon. The tendon of the peroneus longus passes through the ankle posterior to the lateral malleolus and wraps around the sole of the foot. It forms its insertion at the first metatarsal and first (medial) cuneiform bones on the medial edge of the foot. The peroneus longus performs two major functions in the leg by plantar flexing and everting the foot. Working as a plantar flexor, the peroneus longus assists the much larger gastrocnemius and soleus muscles in pointing the toes, allowing the body to stand on its tiptoes. The peroneus longus may also evert the foot by pulling the sole laterally toward the lateral malleolus. Eversion of the foot is an important part of standing on one foot, centering the body's weight over the planted foot. The contraction of the peroneus longus muscle also helps to support the transverse arch of the foot by holding the tarsal bones and metatarsal bones in the correct anatomical position. The word peroneus comes from the Greek word for "clasp," while the word fibula is the Latin translation of the same word. These words refer to how the fibula attaches on both ends to the much thicker tibia like a thin clasp pin connects to the back of a button or brooch.
Peroneus Longus Tendon
The peroneus longus tendon is a stout band of connective tissue that passes behind the lateral malleolus (network of nerves and muscles around the ankle) to insert the peroneus longus muscle at the foot. The peroneus longus muscle is the evertor muscle, meaning to turn the sole of the foot outward. It is a long, strap-like muscle located on the outside of the lower leg. It connects the tibia and the fibula (the lower leg bones) to the foot. It functions in eversion of the foot, assists in plantar flexion (moving it downward), and helps support the arch of the foot.
Peroneus Tertius Muscle
The peroneus tertius muscle may be called the fifth tendon and is part of the extensor digitorum longus. From the lower third of the fibula's anterior surface, at the interosseous membrane's lower portion and from an intermuscular septum amid the peroneus brevis and it, come the fibers that belong to this tendon. The tendon enters the dorsal surface of the base of the little toe's metatarsal bone after it goes under the transverse and cruciate crural ligaments in the canal that also includes the extensor digitorum longus. The deep fibular nerve activates the peroneus tertius muscle. This is not the case for the other peroneal muscles. The superficial fibular nerve activates them. This is because the peroneus tertius is part of the anterior compartment. The peroneus tertius muscle functions to flip the foot at the ankle joint and has weak dorsiflexion of the ankle joint.
Piriformis Muscle
The piriformis muscle, whose name means "pear-shaped," is a deep muscle of the gluteal region. It is the most superior muscle in a group of six muscles that work together to rotate the thigh laterally at the hip joint and to abduct the thigh as well. The piriformis muscle, whose name means "pear-shaped," is a deep muscle of the gluteal region. It is the most superior muscle in a group of six muscles that work together to rotate the thigh laterally at the hip joint and to abduct the thigh as well. The piriformis muscle is found in the gluteal region deep to the gluteus maximus and inferior to the gluteus minimus. Its origins are spread along the anterior region of the sacrum. From the sacrum it extends laterally, passing through the greater sciatic foramen and crossing the hip joint. As the piriformis muscle approaches its insertion on the greater trochanter of the femur, it gradually tapers to a point, giving it a pear-like shape. Working together with the superior gemellus, inferior gemellus, obturator internus, obturator externus, and quadratus femoris muscles, the piriformis acts as an external rotator of the thigh. It achieves this action by pulling the greater trochanter posteriorly, turning the thigh so that the knee and anterior thigh point away from the opposite leg. These muscles also act as abductors of the thigh by pulling the greater trochanter closer to the body's midline and consequently moving the distal portion of the thigh away from the midline.
Plantar Aponeurosis
The plantar aponeurosis, also called the plantar fascia, is a dense layer of deep fascia on the sole of the foot. It is made up of fibrous connective tissue bands that stretch toward the bottom of the toes. It comes from the tuber calcanei's medial process. The plantar aponeurosis maintains the foot's medial longitudinal arch.
Plantaris Muscle
The plantaris muscle is a weak flexor of the leg at the knee joint and a plantar flexor of the foot at the ankle joint. It is a rudimentary muscle, which is sometimes compared to the one in the forearm (see palmaris longus).
Plantaris Tendon
The plantaris tendon inserts the plantaris muscle at the calcaneus' posterior surface. This plantaris muscle is a weak flexor of the leg at the knee joint and a plantar flexor of the foot at the ankle joint. It is a rudimentary muscle, which is sometimes compared to the one in the forearm (see palmaris longus).
Popliteus Muscle
The popliteus muscle arises from femur and inserts on the tibia posteriorly to flex the leg and rotate it inward.
Quadratus Plantae Muscle
The quadratus plantae muscle helps flex the small toes since it corrects the flexor tendon's oblique vector when it crosses the foot's plantar surface. This, unlike many of the other muscles in the foot, doesn't have a homolog in the hand. It comes from two heads. The larger (or medial) head is muscular and attaches to the calcaneus' medial concave surface. The other, lateral head is tendinous and flat. It stems from the calcaneus' inferior surface on the lateral border, ahead of its tuberosity's lateral process and from the long plantar ligament. These two parts come together and terminate in a flat band. This band inserts into the lateral margin and beneath the flexor digitorum longus tendon's surfaces. Here a groove is created and the tendon fits into it. The flexor digitorum longus tendons receive slips from it that go along to the second, third and fourth toes.
Quadriceps Femoris Tendon
The quadriceps femoris tendon connects the four muscles of the quadriceps femoris muscle to the ilium and femur. This includes a common patellar tendon, which passes over the front of the knee and attaches to the patella (knee cap). This tendon then continues as the patellar ligament to the tibia (lower leg bone).
Rectus Femoris Muscle
The rectus femoris muscle is one part of the large, fleshy group of leg muscles called the quadriceps femoris. This muscle grouping occupies the front and sides of the thigh and is primary extensor of the knee. It is composed of four parts - rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius. These parts connect the ilium and femur to a common patellar tendon, which passes over the front of the knee and attaches to the patella (knee cap). This tendon then continues as the patellar ligament to the tibia (lower leg bone).
Sartorius Muscle
The sartorius muscle is the longest muscle in the entire human body. It is a long, thin, band-like muscle found in the anterior region of the thigh. The sartorius functions as an important flexor and rotator of the thigh at the hip joint. The sartorius muscle arises from the anterior superior iliac spine on the lateral edge of the hip bone. From the lateral hip, it descends obliquely across the hip joint and thigh, running medially and inferiorly toward the medial edge of the knee. At the knee, the sartorius turns more laterally as it descends to insert on the medial side of the tibia in the lower leg. The sartorius muscle is so long that it crosses and acts upon both the hip and knee joints. Acting on the hip joint, the sartorius works as a flexor, abductor, and lateral rotator of the thigh with the assistance of the other major muscles of the hip. At the knee joint the sartorius helps to flex the leg. Combining all of these functions into one movement, the sartorius pulls the foot and ankle toward knee of the opposite leg. The action of the sartorius is used in many situations, such as crossing the legs so that the ankle rests on the knee of the opposite leg; sitting cross-legged; or looking at the sole of one's foot. In fact, the name sartorius (from the Latin word for "tailor") and its nickname, the "tailor's muscle," are derived from the common motion of tailors crossing their legs to sit while working.
Semimembranosus Muscle
The semimembranosus muscle is the third hamstring muscle and is the most inner-located muscle in the back of the thigh. It connects the ischium to the tibia and functions to flex and rotate the leg medially and to extend the thigh.
Semitendinosus Muscle
The semitendinosus muscle is another of the hamstring muscles. It is a long, band-like muscle on the back of the thigh toward the inside, connecting the ischium to the proximal end of the tibia. It is so named because it becomes tendinous in the middle of the thigh, continuing to its movable end as a long, cord-like tendon. It functions to flex and rotate the leg medially and to extend the thigh.
Soleus Muscle
The soleus muscle is a thick, flat muscle located beneath the gastrocnemius. These two muscles make up the calf of the leg. The soleus rises from the tibia and fibula, and it extends to the heel by way of the Achilles tendon. It acts with the gastrocnemius to cause plantar flexion of the foot.
Superior Extensor Retinaculum
The superior extensor retinaculum is a sheet of connective tissue that crosses over the front of the shin above the ankle, attached to both the tibia and fibula. The tissue formations in various regions of the ankle are thickened to form such retinacula in sheaths to hold tendons down as they are crossing the front of the ankle.
Superior Gemellus Muscle
The superior gemellus muscle arises from the ischial tuberosity and inserts on the greater trochanter. It rotates the thigh outward.
Tibialis Anterior Muscle
The tibialis anterior muscle is a long, narrow muscle in the anterior compartment of the lower leg. Arising from origins along the lateral condyle and proximal body of the tibia, it runs down the shin just lateral to the tibia. Just above the ankle, the muscular body of the tibialis anterior ends and its long tendon extends across the medial side of the ankle and into the foot. In the foot, the tendon forms insertions on the first metatarsal and first cuneiform bones. The tibialis anterior functions as a dorsiflexor of the foot by pulling the top, or dorsum, of the foot towards the shin. Dorsiflexion results in the lifting of the toes off the ground, which is an important motion during walking and running to prevent tripping over one's toes. The tibialis anterior also provides a slight inversion of the foot by pulling the plantar surface of the foot toward the body's midline. This motion is important in balancing the body's weight on the foot during locomotion or standing, and is especially important when standing on one foot.
Tibialis Posterior Muscle
The tibialis posterior muscle is one of the dorsal flexor muscles of the foot and ankle. It helps stabilize the foot while walking.
Vastus Intermedius Muscle
The vastus intermedius muscle is one part of the large, fleshy group called the quadriceps femoris, which occupies the front and sides of the thigh and is primary extensor of the knee. It is composed of four parts - rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius. These parts connect the ilium and femur to a common patellar tendon, which passes over the front of the knee and attaches to the patella (knee cap). This tendon then continues as the patellar ligament to the tibia (lower leg bone).
Vastus Lateralis Muscle
The vastus lateralis muscle is the largest of the four muscles that make up the quadriceps femoris group. Like the other muscles in the quadriceps group, is an extensor of the leg at the knee. Its name means "huge lateral" due to its enormous size and location on the lateral side of the thigh.
Vastus Medialis Muscle
The vastus medialis muscle is one of the quadriceps femoris muscle's four muscle divisions. It occupies the sides and front of the thigh and its function is being the primary extensor of the knee.
