Semitendinosus muscle
Encyclopedia
The semitendinosus is a muscle
in the back of the thigh
; it is one of the hamstring
s.
of insertion, is situated at the posterior and medial aspect of the thigh
.
It arises from the lower and medial impression on the tuberosity of the ischium
, by a tendon common to it and the long head of the biceps femoris
; it also arises from an aponeurosis
which connects the adjacent surfaces of the two muscles to the extent of about 7.5 cm. from their origin.
The muscle is fusiform and ends a little below the middle of the thigh in a long round tendon which lies along the medial side of the popliteal fossa
; it then curves around the medial condyle of the tibia and passes over the tibial collateral ligament of the knee-joint
, from which it is separated by a bursa, and is inserted into the upper part of the medial surface of the body of the tibia, nearly as far forward as its anterior crest.
At its insertion it gives off from its lower border a prolongation to the deep fascia of the leg and lies behind the tendon of the sartorius
, and below that of the gracilis
, to which it is united. These three tendons form what is known as the pes anserinus
, so named because it looks like the foot of a goose.
A tendinous intersection is usually observed about the middle of the muscle.
(straighten) the hip joint and flex
(bend) the knee joint
. It also helps medially rotate
the knee.
Muscle
Muscle is a contractile tissue of animals and is derived from the mesodermal layer of embryonic germ cells. Muscle cells contain contractile filaments that move past each other and change the size of the cell. They are classified as skeletal, cardiac, or smooth muscles. Their function is to...
in the back of the thigh
Thigh
In humans the thigh is the area between the pelvis and the knee. Anatomically, it is part of the lower limb.The single bone in the thigh is called the femur...
; it is one of the hamstring
Hamstring
In human anatomy, the hamstring refers to any one of the three posterior thigh muscles, or to the tendons that make up the borders of the space behind the knee. In modern anatomical contexts, however, they usually refer to the posterior thigh muscles, or the tendons of the semitendinosus, the...
s.
Structure
The semitendinosus, remarkable for the great length of its tendonTendon
A tendon is a tough band of fibrous connective tissue that usually connects muscle to bone and is capable of withstanding tension. Tendons are similar to ligaments and fasciae as they are all made of collagen except that ligaments join one bone to another bone, and fasciae connect muscles to other...
of insertion, is situated at the posterior and medial aspect of the thigh
Thigh
In humans the thigh is the area between the pelvis and the knee. Anatomically, it is part of the lower limb.The single bone in the thigh is called the femur...
.
It arises from the lower and medial impression on the tuberosity of the ischium
Tuberosity of the ischium
-External links: - "The Female Perineum: Bones" - "Major Joints of the Lower Extremity: Hip bone "...
, by a tendon common to it and the long head of the biceps femoris
Biceps femoris muscle
The biceps femoris is a muscle of the posterior thigh. As its name implies, it has two parts, one of which forms part of the hamstrings muscle group.-Origin and insertion:It has two heads of origin;...
; it also arises from an aponeurosis
Aponeurosis
Aponeuroses are layers of flat broad tendons. They have a shiny, whitish-silvery color, are histologically similar to tendons, and are very sparingly supplied with blood vessels and nerves. When dissected, aponeuroses are papery, and peel off by sections...
which connects the adjacent surfaces of the two muscles to the extent of about 7.5 cm. from their origin.
The muscle is fusiform and ends a little below the middle of the thigh in a long round tendon which lies along the medial side of the popliteal fossa
Popliteal fossa
The popliteal fossa is a shallow depression located at the back of the knee joint. The bones of the popliteal fossa are the femur and the tibia.-Boundaries:The boundaries of the fossa are:-Roof:...
; it then curves around the medial condyle of the tibia and passes over the tibial collateral ligament of the knee-joint
Knee
The knee joint joins the thigh with the leg and consists of two articulations: one between the fibula and tibia, and one between the femur and patella. It is the largest joint in the human body and is very complicated. The knee is a mobile trocho-ginglymus , which permits flexion and extension as...
, from which it is separated by a bursa, and is inserted into the upper part of the medial surface of the body of the tibia, nearly as far forward as its anterior crest.
At its insertion it gives off from its lower border a prolongation to the deep fascia of the leg and lies behind the tendon of the sartorius
Sartorius muscle
The Sartorius muscle – the longest muscle in the human body – is a long thin muscle that runs down the length of the thigh. Its upper portion forms the lateral border of the femoral triangle.-Origin and insertion:...
, and below that of the gracilis
Gracilis muscle
The gracilis is the most superficial muscle on the medial side of the thigh. It is thin and flattened, broad above, narrow and tapering below.-Origin and insertion:...
, to which it is united. These three tendons form what is known as the pes anserinus
Pes anserinus
Pes anserinus is the anatomic term used to describe two different structures:* Pes anserinus * Pes anserinus...
, so named because it looks like the foot of a goose.
A tendinous intersection is usually observed about the middle of the muscle.
Actions
The semitendinosus helps to extendExtension (kinesiology)
In kinesiology, extension is a movement of a joint that results in increased angle between two bones or body surfaces at a joint. Extension usually results in straightening of the bones or body surfaces involved. For example, extension is produced by extending the flexed elbow. Straightening of...
(straighten) the hip joint and flex
Flexion
In anatomy, flexion is a position that is made possible by the joint angle decreasing. The skeletal and muscular systems work together to move the joint into a "flexed" position. For example the elbow is flexed when the hand is brought closer to the shoulder...
(bend) the knee joint
Knee
The knee joint joins the thigh with the leg and consists of two articulations: one between the fibula and tibia, and one between the femur and patella. It is the largest joint in the human body and is very complicated. The knee is a mobile trocho-ginglymus , which permits flexion and extension as...
. It also helps medially rotate
Internal rotation
In anatomy, internal rotation is rotation towards the center of the body.The muscles of internal rotation include:* of arm/humerus at shoulder** Deltoid muscle** Subscapularis** Teres major** Latissimus dorsi...
the knee.