Hamstring
Encyclopedia
In human anatomy
, the hamstring refers to any one of the three posterior thigh muscles, or to the tendon
s 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 semimembranosus and the biceps femoris. In quadruped
s, it refers to the single large tendon found behind the knee or comparable area.
As shown in the diagram, the human hamstring occupies the posterior of the body of the femur
.
. String refers to tendons, and thus, the hamstrings are the string-like tendons felt on either side of the back of the knee.
Another commonly accepted origin is that legs of ham used to be hung by a hook through the space between the thighbone and the tendons behind the knee. Ham/pork used to be more common in England than beef and lamb.
The three muscles of the posterior thigh
(semitendinosus, semimembranosus, biceps femoris long & short head) flex
(bend) the knee, while all but the short head of biceps femoris extend
(straighten) the hip. The three 'true' hamstrings cross both the hip and the knee joint and are therefore involved in knee flexion and hip extension. The short head of the biceps femoris crosses only one joint (knee) and is therefore not involved in hip extension. With its divergent origin and innervation it is sometimes excluded from the 'hamstring' characterization.
A portion of the adductor magnus is sometimes considered a part of the hamstrings.
.
Semitendinosus and semimembranosus extend the hip when the trunk is fixed; they also flex the knee and medially (inwardly) rotate the lower leg when the knee is bent.
The long head of the biceps femoris extends the hip as when beginning to walk; both short and long heads flex the knee and laterally (outwardly) rotates the lower leg when the knee is bent.
The hamstrings play a crucial role in many daily activities, such as, walking, running, jumping, and controlling some movement in the trunk. In walking, they are most important as an antagonist
to the quadriceps in the deceleration of knee extension.
and/or MRI. The biceps femoris is most commonly injured, followed by semitendinosus. Semimembranosus injury is rare. Imaging is useful in differentiating the grade of strain, especially if the muscle is completely torn. In this setting, the level and degree of retraction can be determined, serving as a useful roadmap prior to any surgery. Those with a hamstring strain of greater than 60mm in length have a greater risk of recurrence.
ACL reconstruction
. In this procedure, a piece of it is used to replace the anterior cruciate ligament
(ACL). The ACL is one of the four major ligaments in the knee.
, the hamstrings are trained with movements like the knee curl
and Romanian deadlift, as well as a part of several other lower body exercises.
Hamstring plays an essential role in characterizing body flexibility
, which is assessed by performing a sit and reach test.
Human anatomy
Human anatomy is primarily the scientific study of the morphology of the human body. Anatomy is subdivided into gross anatomy and microscopic anatomy. Gross anatomy is the study of anatomical structures that can be seen by the naked eye...
, the hamstring refers to any one of the three posterior thigh muscles, or to the tendon
Tendon
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...
s 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 semimembranosus and the biceps femoris. In quadruped
Quadruped
Quadrupedalism is a form of land animal locomotion using four limbs or legs. An animal or machine that usually moves in a quadrupedal manner is known as a quadruped, meaning "four feet"...
s, it refers to the single large tendon found behind the knee or comparable area.
As shown in the diagram, the human hamstring occupies the posterior of the body of the femur
Femur
The femur , or thigh bone, is the most proximal bone of the leg in tetrapod vertebrates capable of walking or jumping, such as most land mammals, birds, many reptiles such as lizards, and amphibians such as frogs. In vertebrates with four legs such as dogs and horses, the femur is found only in...
.
Etymology
The word ham originally referred to the fat and muscle behind the kneeKnee
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...
. String refers to tendons, and thus, the hamstrings are the string-like tendons felt on either side of the back of the knee.
Another commonly accepted origin is that legs of ham used to be hung by a hook through the space between the thighbone and the tendons behind the knee. Ham/pork used to be more common in England than beef and lamb.
The three muscles of the posterior 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...
(semitendinosus, semimembranosus, biceps femoris long & short head) 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, while all but the short head of biceps femoris extend
Extension (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. The three 'true' hamstrings cross both the hip and the knee joint and are therefore involved in knee flexion and hip extension. The short head of the biceps femoris crosses only one joint (knee) and is therefore not involved in hip extension. With its divergent origin and innervation it is sometimes excluded from the 'hamstring' characterization.
| Muscle | Origin | Insertion | Nerve >- | semitendinosus |
ischial tuberosity | medial surface of tibia Tibia The tibia , shinbone, or shankbone is the larger and stronger of the two bones in the leg below the knee in vertebrates , and connects the knee with the ankle bones.... |
tibial Tibial nerve The tibial nerve is a branch of the sciatic nerve. The tibial nerve passes through the popliteal fossa to pass below the arch of soleus.In the popliteal fossa the nerve gives off branches to gastrocnemius, popliteus, soleus and plantaris muscles, an articular branch to the knee joint, and a... >- | semimembranosus |
ischial tuberosity | medial tibial condyle | tibial Tibial nerve The tibial nerve is a branch of the sciatic nerve. The tibial nerve passes through the popliteal fossa to pass below the arch of soleus.In the popliteal fossa the nerve gives off branches to gastrocnemius, popliteus, soleus and plantaris muscles, an articular branch to the knee joint, and a... >- | biceps femoris - long head |
ischial tuberosity | lateral side of the head of the fibula | tibial Tibial nerve The tibial nerve is a branch of the sciatic nerve. The tibial nerve passes through the popliteal fossa to pass below the arch of soleus.In the popliteal fossa the nerve gives off branches to gastrocnemius, popliteus, soleus and plantaris muscles, an articular branch to the knee joint, and a... >- | biceps femoris - short head |
linea aspera Linea aspera The linea aspera is a ridge of roughened surface on the posterior aspect of the femur, to which are attached muscles and intermuscular septum.Its margins diverge above and below.... and lateral supracondylar line of femur |
lateral side of the head of the fibula (common tendon with the long head) | common fibular Common fibular nerve The common fibular nerve , about one-half the size of the tibial nerve, is derived from the dorsal branches of the fourth and fifth lumbar and the first and second sacral nerves.It descends obliquely along the lateral side of the popliteal fossa to the head of the fibula,... |
A portion of the adductor magnus is sometimes considered a part of the hamstrings.
Functions
The hamstrings cross and act upon two joints - the hip and the kneeKnee
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...
.
Semitendinosus and semimembranosus extend the hip when the trunk is fixed; they also flex the knee and medially (inwardly) rotate the lower leg when the knee is bent.
The long head of the biceps femoris extends the hip as when beginning to walk; both short and long heads flex the knee and laterally (outwardly) rotates the lower leg when the knee is bent.
The hamstrings play a crucial role in many daily activities, such as, walking, running, jumping, and controlling some movement in the trunk. In walking, they are most important as an antagonist
Antagonist (muscle)
Most muscles work in pairs, and when a muscle works it needs to have an agonist and an antagonist, unless the muscle's natural state is opposite to that which is produced by the muscle, example Sphincter ani externus muscle....
to the quadriceps in the deceleration of knee extension.
Imaging
Imaging the hamstring muscles is usually performed with an ultrasoundUltrasound
Ultrasound is cyclic sound pressure with a frequency greater than the upper limit of human hearing. Ultrasound is thus not separated from "normal" sound based on differences in physical properties, only the fact that humans cannot hear it. Although this limit varies from person to person, it is...
and/or MRI. The biceps femoris is most commonly injured, followed by semitendinosus. Semimembranosus injury is rare. Imaging is useful in differentiating the grade of strain, especially if the muscle is completely torn. In this setting, the level and degree of retraction can be determined, serving as a useful roadmap prior to any surgery. Those with a hamstring strain of greater than 60mm in length have a greater risk of recurrence.
Use in surgery
The distal semitendinosus tendon is one of the tendons that can be used in the surgical procedureSurgery
Surgery is an ancient medical specialty that uses operative manual and instrumental techniques on a patient to investigate and/or treat a pathological condition such as disease or injury, or to help improve bodily function or appearance.An act of performing surgery may be called a surgical...
ACL reconstruction
Anterior cruciate ligament reconstruction
Anterior cruciate ligament reconstruction is a surgical tissue graft replacement of the anterior cruciate ligament, located in the knee, to restore its function after anterior cruciate ligament injury. The torn ligament is removed from the knee before the graft is inserted through a hole created...
. In this procedure, a piece of it is used to replace the anterior cruciate ligament
Anterior cruciate ligament
The anterior cruciate ligament is a cruciate ligament which is one of the four major ligaments of the human knee. In the quadruped stifle , based on its anatomical position, it is referred to as the cranial cruciate ligament.The ACL originates from deep within the notch of the distal femur...
(ACL). The ACL is one of the four major ligaments in the knee.
Training
In strength trainingStrength training
Strength training is the use of resistance to muscular contraction to build the strength, anaerobic endurance, and size of skeletal muscles. There are many different methods of strength training, the most common being the use of gravity or elastic/hydraulic forces to oppose muscle contraction...
, the hamstrings are trained with movements like the knee curl
Leg curl
The Leg curl is an isolation exercise that targets the hamstring muscles. The exercise involves flexing the lower leg against resistance towards the buttocks....
and Romanian deadlift, as well as a part of several other lower body exercises.
Hamstring plays an essential role in characterizing body flexibility
Flexibility (anatomy)
Flexibility or limberness refers to the absolute range of movement in a joint or series of joints, and length in muscles that cross the joints. Flexibility is variable between individuals, particularly in terms of differences in muscle length of multi-joint muscles...
, which is assessed by performing a sit and reach test.
External links
- Illustration at ucla.edu
- MRI Images demonstrating avulsion fracture of the hamstring muscle origin
- Flexibility Score. www.flexiscore.com. Site accessed on November 14, 2010.
- Hamstring
