Two-headed hamstrings

Synonyms

Latin: Biceps femoris muscle
English: biceps femoris muscle

definition

The biceps thigh muscle got its name due to the fact that it has two separate origins, the lower posterior pelvis and lower thigh. These two "muscle heads" come together in their course and pull towards the outer knee. The muscle belongs to the back thigh muscles, also known as hamstring muscles is called because it comes from the area of ​​the hip joint (lat. ischium) to the lower leg (lat. crus) pulls.
When the muscle contracts, it leads the lower leg towards the thigh / hip and is thus mainly involved in flexing the knee joint.
A special feature of this muscle group is the so-called Lombard paradox. It describes the phenomenon that when the leg is fixed - i.e. when the foot is firmly on the ground - the ischiocrual muscles do not perform their actual function of flexion, but rather an extension in the knee joint supported.

course

Approach: Fibula head (Head fibulae)

Origin: Long head (Caput longum): Ischium (Tuber ischiadicum ossis ischii)

Short head (Caput breve): Roughening of the lower third of the Thighbone (Linea aspera)

Innervation: Long head (Caput longum): Tibial nerve (Segments L5-S2)

Short head (Caput breve): Common fibular nerve (Segments L5-S2)

function

As mentioned, the two-headed thigh muscle belongs to the hamstring muscles on the back of the thigh and is therefore one of the most important Flexors in the Knee joint. Flexion in the knee joint occurs, for example, in a one-legged stance, when the heel is brought to the buttocks. Because the muscle is on the Fibula head, i.e. just below the outer knee, it is the only muscle in the knee joint that can follow rotate outside. The lower leg rotates outwards.
The long head of the muscle can, due to its origin, be at hip joint Support (ischium) also in this movement. He is able to pull the bent leg backwards and stretches thus in the hip joint. He can also turn the leg outwards and therefore counts as a External rotator in the hip joint.

Knee joint: flexion (Flexion) and outward rotation (External rotation)
Hip joint: extension (Extension) and outward rotation (External rotation)

Illustration

common illnesses

The biceps muscles can be damaged from damage to the Sciatic nerve ("Sciatica") may be affected. The two nerves that supply it (N. fibularis communis and N. tibialis) arise from the sciatic nerve. If there is serious damage, the entire ischiocrual musculature on the back of the thigh can fail. Thus, the front thigh muscles of the opponent are missing and painful hyperextension of the knee joint can occur Quadriceps femoris muscle come.
In addition, athletes can experience typical muscle injuries such as overstrain strain, Torn hamstring or more complete Muscle tear come. (Tendon) irritations can also occur.

Strengthening and stretching

In principle, all exercises in which the extension of the leg is intensified and thus the extension group is stretched are suitable for stretching the two-headed thigh muscle. Classically, the athlete tries to achieve this by trying to reach the toes with his fingertips with his legs straight and the back as straight as possible. This stretching exercise is often found to be very uncomfortable and should not be overdone!
The muscles can be strengthened, especially in the gym, on specially designed equipment. All exercises in which the knee joint is bent (if necessary with a counterweight) strengthen the two-headed thigh muscle. (So-called "leg biceps curls")

Synergists:
In the hip joint:
Straightener: Greater and middle gluteal muscle (Mm. Glutei maximus et medius), hemi-tendon muscle (M. semitendinosus), semi-membranous muscle (M. semimembranosus) External rotators: Hip muscle (Mm. Obturatores internus et externus), twin muscle (Mm. Gemelli superior et inferior), quadrangular thigh muscle (M. quadratus femoris), pear muscle (M. piriformis)

In the knee joint:
Flexor: Tailor's muscle (M. sartorius), slender muscle (M. gracilis), half-tendon muscle (M. semitendinosus), two-headed lower leg muscle (M. gastrocnemicus)

Antagonists:
In the hip joint:
Flexor: Iliac lumbar muscle (M. iliopsoas), tailor's muscle (M. sartorius), thigh ligament tensioner (M. tensor fasciae latae), four-headed thigh muscle - straight part (M. rectus femoris) Internal rotators: Gluteus middle and gluteal muscle (Mm. Glutei medius et minimus), thigh ligament tensioner (M. tensor fasciae latae)
In the knee joint:
Extensor: Quadriceps femoris muscle