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Biceps femoris muscle (Short head)

The biceps femoris muscle, short head, is the lateral component of the hamstring group, located in the posterior compartment of the thigh. Unlike the long head, it does not cross the hip joint, and thus only acts on the knee. It contributes to knee flexion, lateral rotation of the leg, and stabilization during dynamic movements such as running and squatting. The short head is frequently involved in hamstring injuries, especially in athletes.

Synonyms

  • Short head of biceps femoris

  • Lateral hamstring (short portion)

  • Fibular biceps muscle (short head)

Origin and Insertion

  • Origin: Arises from the lateral lip of the linea aspera and the lateral supracondylar line of the femur

  • Course: Fibers descend obliquely downward and laterally, deep to the long head of the biceps femoris

  • Insertion: Joins the long head tendon and inserts into the head of the fibula (lateral aspect), sharing an attachment with the fibular collateral ligament

Nerve Supply

  • Common fibular (peroneal) division of the sciatic nerve (roots L5–S2)

Arterial Supply

  • Perforating branches of the profunda femoris artery

  • Inferior gluteal artery branches

  • Popliteal artery muscular branches

Venous Drainage

  • Drains into the profunda femoris vein and popliteal vein → femoral vein

Function

  • Flexion of the knee joint

  • Lateral rotation of the leg when the knee is flexed

  • Provides dynamic stability to the posterolateral aspect of the knee

  • Assists in deceleration during running and directional changes

Clinical Significance

  • Common site of injury in athletes (hamstring strain, partial tears)

  • Can be involved in tendinopathy, avulsion injuries, or myotendinous junction tears

  • Plays a role in posterolateral corner injuries of the knee

  • May compress or be affected by pathology of the common fibular nerve near fibular head

MRI Appearance

T1-weighted images:

  • Muscle belly shows low-to-intermediate signal intensity

  • Surrounding fat is bright, aiding definition

  • Chronic fatty infiltration appears as bright signal within fibers

T2-weighted images:

  • Muscle shows low-to-intermediate baseline signal

  • Injury, edema, or inflammation appears as bright hyperintensity, especially near the myotendinous junction

STIR (Short Tau Inversion Recovery):

  • Normal muscle: low-to-intermediate signal

  • Acute injury, strain, or inflammation: bright hyperintensity

T1 Fat-Sat Post-Contrast:

  • Normal muscle: mild homogeneous enhancement

  • Pathology (myositis, tears, tumors): heterogeneous or focal enhancement

  • Abscess or necrosis: rim enhancement with central non-enhancing zone

CT Appearance

Non-Contrast CT:

  • Muscle appears as soft tissue density lateral to the distal femur

  • Muscle injuries (hematoma, rupture) appear as regions of altered density

  • Chronic fatty degeneration: focal low-density areas within muscle belly

Post-Contrast CT:

  • Normal muscle: mild uniform enhancement

  • Pathological changes (inflammation, tumor, infection): heterogeneous or nodular enhancement

  • Abscess: rim enhancement with central low attenuation

MRI image

Biceps Femoris Muscle (Short Head) MRI coronal anatomy image-img-00000-00000

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Biceps Femoris Muscle, Short Head MRI axial anatomy image-img-00000-00000_00001

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Biceps Femoris Muscle, Short Head MRI axial anatomy image-img-00000-00000_00002

MRI image

Biceps Femoris Muscle, Short Head MRI axial anatomy image-img-00000-00000

CT image

Biceps Femoris Muscle (Short Head) ct axial image 1

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Biceps Femoris Muscle (Short Head) ct axial image 2

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Biceps Femoris Muscle (Short Head) ct axial image 3

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Biceps Femoris Muscle (short Head) ct coronal image

MRI image

Biceps femoris (Short head) muscle mri image

MRI image

Biceps femoris (Short head) muscle