Thigh Muscles

Biceps Femoris – Functional Anatomy

Overview

Here, you will find the basic anatomy and Physiology of the biceps femoris muscle. The biceps femoris is a two-headed muscle on the lateral thigh. It belongs to the hamstring group.

Biceps femoris with sacrotuberous ligament – posterior view

Origin

  • ischial tuberosity

Insertion

  • fibular head
  • (tibia, femur)

Function

  • flex knee joint
  • extend hip
  • (external rotation at the knee)

Nerve

  • sciatic nerve

Hamstrings – posterior view

Functional Considerations

Involvement in Exercise

There are a multitude of studies about hamstring function, especially related to exercise. This meta-study is particularly extensive.

Knee Balance

This meta-study reviews the anatomy of distal attachments of the biceps femoris. It asserts that the biceps femoris is significant in balancing the knee. My clinical experience indicates the same.

Quadriceps Balance

Many seminars on the clinical treatment of the thigh explore the balance between the quadriceps and hamstrings. Typically, they conclude that when one is overpowering, it creates pain in the antagonist, hip, and low back. Again, my clinical experience supports this.

Hamstrings & Quadratus Lumborum

Low Back Balance

The low back is strongly impacted by hamstring length. Its connection to the base of the pelvis can restrict pelvic rotation, creating stress on the low back. Muscles like the quadratus lumborum, which is known for its pain patterns, are directly torqued through their mutual attachment to the pelvis. Of course, many other muscles, such as multifidi and erector spinae, are impacted.

Biceps femoris highlighted in gold – lateral view

Anomalies, Etc.

Short head

This study reveals notable variations in the short head of the biceps femoris. More specifically, it varies in size, attachment, and absence. Variations are more common in the Korean Population. This study discusses the impact on the lateral peroneal nerve because of variations in the structures for its passage.

Fibular Attachment

Studies on this vary. However, they focus on the attachments to the femur and tibia. This meta-study finds that attachment to the tibia and femur is the norm. Therefore, standard anatomical descriptions of the attachment of the biceps femoris should be revised.

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Tony Preston has a practice in Atlanta, Georgia, where he sees clients. He has written materials and instructed classes since the mid-90s. This includes anatomy, trigger points, cranial, and neuromuscular.

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