Biceps Femoris Muscle Anatomy

Overview
Origin Long head: Ischial tuberosity
Short head: Linea aspera and the lateral supracondylar line of the femur
Insertion Long & short head: Lateral head of fibula
Action Long & short head: Knee flexion and lateral rotation of leg
Long head: Hip extension
Nerve Long head: Tibial division of sciatic nerve (L5, S1, S2)
Short head: Common fibular division of sciatic nerve (L5, S1, S2)
Artery Long & short head: Deep femoral artery and perforating arteries
Long head: Perforating branches from profunda femoris artery

Location & Overview

The biceps femoris muscle is one of the three muscles which are a part of the hamstrings muscle group. The other two are: The semimembranosus and semitendinosus. The biceps femoris is a two-part muscle consisting of a long and a short head. The biceps femoris muscle is located in the posterior thigh. The long head crosses the hip and knee joint whereas the short head only crosses the knee joint [1].

biceps femoris muscle anterior view

Here we can see pictured the biceps femoris muscle in isolation from an anterior view.

short head of the biceps femoris muscle

Here we can see pictured only the short head of the biceps femoris muscle. The short head is underneath the long head.

hamstring muscles from a superficial view

Here we can see the hamstring muscles from a superficial view. The biceps femoris is one of the hamstring muscles. The other two are the semimembranosus and semitendinosus.

biceps femoris from a superficial view

Here we can see just the biceps femoris from a superficial view (both long and short heads).

short head of the biceps femoris from a superficial view

Here we can see only the short head of the biceps femoris from a superficial view (highlighted in green).

long head of the biceps femoris from a superficial view

Here we can see only the long head of the biceps femoris from a superficial view (highlighted in green).

Origin & Insertion

The long head of the biceps femoris muscle originates on the ischial tuberosity of the hip. Whereas the short head originates on the linea aspera to the supracondylar line of the femur [2] [3].

The linea aspera is a roughened ridge on the femur’s posterior shaft. The lateral supracondylar line is the lateral ridge of the popliteal surface of the femur. The popliteal surface is a smooth triangular area outlined by two ridges. The ridges are on the outside of the triangle called supracondylar lines (a medial and lateral ridge) [4]. Both of these ridges are essentially continuations of the line of the linea aspera. The pictures at the bottom of this page have a labelled diagram to help better illustrate this.

As for the insertion point of the bicep femoris muscle. It is located on the lateral side of the head of the fibula. The tendon is split at this location by the fibular collateral ligament of the knee [5].

origin of the biceps femoris long head

Here we can see the origin of the biceps femoris long head at the ischial tuberosity (marked in red).

origin of the biceps femoris short head

Here we can see the origin of the biceps femoris short head at the linea aspera and lateral supracondylar line of the femur (marked in red).

location of the linea aspera and lateral supracondylar line of the femur

Here we can see a picture identifying the location of the linea aspera and lateral supracondylar line of the femur.

insertion points of the long and short heads of the biceps femoris

Here we can see the insertion points of the long and short heads of the biceps femoris marked in blue on the lateral head of fibula.

Actions

The primary role of the biceps femoris muscle is knee flexion. Due to the long head of the muscle originating at the ischial tuberosity of the hip, it is also able to assist in hip extension. The long head is stronger at knee flexion when the hip is flexed and stronger at hip extension when the knee is extended. The biceps femoris also assists in lateral rotation of the leg. Because the long head crosses the hip, it can assist in lateral rotation of the femur. The short head can only laterally rotate the tibia because it only crosses the knee joint. The biceps femoris assists in lateral rotation of the tibia when the knee is slightly bent. As for lateral rotation of the femur, the biceps femoris assists in this when the hip is extended [6] [7] [8].

Innervation

The long head of the biceps femoris muscle is innervated by the tibial division of sciatic nerve (L5, S1, S2). The short head is innervated by the common fibular division of sciatic nerve (L5, S1, S2) [9].

Blood Supply

Blood is supplied to the biceps femoris by the deep femoral artery, perforating arteries and the longhead has a blood supply from the perforating branches from profunda femoris artery [10].

Want some flashcards to help you remember this information? Then click the link below:
Biceps Femoris Flashcards

References

References
1, 3, 4, 6 Moore KL, Agur AMR, Dalley AF. Clinically Oriented Anatomy. 8th ed. Philadelphia: Lippincot Williams & Wilkins; 2017.
2, 5, 8 Rodgers CD, Raja A. Anatomy, Bony Pelvis and Lower Limb, Hamstring Muscle. [Updated 2021 Aug 11]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK546688/
7, 9 Afonso J, Rocha-Rodrigues S, Clemente FM, et al. The Hamstrings: Anatomic and Physiologic Variations and Their Potential Relationships With Injury Risk. Front Physiol. 2021;12:694604. Published 2021 Jul 7. doi:10.3389/fphys.2021.694604
10 Tomaszewski KA, Henry BM, Vikse J, Pękala P, Roy J, Svensen M, Guay D, Hsieh WC, Loukas M, Walocha JA. Variations in the origin of the deep femoral artery: A meta-analysis. Clin Anat. 2017 Jan;30(1):106-113. doi: 10.1002/ca.22691. Epub 2016 Feb 2. PMID: 26780216.