Anatomy of the popliteus muscle (m. popliteus)
The popliteus muscle (musculus popliteus) is a relatively small, but functionally significant structure of the lower limb.
Muscle fixation points:
- Origin: the muscle originates from the lateral femoral condyle and also blends into the capsule of the knee joint. When studying this section, students often make mistakes in tests by choosing incorrect options, such as the lateral tibial condyle, medial femoral condyle, or the head of the fibula. It is important to remember specifically the lateral femoral condyle.
- Insertion: distally, the muscle fibers run toward the posterior surface of the tibia, where they attach just above the soleus line (linea m. solei).
Functional significance: The function of the popliteus muscle is leg flexion. In addition, it performs medial rotation of the leg. One of the most important biomechanical tasks is tensioning the knee joint capsule during movement, which prevents it from being pinched between the articular surfaces.
Innervation and blood supply: Nerve impulses are supplied to the muscle via branches of the tibial nerve — n. tibialis (roots L₄–S₁). Oxygen and nutrient supply to the muscle tissue is provided by the popliteal artery — a. poplitea.
Dorsal interosseous muscles (mm. interossei dorsales)
As part of studying the muscular system of the lower limb, the group of dorsal interosseous muscles (musculi interossei dorsales) is also examined, consisting of four separate muscles.
Location and structure: These muscles are localized in the interosseous spaces on the dorsal side of the foot. Structurally, they are bicipital (in test items, they are sometimes confused with bipennate, unipennate, or digastric muscles, which is fundamentally incorrect).
Attachment points:
- Origin: each of the four muscles originates from the opposing surfaces of adjacent metatarsal bones, filling the spaces between them.
- Insertion: distally, the tendons run toward the base of the proximal phalanges of digits II–IV of the foot and also blend into the dorsal aponeurosis.
Functions and blood supply of the interosseous muscles
The action of the dorsal interosseous muscles of the foot is strictly specialized and aimed at controlling the position of the toes.
Biomechanics: The main function is the abduction of digits II–IV from the longitudinal axis of the foot (which is conventionally taken as the axis of digit II). In addition, they play an important role in stabilizing the metatarsophalangeal joints during walking and weight-bearing.
Innervation and blood supply:
- Innervation: provided by the lateral plantar nerve — n. plantaris lateralis (segments S₁–S₂).
- Arterial blood supply: blood is supplied from the plantar arch (arcus plantaris) and dorsal metatarsal arteries (aa. metatarseae dorsales). In tests, erroneous options such as dorsal digital, plantar metatarsal, or lateral tarsal arteries should be avoided.
Briefly: answers to topical questions
Which muscles are synergists of the popliteus muscle during leg flexion?
The synergists of the popliteus muscle in leg flexion are the muscles of the posterior compartment of the thigh. These include:
- Semitendinosus muscle (m. semitendinosus) — acts as a leg flexor.
- Semimembranosus muscle (m. semimembranosus) — flexes the leg and rotates it medially.
- Biceps femoris muscle (m. biceps femoris) — flexes the leg and rotates it laterally.
To remember the function of the dorsal interosseous muscles, use the DAB rule: Dorsal ABduct — dorsal muscles abduct the digits (in this case, digits II–IV away from the axis of digit II).
Class and exam questions
Where does the popliteus muscle originate?
The muscle originates from the lateral femoral condyle and the knee joint capsule. It is a misconception to think that it originates from the fibular head.
What is the role of the popliteus muscle in relation to the joint capsule?
It tensions the knee joint capsule, which protects it from being pinched between the bones during leg flexion.
What does the DAB rule mean?
This is an abbreviation for Dorsal ABduct, which serves as a reminder that the dorsal interosseous muscles perform abduction of the digits.
What else to study on this topic
- Anatomical landmarks of the tibia: soleus line (linea m. solei)
- Topography of the lateral femoral condyle
- Formation and branches of the plantar arch (arcus plantaris)
- Course and distribution of the branches of the tibial nerve (n. tibialis)
- Structure of the dorsal aponeurosis of the foot
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