[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Anatomy](https://durgical.com/en/anatomy/) › [Lower limb](https://durgical.com/en/anatomy/region/lower-limb/) › Vastus intermedius [Muscular system](https://durgical.com/en/anatomy/system/muscular-system/) · [Lower limb](https://durgical.com/en/anatomy/region/lower-limb/) # Vastus intermedius The vastus intermedius is the deepest quadriceps muscle, lying directly on the femur under the others; it straightens the knee. Official name: Vastus intermedius muscle [See in 3D →](https://durgical.app/?from=durgipedia&lang=en#region=lower_limb&select=vastus_intermedius&side=r) Opens in the Durgical app, no sign-up needed. ## What it is The deepest quadriceps muscle, lying on the front of the femur. ## What it does Straightens the knee. ## Key points - The deepest quadriceps head lies right on the femur, so a direct blow crushes it against bone: a typical setting for a thigh contusion and later myositis ossificans - Slips from its deep surface (the articularis genus, often described as a separate muscle) lift the suprapatellar bursa as the knee straightens - Forms the deepest layer of the quadriceps tendon, under the vasti and the rectus femoris ## Key facts **Origin** Anterior and lateral surfaces of upper two-thirds of femoral shaft **Insertion** Deep surface of quadriceps tendon; base of [patella](https://durgical.com/en/anatomy/patella/); tibial tuberosity via [patellar ligament](https://durgical.com/en/anatomy/patellar-ligament/) **Action** Extends knee **Nerve** [Femoral nerve](https://durgical.com/en/anatomy/femoral-nerve/) (L2–L4) **Blood supply** Lateral circumflex [femoral artery](https://durgical.com/en/anatomy/femoral-artery/); [deep femoral artery](https://durgical.com/en/anatomy/deep-femoral-artery/) ## Relations **Superficial** [Rectus femoris](https://durgical.com/en/anatomy/rectus-femoris-muscle/) **Deep** Anterior and lateral surfaces of the femoral shaft **Medial** [Vastus medialis](https://durgical.com/en/anatomy/vastus-medialis-muscle/), partly blended with it **Lateral** [Vastus lateralis](https://durgical.com/en/anatomy/vastus-lateralis-muscle/), partly blended with it **Below** Articularis genus and the [suprapatellar bursa](https://durgical.com/en/anatomy/suprapatellar-bursa/), between the [quadriceps tendon](https://durgical.com/en/anatomy/tendon-of-quadriceps-femoris-muscle/) and the front of the [femur](https://durgical.com/en/anatomy/femur/) ## How to find it It cannot be felt on its own. On transverse ultrasound of the mid-thigh it is the layer lying directly on the bright femoral cortex, under the rectus femoris; both are measured to follow quadriceps wasting. ## Examination - Patellar (knee-jerk) reflex: a tap on the patellar ligament contracts all four quadriceps heads; a reduced or absent reflex points to the femoral nerve or the L3–L4 roots (mainly L4) ## On imaging On transverse ultrasound of the mid-thigh it is the deepest layer, lying on the bright femoral cortex under the rectus femoris; the two are measured together to track quadriceps wasting. After a direct blow, ultrasound or MRI show a haematoma inside it. If a firm lump persists, radiographs after a few weeks show the faint rim of calcification of myositis ossificans, which CT confirms. ## Common problems - Strains (pulled muscle) from sprinting or kicking; bruising from a direct blow. - Weakness and shrinking after knee injury or surgery, which rehabilitation works to rebuild. ## How it is diagnosed Physical exam; ultrasound or MRI for significant injuries. ## Treatment - Rest, ice, then progressive strengthening with a physical therapist. ## Clinical notes - After a femoral shaft fracture or thigh surgery it can scar to the bone and limit knee bending; a surgical release of the quadriceps (quadricepsplasty) may then be needed - The severity of a thigh contusion is commonly graded by how much knee flexion is still possible in the first days ## Anatomical variants - Tensor of the vastus intermedius: an extra muscle belly between the vastus lateralis and the vastus intermedius, described in several forms ## Development From the dorsal muscle mass, like the other quadriceps heads; its deep slips form the articularis genus, which lifts the suprapatellar bursa, itself an upward pouch of the knee joint cavity. ## Related conditions - [Patellar fracture](https://durgical.com/en/conditions/patellar-fracture/) - [Femoral shaft fracture](https://durgical.com/en/conditions/femoral-shaft-fracture/) ## Test yourself Think of the answer, then tap the question to see it. ## Why is the vastus intermedius typically involved in a thigh contusion and later myositis ossificans? It is the deepest quadriceps head, lying directly on the femur, so a direct blow crushes it against the bone. ## Which slips from the deep surface of the vastus intermedius lift the suprapatellar bursa as the knee straightens? The articularis genus, often described as a separate muscle. ## After a femoral shaft fracture, how can the vastus intermedius limit knee movement? It can scar to the bone and limit knee bending; a surgical release of the quadriceps (quadricepsplasty) may then be needed. [Add to my cards (3)](https://durgical.app/estudiar/?add=/en/anatomy/vastus-intermedius-muscle/) Educational information, not medical advice. For any symptom, see a health professional. ## Its names **Official Latin (TA2)** musculus vastus intermedius TA2 2619 **Official Spanish (DeCS)** Músculo vasto intermedio DeCS D052097 **English (TA2)** Vastus intermedius muscle ## Related - [Rectus femoris](https://durgical.com/en/anatomy/rectus-femoris-muscle/) - [Vastus medialis](https://durgical.com/en/anatomy/vastus-medialis-muscle/) - [Vastus lateralis](https://durgical.com/en/anatomy/vastus-lateralis-muscle/) - [Femoral nerve](https://durgical.com/en/anatomy/femoral-nerve/) - [Femoral artery](https://durgical.com/en/anatomy/femoral-artery/) - [Vastus intermedius tendon](https://durgical.com/en/anatomy/tendon-of-vastus-intermedius/) - [Femur](https://durgical.com/en/anatomy/femur/) Sources: Terminologia Anatomica (TA2); [DeCS](https://decs.bvsalud.org/es/ths/resource/?id=50351&filter=ths_termall&q=M%C3%BAsculo%20Cu%C3%A1driceps); [Anatomy, Bony Pelvis and Lower Limb: Thigh Quadriceps Muscle](https://www.ncbi.nlm.nih.gov/books/NBK513334/). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/anatomy/vastus-intermedius-muscle/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/anatomy/vastus-intermedius-muscle/