MRCS Part B Revision · Anatomy
Knee 2 — MRCS Part B Anatomy
By Dr Richard Miller, MBChB FRCS · Reviewed
Knee 2 is a surgical anatomy station. Three of the seventeen examined stations in the MRCS Part B OSCE are surgical anatomy. The anatomy stations put a prosected specimen, a model or an image in front of you and ask you to identify structures and say what they do, what they relate to and what happens when they are injured.
What you need to know for the Knee 2 station
The knee opened from the front, with the ligaments the examiner will expect you to know by attachment and by the injury each one prevents.
Cruciate ligaments
The anterior cruciate ligament runs from the anterior intercondylar area of the tibia backwards and laterally to the inner side of the lateral femoral condyle. It stops the tibia sliding forwards on the femur and limits hyperextension and rotation; it fails in a twisting, non-contact injury and the knee swells within an hour from its own blood supply. The posterior cruciate ligament runs from the posterior intercondylar area forwards and medially to the inner side of the medial femoral condyle. It stops the tibia sliding backwards and is torn when the flexed knee strikes a dashboard. The two cross in the intercondylar notch and are named by where they attach on the tibia.
Collateral ligaments
The medial (tibial) collateral ligament is a broad, flat band from the medial epicondyle of the femur to the medial tibial condyle and the shaft below it, with deep fibres attached to the medial meniscus. It resists valgus force, so it is injured by a blow to the outside of the knee, and the meniscus often goes with it. The lateral (fibular) collateral ligament is a cord from the lateral epicondyle to the fibular head, free of both the capsule and the lateral meniscus, with the popliteus tendon passing beneath it. It resists varus force.
Extensor mechanism
The four heads of quadriceps converge on the patella through the quadriceps tendon, and the patellar ligament carries their pull from the lower pole of the patella to the tibial tuberosity. The medial and lateral retinacula, from vastus medialis and lateralis, run either side of the patella to the tibia and keep the mechanism working when the patella is fractured without displacement. The patella is a sesamoid bone that lengthens the lever arm of quadriceps; vastus medialis obliquus pulls it medially against the tendency of the Q angle to draw it laterally.
Hamstring attachments
Semitendinosus, gracilis and sartorius insert together on the anteromedial tibia as the pes anserinus, over a bursa that can become inflamed. Semimembranosus inserts on the back of the medial tibial condyle and sends an expansion up and laterally as the oblique popliteal ligament, which strengthens the back of the capsule. Biceps femoris inserts on the head of the fibula.
The intercondylar notch
The deep hollow between the femoral condyles at the back, containing the cruciate ligaments. It matters because a narrow notch is associated with anterior cruciate rupture, and because the cruciates and the meniscal horns within it are what a surgeon sees on entering the joint from the front.
Images from this station
What are you asked at the Knee 2 station?
The station runs to 13 questions over nine minutes. These are the questions as they are put to you; the model answers are in the question bank.
- Identify structure 1 and 2
- Identify structures 3-5
- Identify structures 6 and 7
- Identify structures 8-10
- Identify structures 11 and 12
- Identify structures 13 and 14
- Identify structures 15 and 16
- Identify structures 17-19
- What is the name of structure 20 onto which structures 17-19 attach
- What muscle is structure 21?
- Identify structures 22 and 23
- What is area 24?
And 1 more at this station.
How is the anatomy station marked in MRCS Part B?
An anatomy station is marked out of 20, and all 20 marks go to clinical knowledge and its application. No communication, technical-skill or professionalism marks are available in an anatomy bay, which is unusual: in most other stations more than half the marks sit outside your factual knowledge.
FAQ
What does the Knee 2 station ask?
It opens with "Identify structure 1 and 2" and runs to 13 questions over nine minutes. An anatomy station is marked out of 20, and all 20 marks go to clinical knowledge and its application. No communication, technical-skill or professionalism marks are available in an anatomy bay, which is unusual: in most other stations more than half the marks sit outside your factual knowledge.
How many anatomy stations are there in MRCS Part B?
Three of the seventeen examined stations are surgical anatomy, and two more are surgical pathology. Together they make up the five Anatomy and surgical pathology stations of the Applied Knowledge component.
How are the anatomy stations marked?
Each station is marked out of 20 and all 20 marks are awarded for clinical knowledge and its application. You also receive a separate global rating of pass, borderline or fail for the station.
Are the specimens real?
Yes. Anatomy bays use prosected cadaveric specimens, models and images. Candidates report being shown photographs of specimens as well as the specimens themselves, so practise on real dissection photography rather than diagrams alone.
What happens if I get an early question wrong?
The intercollegiate guidance says that if a wrong answer would affect your performance on later questions at the same station, the examiner gives you the correct answer before moving on. One mistake does not have to cost you the whole bay.
How many stations are in the MRCS Part B OSCE?
Seventeen examined stations of nine minutes each, with a minute to read the task before each one. Two preparation stations and at least one rest station bring the circuit to about twenty, and the exam takes about three and a half hours.
What is the pass mark for MRCS Part B?
There is no published pass mark. The cut score is set separately for Applied Knowledge and Applied Skills, for each circuit, by borderline regression. Published pass rates across the 2024/25 diets ranged from 51% to 66%.
Can I fail a station and still pass?
Yes. There is no rule about how many stations you may fail: the cut score applies to your total mark in each component, so a weak station costs the marks you lost on it and strong stations elsewhere can make them back. Applied Knowledge and Applied Skills are passed separately and must both be passed at the same sitting, so a strong anatomy performance cannot rescue a weak communication one.
Dr Richard Miller, MBChB FRCS
Station summaries are reviewed against the current intercollegiate MRCS syllabus and the published marking blueprint. Guidance changes between diets: check the royal colleges' own pages before relying on a date, a fee or a threshold.
Practise this station
The question bank carries the model answer to every question above, with the rest of the anatomy stations.
More anatomy stations