MRCS Part B Revision · Anatomy
Knee 1 — MRCS Part B Anatomy
By Dr Richard Miller, MBChB FRCS · Reviewed
Knee 1 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 1 station
Two prosections of the knee: the joint opened to show the menisci and cruciates, and the popliteal side with its neurovascular bundle and the tendons around it.
The joint
A modified hinge with three articulations in one synovial cavity: the medial and lateral femoral condyles on the tibial plateau, and the patella in the patellar groove of the femur. The femoral condyles are convex in both planes and the tibial plateau nearly flat, so the joint depends on the menisci and ligaments rather than its bones. Near full extension the femur rotates medially on the tibia to lock the knee (the “screw-home” movement) and popliteus unlocks it.
Menisci
Crescents of fibrocartilage on the tibial plateau, thick at the edge and thin in the middle, attached at their horns to the intercondylar area and around their rims to the capsule by coronary ligaments. The medial meniscus is C-shaped and fixed to the medial collateral ligament, so it moves little and tears more often. The lateral meniscus is nearly circular, separated from the lateral collateral ligament by the popliteus tendon, and moves freely. Only the outer third has a blood supply from the geniculate vessels, which is the only part that heals when repaired. They spread load, deepen the plateau and help the ligaments with stability.
Cruciate ligaments
Both lie inside the capsule but outside the synovium. The anterior cruciate runs from the anterior intercondylar area of the tibia up and back to the medial side of the lateral femoral condyle; it resists anterior translation of the tibia and hyperextension, and is torn by a pivoting injury on a planted foot. The posterior cruciate runs from the posterior intercondylar area up and forward to the lateral side of the medial femoral condyle; it is stronger, resists posterior translation, and is torn by a dashboard injury with the knee flexed.
Popliteal fossa
Bounded above by biceps femoris laterally and semimembranosus with semitendinosus medially, and below by the two heads of gastrocnemius. From deep to superficial its contents are the popliteal artery, the popliteal vein and the tibial nerve, with the common peroneal nerve running along the medial edge of biceps to the fibular neck. The artery lies on the floor against the femur and the capsule, which is why a posterior knee dislocation or a supracondylar fracture tears it, and why every knee dislocation needs its distal pulses documented.
Tendons around the knee
Medially the pes anserinus — sartorius, gracilis and semitendinosus — inserts on the upper tibia below the joint line, with semimembranosus behind it on the medial tibial condyle. Laterally biceps femoris inserts on the fibular head, straddling the lateral collateral ligament, and the iliotibial band on Gerdy's tubercle of the tibia.
Images from this station
What are you asked at the Knee 1 station?
The station runs to 14 questions over nine minutes. A prompt the station repeats — against each marker on a specimen, for instance — is listed once here; the model answers are in the question bank.
- Identify this specimen
- Identify structures 1-3
- Identify structures 4 and 5
- Identify structures 6-8
- Identify structures 9 and 10
- Identify ligaments 11 and 12
- What lie in areas 13 and 14?
- Identify structures 11-13
- What is structure 14?
- Identify tendons 15 and 16
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 1 station ask?
It opens with "Identify this specimen" and runs to 14 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