MRCS Part B Revision · Anatomy
Elbow — MRCS Part B Anatomy
By Dr Richard Miller, MBChB FRCS · Reviewed
Elbow 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 Elbow station
Three specimens of the elbow: the cubital fossa with its neurovascular contents, the joint opened to show its ligaments and fossae, and the bony attachments around the epicondyles.
Cubital fossa
A triangle bounded laterally by brachioradialis, medially by pronator teres, and above by a line between the two epicondyles. Its floor is brachialis and supinator; its roof is deep fascia strengthened by the bicipital aponeurosis, with the median cubital vein and the medial and lateral cutaneous nerves of the forearm on top. From lateral to medial the contents are the radial nerve (dividing into superficial and deep branches), the biceps tendon, the brachial artery dividing into radial and ulnar arteries, and the median nerve — “Really Need Beer To Be At My Nicest”.
The joint
A synovial hinge between the trochlea and capitulum of the humerus and the trochlear notch of the ulna and head of the radius, sharing its capsule with the proximal radio-ulnar joint. The coronoid fossa above the trochlea receives the coronoid process in flexion; the radial fossa above the capitulum receives the radial head; the olecranon fossa behind receives the olecranon in extension. The capsule is thin front and back, so effusions bulge on either side of the olecranon, and posterior fat-pad displacement on a radiograph is the sign of an occult fracture.
Ligaments
- Ulnar (medial) collateral ligament — from the medial epicondyle in three bands: anterior to the coronoid process (the strongest, and the one that matters for valgus stability), posterior to the olecranon, and a transverse band. The ulnar nerve passes behind the medial epicondyle over it.
- Radial (lateral) collateral ligament — from the lateral epicondyle, fanning into the annular ligament; the lateral ulnar collateral part runs to the supinator crest and prevents posterolateral rotatory instability.
- Annular ligament — a collar from the front to the back of the radial notch of the ulna, holding the radial head while it spins in pronation and supination. A child's “pulled elbow” is the head slipping under it.
Attachments
Medial epicondyle: the common flexor origin (pronator teres, flexor carpi radialis, palmaris longus, flexor digitorum superficialis, flexor carpi ulnaris) — golfer's elbow. Lateral epicondyle: the common extensor origin (extensor carpi radialis brevis, extensor digitorum, extensor digiti minimi, extensor carpi ulnaris) — tennis elbow, most often in extensor carpi radialis brevis. Olecranon: triceps. Coronoid process: brachialis. Radial tuberosity: biceps.
Images from this station
What are you asked at the Elbow station?
The station runs to 21 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.
- Describe the boundaries and contents of the antecubital fossa
- Identify structures 1-3
- Identify structures 4-6
- Identify structures 7-9
- Identify structures 10-12
- Identify radial nerve branches 13-15
- Identify nerve 16
- Identify muscles 17-19
- Identify structure 20
- Identify fossae 4 and 5
- Identify structures 6-8
- Identify structures 9-11
And 8 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 Elbow station ask?
It opens with "Describe the boundaries and contents of the antecubital fossa" and runs to 21 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