Ear 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 Ear station
A section through the temporal bone and the ear, with the two middle-ear muscles, the nerves that cross the cavity, and the physiology of pressure as the questions that go beyond naming.
The three parts
The external ear is the auricle and the external acoustic meatus, about 2.5 cm long, cartilage in its outer third and bone in its inner two-thirds, curving so that the auricle must be pulled up and back to see the drum. The tympanic membrane closes it, set obliquely, with the handle of the malleus fixed to it and the cone of light in its anterior inferior quadrant. The middle ear is the air-filled tympanic cavity in the petrous temporal bone, with its attic (the epitympanic recess) above the drum, the mastoid antrum and air cells behind, and the auditory tube leading forward to the nasopharynx. The inner ear is the bony labyrinth, the cochlea, vestibule and semicircular canals, with the membranous labyrinth inside it.
The middle ear and its walls
The lateral wall is the drum. The medial wall is the promontory of the basal turn of the cochlea, with the oval window above and behind it, closed by the footplate of the stapes, and the round window below, closed by a membrane; the facial nerve runs across the medial wall above the oval window, in its canal, and the lateral semicircular canal bulges above that. The roof is the tegmen tympani, a thin plate under the middle cranial fossa; the floor is over the jugular bulb; the anterior wall has the opening of the auditory tube and the canal for tensor tympani, and the internal carotid artery behind it.
The ossicles carry the vibration of the drum across the cavity: the malleus attached to the drum, the incus between, and the stapes in the oval window. They match the low impedance of air to the high impedance of the fluid of the cochlea, by the lever action of the chain and by the ratio of the drum's area to the footplate's, about 17 to 1, which together gain about 25 decibels.
The two muscles
Tensor tympani, from the canal above the auditory tube to the handle of the malleus, supplied by the mandibular nerve, pulls the drum inwards and tightens it. Stapedius, the smallest muscle in the body, from the pyramid on the posterior wall to the neck of the stapes, supplied by the facial nerve, tilts the stapes and damps its movement. Both contract reflexly to loud sound and to the patient's own voice and chewing, protecting the cochlea. Paralysis of stapedius in a facial palsy above its branch gives hyperacusis, and that is how the level of a facial nerve lesion is placed.
Nerves crossing the cavity
The chorda tympani, a branch of the facial nerve, enters from behind, crosses the medial surface of the drum between the handle of the malleus and the long process of the incus, and leaves in front to join the lingual nerve; it carries taste from the front two-thirds of the tongue and the parasympathetic fibres for the submandibular and sublingual glands, so it is at risk in middle-ear surgery. The tympanic branch of the glossopharyngeal nerve forms a plexus on the promontory and leaves as the lesser petrosal nerve, carrying the parasympathetic supply for the parotid gland to the otic ganglion. The facial nerve itself runs through the cavity in its bony canal and can be exposed by cholesteatoma.
Pressure
The drum vibrates best when the pressure on its two sides is equal, and the auditory tube is what equalises the middle ear with the atmosphere, opening on swallowing and yawning by the pull of tensor and levator veli palatini. Ascending in an aircraft, the middle ear vents easily; descending, the tube is pushed shut and the negative pressure sucks the drum in, giving pain, deafness and eventually a haemorrhage or a rupture (barotrauma), which is why one swallows on landing. A blocked tube in a child leads to the negative pressure, the effusion and the conductive deafness of glue ear, treated with a grommet that vents the cavity through the drum.
Images from this station
What are you asked at the Ear station?
The station runs to 12 questions over nine minutes. These are the questions as they are put to you; the model answers are in the question bank.
- Which two muscles are found in the middle ear and what is their function?
- Identify structures 1-3
- Identify structures 4-6
- Identify structures 7-9
- Identify structures 10-12
- What is structure 13?
- Identify structures 14-16
- Identify structures 17-19
- Identify structures 20-22
- Identify structures 23-25
- Which parasympathetic nerves run through the middle ear and what do they supply?
- How does pressure affect the middle ear?
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 Ear station ask?
It opens with "Which two muscles are found in the middle ear and what is their function?" and runs to 12 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