NRE Step 1 Anatomy MCQs
12 sample questions from the 265 Anatomy questions in NRE-1 Prep. Choose an answer to see why it is right and why each other option is wrong.
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Sample Anatomy questions
1. A 34-year-old man falls from a motorbike onto his right shoulder. X-ray shows a fracture through the surgical neck of the humerus. Which finding is most likely on examination?
Answer: Numb skin over the lower deltoid. The axillary nerve winds around the surgical neck of the humerus with the posterior circumflex humeral artery. Injury weakens deltoid (abduction 15–90°) and teres minor, and removes sensation over the "regimental badge" area of the upper lateral arm. Test this sensation before and after any shoulder reduction.
- Wrist drop with dorsal hand numbness: Wrist drop follows a mid-shaft fracture damaging the radial nerve in the spiral groove, not a surgical-neck fracture.
- Winged scapula on pushing a wall: Long thoracic nerve injury follows chest wall surgery or stretch.
- Numb skin over the lateral forearm: Musculocutaneous nerve injury — rare in isolation with this fracture.
2. During an abdominal hysterectomy, the surgeon clamps the uterine artery close to the lateral side of the cervix. Which structure is most at risk here?
Answer: Ureter. The ureter passes beneath the uterine artery about 1.5–2 cm lateral to the cervix, on its way to the bladder. Clamping or ligating the artery here can catch, crush or divide the ureter. It is also at risk at the pelvic brim, near the infundibulopelvic ligament.
- Internal iliac artery: The internal iliac artery lies higher on the pelvic side wall, away from the cervix.
- Obturator nerve: The obturator nerve runs on the lateral pelvic wall, not beside the cervix.
- Pudendal nerve: The pudendal nerve leaves the pelvis near the ischial spine, posterolateral to the operative field.
3. Where does the parotid (Stensen) duct open into the mouth?
Answer: Opposite the upper second molar. Parotid duct: emerges from anterior border of the gland, crosses masseter (palpable when clenching), pierces buccinator and opens into the vestibule opposite the upper second molar crown. Submandibular (Wharton) duct opens on the sublingual papilla beside the lingual frenulum (stones commonest here — long, upward course, viscous alkaline secretion). Sublingual gland: multiple small ducts on the sublingual fold. Parotid secretion: parasympathetic via glossopharyngeal nerve → otic ganglion → auriculotemporal nerve.
- Floor of mouth beside frenulum: The floor of the mouth beside the frenulum is the submandibular duct opening.
- Opposite the lower first premolar: The parotid duct opens opposite the upper molar, not the lower premolar.
- Sublingual fold: The sublingual fold is where the sublingual ducts open.
4. A cyclist has weakness of finger abduction and adduction and clawing of the ring and little fingers, but sensation over the dorsum of the hand’s medial side is normal. Where is the ulnar nerve compressed?
Answer: Guyon’s canal at the wrist. Ulnar nerve lesions: at elbow (cubital tunnel) — weakness of FCU and FDP to ring/little fingers (less clawing — ‘ulnar paradox’), hypothenar/interossei wasting, sensory loss on palmar and dorsal medial hand (dorsal cutaneous branch arises proximal to wrist). At wrist (Guyon’s canal — cyclists, ganglion, hook of hamate fracture): intrinsic weakness with marked clawing, palmar sensory loss but dorsal sensation preserved. Froment sign: adductor pollicis weakness.
- Cubital tunnel at the elbow: At the cubital tunnel, dorsal sensation would be lost.
- Carpal tunnel: The carpal tunnel contains the median nerve.
- Brachial plexus lower trunk: A lower trunk lesion causes a wider deficit.
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5. A pharyngeal pouch (Zenker diverticulum) herniates through which weak area?
Answer: Killian dehiscence. Pharyngeal pouch (Zenker): posterior pulsion diverticulum through Killian dehiscence — between thyropharyngeus and cricopharyngeus parts of the inferior constrictor — due to cricopharyngeal dysfunction; elderly men: dysphagia, regurgitation of undigested food, halitosis, gurgling neck lump, aspiration. Barium swallow diagnoses (avoid blind OGD — perforation). Treatment: endoscopic stapling (cricopharyngeal myotomy) or open excision.
- Laimer triangle: Laimer triangle lies below cricopharyngeus.
- Piriform fossa: The piriform fossa is a normal recess.
- Vallecula: The vallecula is a normal recess.
6. Which signalling centre in the limb bud determines anteroposterior patterning (thumb vs little finger), and which molecule does it secrete?
Answer: ZPA — sonic hedgehog. Limb bud signalling centres: apical ectodermal ridge (AER — FGFs) → proximodistal outgrowth (removal → truncated limb); zone of polarising activity (ZPA, posterior mesenchyme — sonic hedgehog) → anteroposterior axis (ectopic ZPA → mirror duplication/polydactyly); dorsal ectoderm (Wnt7a) → dorsoventral. HOX genes specify segment identity. Limb development occurs weeks 4–8 — thalidomide (phocomelia) acts then.
- Apical ectodermal ridge — FGF: The AER drives proximodistal outgrowth.
- Dorsal ectoderm — Wnt7a: Dorsal ectoderm sets dorsoventral pattern.
- Progress zone — retinoic acid: The progress zone is not the AP organiser.
7. The normal umbilical cord contains which vessels, surrounded by what?
Answer: Two arteries, one vein in Wharton’s jelly. Umbilical cord: two umbilical arteries (deoxygenated blood to placenta) and one umbilical vein (oxygenated blood to fetus), embedded in Wharton’s jelly (mucoid connective tissue protecting vessels), covered by amnion; remnants of allantois and vitelline duct. Single umbilical artery (~1%) is associated with renal and cardiac anomalies and growth restriction — detailed anomaly scan. Velamentous insertion → vasa praevia risk.
- One artery, two veins in amnion only: There are two arteries and one vein, not one artery and two veins.
- Two arteries, two veins in chorion: There is one vein, not two.
- One artery, one vein in decidua: A single artery is abnormal.
8. A 3-month-old is profoundly floppy with tongue fasciculations, absent reflexes and paradoxical breathing, but alert with normal eye movements. Which cells degenerate?
Answer: Anterior horn cells. Spinal muscular atrophy (SMN1 deletion, AR): degeneration of anterior horn cells → LMN weakness — type 1 (Werdnig–Hoffmann, infantile): severe hypotonia, areflexia, tongue fasciculations, bell-shaped chest, respiratory failure, alert face; types 2–4 milder/later. Treatments: nusinersen (antisense, SMN2 splicing), onasemnogene (gene therapy), risdiplam. Differentials of floppy infant: central (hypoxic injury, Prader–Willi) vs peripheral (SMA, myopathy, myasthenia, botulism).
- Neuromuscular junction: NMJ disorders include botulism and myasthenia.
- Muscle fibres: Myopathy shows a high CK without fasciculations.
- Upper motor neurons: UMN lesions cause spasticity and hyperreflexia.
9. Which nerve and artery pass through the quadrangular space and are at risk in a surgical neck of humerus fracture?
Answer: Axillary nerve, posterior circumflex. Quadrangular space: bounded by teres minor (above), teres major (below), long head of triceps (medial), surgical neck of humerus (lateral) — transmits axillary nerve and posterior circumflex humeral artery (fracture of surgical neck, anterior shoulder dislocation → deltoid paralysis, ‘regimental badge’ sensory loss). Triangular space: circumflex scapular artery. Triangular interval: radial nerve and profunda brachii artery. Suprascapular nerve: suprascapular notch (under ligament; artery above) → supraspinatus, infraspinatus.
- Radial nerve and profunda brachii: The radial nerve and profunda run in the triangular interval and spiral groove.
- Circumflex scapular artery: The circumflex scapular artery passes through the triangular space.
- Suprascapular nerve and vessels: The suprascapular nerve passes through the suprascapular notch.
10. Below the arcuate line, what forms the posterior relation of the rectus abdominis muscle?
Answer: Transversalis fascia only. Rectus sheath: above the arcuate line (~one-third of way from umbilicus to pubis) — anterior: external oblique + anterior lamina of internal oblique; posterior: posterior lamina of internal oblique + transversus abdominis. Below the arcuate line all aponeuroses pass anterior; posteriorly only transversalis fascia (weak — Spigelian hernias). Inferior epigastric vessels enter the sheath at the arcuate line — rectus sheath haematoma (anticoagulated, coughing) below it can be large.
- Aponeurosis of internal oblique and transversus: Those aponeuroses lie posterior above the arcuate line.
- External oblique aponeurosis: External oblique is always anterior.
- Peritoneum directly without fascia: Fascia lies between muscle and peritoneum.
11. During submandibular gland excision, which structures lie superficial (lateral) to the hyoglossus muscle?
Answer: Lingual, hypoglossal nerves. Hyoglossus relations: superficial (lateral) — lingual nerve (above, loops under submandibular duct), submandibular ganglion, submandibular duct, deep part of submandibular gland, hypoglossal nerve (below) with its veins; deep (medial) — lingual artery, glossopharyngeal nerve, stylohyoid ligament. Lingual nerve ‘double-crosses’ the duct. Nerves at risk in submandibular gland excision: marginal mandibular (VII), lingual, hypoglossal.
- Lingual artery and vein: The lingual artery and vein lie deep to hyoglossus.
- Glossopharyngeal nerve trunk: The glossopharyngeal nerve lies deep and posterior.
- External carotid artery: The external carotid is not on hyoglossus.
12. An extra small nipple is found on the lower chest wall of a newborn below the normal nipple. Along which embryological line do these occur?
Answer: Milk (mammary) line. Polythelia (supernumerary nipples) and polymastia (accessory breast tissue) occur along the embryonic milk lines (mammary ridges) from axilla to groin — commonest site just below the normal breast; accessory axillary breast tissue may enlarge in pregnancy/lactation. Usually benign; occasional association with renal anomalies. Amastia/athelia: absent breast/nipple (Poland syndrome — absent pectoralis major, ipsilateral syndactyly).
- Linea alba: The linea alba is the midline.
- Semilunar line: The semilunar line is the rectus border.
- Dermatome T4 only: A dermatome is not an embryological line.
Topics covered
Embryology, Abdomen, Neuroanatomy, Head & neck, Upper limb, Lower limb, Thorax, Pelvis, Anorectum, Back, Quadrate lobe, Falciform ligament, Parotid duct opening, Renal vascular segments, Ureteric constrictions, Contents of spermatic cord, Calot’s triangle, Epiploic foramen, Ulnar nerve in Guyon’s canal, Tarsal tunnel syndrome, Cubital fossa contents, Thoracic duct, Left recurrent laryngeal nerve, Carotid sheath, Killian dehiscence, SA node blood supply, Capacitation and acrosome reaction, Oocyte meiotic arrest, Bilaminar disc, Notochord remnant, Limb development signalling, Sex determination, Genital homologues, Foramen caecum, Pharyngeal arch derivatives, Neural crest derivatives, Umbilical cord structure, Embryonic remnants of the gut, Mesonephric vs paramesonephric, Germ layer derivatives
Frequently asked questions
How many NRE Step 1 Anatomy questions are in the bank?
There are 265 Anatomy questions in NRE-1 Prep, each with an explanation for every option.
Are these past paper questions?
No. Every question is original, written by us and mapped to the published PMDC NRE syllabus.
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