Page 4 of 4
AN43.1-9 | Head & neck Joints, Histology, Development, Radiography & Surface marking — Gate Quiz
Click any question card to reveal the correct answer.
The atlantoaxial joint is primarily responsible for which movement of the head?
Correct! The atlantoaxial (C1-C2) joint primarily allows ROTATION of the head — approximately 40-45° each side (50% of total cervical rotation). The dens of the axis acts as a pivot around which the atlas rotates. The atlantooccipital joint (C0-C1) allows nodding (flexion/extension) — saying "yes."
Craniocervical joints: Atlantooccipital (C0-C1) = nodding, yes movement, flexion/extension (ellipsoid condyloid joint). Atlantoaxial (C1-C2) = rotation, no movement (pivot joint with median + 2 lateral joints). Key stabiliser: transverse ligament of atlas for atlantoaxial. Alar ligaments limit excessive rotation.
Incorrect. Atlantoaxial = ROTATION (saying "no"). Atlantooccipital = NODDING (saying "yes").
Click to reveal answer
A 10-year-old child with Down syndrome is cleared for participation in sports. Before contact sports, a lateral cervical X-ray is taken. The atlantoaxial interval (ADI — distance between anterior arch of C1 and the dens) measures 4 mm. The correct interpretation is:
Correct! In children (under ~15 years), the ADI may be up to 5 mm due to ligamentous laxity in normal children (and more so in Down syndrome). An ADI of 4 mm in a child is at the upper range of acceptable limits but does not automatically mandate surgery. However, in Down syndrome — where the transverse ligament is inherently lax — an ADI of 4 mm with contact sports is a risk for cord compression. Most sports authorities restrict contact sports if ADI >4.5 mm in children with Down syndrome.
ADI normal limits: Adults ≤3 mm (>3 mm = transverse ligament pathology). Children ≤5 mm (ligamentous laxity is physiological). Down syndrome: Ligamentous hypotonia → ADI may exceed normal → atlantoaxial instability. Special Olympics requires lateral cervical X-ray before contact sports. Signs of cord compression: myelopathy, gait disturbance, hyperreflexia.
Incorrect. ADI limits: Adults ≤3 mm, Children ≤5 mm. In a 10-year-old, 4 mm is borderline — within the stated paediatric limit but in Down syndrome, extra caution is warranted. Sports governing bodies typically restrict contact sports in Down syndrome children with ADI >4.5 mm.
Click to reveal answer
On histological examination, a salivary gland shows exclusively serous acini (no mucous cells) with prominent striated ducts. This is most consistent with:
Correct! The parotid gland is the only major salivary gland that contains ONLY serous acini — no mucous cells. The serous acini are basophilic (zymogen granules) with striated ducts (for electrolyte modification). Compare: submandibular = mixed (predominantly serous); sublingual = predominantly mucous.
Salivary gland histology mnemonic — PBS (from pure to most mucous): Parotid = pure Serous only. Submandibular = mixed (Serous > mucous, serous demilunes). Sublingual = predominantly mucoUS. Minor salivary glands (palate, buccal, labial) = purely mucous. Striated ducts = high protein secretion (parotid prominent; submandibular moderate).
Incorrect. The pure serous gland is the PAROTID. Submandibular = mixed (serous >> mucous, serous demilunes). Sublingual = predominantly mucous with serous demilunes. Palatal minor glands = predominantly mucous.
Click to reveal answer
A 6-year-old child has a midline neck swelling at the level of the hyoid bone that moves upward on both swallowing and tongue protrusion. The embryological origin of this swelling is:
Correct! The thyroid gland originates at the foramen caecum (junction of anterior 2/3 and posterior 1/3 of tongue) and descends to the neck via the thyroglossal duct. When this duct fails to obliterate, a thyroglossal duct cyst forms — most commonly at or below the hyoid bone. The connection to the tongue (via the duct remnant passing through the hyoid bone) explains why it moves with BOTH swallowing AND tongue protrusion.
Thyroglossal duct cyst: Most common congenital neck swelling. Midline or paramidline. Moves on BOTH swallowing + tongue protrusion (distinguishes from other midline swellings). Most common at hyoid level. Treatment: Sistrunk's operation = excise cyst + middle 1/3 of hyoid bone + tract to foramen caecum (to prevent recurrence). Compare: Branchial cyst = LATERAL neck, anterior to SCM, moves only with swallowing.
Incorrect. Thyroglossal duct cyst = remnant of the thyroid's descent from the foramen caecum at the tongue base → down through the hyoid bone → to the neck. It is NOT a branchial remnant.
Click to reveal answer
Unilateral cleft lip results from failure of fusion of which embryological processes?
Correct! Cleft lip results from failure of the maxillary process to fuse with the medial nasal process (part of the frontonasal prominence). This fusion normally forms the lateral upper lip, the nostril floor, and the primary palate. Failure → paramedian cleft lip (lateral to the philtrum).
Face development from 5 processes: 1 Frontonasal (forehead, bridge, medial nose, philtrum, primary palate) + 2 Maxillary (cheeks, lateral upper lip, secondary palate) + 2 Mandibular (lower face). Cleft lip: maxillary ↔ medial nasal process failure. Cleft palate: palatine shelves fail to fuse with each other + nasal septum. Combined CLP = both defects. Epidemiology: most common in India; associated with folic acid deficiency.
Incorrect. Cleft LIP = maxillary process + medial nasal process fusion failure. Cleft PALATE = palatine shelf fusion failure. These are distinct developmental failures that often coexist.
Click to reveal answer
In a patient with complete upper airway obstruction who cannot be intubated, the anaesthetist performs emergency cricothyrotomy. The cricothyroid membrane is incised. This membrane lies between:
Correct! The cricothyroid membrane connects the INFERIOR border of the thyroid cartilage to the SUPERIOR border of the cricoid cartilage. It is the standard site for emergency cricothyrotomy — identified by palpating the cartilage prominences in the midline of the neck.
Cricothyrotomy landmarks: Feel the laryngeal prominence (thyroid cartilage notch), slide finger inferiorly to the cricothyroid membrane (soft depression), then the hard cricoid cartilage below. Incision is horizontal through the lower 1/3 of the membrane. Vertebral level: thyroid cartilage = C4-5, cricoid = C6. Cricothyrotomy = temporary airway (convert to tracheostomy within 24-48h to prevent subglottic stenosis).
Incorrect. The cricothyroid membrane is between the INFERIOR border of thyroid cartilage and the SUPERIOR border of cricoid cartilage. Landmarks: thyroid cartilage (Adam's apple) above, cricoid below, membrane between them.
Click to reveal answer
On a lateral skull X-ray, the pituitary fossa (sella turcica) is identified as a saddle-shaped depression in the floor of the middle cranial fossa. It is located in the body of which bone?
Correct! The sella turcica ("Turkish saddle") is located in the body of the sphenoid bone, forming the floor of the middle cranial fossa. The pituitary gland sits within it. On lateral skull X-ray, the floor of the sella is seen as a double line in pituitary adenomas (asymmetric expansion).
Lateral skull X-ray landmarks: Sella turcica (sphenoid body) = pituitary fossa. Anterior clinoid processes + posterior clinoid processes bracket the sella. Calcified pineal = midline (if displaced = SOL). Vascular grooves = middle meningeal artery. Mastoid air cells = temporal bone (posterior). Floor of anterior cranial fossa (cribriform plate = ethmoid). Internal occipital protuberance (posterior).
Incorrect. The sella turcica is in the SPHENOID bone. The sphenoid forms the central floor of the middle cranial fossa and is the most complex bone in the skull.
Click to reveal answer
In performing a vertebral angiogram via the femoral artery approach, the catheter is navigated into the vertebral artery. The vertebral artery typically enters the transverse foramen at which cervical level?
Correct! The vertebral artery normally enters the transverse foramen of C6 (sixth cervical vertebra). It ascends through the transverse foramina of C6 to C1 (passing through C6, C5, C4, C3, C2, C1 transverse foramina), then curves medially and posteriorly over the atlas to enter the skull via the foramen magnum.
Vertebral artery: Arises as first branch of subclavian artery → ascends to enter transverse foramen at C6 → ascends through C6-C1 foramina → loops posteriorly around atlas → enters foramen magnum → joins opposite vertebral → forms basilar artery. C7 transverse foramen: usually small; vertebral artery does NOT pass through it in 90%+ of cases — important in C7 root block procedures.
Incorrect. The vertebral artery enters the transverse foramen at C6 in the majority of cases (>90%). It does NOT enter at C7 (the C7 transverse foramen is usually small and does not transmit the vertebral artery). Occasionally enters at C5 or C7 as a variant.
Click to reveal answer
The olfactory epithelium (neuroepithelium) in the superior nasal cavity contains which specialised cell type that serves as the primary olfactory receptor?
Correct! The olfactory receptor cells are BIPOLAR NEURONS — the only neurons in the human body with the capacity for regeneration throughout life (from basal cells). Their DENDRITIC end extends to the surface and bears olfactory cilia (modified nonmotile cilia) that project into the mucus layer and bear odorant receptors. Their axonal processes gather into bundles (fila olfactoria) forming CN I.
Olfactory epithelium cell types (pseudostratified columnar): (1) Bipolar olfactory receptor neurons — have olfactory cilia (odorant receptors), axons form CN I bundles through cribriform plate. (2) Sustentacular (supporting) cells — tall columnar cells; microvilli on surface; support and metabolise odorants. (3) Basal cells — stem cells; enable lifelong olfactory neuron regeneration (unique). Bowman's glands (olfactory glands) in lamina propria provide watery mucus.
Incorrect. The primary receptor cells in olfactory epithelium are BIPOLAR OLFACTORY NEURONS with apical olfactory cilia (bearing odorant receptors). Sustentacular cells provide support; basal cells provide regeneration; Bowman's glands produce the mucus layer.
Click to reveal answer
The muscles of facial expression are derived from which pharyngeal arch, and their motor nerve supply confirms this by being:
Correct! The muscles of facial expression are derived from the SECOND pharyngeal arch (hyoid arch). The nerve of the second arch is the FACIAL NERVE (CN VII). This is why all muscles of facial expression (frontalis, orbicularis oculi, orbicularis oris, buccinator, platysma, etc.) are supplied by CN VII.
Pharyngeal arch nerves (for exams): 1 → CN V (mastication: temporalis, masseter, pterygoids, mylohyoid, ant. digastric, tensor tympani, tensor palati). 2 → CN VII (facial expression: all facial muscles, stapedius, stylohyoid, post. digastric). 3 → CN IX (stylopharyngeus only). 4 → CN X sup. laryngeal (pharyngeal constrictors, cricothyroid, levator palati). 6 → CN X rec. laryngeal (all intrinsic laryngeal muscles except cricothyroid).
Incorrect. Second pharyngeal arch → facial nerve (CN VII) → muscles of facial expression, stapedius, stylohyoid, posterior digastric. First arch → CN V → muscles of mastication. Third arch → CN IX → stylopharyngeus.
Click to reveal answer