H & N Spotters Test - 1: Complete Answers

Spotter 1 - Anterior Triangle of the Neck

• Digastric muscle (anterior and posterior bellies)
• Stylohyoid muscle
• Mylohyoid muscle
• Thyrohyoid muscle
• Sternohyoid muscle
• Omohyoid muscle (superior belly)

1. Submental triangle - unpaired, below the chin
2. Digastric (submandibular) triangle - bilateral, below the mandible
3. Carotid triangle - bilateral, contains carotid vessels
4. Muscular (omotracheal) triangle - bilateral, contains strap muscles

• Ansa cervicalis (C1, C2, C3) - supplies infrahyoid strap muscles
• Mylohyoid nerve (branch of inferior alveolar nerve, V3) - mylohyoid and anterior belly of digastric
• Facial nerve (CN VII) - posterior belly of digastric and stylohyoid
• CN XII (hypoglossal) - carries C1 fibres to thyrohyoid and geniohyoid

Spotter 2 - Digastric Muscle

• Anterior belly: digastric fossa on the inner aspect of the lower border of the mandible
• Posterior belly: mastoid notch (digastric groove) of the mastoid process of the temporal bone

• Anterior belly: Mylohyoid nerve (branch of inferior alveolar nerve - mandibular division of trigeminal, CN V3)
• Posterior belly: Facial nerve (CN VII) - digastric branch

Spotter 3 - Mylohyoid Muscle (or Hyoglossus / Thyrohyoid based on context)

Given the attachment and nerve supply question pattern, this is most likely the Mylohyoid muscle.

• Origin: Mylohyoid line (oblique internal ridge) on inner surface of the mandible
• Insertion: Anterior fibres - median fibrous raphe; Posterior fibres - upper border of the body of hyoid bone

Spotter 4 - Neck Diagram: Structure No. 8

In standard H&N diagrams showing the anterior triangle with numbered structures, structure 8 is typically the Internal Jugular Vein or the Common Carotid Artery depending on the diagram used. In a commonly used carotid triangle diagram, structure 8 is often the Internal Jugular Vein.

• Vagus nerve (CN X) - runs within the carotid sheath between the common carotid artery and internal jugular vein
• Sympathetic chain - lies posterior to the carotid sheath

Spotter 5 - Tongue

Spotter 6 - Submandibular (Wharton's) Duct / Lymph Node

Based on "where does it drain?" question, this is likely the Submandibular gland/duct or a lymph node group.

• Secretomotor (parasympathetic): Chorda tympani (CN VII) → lingual nerve → submandibular ganglion → postganglionic fibres to gland
• Sympathetic (vasoconstrictor): Superior cervical ganglion via plexus on facial artery
• Sensory: Lingual nerve (CN V3)

Spotter 7 - Parapharyngeal Space (Lateral Pharyngeal Space)

• Superiorly: Base of skull (foramen lacerum, jugular foramen)
• Anteriorly: Pterygomandibular space / submandibular space
• Posteriorly: Retropharyngeal space
• Medially: Pharynx
• Inferiorly: Continuous with submandibular space and parotid space
• Lateral pharyngeal space communicates with: Retropharyngeal space, submandibular space, parotid space, and through stylomastoid foramen

• Acts as a pathway for spread of infection from teeth, tonsils, and parotid
• Contains the carotid sheath (internal carotid artery, internal jugular vein, CN IX, X, XI, XII, sympathetic chain)
• Facilitates fascial plane communication between spaces of the neck

Spotter 8 - Retropharyngeal Space

• Retropharyngeal lymph nodes (nodes of Rouvière) - drain nasopharynx, posterior nasal cavity, adenoids, middle ear
• These lymph nodes are present in children up to age 3-5 years and then involute
• Prevertebral fascia (posterior wall)
• Buccopharyngeal/visceral fascia (anterior wall)

• Retropharyngeal abscess - most common in children <3 years; presents with neck stiffness, dysphagia, drooling, stridor
• Spread of infection: can track down into the superior mediastinum (danger space - space 4) causing mediastinitis
• Can cause airway compromise requiring emergency drainage
• On lateral neck X-ray: widening of prevertebral soft tissue (>7 mm at C2, >14 mm at C6) suggests abscess

Spotter 9 - Jugular Foramen

• Petrous part of the temporal bone (anterolateral part)
• Occipital bone (posteromedial part)

• The foramen itself transmits the internal jugular vein (beginning/superior bulb)
• Supplied by branches of the ascending pharyngeal artery and occipital artery

• Jugular foramen syndrome (Vernet's syndrome): paralysis of CN IX, X, XI as they pass through the foramen
• Glossopharyngeal neuralgia
• Glomus jugulare tumour (paraganglioma) - most common tumour here; presents with pulsatile tinnitus, hearing loss, lower cranial nerve palsies
• Contents (anterior compartment/pars nervosa): CN IX, inferior petrosal sinus; (posterior compartment/pars vascularis): CN X, CN XI, jugular bulb
• Thrombosis of internal jugular vein can occur here

Spotter 10 - Suboccipital Triangle

• It is a purely motor nerve (no sensory component to skin)
• Supplies all four muscles of the suboccipital triangle: rectus capitis posterior major, rectus capitis posterior minor, superior oblique, inferior oblique

• Suboccipital nerve (C1 posterior ramus)
• Vertebral artery (3rd part, V3 segment)
• Suboccipital venous plexus

Spotter 11 - Hydrocephalus

1. Communicating (non-obstructive) hydrocephalus - CSF can flow between ventricles and subarachnoid space but is not absorbed properly
2. Non-communicating (obstructive) hydrocephalus - obstruction within the ventricular system (e.g., aqueduct of Sylvius stenosis)
3. Normal pressure hydrocephalus (NPH) - enlarged ventricles with normal CSF pressure; triad: dementia + gait disturbance (magnetic gait) + urinary incontinence
4. Ex vacuo hydrocephalus - ventricular enlargement due to cerebral atrophy (not true hydrocephalus)

• Overproduction of CSF (rare - choroid plexus papilloma)
• Obstruction to flow (aqueductal stenosis, Chiari malformation, tumours)
• Impaired absorption (post-meningitis, subarachnoid haemorrhage, sagittal sinus thrombosis)

• CSF production rate: ~500 mL/day; total volume ~150 mL at any time

• Primarily via arachnoid granulations (Pacchionian bodies/villi) - project into dural venous sinuses (mainly superior sagittal sinus); CSF drains into venous blood by a pressure-dependent one-way valve mechanism
• Also via: cranial and spinal nerve root sheaths (lymphatic drainage), ependymal cells, glymphatic system (recently described)
• Pressure gradient: CSF pressure (~150 mmH₂O) > venous sinus pressure (~90 mmH₂O)

Spotter 12 - Cleft Palate

• The palate develops from two components:
  1. Primary palate (premaxilla/median palatine process) - formed by the frontonasal process; gives rise to palate anterior to the incisive foramen
  2. Secondary palate - formed by the two lateral palatine processes (shelves) growing from the maxillary processes
• Critical event: the lateral palatine shelves are initially vertical (flanking the tongue); around week 7-8, they elevate horizontally above the tongue and fuse with each other in the midline, with the primary palate anteriorly, and with the nasal septum superiorly
• Failure of fusion of lateral palatine processes = cleft palate
• Cleft palate is associated with failure of mesenchymal penetration and epithelial apoptosis at the fusion line
• More common in females (opposite of cleft lip)
• Critical period: 6th-9th week of intrauterine life

1. Cleft lip (harelip) - failure of fusion of maxillary process with medial nasal process
2. Bifid uvula - minor form of cleft palate
3. Submucous cleft palate - bony defect covered by mucosa
4. Pierre Robin sequence - micrognathia + glossoptosis + cleft palate
5. Velopharyngeal insufficiency
6. Associated syndromes: Van der Woude syndrome, Stickler syndrome, 22q11 deletion (DiGeorge)

Spotter 13 - Anterior Fontanelle

• Posterior fontanelle closes at 6-8 weeks after birth
• Sphenoidal (anterolateral) fontanelle closes at 3 months
• Mastoid (posterolateral) fontanelle closes at 12-18 months

• Bulging of anterior fontanelle = raised intracranial pressure (ICP): meningitis, hydrocephalus, intracranial haemorrhage, pseudotumour cerebri, vitamin A toxicity
• Depressed/sunken anterior fontanelle = dehydration / hypovolemia

Spotter 14 - Parotid Gland (Parotitis / Parotid Swelling)

1. Facial nerve (CN VII) - most important; divides into temporofacial and cervicofacial divisions, then into 5 terminal branches (temporal, zygomatic, buccal, marginal mandibular, cervical) - the "nerve plane" divides the gland into superficial and deep lobes
2. Retromandibular vein (posterior facial vein) - formed by union of superficial temporal vein and maxillary vein
3. External carotid artery - divides within the gland into maxillary artery (deep) and superficial temporal artery
4. Parotid lymph nodes (intraparotid and periparotid)

• The parotid gland is enclosed within the parotid fascia, which is derived from the investing layer of deep cervical fascia
• Superficial layer: thick and well-defined - limits superficial swelling (hence pain in parotitis)
• Deep layer: thin and deficient at the stylomandibular tunnel (between stylomandibular ligament and ramus of mandible) - allows the deep lobe to herniate into the parapharyngeal space
• Stylomandibular ligament: thickening of parotid fascia between the styloid process and angle of mandible - separates parotid from submandibular gland
• The fascial capsule sends septa into the gland making it difficult to shell out the gland without injuring the facial nerve

1. Preganglionic fibres arise from the inferior salivatory nucleus in the medulla
2. Travel in CN IX (glossopharyngeal nerve)
3. Pass via Jacobson's nerve (tympanic branch of CN IX)
4. Form the tympanic plexus on the promontory of middle ear
5. Continue as the lesser petrosal nerve
6. Exit through foramen ovale (or a small canal between petrous temporal and greater wing of sphenoid) - sometimes through canaliculus innominatus
7. Synapse in the otic ganglion (just below foramen ovale)
8. Postganglionic fibres travel with the auriculotemporal nerve (branch of V3) to reach the parotid gland

Spotter 15 - Ptosis / Lateral Squint (Eye Defect)

• Ptosis: Levator palpebrae superioris (CN III)
• "Down and out" position: Paralysis of superior rectus, inferior rectus, medial rectus, inferior oblique (all CN III) → unopposed action of superior oblique (CN IV) + lateral rectus (CN VI)