Neck Flashcards
What 3 nerves are at risk during excision of submandibular gland and how do you test them?
Marginal mandibular division of facial nerve - Supplies depressor labii inferioris, mentalis and depressor anguli oris - Distorted smile Lingual nerve - CN V3: somatic sensation to anterior 2/3 tongue - CN VII: Taste to anterior 2/3 tongue Hypoglossal - CN XII - All intrinsic tongue muscles - All extrinsic tongue muscles (genioglossus, styloglossus, hyoglossus). Except palatoglossus (CN X) Nerve to mylohyoid (V3)
Gland secretion type (parotid, SMG, SLG)
- Parotid: Serous acini - Submandibular: Mucinous and serous acini - Sublingual: Mucinous acini
Parasympathetic innervation to SMG
- Superior salivatory nucleus > CN VII (chorda tympani) > Submandibular ganglion > Lingual nerve (CN V3 + CN VII) to innervate SMG
Identify SMG duct. Where does it drain?
- Wharton’s Duct - ~ 5cm long - Opens into floor of mouth, either side of frenulum
DDX SMG lump
- STONES: Sialolithiasis - INFECTION: Acute siladenitis - NEOPLASIA: Malignant (Adenoid cystic), benign (pleomorphic adenoma) - NON-PARENCHYMAL: Lymph node, sebaceous cyst, lipoma
MC parotid cancer
- Mucoepidermoid adenocarcinoma
Lymphatic drainage of parotid
- Deep and superficial pre-auricular nodes - Drain into the deep cervical chain
Nerve supply to parotid
- PARASYMPATHETIC: Auriculotemporal nerve from Otic ganglion (ISN > LPN > Otic > ATN) - SOMATIC SENSORY: • Gland > Auriculotemporal nerve • Capsule > Greater auricular nerve
Which cranial nerves carry parasympathetic fibers?
3, 7, 9, 10 • III: EWN > CN III > Ciliary Ganglion > Short ciliary nerves > Ciliary muscles > Pupillary constriction • VII: SSN > GPN (VII) > Pterygopalatine ganglion > Lacrimal gland SSN > Chorda tympani (VII) > Submandibular ganglion > lingual nerve > SMG IX: ISN > LPN (CN IX) > Otic > Auriculotemporal nerve > Parotid X >Parasympathetics to thoracic and abdominal viscera
Branches of greater auricular nerve?
- Anterior > Capsule of parotid - Lobular > Ear lobe - Posterior > mastoid
Draw incision for parotidectomy
- Incision posterior to mandible down to angle and parallel to anterior border of SCM - Small retroauricular portion > Risk to GAN - Pre-auricular incision (doesn’t risk GAN)

Sensory domain of GAN?
- C2/3
- Angle of mandible
- Lobe of ear
- Lower medial aspect of pinna
- Parotid capsule
What is Frey’s syndrome
- Syndrome characterised by gustatory sweating
- Damage to auriculotemporal nerve (V3)
- Auriculotemporal nerve carries parasympathetic fibers to parotid from otic ganglion
- Damage may lead to cross innervation with sympathetic nerve fibres supplying sweat glands
- Abnormal sweating/ salivation
Embryology of thyroid
- Develops from 1st and 2nd pharyngeal pouches
- Thyroglossal tract develops from foramen caecum (base oif tongue)
- Descends inferiorly in the midline
- Expansion of caudal end of tract gives rise to thyroid gland
Formation of thyroglossal cyst
- Midline neck mass that moves up on swallowing and tongue protrusion
- Patent thyroglossal duct
- Mx: Sistrunk procedure. Resection of cyst, mid-portion of hyoid bone.
Overview of thyroxine production
- Thyroid composed of follicles, outer layer of cuboidal epithelium and inner colloid
- Follicles produce thyroxine
- Pumping of iodide into follicular cell
- TPO joins iodide to form iodine, iodine then joined to tyrosine on colloid
- Forms monoiodotyrosine and diiodotyrosine
- Combine to form T3 and T4 (thyroxine)
- Stored in colloid bound to thyroglobulin
- Released by exocytosis when needed
- Parafollicular cells secrete calcitonin
Which is more biologically active T4/T3?
- More T4 is produced although T3 more biologically active
Why does thyroid move up on swallowing?
- Berry’s ligament
- Attaches thyroid gland to trachea
Blood supply to thyroid
- Superior thyroid artery > First branch of ECA
- Inferior thyroid artery > Thyrocervical trunk (branch of SCA)
Venous drainage THYROID
- Superior thyroid vein IJV
- Middle thyroid vein IJV
- Inferior thyroid vein Left brachiocephalic vein
Nerves at risk during thyroidectomy, what vessels are close by
- SLN > near superior thyroid artery (External branch, motor to cricothyroid)
- RLN > near inferior thyroid artery
Which vessels of thyroid related to sympathetic trunk?
- Inferior thyroid artery (branch of TCT) runs posterior to sympathetic chain

Describe course of recurrent laryngeal nerves
- Branches of the vagus nerve (CN X)
- Motor supply to all muscles of larynx and sensation below vocal cords
- Right RLN hooks under the right subclavian artery and ascends in trachea-oesophageal groove
- Left RLN hooks under arch of aorta by the ligamentum arteriosum (ductus arteriosus remnant) and ascends in left trachea-oesophageal groove
Lymphatic drainage thyroid
- Paratracheal and deep cervical
Which thyroid cancer spreads via lymph
- Papillary
- MC thyroid cancer
Cell of origin of medullary carcinoma
- Parafollicular C-cells
- Produced calcitonin
Where would you perform cricothyroidotomy
- Incision is made through cricothyroid membrane to establish a surgical airway if failed ETT
- Laryngeal prominence = superior border of thyroid cartilage
- Immobilise larynx
- Vertical skin incision on anterior larynx
- Blunt dissection using finger down to cricothyroid membrane
- Horizontal stab incision through CTM
- Insert bougie, confirm position with tracheal clicks felt as bougie passes over tracheal rings
- Pass tracheal tube over bougie
- Remove bougie, inflate cuff and secure. Confirm position with capnography
Why does bronchial carcinoma cause a hoarse voice?
- Vocal cord paralysis due to pressure effect on RLN
Where are parathyroid glands?
- 2 parathyroid glands on each side of neck (superior and inferior)
- Deep to lateral aspect of thyroid gland
- Superior = lateral to RLN at level of 1st tracheal ring
- Inferior = medial to RLN at variable position
Development of parathyroid glands?
- Superior from 4th pharyngeal pouch
- Inferior from 3rd pharyngeal pouch
Blood supply parathyroid glands
- Both supplied by inferior thyroid artery
Commonest location of ectopic parathyroid gland?
- Tail of thymus
- Also found in mediastinum and in the thyroid
- Intra-op PTH levels useful for localising single adenoma (cause of primary hyperPTH in 80%)
Fascial layers of neck and contents
- Investing > SCM and trapezius
- Pre-tracheal > Strap muscles, thyroid, trachea, oesophagus
- Pre-vertebral > Verebrae, scalene muscles, deep muscles of back and pre-vertebral muscles
- Carotid sheath > CCA, vagus, IVJ