Neck

Question 1

What 3 nerves are at risk during excision of submandibular gland and how do you test them?

Answer 1

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)

Question 2

Gland secretion type (parotid, SMG, SLG)

Answer 2

• Parotid: Serous acini - Submandibular: Mucinous and serous acini - Sublingual: Mucinous acini

Question 3

Parasympathetic innervation to SMG

Answer 3

• Superior salivatory nucleus > CN VII (chorda tympani) > Submandibular ganglion > Lingual nerve (CN V3 + CN VII) to innervate SMG

Question 4

Identify SMG duct. Where does it drain?

Answer 4

• Wharton’s Duct - ~ 5cm long - Opens into floor of mouth, either side of frenulum

Question 5

DDX SMG lump

Answer 5

• STONES: Sialolithiasis - INFECTION: Acute siladenitis - NEOPLASIA: Malignant (Adenoid cystic), benign (pleomorphic adenoma) - NON-PARENCHYMAL: Lymph node, sebaceous cyst, lipoma

Question 6

MC parotid cancer

Answer 6

• Mucoepidermoid adenocarcinoma

Question 7

Lymphatic drainage of parotid

Answer 7

• Deep and superficial pre-auricular nodes - Drain into the deep cervical chain

Question 8

Nerve supply to parotid

Answer 8

• PARASYMPATHETIC: Auriculotemporal nerve from Otic ganglion (ISN > LPN > Otic > ATN) - SOMATIC SENSORY: • Gland > Auriculotemporal nerve • Capsule > Greater auricular nerve

Question 9

Which cranial nerves carry parasympathetic fibers?

Answer 9

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

Question 10

Branches of greater auricular nerve?

Answer 10

• Anterior > Capsule of parotid - Lobular > Ear lobe - Posterior > mastoid

Question 11

Draw incision for parotidectomy

Answer 11

• 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)

Question 12

Sensory domain of GAN?

Answer 12

• C2/3
• Angle of mandible
• Lobe of ear
• Lower medial aspect of pinna
• Parotid capsule

Question 13

What is Frey’s syndrome

Answer 13

• 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

Question 14

Embryology of thyroid

Answer 14

• Develops from 1^st and 2^nd 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

Question 15

Formation of thyroglossal cyst

Answer 15

• 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.

Question 16

Overview of thyroxine production

Answer 16

• 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

Question 17

Which is more biologically active T4/T3?

Answer 17

• More T4 is produced although T3 more biologically active

Question 18

Why does thyroid move up on swallowing?

Answer 18

• Berry’s ligament
• Attaches thyroid gland to trachea

Question 19

Blood supply to thyroid

Answer 19

• Superior thyroid artery > First branch of ECA
• Inferior thyroid artery > Thyrocervical trunk (branch of SCA)

Question 20

Venous drainage THYROID

Answer 20

• Superior thyroid vein  IJV
• Middle thyroid vein  IJV
• Inferior thyroid vein  Left brachiocephalic vein

Question 21

Nerves at risk during thyroidectomy, what vessels are close by

Answer 21

• SLN > near superior thyroid artery (External branch, motor to cricothyroid)
• RLN > near inferior thyroid artery

Question 22

Which vessels of thyroid related to sympathetic trunk?

Answer 22

• Inferior thyroid artery (branch of TCT) runs posterior to sympathetic chain

Question 23

Describe course of recurrent laryngeal nerves

Answer 23

• 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

Question 24

Lymphatic drainage thyroid

Answer 24

• Paratracheal and deep cervical

Question 25

**Which thyroid cancer spreads via lymph**

Answer 25

* Papillary * MC thyroid cancer

Question 26

**Cell of origin of medullary carcinoma**

Answer 26

* Parafollicular C-cells * Produced calcitonin

Question 27

**Where would you perform cricothyroidotomy**

Answer 27

* 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

Question 28

**Why does bronchial carcinoma cause a hoarse voice?**

Answer 28

* Vocal cord paralysis due to pressure effect on RLN

Question 29

**Where are parathyroid glands?**

Answer 29

* 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 1^st tracheal ring * Inferior = medial to RLN at variable position

Question 30

**Development of parathyroid glands?**

Answer 30

* Superior from 4^th pharyngeal pouch * Inferior from 3^rd pharyngeal pouch

Question 31

**Blood supply parathyroid glands**

Answer 31

* Both supplied by inferior thyroid artery

Question 32

**Commonest location of ectopic parathyroid gland?**

Answer 32

* 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%)

Question 33

**Fascial layers of neck and contents**

Answer 33

* 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