Head And Neck Glands

Thyroid gland

• Two symmetrical lobes connected by isthmus
• Contained within pretracheal fascia
• Sit in front of the second, third and fourth tracheal rings
• Development
• Begins on the floor of the early pharynx
• Descends to its adult position
• Thyroglossal duct develops from the foramen caecum of the tongue
• Descends between the first and second pharyngeal arches to the opening of the trachea

• Arterial supply
• Superior thyroid artery (branch of the external carotid)
• Inferior thyroid artery (branch of the thyrocervical trunk from the subclavian)
• Thyroidea ima artery (present in only 3% people)
• Venous drainage
• Superior thyroid vein (enters internal jugular or facial vein)
• Middle thyroid (enters internal jugular)
• Inferior thyroid (forms a plexus draining into the left brachiocephalic vein)

• The recurrent laryngeal nerve is closely associated with the inferior thyroid artery and passes behind the middle part of the glands lobes to enter the larynx

• The external laryngeal nerve runs alongside the superior thyroid artery
• The thyroid moves upwards with the larynx on swallowing

Submandibular gland

• Mixed mucous and serous gland
• Large superficial and small deep parts
• Embryology: develops as a tubular endodermal outgrowth from the floor of the mouth

• Submandibular duct emerges from the superficial part and runs between the mylohyoid and the hyoglossus (which is overlies)

• Opens into the floor of the mouth beside the frenulum
• Related to the facial artery antero-superiorly

• Parasympathetic secretomotor fibres derive from the chorda tympani and synapse in the submandibular ganglion with postganglionic fibres which directly reach the gland

Parotid gland

• Serous gland
• Enclosed in tough capsule derived from cervical fascia

• Located between the mastoid process, the sternomastoid, ramus of the mandible and the styloid process

• Positioned behind the temporomandibular joint
• Associated with (superficial to deep)
• Facial nerve (divides into 5 terminal branches within the gland)
• Retromandibular vein
• External carotid and its branches

• Auriculotemporal nerve (postganglionic parasympathetic fibres from the otic ganglion and inferior salivatory nucleus. The preganglionic fibres are from the lesser petrosal nerve of the glossopharyngeal)

• Parotid emerges anteriorly and opens opposite the second upper molar