Hey, everyone. This is Matt from Kenhub! And in this tutorial, we will discuss the anatomy, innervation, and function of the parotid gland.
The parotid gland, the largest of all three head salivary glands is a pyramidal-shaped gland located in the parotidomasseteric region.
The anatomy and innervation related to the parotid gland is fairly complex, so stay with me, and I’ll break it down as much as possible. As to its function, well, that’s simple. It makes 30% of the saliva produced in the body and drains it into the mouth.
The gland is bilateral, paired, and sits on either side of the face in the preauricular area behind and upon the mandibular ramus. There, it is encapsulated by the masseteric fascia deriving from the deep cervical fascia.
The parotid plexus branches of the facial nerve passes through the parotid gland and divides it into a superficial and deep part but does not innervate it.
The parotid duct, also known as Stensen’s duct, drains the saliva into the oral cavity opposite the upper second molar tooth via the parotid papilla.
In its course, the parotid duct crosses the masseter and pierces through the buccinator. Gland tissues along the parotid duct and lying on the masseter muscle are referred to as accessory parotid glands.
In describing its location in the face, we need to understand its relation to the surrounding anatomy. The parotid is bordered anteriorly by the masseter muscle and the mandibular ramus and superiorly by the external acoustic meatus and the condyle of the mandible and the glenoid fossa.
Posterior to the gland is the mastoid process of the temporal bone and the sternocleidomastoid muscle and inferiorly by the angular tract of Eisler can be found.
On the medial side, which is not covered by the capsule, the styloid process and the transverse process of the atlas are visible. Due to the constant production of saliva, especially during meal times, the parotid gland is well profused.
The maxillary and superficial temporal arteries, two terminal branches of the external carotid artery, provide by the major blood supply. The venous blood drains to the retromandibular or posterior facial vein which runs lateral to the carotid artery.
The parotid gland is innervated by various nerves from different sources. The sensory innervation is provided by the auriculotemporal nerve deriving from the mandibular branch of the trigeminal nerve. The parasympathetic innervation which stimulates the saliva production is carried by the glossopharyngeal nerve to the otic ganglion via the lesser petrosal nerve. From there, the parasympathetic post ganglionic neurons reach the gland via the auriculotemporal nerve. Furthermore, the gland receives sympathetic innervation from direct fibers of the external carotid plexus.