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Questions and Answers
The region situated below and anterior to the ear, and inferior to the zygomatic arch, is identified as the parotid region.
The region situated below and anterior to the ear, and inferior to the zygomatic arch, is identified as the parotid region.
True (A)
The masseter muscle, crucial for mastication, is described as having two distinct heads, fused together on the zygomatic arch.
The masseter muscle, crucial for mastication, is described as having two distinct heads, fused together on the zygomatic arch.
False (B)
The superficial part of the masseter muscle originates from the anterior two-thirds of the superior border of the zygomatic arch.
The superficial part of the masseter muscle originates from the anterior two-thirds of the superior border of the zygomatic arch.
False (B)
Fibres of the superficial part of the masseter muscle slope downwards at an angle of $60°$ relative to the zygomatic arch.
Fibres of the superficial part of the masseter muscle slope downwards at an angle of $60°$ relative to the zygomatic arch.
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The intermediate part of the masseter muscle arises from the distal third of the zygomatic arch.
The intermediate part of the masseter muscle arises from the distal third of the zygomatic arch.
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The masseteric nerve traverses between the superficial and intermediate parts of the masseter muscle.
The masseteric nerve traverses between the superficial and intermediate parts of the masseter muscle.
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A branch from the facial artery is the primary source of blood supply running between the superficial and intermediate parts of the masseter muscle.
A branch from the facial artery is the primary source of blood supply running between the superficial and intermediate parts of the masseter muscle.
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The vessel accompanying the masseteric nerve is recognized as the primary source of blood supply to the masseter muscle.
The vessel accompanying the masseteric nerve is recognized as the primary source of blood supply to the masseter muscle.
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The masseter muscle receives its nerve supply from the masseteric branch originating from the posterior division of the mandibular nerve.
The masseter muscle receives its nerve supply from the masseteric branch originating from the posterior division of the mandibular nerve.
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The parotid gland is characterized as a predominantly mucous salivary gland with a few serous acini.
The parotid gland is characterized as a predominantly mucous salivary gland with a few serous acini.
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The parotid gland is described as having a regular, symmetrical shape due to its well-defined borders.
The parotid gland is described as having a regular, symmetrical shape due to its well-defined borders.
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The parotid sheath, a tough capsule surrounding the gland, is derived from the superficial layer of deep cervical fascia.
The parotid sheath, a tough capsule surrounding the gland, is derived from the superficial layer of deep cervical fascia.
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The lower pole of the parotid gland is positioned superior and anterior to the angle of the mandible.
The lower pole of the parotid gland is positioned superior and anterior to the angle of the mandible.
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The anterior surface of the parotid gland is described as V-shaped, embracing the ramus of the mandible.
The anterior surface of the parotid gland is described as V-shaped, embracing the ramus of the mandible.
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The stylomandibular ligament is situated between the anterior surface of the parotid gland and the masseter muscle.
The stylomandibular ligament is situated between the anterior surface of the parotid gland and the masseter muscle.
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The superficial temporal and internal carotid arteries are terminal branches of the external carotid artery that leave the deeper part of the anterior surface of the parotid gland.
The superficial temporal and internal carotid arteries are terminal branches of the external carotid artery that leave the deeper part of the anterior surface of the parotid gland.
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The internal jugular vein and the external carotid artery are positioned deep to the styloid process in relation to the parotid gland.
The internal jugular vein and the external carotid artery are positioned deep to the styloid process in relation to the parotid gland.
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Within the parotid gland, the retromandibular vein is situated more superficially than the facial nerve.
Within the parotid gland, the retromandibular vein is situated more superficially than the facial nerve.
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The parotid duct, also known as Wharton's duct, is approximately 5 cm in length.
The parotid duct, also known as Wharton's duct, is approximately 5 cm in length.
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Secretomotor fibers to the parotid gland originate from cell bodies within the ciliary ganglion, reaching the gland via the auriculotemporal nerve.
Secretomotor fibers to the parotid gland originate from cell bodies within the ciliary ganglion, reaching the gland via the auriculotemporal nerve.
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The parotid gland's sensory innervation is derived from the great auricular nerve (C2), while the parotid fascia receives sensory fibers from the auriculotemporal nerve.
The parotid gland's sensory innervation is derived from the great auricular nerve (C2), while the parotid fascia receives sensory fibers from the auriculotemporal nerve.
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The parotid gland, unlike other major salivary glands, is characterized histologically by predominantly mucous acini, few ducts, and a sparse distribution of fat cells.
The parotid gland, unlike other major salivary glands, is characterized histologically by predominantly mucous acini, few ducts, and a sparse distribution of fat cells.
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The submandibular gland contains a mixture of serous and mucous acini, including mucous acini with serous demilunes, and has fewer ducts compared to the parotid gland.
The submandibular gland contains a mixture of serous and mucous acini, including mucous acini with serous demilunes, and has fewer ducts compared to the parotid gland.
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The sublingual gland is composed almost entirely of serous acini and has numerous ducts.
The sublingual gland is composed almost entirely of serous acini and has numerous ducts.
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The parotid gland develops from a groove in the cheek (ectoderm) that transforms into a tunnel, with cell proliferation at the blind end forming the gland.
The parotid gland develops from a groove in the cheek (ectoderm) that transforms into a tunnel, with cell proliferation at the blind end forming the gland.
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A parotidectomy involves navigating the trigeminal nerve.
A parotidectomy involves navigating the trigeminal nerve.
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The skin incision during a parotidectomy includes the platysma muscle.
The skin incision during a parotidectomy includes the platysma muscle.
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The facial nerve trunk is accessed posterior to the anterior margin of the external meatus cartilage, superior to the stylohyoid and digastric muscles.
The facial nerve trunk is accessed posterior to the anterior margin of the external meatus cartilage, superior to the stylohyoid and digastric muscles.
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The stylomastoid branch of the posterior auricular artery lies superficial to the facial nerve and serves as a landmark for its location.
The stylomastoid branch of the posterior auricular artery lies superficial to the facial nerve and serves as a landmark for its location.
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A total parotidectomy, unlike a superficial parotidectomy, might involve fracturing the zygomatic process and dividing the sphenomandibular ligament.
A total parotidectomy, unlike a superficial parotidectomy, might involve fracturing the zygomatic process and dividing the sphenomandibular ligament.
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Study Notes
Parotid Region Anatomy
- The parotid region is located below and in front of the ear, and below the zygomatic arch.
- Key features include the parotid gland and masseter muscle (part of the mastication group).
Masseter Muscle
- The masseter muscle arises from the zygomatic arch.
- Structurally contains three heads (though typically described as two), which are fused on the arch.
- Anteriorly, the three sets fuse. Posteriorly, they diverge to allow for the passage of the masseteric nerve and artery.
- The superficial part is the largest, arising from the anterior two-thirds of the zygomatic arch. Its fibers slope down 45 degrees and insert into a wide area of the mandible's lower border and ramus.
- The upper part of the muscle is covered by aponeurotic fibers to slide over structures, while the lower portion is fleshy.
- Middle and deep parts arise from the middle and deep surfaces of the arch respectively, inserting vertically downwards into the mandibular ramus. Their insertions fuse with superficial fibers anteriorly but remain separate posteriorly.
- The masseteric nerve passes between the deep and intermediate parts, and a branch of the superficial temporal/transverse facial artery runs between the superficial and intermediate parts.
- The artery is the primary blood supply, and the artery accompanying the nerve is smaller.
- Nerve supply: masseteric branch of the mandibular nerve's anterior division.
- Action: Closes the jaw, elevates and pulls forward the angle of the mandible.
Parotid Gland
- Predominantly serous salivary gland, with few mucous acini.
- Irregular shape, filling the space between the mastoid process, mandibular ramus, and styloid process.
- Regions include upper and lower poles, lateral, anterior, and deep surfaces.
- Enclosed by a tough capsule called the parotid sheath (part of the deep cervical fascia).
- Mumps (viral infection) causes swelling within the tight fibrous capsule.
- Upper pole: small, concave, adheres to the external acoustic meatus cartilage, adjacent to the temporomandibular joint capsule.
- Lower pole: rounded, below/behind mandible angle, indented by mandible & sternocleidomastoid. Overlaps the posterior belly of digastric.
- Lateral surface: subcutaneous and almost flat.
- Anterior surface: U-shaped, wraps around mandibular ramus, with masseter externally and medial pterygoid internally. Stylomandibular ligament separates it from medial pterygoid and submandibular gland. Anterolateral border is formed by merging of the lateral and anterior surfaces.
- Deep surface (posteromedial): irregular and complex, indented by mastoid process/muscles, styloid process/muscles/ligaments. External carotid artery enters the gland through the lower part. Styloid process separates it from internal jugular vein and internal carotid artery. Facial nerve branches enter between styloid and mastoid processes.
- Contents (superficial to deep): facial nerve, retromandibular vein, external carotid artery.
- Branches from facial nerve emerge behind the anterior border.
- The external carotid artery and its branches are the deepest.
- The gland also contains preauricular lymph nodes, and filaments of auriculotemporal nerve with secretomotor fibers.
- Lymph drainage to lymph nodes within the parotid sheath, then to cervical nodes with the external carotid artery.
Parotid Duct
-
5 cm long (Stensen's duct).
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Passes across masseter, around its anterior border, and pierces the buccinator.
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Palpable between the intertragic notch and the philtrum midpoint.
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Opens on the cheek's mucous membrane opposite the second upper molar.
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A valve-like flap prevents gland inflation during intraoral pressure.
Accessory Parotid Gland
- Usually located on the masseter, between duct and zygomatic arch.
- Several ducts connect it to the parotid duct.
- Located on the tendinous portion of masseter.
Blood Supply
- Branches from the external carotid artery.
- Venous return to the retromandibular vein.
Nerve Supply
- Secretomotor fibers: otic ganglion via auriculotemporal nerve. Pre-ganglionic fibers from inferior salivary nucleus in medulla via glossopharyngeal nerve, tympanic branch, tympanic plexus, and lesser petrosal nerve.
- Sympathetic fibers (vasoconstrictor): superior cervical ganglion via external carotid and middle meningeal artery plexus.
- Sensory fibers: auriculotemporal nerve. Parotid fascia receives sensory innervation from great auricular nerve (C2).
Development
- An ectodermal groove in the cheek becomes a tunnel; cell proliferation forms the gland.
Surgical Approach (Parotidectomy)
- S-shaped incision (in front of ear, back to mastoid, down/forward below mandible angle).
- Skin incision includes platysma.
- Gland retracted forward to expose posterior digastric, stylohyoid, & external meatus cartilage.
- Facial nerve approached in front of cartilage; stylomastoid branch (posterior auricular artery) is a superficial guide.
- Cartilage arrowhead points toward nerve.
- Parotid duct divided at masseter's anterior border.
- Total parotidectomy involves dissecting further, ligating external carotid, superficial temporal, maxillary arteries and veins. Styloid process may need fracturing, stylo-mandibular ligament may need division.
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Description
Explore the anatomy of the parotid region, located below and in front of the ear. This quiz covers key features, including the parotid gland and the structure of the masseter muscle. Test your knowledge of the anatomy involved in mastication and the relevant muscle functions.
