Facial Blood Supply, Salivary Glands, Mastication Muscles, Submandibular Region
Facial Blood Supply Facial artery § § §
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Branch of external carotid a. Runs forward over digastric and submandibular gland Loops around mandible (where it is palpable), at anterior border of masseter, to enter the face Follows a tortuous course to medial angle of eye Lies deep to most facial muscles Branches - Inferior labial a. - Superior labial a. - Angular a.
Superficial temporal a. § §
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Terminal branch of external carotid a. Ascends in front of ear (where it is palpable) to supply temporal and anterior portion of scalp Transverse facial a. - runs above parotid duct to supply the cheek region medial to neck of mandible
3.
Maxillary artery § § §
Branch of external carotid a. Entrance to infratemporal fossa medial to neck of mandible Branches - Inferior alveolar a. - Middle meningeal a. • Enters skull foremen spinosum • Supplies cranium and dura - Posterior superior alveolar a. - Ophthalmic artery - Middle meningeal a. • Supratrochlear • Supraorbital
Venous drainage § § § § §
Vein follow the arteries and drain into common facial vein and retromandibular vein Deep connections of facial veinCommunication between supraorbital & superior ophthalmic vein With pterigoid plexus of vein through deep facial vein. Superior ophthalmic vein & ptergoid plexus of vein communicate with cavernous sinus
Facial vein • • •
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Begins at medial angle of eye (angular vein) Runs downward and backward through the face, posterior to the facial artery Below angle of mandible, joins anterior branch of retromandibular vein to form common facial vein, which drains into internal jugular vein Connections with cavernous sinus through the ophthalmic vein, and also through pteygoid plexus via the deep facial vein
“Danger area:” lies between root of nose and two angles of mouth; in this area the facial vein has no valves Retromandibular vein § §
Formed by union of superficial temporal and maxillary veins Divides into an anterior branch that unites with facial vein and a posterior branch that joins posterior auricular vein to become external jugular vein
Pterygoid plexus § § §
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Located between and around muscles of mastication Receives blood from all regions supplied by maxillary a. Communicates with - Face by deep facial veins - Cavernous sinus by veins draining base of skull Provides possible pathway for spread of infection to cranial cavity
Parotid gland: The parotid gland is the largest of the salivary glands. It is found wrapped around the mandibular ramus, and it secretes saliva through Stensen’s duct into the oral cavity, to facilitate mastication and swallowing The parotid gland is found overlying the mandibular ramus and anterior and inferior to the external ear. The gland occupies the parotid fascial space, an area posterior to the mandibular ramus, anterior and inferior to the ear. The gland extends irregularly from the zygomatic arch to the angle of the mandible. This gland is effectively palpated (can be felt) bilaterally. Start anterior to each ear and move to the cheek area and then inferior to the angle of the mandible.
Above the parotid gland lies the external auditory meatus and temporo-mandibular joint. Below, the parotid overlaps the posterior belly of the digastric. Medially lies the styloid process. Posteriorly, the parotid overflows the sternocleidomastoid and anteriorly it overlies the mandible with the overlying masseter. The parotid gland resembles a three sided pyramid. The apex of the pyramid is directed downwards. the gland has four surfaces: (1) superior (2) superficial (3) anteromedial & (4) posteromedial. The surfaces are separated by three borders: (1) anterior (2) posterior & (3) medial Structures which pass through parotid gland: § §
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The facial nerve and its branches run through the gland superficial to the retromandibular vein The external carotid artery, which gives off its two terminal branches, the maxillary artery and the superficial temporal artery, inside the gland The retromandibular vein
Submaxillary Gland §
Mostly situated in the submaxillary triangle, reaching forward to the anterior belly of the Digastric and backward to the stylomandibular ligament, which intervenes between it and the parotid gland.
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Submaxillary duct (Wharton’s duct) is about 5 cm. long, and begins by numerous branches from the deep surface of the gland, and runs forward between and opens by a narrow orifice on the summit of a small papilla, at the side of the lingual frenulum.
Sublingual Gland §
Beneath the mucous membrane of the floor of the
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Sublingual duct (Bartholin’s duct), opens into the submaxillary duct
Muscles of Mastication Mastication is accomplished through the activity of the four muscles of mastication. Each of these primary muscles of mastication is paired, with each side of the mandible possessing one of the four. § § § §
The masseter The temporalis The medial pterygoid The lateral pterygoid
Unlike most of the other facial muscles, which are innervated by the facial nerve (CN VII) the muscles of mastication are all innervated by the mandibular branch (V3) of the trigeminal nerve. This is a testament to their shared embryological origin from the first branchial arch. Masseter Quadrangular muscle covering lateral aspect of ramus; coronoid process of mandible. Origin: Inferior border & medial surface of zygomatic arch Insertion: Lateral surface of ramus of mandible & coronoid process Innervation: Mandibular nerve via masseteric nerve Action: Elevates, protrudes mandible closes jaws; Deep fibres retrude mandible Temporalis Extensive fan-shaped muscle covering temporal region. Powerful masticatory muscle. Origin: Floor of temporal fossa and Deep surface of temporal fascia Insertion: Tip & medial surface of coronoid process, Anterior border mandible ramus Action: Elevates mandible- closing jaws; Posterior fibers retrude mandible after protrusion
Medial Pterygoid Thick, quadrilateral muscle that also has two heads of origin, Embraces inferior head of lateral pterygoid muscle, It is located deep to ramus of mandible Origin: Deep head - medial surface of lateral pterygoid plate; pyramidal process of palatine bone; Superficial head - tuberosity of maxilla. Insertion: Medial surface of ramus of mandible, inferior to mandibular foramen Innervation: Mandibular nerve via medial pterygoid nerve Actions: Elevates mandible-closes jaw; Acting together protrude mandible; Acting alone protrudes side of jaw; Acting alternately produce grinding motion Lateral Pterygoid Short, thick muscle having two heads of origin, Is a conical muscle with its apex pointing posteriorly Origin: Superior head - infratemporal surface & infratemporal crest of greater wing of sphenoid bone; Inferior head - Lateral surface of lateral pterygoid plate Insertion: Lower head - to neck of mandibular condyle; Upper head - to articular disc capsule of TM joint Innervation: Mandibular nerve via lateral pterygoid nerve from anterior trunk Action: Acting together - protrude mandible and depress chin; Acting alone & alternately- produce side-to-side movements of mandible Cervical Triangles The side of the neck presents a somewhat quadrilateral outline, limited, above, by the lower border of the body of the mandible, and an imaginary line extending from the angle of the mandible to the mastoid process; below, by the upper border of the clavicle; in front, by the middle line of the neck; behind, by the anterior margin of the Trapezius. This space is subdivided into two large triangles by the Sternocleidomastoid, which passes obliquely across the neck, from the sternum and clavicle below, to the mastoid process and occipital bone above. The triangular space in front of this muscle is called the anterior triangle; and that behind it, the posterior triangle.
The anterior triangle is bounded, in front, by the middle line of the neck; behind, by the anterior margin of the Sternocleidomastoid; its base, directed upward, is formed by the lower border of the body of the mandible, and a line extending from the angle of the mandible to the mastoid process; its apex is below, at the sternum. This space is subdivided into four smaller triangles by the Digastric above, and the superior belly of the The external and internal carotids lie side by side, the external being the more anterior of the two. The following branches of the external carotid are also met with in this space: the superior thyroid, running forward and downward; the lingual, directly forward; the external maxillary, forward and upward; the occipital, backward; and the ascending pharyngeal, directly upward on the medial side of the internal carotid. The veins met with are: the internal jugular, which lies on the lateral side of the common and internal carotid arteries; and veins corresponding to the above-mentioned branches of the external carotid— the superior thyroid, the lingual, common facial, ascending pharyngeal, and sometimes the occipital—all of which end in the internal jugular. The nerves in this space are the following. The hypoglossal nerve crosses both the internal and external carotids above, curving around the origin of the occipital artery. Within the sheath, between the artery and vein, and behind both, is the vagus nerve; behind the sheath, the sympathetic trunk. On the lateral side of the vessels, the accessory nerve runs for a short distance before it pierces the Sternocleidomastoid; and on the medial side of the external carotid, just below the hyoid bone, may be seen the internal branch of the superior laryngeal nerve; and, still more inferiorly, the external branch of the same nerve. The upper portion of the larynx and lower portion of the pharynx are also found in the front part of this space.
The posterior triangle is bounded, in front, by the Sternocleidomastoid; behind, by the anterior margin of the Trapezius; its base is formed by the middle third of the clavicle; its apex, by the occipital bone. The space is crossed, about 2.5 cm. above the clavicle, by the inferior belly of the omohyoid. The submaxillary or digastric triangle corresponds to the region of the neck immediately beneath the body of the mandible. It is bounded, above, by the lower border of the body of the mandible, and a line drawn from its angle to the mastoid process;below, by the posterior belly of the Digastricus and the Its floor is formed by the Mylohyoideus, Hyoglossus, and constrictor pharyngis superior. It is divided into an anterior and a posterior part by the stylomandibular ligament. The anterior part contains the submaxillary gland, superficial to which is the anterior facial vein, while imbedded in the gland is the external maxillary artery and its glandular branches; beneath the gland, on the surface of the mylohyoideus, are the submental artery and the mylohyoid artery and nerve. The posterior part of this triangle contains the external carotid artery, ascending deeply in the substance of the parotid gland; this vessel lies here in front of, and superficial to, the internal carotid, being crossed by the facial nerve, and gives off in its course the posterior auricular, superficial temporal, and internal maxillary branches: more deeply are the internal carotid, the internal jugular vein, and the vagus nerve, separated from the external carotid by the styloglossus and stylopharyngeus, and the glossopharyngeal nerve.
Suggested Reading: Wexler A. (2008) Craniofacial Anatomy. In Thaller S, Bradley J, Garri J: Craniofacial Surgery (pp. 7-40). New York: Informa Healthcare USA. Netter F. Atlas of Human Anatomy. Grey H and Lewis W: Grey’s Anatomy 12th Edition. Philadelphia: Lea & Febiger, 1918. New York, Bartleby.com, 2000. Available at: http://www.bartleby.com/107/ Â