Note: The parotid gland is found at the inferolateral aspect of the face. The gland is located in the parotid fossa, an irregular space bordered by the ramus of the mandible and masseter m. anteriorly, the mastoid process and sternocleidomastoid m. posteriorly, the temporomandibular joint (TMJ) and external acoustic meatus superiorly, and the angular tract (a thick band of connective tissue, extending from the angle of the mandible to the hyoid bone) inferiorly.

Note: Parotid fascia invests the parotid gland. The parotid gland contains branches of the facial n. (CN VII), which innervate facial mm.

Note: The parotid gland is innervated by preganglionic parasympathetic fibers originating in the glossopharyngeal n. (glossopharyngeal n. → tympanic n. → lesser petrosal n.). These fibers synapse in the otic ganglion, which is associated in location with the deep portion of the mandibular n. (V3) trunk, just inferior to the foramen ovale. Postganglionic fibers are transmitted to the parotid gland via the auriculotemporal n. (of V3).

2.) Locate the proximal portion of the parotid (Stensen’s) duct as it exits the parotid gland. Small branches of the facial n. (CN VII) will likely also be visible in this area. Do NOT dissect or follow the duct or facial n. branches at this time. Occasionally, a small accessory parotid gland is present.

Note: The parotid (Stensen’s) duct typically arises at the anterior border of the parotid gland, travels superficial to the masseter m., and dives deep to (and through) the buccinator m. The parotid duct is variable in path and size, but is typically 1-3 mm in diameter. The parotid duct conducts saliva from the parotid gland, through the buccinator m., opening through the papilla of parotid (Stensen’s) duct opposite the maxillary second molars.

Note: The facial n. exits the stylomastoid foramen, then divides into two divisions: the temporofacial division (superiorly) and the cervicofacial division (inferiorly). The temporofacial division typically gives rise to the temporal brs., zygomatic brs., and a portion of the buccal brs. The cervicofacial division typically gives rise to a portion of the buccal brs., marginal mandibular br., and the cervical br.

Note: The stylomastoid foramen is between the mastoid and styloid processes of the temporal bone, and transmits the facial n.

Note: Accessory parotid glands, if present, are typically located between the zygomatic arch superiorly and parotid duct inferiorly. These glands can be attached to the parotid gland proper, or more commonly detached.

Photo 2. Parotid gland with proximal portions of facial n. brs.

3.) Look into the the oral cavity of the donor. At approximately the level of the 2nd maxillary molars, locate the papilla of parotid gland of the oral mucosa.

Photo 3. Papilla of parotid duct

Locate neurovasculature superior to parotid gland and posterior to ear

Find these structures:

• Auriculotemporal n.

• Superficial temporal a. & v.

• Posterior auricular a. & v.

• Occipital a.

4.) Using blunt dissection superior to the parotid gland, locate the auriculotemporal n. and superficial temporal a. & v.

Note: The auriculotemporal n. is a branch of the mandibular n. (V3). The auriculotemporal n. serves three functions, germane to this lab:

1. transmitting secretomotor postganglionic parasympathetic fibers to the parotid gland (from the otic ganglion; preganglionic fibers from glossopharyngeal n.),

2. afferently serving the temporomandibular joint, and

3. afferently serving the skin of the: tragus of the ear, the external auditory meatus, and the area anterosuperior to the ear. 

Note: The cutaneous portion of the auriculotemporal n. may be found just posterior to, and accompanying, the superficial temporal a. and v. superiorly from the parotid gland.

Note: The superficial temporal a. and the maxillary a. are the terminal branches of external carotid a. The superficial temporal v. and the maxillary v. join to form the retromandibular v. The proximal portions of the superficial temporal a. & v. are located within the parotid gland.

Photo 4. Auriculotemporal n., cutaneous portion and superficial temporal a. & v.

5.) Locate the posterior auricular a. and occipital a. With removal of the trapezius in previous labs the occipital a. may have been removed.

Note: Posterior auricular a. can be located just posterior to the ear, and often anastomoses with the occipital a., which is more posteriorly located on the back of the scalp. The occipital a. is located with the greater occipital n., a branch of the dorsal primary ramus of spinal n. C2. Both the posterior auricular a. and occipital a. are branches of external carotid a.

Note: Posterior auricular a. supplies muscles in the anterior neck, including posterior belly of digastric m., sternocleidomastoid m., and stylohyoid m., as well as the parotid gland. The occipital a. supplies portions of the posterior scalp and neck, as well as lateral neck.

Photo 5. Origins of posterior auricular and occipital aa.

Unilaterally, complete a deep dissection of the parotid gland

Find these structures:

• Facial n. (CN VII)

• Retromandibular v.

  • Superficial temporal v.

  • Maxillary v.

• External jugular v.

  • Posterior auricular v.

• Internal jugular v.

  • Facial v.

6.) For the deep dissection, carefully remove portions of the parotid gland with blunt dissection. Trace facial n. branches to the temporofacial and cervicofacial divisions, and follow these divisions until they condense as a main trunk. Continue to trace the main trunk of the facial n. until you reach its emergence from the skull at the stylomastoid foramen. Alternatively, you could directly locate the stylomastoid foramen using targeted, blunt dissection, and then trace the main trunk of the facial n. toward the face.

Note: Three neurovascular structures typically travel through the the parotid gland (anterior to the external auditory meatus). From superficial-to-deep, they are the:

• facial n. (CN VII),

• retromandibular v., and

• external carotid a.

Photo 6. Facial n. emerging from the stylomastoid foramen

7.) Locate the retromandibular v., and follow it to the potential junctions with: 1) the facial v. (into the internal jugular v.), and 2) the posterior auricular v. (to form the external jugular v.).

Note: The superficial temporal v. typically unites with the maxillary v. to form the retromandibular v. The maxillary v. is a short vein formed by the coalescence of numerous veins of the pterygoid plexus. It accompanies the maxillary a.

Photo 7. Superficial temporal + maxillary v. = retromandibular v.

Note: The retromandibular v. may divide into anterior and posterior divisions. The anterior division of the retromandibular v. typically unites with the facial v. before joining with the internal jugular v. The posterior division of the retromandibular v. typically unites with the posterior auricular v. to form the external jugular v.

Photo 8. Retromandibular v.; anterior and posterior divisions

Clean and locate the muscles and submandibular gland in the deep neck

Find these structures:

• Digastric m.

  • Anterior belly

  • Posterior belly

• Stylohyoid m.

• Mylohyoid m.

• Hyoglossus m.

• Submandibular gland

• External carotid a.

  • Superior thyroid a.

    • Superior laryngeal a.

  • Ascending pharyngeal a.

  • Lingual a.

  • Facial a.

8.) Clean the anterior and posterior bellies of the digastric m.

Note: The digastric m. consists of two bellies (anterior and posterior) connected by an intermediate tendon. The anterior belly attaches to the mandible, the posterior belly attaches to the temporal bone, and the intermediate tendon anchors to the hyoid bone via a fibrous loop. Formed from the mesenchyme of the 1st (anterior) and 2nd (posterior) pharyngeal arches, each belly is separately innervated. The anterior belly is innervated by the nerve to mylohyoid (a branch of inferior alveolar n.,V3), whereas the posterior belly is innervated by the facial n. (CN VII). The digastric m. may either weakly depress the mandible, or elevate the hyoid bone.

Note: The submandibular (digastric) triangle is the most superior region of the anterior cervical triangle. It is bordered inferiorly by the anterior and posterior bellies of the digastric m., and superiorly by the mandible; typically contains the submandibular gland and the facial a. & v.

Photo 9. Submandibular triangle

9.) Within the submandibular triangle, locate the superficial part of the submandibular gland.

Note: The submandibular gland is one of the three main salivary glands (parotid, submandibular, and sublingual glands), and is innervated by postganglionic branches from the submandibular ganglion. Presynaptic (preganglionic) parasympathetics are derived from the chorda tympani n. (CN VII).The superficial portion of this gland is located in the submandibular triangle near the angle of the mandible.

Photo 10. Suprahyoid mm.

10.) Locate the facial a.

Note: The facial a. traverses the submandibular triangle before emerging over the body of the mandible (anterior to the masseter m.), accompanied by the facial v., deep to the branches of the facial n. The artery ascends and supplies structures of the face.

Photo 11. Facial a. & v.

11.) Identify any submandibular and submental lymph nodes in this area. Recall that lymph nodes are often difficult to distinguish and are easily removed during other dissection procedures, such as skinning or during reflection of muscles.

Note: There are typically three submandibular nodes: one is typically located anterior to the superficial part of the submandibular gland, while the other two are positioned on either side of the facial a. near the ramus of the mandible. Many smaller lymph vessels from a wide area drain into the submandibular lymph nodes (nose, cheek, upper and lateral lip areas).

Note: Submental nodes are located in the submental triangle and drain the structures within the submental triangles on the inferior portion of the mylohyoid mm, and will drain into either the submandibular or jugulo-omohyoid nodes.

Photo 12. Submandibular and submental lymph nodes

12.) Clean the stylohyoid m., and observe the muscle’s attachment sites.

Note: The stylohyoid m. is located medial and parallel to the posterior belly of digastric m. The stylohyoid m. belly divides around the intermediate tendon of the digastric m. Like the posterior belly of the digastric m., the stylohyoid m. is innervated by the facial n. (CN VII). It elevates the hyoid bone.

Photo 13. Stylohyoid m.

13.) Cut the intermediate tendon of the digastric m. Reflect the posterior belly of the digastric m. superolaterally. In addition, relieve the stylohyoid m. from the hyoid bone, and reflect it superiorly. The retromandibular v. may also be reflected superiorly.

Photo 14. Procedural: cutting the intermediate tendon on the digastric m.

14.) Locate the terminal branches of external carotid a.: maxillary a. and superficial temporal a. Recall that the superficial temporal a. was located superior to the parotid gland earlier in this lab.

Photo 15. Terminal branches of the external carotid a.

Note: The maxillary a. is significantly larger than the superficial temporal a., but will be better visualized during dissection of the infratemporal fossa. The maxillary a. extends from the external carotid a. to the pterygopalatine fossa, and has three parts: mandibular, pterygoid, and pterygopalatine.

15.) Locate as many of the branches of the external carotid a. as possible. Specifically locate: superior thyroid a. (and nearby superior thyroid v.), lingual a., and facial a.

Note: The external carotid a. is the primary source of blood to the face and superficial head. The external carotid has eight branches:

• superior thyroid a.,

• ascending pharyngeal a.,

• lingual a.,

• facial a.,

• occipital a.,

• posterior auricular a.,

• maxillary a.,

• superficial temporal a.,

which may be remembered by the mnemonic: “Some Anatomists Like Freaking Out Poor Medical Students.”

Note: The superior thyroid a. is typically the first anterior branch of the external carotid a., and descends to the thyroid gland. The superior laryngeal a. is a branch of the superior thyroid a., and accompanies the internal br. of superior laryngeal n. through the thyrohyoid membrane.

Photo 16. Superior thyroid a.

Note: The lingual a. and facial a. are anterior branches of the external carotid a, and are typically the largest of the proximal external carotid branches. The facial a. may branch from the external carotid a. in a common branch with, or just superior to, the lingual a. The lingual a. can be seen in this area passing deep to the hyoglossus m. to supply the majority of the floor of the mouth and tongue. This artery will be further dissected in the oral cavity.

Photo 17. Facial and lingual aa.

16.) Locate the hypoglossal n. (CN XII) in association with the facial a. as it passes deep to the mylohyoid m.

Note: The hypoglossal n. (CN XII) provides efferent innervation to nearly all extrinsic and intrinsic muscles of the tongue, excluding palatoglossus m. (innervated by the vagus n., CN X).

Photo 18. Hypoglossal n. (CN XII), facial a., mylohyoid m.

17.) Deep to the hypoglossal n. (CN XII) and the mylohyoid m., identify the hyoglossus m. The mylohyoid m. and submandibular gland may need to be reflected, for this identification. If needed, relieve the mylohyoid m. from its attachment to the mandible (mylohyoid line), and reflect towards the hyoid. The submandibular gland can be reflected superiorly. Retain all neurovasculature in this area.

Note: The hyoglossus m. extends from the greater horn and body of the hyoid bone to the side of the tongue. When contracted, the hyoglossus depresses the side of the tongue and retracts the tongue.

Photo 19. Hyoglossus m., deep to hypoglossal n. (CN XII)

Locate features of the nose and mouth

Find these structures:

• Ala of the nose

• Nasal columella

• Philtrum

• Nasolabial fold

• Mentolabial fold

18.) Examine the external features of the nose, and appreciate the relationship between the nose and the upper lip.

Note: The nostrils are surrounded by cartilage-supported lateral arches called the ala of nose. ‘Ala’ (L) is a wing or wing-like structure.  

Note: The nasal columella is the skin-covered external portion of the nasal septum.

Note: The philtrum is the region of the upper lip between the nasal columella and the vermilion border. The philtrum is bounded laterally by philtral ridges.

Photo 20. Nose

Note: When present, nasolabial folds extend from lateral to the nose and curve toward the angles of the mouth. They are often referred to as ‘smile lines,’ and often deepen with age.

Note: When present, the mentolabial fold is a horizontal cleft between the lower lip and the chin.

Photo 21. Nose and mouth

Skin the face

19.) Remove the remainder of the skin from the face. Do not skin the nose or ears. Skin near the eyes, but do not skin the (palpebral parts of the orbicularis oculi m.) eyelids.

Note: The skin of the face rests upon a layer of fibro-adipose tissue of various depths, which is superficial to the superficial musculo-aponeurotic system (SMAS), a fascial layer that invests the muscles of facial expression to a variable extent. The SMAS extends from the platysma mm. of the cervical region to the epicranial aponeurosis of the cranium. Branches of the facial n. (CN VII) are found deep to the SMAS. The fibro-adipose tissue is rich with dense connective tissues, thus allowing the facial muscles to move and shape the skin of the face.

Photo 22. Procedural: skinned face

20.) Review the location of the parotid gland from the previous session. Locate facial n. brs. and the parotid duct emerging from the anterior margin of the parotid.

Photo 23. Parotid gland, with proximal portions of facial n. brs.

21.) Determine a dissection plan for each side of the face: a superficial dissection (which will retain the facial n. branches, and include facial mm.) and a deep dissection (which will include facial mm. and cutaneous nn.).

Clean the fascia of the superficial face, and locate branches of the facial (CN VII) n., superficial side

Find these structures:

• Facial n. (CN VII) brs.

  • Temporal brs.

  • Zygomatic brs.

  • Buccal brs.

  • Marginal mandibular br.

  • Cervical br. (seen previously)

• Parotid duct

5.) Trace and clean the facial n. branches to their distal connections and reaches. Often it is difficult to distinguish facial n. brs. and the tough, fibro-adipose tissue in this area. Superficial, medial portions of the parotid gland may be removed to find larger trunks of the facial n., in order to better trace the smaller, distal connections. Make sure to retain the bulk of the parotid gland on this section of the head. Try to preserve any connections among these branches, especially in the vicinity of the buccal brs. As you work medially from the parotid, locate the parotid (Stensen’s) duct, and clean the duct to its course through the buccinator m.

Photo 24. Parotid gland, duct, and facial n. brs.

Note: The facial n. exits the stylomastoid foramen, then divides into two divisions: the temporofacial division (superiorly) and the cervicofacial division (inferiorly). These divisions and their branches course through the parotid gland. The temporofacial division typically gives rise to the temporal brs., zygomatic brs., and a portion of the buccal brs. The cervicofacial division typically gives rise to a portion of the buccal brs., marginal mandibular br., and the cervical br.

Note: The stylomastoid foramen sits between the mastoid and styloid processes of the temporal bone, and transmits the facial n.

Note: The parotid duct typically arises at the anterior border of the parotid gland, travels superficial to the masseter m., dives into the buccal fascial space, and then pierces the buccinator m. The parotid duct is variable in path and size, but is typically 1-3 mm in diameter. The parotid duct conducts saliva from the parotid gland, through the buccinator m., opening through a papilla of mucosa opposite the maxillary second molars.  

Photo 25. Facial n. brs. and divisions

Locate and remove fascia from the facial muscles

22.) While mindful of the facial n. brs. and parotid duct, clean any remaining subcutaneous fibro-adipose tissue from the SMAS to reveal the craniofacial and epicranial muscles.

Note: Muscles of the superficial head fall into two major groups: epicranial and craniofacial. Epicranial muscles are few, primarily act upon the scalp, and are best represented by the occipitofrontalis m.: a muscle with two bellies (frontal and occipital) connected by an intermediate epicranial aponeurosis. Craniofacial muscles are located in the facial region and are often referred to as muscles of facial expression, as they move the skin of the face.

Find these structures:

• Epicranial muscles

  • Occipitofrontalis m.

    • Frontal belly

    • Epicranial aponeurosis

    • Occipital belly

• Craniofacial muscles (of facial expression)

  • Orbicularis oculi m.

    • Orbital part

  • Corrugator supercilii m.

  • Buccinator m.

  • Orbicularis oris m.

  • Levator labii superioris m.

  • Levator anguli oris m.

  • Zygomaticus major m.

  • Zygomaticus minor m.

  • Risorius m.

  • Depressor anguli oris m.

  • Depressor labii inferioris m.

  • Mentalis m.

  • Nasalis m.

    • Transverse part (compressor naris m.)

    • Alar part (dilator naris m.)

  • Levator labii superioris alaeque nasi m.

Note: The frontal belly of the occipitofrontalis m. is sometimes referred to as the frontalis m. It connects the skin of the brow with the epicranial aponeurosis. When active, the frontal belly moves the brow superiorly and creases the forehead. The frontal belly is innervated by temporal brs. of the facial n. The occipital belly is sometime referred to as the occipitalis m., and connects the epicranial aponeurosis to the superior nuchal line of the occipital bone. The occipital belly is innervated by the posterior auricular br. of the facial n.

Note: Many of the upper motor neurons of the temporofacial division originate bilaterally in the cerebral cortex, whereas the upper motor neurons for the cervicofacial division are sourced in the contralateral cerebral cortex. A cerebrovascular accident (CVA, or a stroke) may typically present with contralateral facial muscle paralysis of the lower face, whereas facial n. (Bell’s) palsy typically presents with total ipsilateral facial muscle paralysis. Thus, an individual suffering a CVA may be able to elevate the skin of their brow (wrinkle the forehead), whereas an individual with a facial n. palsy cannot elevate the skin of their brow.

Photo 26. Frontal belly & epicranial aponeurosis of occipitofrontalis m.

Photo 27. Frontal belly, epicranial aponeurosis, and occipital belly of occipitofrontalis m.

Note: A series of three muscles, auricularis anterior, superior, & posterior, attach the auricle of the ear to either the epicranial aponeurosis (anterior & superior mm.), or the mastoid process (posterior m.). The auricularis muscles are typically quite gracile, and often greatly atrophy with age. When activated, the auricularis mm. pull on the auricle of the ear (wiggle the ear).

Photo 28. Auricularis mm.

Note: The orbicularis oculi m. is a sphincteric, circumferential muscle of three parts (orbital, palpebral, and lacrimal), surrounding the orbit. The orbital part encircles the palpebral part. The palpebral part is typically involuntarily controlled (blinking), whereas the orbital part is typically voluntarily controlled (shutting the eyes tightly). The orbicularis oculi is innervated by temporal and zygomatic brs. of the facial n.

Photo 29. Orbicularis oculi m.

Note: The corrugator supercilii mm. connect the medial aspects of the superciliary arches of the frontal bone (deep to the orbicularis oculi mm.) with the skin of the medial brow. When activated, these muscles pull down on the skin of (furrow) the brow. The corrugator supercilii mm. are innervated by the temporal brs. of the facial n.

Photo 30. Corrugator supercilii mm.

Note: The craniofacial muscles controlling the shape and positioning of the lips (and thus the mouth) converge into dense fibromuscular ‘wheels’ at each angle of the mouth. This structure is called the modiolus, and can be palpated between the skin and oral mucosa.

Note: The shape and positioning of the lips is controlled by several buccolabial muscles controlling the upper lip (e.g. levator labii superioris m.,), lower lip, oral opening (e.g. zygomaticus major & minor mm., levator anguli oris m., risorius m., depressor anguli oris m., and orbicularis oris m.), and cheeks (e.g. buccinator m.).

Note: The levator labii superioris m., zygomaticus minor m., & zygomaticus major m. form a series of medial-to-lateral connections between the modiolus and the lower margin of the orbit/zygomatic bone. These three muscles are innervated by zygomatic and buccal brs. of the facial n. (CN VII). The levator labii superioris m. elevates and weakly everts the upper lip. The zygomaticus minor m. elevates the upper lip to expose the maxillary incisors and canines. The zygomaticus major m. elevates and draws the angle of the mouth laterally. These three muscles activated sequentially contribute to an increasingly wide smile.

Note: The infra-orbital (= canine) fascial space is deep to the “quadratus labii superioris m.” group, which consists of the levator labii superioris alaeque nasi m., levator labii superioris m., and the zygomaticus minor m. The buccal fascial space is continuous posteriorly with the infra-orbital space. Odontogenic infections of the ipsilateral canine or first premolar may spread to this space, causing infra-orbital edema. Left untreated, infection may spread to either the buccal space, and/or to the orbital vasculature, and the cavernous sinuses beyond. The angular a. & v. and the infra-orbital n. (of V2) are found in this space.

Note: With the advanced ages of many anatomical donors, it is not uncommon for some of the buccolabial mm. to have significantly atrophied. If you cannot find particular muscles on your donor, look at other donors or plastinated specimens.

Photo 31. Buccolabial muscles

Note: The levator anguli oris m. attaches the modiolus of the mouth to the canine fossa of the maxilla. Innervated by buccal brs. of the facial n., when activated, the levator anguli oris m. pulls the angle of the mouth laterally and superiorly.

Note: The risorius m., a highly variable muscle, attaches the modiolus of the mouth to the parotid fascia, and surrounding structures. The risorius m. is innervated by buccal brs. of the facial n. When activated, the risorius pulls the corners of the mouth laterally, as in a smirk.

Note: The depressor anguli oris draws the modiolus inferiorly and laterally, towards the oblique line of the mandible. The depressor anguli oris m. is innervated by buccal and marginal mandibular brs. of the facial n.

Photo 32. Buccolabial muscles: depressor anguli oris, risorius mm.

Note: The depressor labii inferioris m. attaches the skin of the lower lip to the oblique line of the mandible. Innervated by the marginal mandibular br. of the facial n., when activated the depressor labii inferioris m. draws the lower lip inferiorly.

Note: The mentalis m. attaches the skin of the chin to the incisive fossa of the mandible. The mentalis m. is innervated by the marginal mandibular br. of the facial n., when activated the mentalis m. elevates the skin of the chin and lower lip (to form a pout).

Photo 33. Buccolabial muscles: depressor labii inferioris m. & mentalis m.)

Note: The orbicularis oris m. is a complex association of quadrants (upper, lower, right, & left) of muscle that encircle the oral opening. When activated in total, these quadrants purse (pucker) the lips, such as to enable the gesture of a kiss. The orbicularis oris m. is innervated by buccal and marginal mandibular brs. of the facial n.

Note: The buccinator m. covers the area superficial to the lateral teeth-bearing regions of the maxilla and mandible. The buccinator m. is innervated by buccal brs. of the facial n. When activated, the buccinator m. draws the cheeks toward the teeth (to bring food into the occlusal plane) while tightening the buccal mucosa (to withdraw the mucosa from the occlusal plane). The buccinator m. also forcefully directs and/or expels air from the cheeks, such as when playing a wind instrument, or when whistling.

Photo 34. Buccolabial muscles: orbicularis oris m. & buccinator m.

23.) Skin the entirety of the nose, and locate the nasal muscles.

Note: The external structure of the nose is covered by two muscles: medially, the nasalis m., and laterally, the levator labii superioris alaeque nasi m.

Note: The nasalis m. consists of two distinct parts: the transverse part (compressor naris m.) and the alar part (dilator naris m.). The nasalis m. is innervated by both zygomatic and buccal brs. of the facial n. The transverse part attaches the portion of the maxilla superolateral to the incisive fossa to the midline of the bridge of the nose. When activated, the transverse part compresses the naris. The alar part attaches the alar cartilage to the portion of the maxilla superolateral to the incisive fossa (medial to the attachment of the transverse part). When activated, the alar part dilates the naris.

Note: The levator labii superioris alaeque nasi m. attaches the frontal process of the maxilla to both: fascia superficial to the alar part of the nasalis m. and the skin superficial to the levator labii superioris m. The levator labii superioris alaeque nasi m. is innervated by both zygomatic and buccal brs. of the facial n. When activated, this muscle dilates the naris and elevates the upper lip.

Photo 35. Nasal muscles

Locate cutaneous branches of the trigeminal n. (CN V), deep side

Find these structures:

• Cutaneous branches of trigeminal n. (CN V)

  • Supra-orbital n. (of V1)

  • Infra-orbital n. (of V2)

  • Mental n. (of V3)

  • Auriculotemporal n. (of V3)

Note: The trigeminal n. (CN V) is responsible for innervating muscles of mastication (efferent) and sensation of the skin of the face (afferent). The trigeminal n. has three divisions: ophthalmic n. (V1), maxillary n. (V2), and mandibular n. (V3). The complete courses and functions of these divisions will be seen and discussed in subsequent sessions. A focus of this session are the nerves (and their branches) of these divisions afferently serving the skin of the face.

Photo 17. Lateral view of face showing regions afferently served by V1, V2, & V3

24.) Using blunt dissection with minimal disruption of the surrounding tissue, locate the:  supra-orbital foramen (or notch), infra-orbital foramen, and the mental foramen. Find and identify the nerves they transmit.

Note: The supra-orbital n. is the terminal continuation of the frontal n. through the supra-orbital notch or foramen to afferently serve the conjunctiva, mucosa of the frontal sinus, and skin of the superior palpebra, forehead, and epicranial scalp. The supra-orbital n. is a branch of the ophthalmic n. (V1). Variations of crania include those with supra-orbital notches and those with supra-orbital foramen. Either of these structures, when present, are found along the superior rim of the orbit, nearly halfway between the midpoint of the superior rim and the medial rim of the orbit.

Note: The supratrochlear n. is also a continuation of the frontal n. (the supra-orbital n. and supratrochlear n. arise from the bifurcation of the frontal n. in the superior orbit). The supratrochlear n. gets its name from passing superiorly to the trochlea of the superior oblique m. in the orbit. It innervates the skin of the: medial forehead and eyelid, and the medial sclera of the eye.  

Note: The infra-orbital n. is the branch of the maxillary n. (V2) which exits the infra-orbital foramen of the maxilla. The infra-orbital foramen is below the orbit, approximately in-line with (or just lateral to) the supra-orbital foramen (or notch) above. The infra-orbital n. afferently supplies the mucosa of the maxillary sinus and gingiva, and skin of the: inferior palpebra, the lateral nose, upper lip, and cheek.

Note: Before arising through the infra-orbital foramen as the infra-orbital n., the maxillary n. (V2) gives off the zygomatic n., which bifurcates into the zygomaticotemporal n. and the zygomaticofacial n., each named for the foramen through which they exit the skull. The zygomaticotemporal n. innervates the skin superolateral to the orbit, and may also carry postganglionic parasympathetic fibers (secretomotor) to the lacrimal gland (a pathway to be discussed in a later session). The zygomaticofacial n. innervates skin lateral to the orbit.

Note: The mental n. is the terminal continuation of the inferior alveolar n., a branch of the mandibular n. (V3), which passes through the mental foramen of the mandible to afferently serve the mandibular gingiva, and skin of the: lower lip and chin.  

Photo 36. Supra-orbital n., supratrochlear n., infra-orbital n., and mental n.

Photo 37. Supra-orbital, infra-orbital, and mental foramina

25.) Using blunt dissection, locate the cutaneous portion of the auriculotemporal n.

Note: As previously discussed, the auriculotemporal n. is a branch of the mandibular n. (V3). The auriculotemporal n. serves several functions:

• 1. transmitting secretomotor postganglionic parasympathetic fibers to the parotid gland (from the otic ganglion; preganglionic fibers from glossopharyngeal n.),

1. afferently serving the termporomandibular joint, and

2. afferently serving the skin of the: tragus of the ear, the external auditory meatus, and the area anterosuperior to the ear.

Note: The cutaneous portion of the auriculotemporal n. may be found accompanying the superficial temporal a. & v. superiorly from the parotid gland.

Photo 38. Auriculotemporal n., cutaneous portion

Locate vasculature of the face

Find these structures:

• Veins

  • Superficial temporal v.

  • Facial v.

    • Deep facial v.

    • Angular v.

• External carotid a.

  • Facial a.

    • Superior labial br.

    • Inferior labial br.

    • Lateral nasal br.

    • Angular a.

  • Superficial temporal a.

26.) On the side of face with the parotid gland removed, locate the retromandibular v. and its superior tributary, the superficial temporal v. Follow the retromandibular v. to its potential junctions with the facial v. (into the internal jugular v.) and the posterior auricular v. (to form the external jugular v.).

Note: The superficial temporal v. typically accompanies the superficial temporal a. and the auriculotemporal n. superior to the parotid gland.

Note: The superficial temporal v. typically unites with the maxillary v. to form the retromandibular v. The retromandibular v. may divide into anterior and posterior divisions. The anterior division of the retromandibular v. typically unites with the facial v. before joining the internal jugular v. The posterior division of the retromandibular v. typically unites with the posterior auricular v. to form the external jugular v.

Photo 39. Facial veins

27.) Locate the facial a. and v. Trace the course of the facial a. from the external carotid a. to the medial aspect of the eye. Locate the major branches of the facial a. Locate major branches of the facial v.

Note: The superior thyroid a., the lingual a., and the facial a. are typically the first three anteriorly oriented branches of the external carotid a.

Note: The facial a. traverses the submandibular triangle before emerging over the body of the mandible (anterior to the masseter m.), accompanied by the facial v., deep to the branches of the facial n. The artery ascends and supplies structures of the face.

Photo 40. Lateral view of the facial a.

Note: The facial a. has several branches, major branches include the: inferior labial br., superior labial br., and the nasal br. The labial branches adjacent to the modiolus of the mouth and run courses between the orbicularis oris m. and the mucous membrane. The labial branches often anastomose with their contralateral counterparts. The lateral nasal br. often arises lateral to the nose, and anastomoses with its contralateral counterpart. In some cases, the lateral nasal br. may arise from the superior labial br. The angular a. is the terminal branch of the facial a. that courses toward the medial canthus of the eye.

Photo 41. Facial a. brs.

Note: The facial v. and its branches mirror the distribution of the facial a. and its branches. The angular v. is valveless and receives the supra-orbital v. and supratrochlear v. to drain the forehead and regions medial to the eye. The deep facial v. drains the pterygoid plexus of veins and deep face, is valveless, and joins the facial v. anterior to the masseter m.

Note: Anastomoses between facial v. branches may allow infections a direct route into the cavernous sinus. For example, anastomoses between the angular v. and the superior and inferior ophthalmic vv. may allow infections from the ‘danger area of the face’ a direct route into the cavernous sinus. Likewise, infections may move through the deep facial v. through the pterygoid plexus of veins into the cavernous sinus.

Photo 42. Facial v. & brs.