Head and Neck 1: Face/scalp, infratemporal fossa, pterygopalatine fossa

Lab Objectives Quick Tips

Using the Sectra table, you will identify features of the superficial and deep face. Bolded terms are in the objectives for this lab.

The face, scalp, infratemporal fossa, and pterygopalatine fossa

“The dissection of the head is foremost a dissection of the course and distribution of the cranial nerves and the branches of the external carotid artery. All of the cranial nerves and many blood vessels pass through openings in the skull.” – Grant’s Dissector 16th ed.

Use the following view to review the bones of the skull:

Skull

Identify the following bony features (they cannot be highlighted on the model, so use the diagrams below to find these features):

• Frontal bone: supraorbital margin
• Nasal bones
• Maxillia: alveolar process
• Mandible: alveolar process, mental protuberance, angle
• Temporal bone: mastoid process
• Occipital bone: external occipital protuberance
• Zygomatic bone
• Zygomatic arch
• Spaces between the sphenoid and maxillary bones: pterygomaxillary fissure, inferior orbital fissure
• Palatine bone: sphenopalatine foramen

As you identify and dissect muscles, you should review their origin, insertion, innervation, and action(s). As you identify and dissect neurovascular structures, you should review their pathways.

If you are having trouble highlighting narrow structures (arteries, veins, nerves), you can search for them by selecting the Anatomy tab, typing the name of the structure in the search box, and selecting the sun icon next to the listed structure. You can dissect these structures by selecting the eye icon.

As you highlight a structure, note that the structure will also be highlighted in the multiplanar reconstructed (MPR), or cross-sectional images in the leftmost pane. All structures should be identified on the MPR images. Using three fingers, scroll through the MPR images to understand the three-dimensional relationships between different structures as you work though the lab. Structures that are difficult to identify in the MPR images will have additional links to assist you.

The scalp

Most of the layers of the scalp are not identifiable, review them in the diagram below: skin, connective tissue, aponeurosis, loose connective tissue, and periosteum

The superficial face

Use the following view to identify the muscles of facial expression:

The head

• Identify the frontalis muscle
• Identify the orbicularis oculi muscle. You will need to dissect the orbital part to identify the palpebral part, and the corrugator supercilii
• Identify the levator labii superioris, levator anguli oris, buccinator, zygomaticus major, and zygomaticus minor muscles (MPR)
• Identify the orbicularis oris muscle
• Identify the depressor anguli oris, depressor labii inferioris, mentalis, and platysma muscles (MPR)

• Identify the facial nerve (CN VII). The superficial branches are not identifiable, identify them on the diagrams below: temporal, zygomatic, buccal, mandibular, cervical, and posterior auricular branches

Q1: What is Bell’s palsy? What nerve(s) and muscle(s) are affected? (answer)

• Dissect the platysma and identify the facial artery and facial vein (MPR)
• Identify the angular vein (the angular artery is not present on the model)
• Identify the supraorbital veins, supratrochlear veins, and the ophthalmic arteries (the supraorbital and supratrochlear arteries and nerves are not visible on the model)
• The infratrochlear, infraorbital, and mental nerves, arteries, and veins are not visible on the model. Identify them on the diagrams below

Parotid and temporal regions

• Identify and dissect the parotid gland and parotid duct
• Identify the external jugular veins, superficial temporal veins, posterior auricular, maxillary, and retromandibular veins
• On the left side of the model, identify the great auricular nerve and lesser occipital nerve
• Identify the temporalis muscle and the superficial temporal arteries (you may need to dissect the superficial temporal veins to see the arteries)

Q2: What are the boundaries of the infratemporal fossa? (you may want to go back to the osteology-only view to answer this question) (answer)

Infratemporal and pterygopalatine fossae

• Identify and dissect the masseter muscle
• Dissect the superficial temporal vein, retromandibular vein, temporalis muscle, and the “body” of the mandible
• Identify the medial pterygoid and lateral pterygoid muscles (MPR)
• Identify the visible branches of the external carotid artery: the maxillary, superficial temporal and inferior alveolar arteries
• Identify the lingual nerve, inferior alveolar nerve, and nerve to myohyoid
• Deep structures in the infratemporal muscle are not visible on the model. Use the diagrams below to identify: sphenopalatine artery, middle meningeal artery, deep temporal arteries, auriculotemporal nerve, pterygopalatine ganglion, and chorda tympani

Q3: Describe the special sensory, general sensory, and motor innervation of the tongue. (answer)

Q4: What are the boundaries of the pterygopalatine fossa? (answer)

End of Sectra activity

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Answers to activity questions

Below are answers to questions asked during the activity. Clicking the ‘back to lab’ link below each answer will take you back to the question (you may need to scroll up a little to view the question again).

 

Q1: What is Bell’s palsy? What nerve(s) and muscle(s) are affected?

• Bell’s palsy is paralysis of some or all of the facial muscles on the right or left side, caused by injury to the facial nerve (CN VII). The affected side will sag, causing distorted facial expression.

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Q2: What are the boundaries of the infratemporal fossa?

• Superior: zygomatic arch superficially, infratemporal crest of the sphenoid bone deeply
• Lateral: ramus of the mandible
• Anterior: infratemporal surface of the maxilla
• Medial: lateral plate of the pterygoid process
• Roof: greater wing of the sphenoid bone

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Q3: Describe the special sensory, general sensory, and motor innervation of the tongue.

• Motor ennervation (entire tongue): hypoglossal nerve (CN XII)
  • exception: the palatoglossus muscle is ennervated by the vagus nerve (CN X)
• General sensory and special sensory from posterior third: glossopharyngeal nerve (CN IX)
• General sensory from anterior two-thirds: Lingual nerve (branch of mandibular division of trigeminal nerve CN V3)
• Special sensory from anterior two-thirds: chorda tympani (branch of facial nerve CN VII)

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Q4: What are the boundaries of the pterygopalatine fossa?

• Anterior: infratemporal surface of maxilla
• Posterior: pterygoid process and anterior surface of the greater wing of sphenoid bone
• Medial: perpendicular plate of the palatine bone
• Lateral: pterygomaxillary fissure
• Inferior: palatine bone

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