Table XIII

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Man’s head and neck showing the superficial vessels of the brain, the divisions of the trigeminal nerve and the hypoglossal nerve

The skull is open and, on the left, the dura mater has been removed; in this way the external surface of the cerebral hemisphere is visible and still covered by the pia mater and the vessels. We can therefore recognize the branches of the middle cerebral artery, that exit from the lateral sulcus; the cerebral superficial veins can be seen climbing up the sagittal sinus of the dura mater.

More deeply, under the cerebral hemisphere, the trigeminal ganglion (of Gasser) is shown with the three divisions of the trigeminal nerve, that can be partly followed on the face. Inside the orbit the side wall has been removed, so we can see, on the top, the three nerves of the first branch: the lacrimal nerve on the outside headed to the homonymous gland, the frontal nerve close to the vault and the nasociliary, more medial, which emits the long ciliary nerves for the eyeball. Below, we can notice the second division coursing over the orbital floor towards the infra-orbital canal. It has already emitted the palatine nerves which descend behind the tuberosity of the maxillary and the posterior superior alveolar nerves; some of which can be found in front of the opened maxillary sinus.

Applied to the buccinator muscle we can see the buccinator nerve of the third division, which descend inferiorly and then arches forwards to the edge of the tongue where it expands under the mucosa and where it is also connected to the submandibular ganglion and laid upon the homonymous gland (here partly amputated).

In this model, the petrous portion of the temporal bone has been scalpelled, and the facial canal and tympanic cavity opened, so we can see the chorda tympani which arises from the intrapetrous portion of the facial and crosses the tympanic cavity laying on the tympanic membrane to reach the lingual nerve; the union of the latter with this nerve is not visible here because the middle meningeal artery is placed in front of it (the artery is easily recognizable being inside the ring formed around it by the auriculotemporal nerve of the third division of the trigeminal nerve).

In the end the hypoglossal nerve is shown; at first it goes behind the internal carotid artery, with an ample curve directed anteriorly, then on its side and on that of the external carotid and then, finally, crosses the inferior external maxillary artery on the underside of the tongue.

AdminTable XIII