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Left Lateral Exposure of Brain, Infratemporal Fossa, and Neck

Surgical Correlation


Left lateral exposure of brain, infratemporal fossa, and neck. The dura mater and arachnoid layers of the meninges have been removed to expose part of the brain. The inferior frontal gyrus, represented by the pars orbitalis, triangularis, and opercularis, is separated from the temporal lobe and its superior, middle, and inferior temporal gyri, by the lateral or Sylvian sulcus. The precentral gyrus or primary motor cortex is the posterior portion of the frontal lobe. It is separated from the postcentral gyrus or primary somatosensory cortex of the parietal lobe by the central sulcus. The tentorium cerebelli (not labeled) separates the cerebrum from the cerebellum. A portion of the sigmoid venous sinus is in view along with the superior petrosal vein. The latter drains the anterior and lateral surfaces of the brainstem and parts of suboccipital and tentorial surfaces and empties into the superior petrosal sinus. In the infratemporal fossa the lateral pterygoid muscle has been removed; only the medial pterygoid remains. The maxillary artery, one of the terminal branches of the external carotid artery, traverses this space giving rise to several branches, such as those shown here: inferior alveolar, middle meningeal, anterior deep temporal, posterior superior alveolar, and infraorbital arteries. The sphenopalatine artery continues through the pterygomaxillary fissure into the pterygopalatine fossa. The buccal and auriculotemporal branches of the mandibular nerve can also be seen as well as the inferior alveolar and lingual nerves that descend on the medial pterygoid to the mandibular canal and floor of the mouth, respectively. The inferior alveolar nerve gives rise to the mylohyoid nerve, motor to the mylohyoid and anterior digastric muscles. In the lateral neck, the common carotid artery divides into its external and internal carotid branches. The cervical segment of the ICA continues as the petrous segment once it enters the carotid canal. The internal jugular vein emerges from the nearby jugular foramen and descends in the neck. The hypoglossal nerve emerges between the IJV and proximal part of the ECA and courses forward superficial to the hyoglossus muscle. It then passes deep to the mylohyoid muscle to supply motor innervation to the intrinsic and extrinsic muscles of the tongue, except palatopharyngeus. Deep neck musculature has been removed to show portions of the obliquus capitis inferior and superior muscles, which have common attachments to the transverse process of the atlas vertebra. (Image courtesy of PA Rubino)