Stepwise Dissection Focusing on the Lower Clivus. A, The mucosa on the right half of the posterior nasopharyngeal wall has been removed. The pharyngobasilar fascia covering the longus capitis muscle and firmly connecting to the inferior surface of the occipital and temporal bones is the most anterior layer encountered after opening the mucosa. The tensor veli palatini muscle descends along the anterolateral aspect of the cartilaginous part of the eustachian tube and turns medially around the pterygoid hamulus of the medial pterygoid plate to insert into the soft palate. B, The pterygoid process and the pharyngobasilar fascia have been removed, and the midportion of the tensor veli palatini has been divided. The longus capitis muscle, the second layer of the posterior nasopharyngeal wall, attaches to the clivus lateral to the pharyngeal tubercle. The levator veli palatini descends along the inferior aspect of eustachian tube before attaching to the soft palate. C, View focusing on the right side. The superior pharyngeal constrictor muscle, the upper edge of which is located at the C1 level, slightly inferior to the level of the soft palate, inserts into the pharyngeal raphe, which attaches above to the pharyngeal tubercle. The internal carotid artery ascends just lateral to the longus capitis muscle. D, The levator veli palatini has been removed to expose the salpingopharyngeus muscle, which attaches to the inferior part of the cartilaginous eustachian tube, and passes downward to blend with the posterior fasciculus of the palatopharyngeus muscle. E, The right tensor and levator veli palatini and longus capitis muscles have been removed, and the eustachian tube has been detached from the soft palate and retracted laterally. The rectus capitis anterior, located behind the longus capitis muscle, arises on the lateral mass and adjacent part of the transverse process of the atlas and attaches to the anterior surface of the occipital bone above the occipital condyle. The hypoglossal nerve and neuromeningeal branches of the ascending pharyngeal artery course along the lateral edge of the rectus capitus anterior. The petrosal venous confluence is situated lateral and deep to the rectus capitis anterior muscle around the extracranial orifice of the hypoglossal canal and petrosal part of the jugular foramen. F, The rectus capitis anterior muscle and the petrosal venous confluence have been removed. The internal carotid artery has been retracted laterally to expose the anterior edge of the extracranial orifice of the jugular foramen. The supracondylar groove, located just above the occipital condyle, is the site of attachment of the rectus capitis anterior muscle. The pharyngeal tubercle and the anterior edge of the extracranial orifice of the jugular foramen are located at approximately the same level. (Images courtesy of AL Rhoton, Jr.)