* Locate the external occipital protuberance. Determine the degree of flexion and extension possible in the occipitoatlantal joint with reference to this and the transverse processes of the atlas. These three landmarks are used to determine the placing of a needle for cerebrospinal; fluid collection from the cerebellomedullary cistern. | * Locate the external occipital protuberance. Determine the degree of flexion and extension possible in the occipitoatlantal joint with reference to this and the transverse processes of the atlas. These three landmarks are used to determine the placing of a needle for cerebrospinal; fluid collection from the cerebellomedullary cistern. |