CT-scan imaging of iron marked chorda tympani nerve: anatomical study and educational perspectives

Abstract

The chorda tympani nerve (CTN) is the last collateral branch of the facial nerve in its third intraosseous portion just over the stylomastoid foramen. After a curved course against the medial aspect of the tympanum where it is likely to be injured in middle ear surgery, CTN reaches the lingual nerve in the infratemporal fossa. Knowledge of CTN topographic anatomy is not easily achieved by the students because of the deep location of this thin structure. The aim of this study was to assess the spatial relationships of the CTN in the infratemporal fossa. Therefore, ten nerves were dissected in five fresh cadavers. All the nerves were catheterized with a 3/0 wire. After a meticulous repositioning of surrounding structures, standard X-ray and CT scan examinations were performed with multiplanar acquisitions and three-dimensional surface rendering reconstructions. Ventral projection of the CTN corresponded to the middle of the maxillary sinus. Lateral landmark was the mandibular condyle. The CTN was present and unique in all the dissections. The average length of the nerve, as measured on CT scans, was 31.8 mm (29-34, standard deviation of 1.62); the anastomosis of the CTN to the lingual nerve was located at a mean 24.9 mm below the skull base (24-27, standard deviation of 0.99), approximately in the same horizontal plane as the lower part of the mandibular notch. The acute angle opened dorsally and cranially between CTN and LN measured mean 63.2° (60-65, standard deviation of 1.67). Three-dimensional volumetric reconstructions using surface rendering technique provided realistic educational support at the students' disposal.

Proximity of Axillary Nerve During Cortical Button Repair of Pectoralis Major Tendon Rupture

“…Tissue quality is different from in vivo tissue; however, the specimens were fresh frozen and carefully preserved to be as clinically accurate as possible. Finally, the preparation of the axillary nerve with the wire may have disrupted the anatomy; however, this is an acceptable technique, which has been used previously in neuro-anatomical investigations [15].…”

“…The wire was then advanced along the nerve. This technique of marking a nerve with wire has previously been described when marking the lingual and chorda tympani nerves [15]. The specimens were then turned to lie prone, and a posterior approach to the shoulder was performed.…”

Dissection and Exposure of the Whole Course of Deep Nerves in Human Head Specimens after Decalcification

“…Because dissections are unlikely to be performed by all the students [2], making good teaching prosections for gross anatomy laboratories and museums is very important.…”

“…After reviewing the literature [2–9], it was found that most studies paid attention to different points of the deep nerves of the human head without studying the whole course of the nerves. Some authors viewed parts of the deep nerves, some observed deep nerves using microscopic or CT imaging techniques.…”

“…Some authors viewed parts of the deep nerves, some observed deep nerves using microscopic or CT imaging techniques. Trost et al [2] studied the chorda tympani by marking the nerve with 3/0 iron wire in the infratemporal fossa. After meticulous repositioning of surrounding structures, standard radiography and CT scan examinations were performed.…”