Lingual Nerve Measurements in Cadaveric Dissections: Clinical Applications.

PURPOSE: Lingual nerve (LN) injury is quite prevalent despite its long-known anatomic course. The purpose of this study was to accurately predict the LN pathway by identifying and measuring close anatomic landmarks; these measurements should help lessen the incidence of LN injury. MATERIALS AND METHODS: LN dissection was carried out on 15 halved cadaver skulls (total, 28 specimens). RESULTS: On average, the LN position was approximately 7 mm below the alveolar crest at the distal end of the mandibular second molar, 5.5 mm anterior to the lingula, and 14.6 mm distal to the alveolar crest at the mandibular second molar. From the base of the skull, the LN traveled 5 mm anteriorly to the inferior alveolar nerve and inferiorly to the posterior attachment of the mylohyoid muscle (approximately 1.5 cm distal to the mandibular second molar), where it turned anteromedially and traveled 7 mm inferiorly to the alveolar crest at the mandibular second molar. CONCLUSION: Given the multiple procedures by dental practitioners and maxillofacial surgeons, the LN is at high risk for injury. This study validates the proximity of the LN to anatomic structures commonly encountered during head and neck procedures.

Clinical Anatomy of the Lingual Nerve: A Review.

PURPOSE: Knowledge of lingual nerve anatomy is of paramount importance to dental practitioners and maxillofacial surgeons. The purpose of this article is to review lingual nerve anatomy from the cranial base to its insertion in the tongue and provide a more detailed explanation of its course to prevent procedural nerve injuries. MATERIALS AND METHODS: Fifteen human cadavers from the University of Alabama at Birmingham School of Medicine's Anatomical Donor Program were reviewed. The anatomic structures and landmarks were identified and confirmed by anatomists. Lingual nerve dissection was carried out and reviewed on 15 halved human cadaver skulls (total specimens, 28). RESULTS: Cadaveric dissection provides a detailed examination of the lingual nerve from the cranial base to tongue insertion. The lingual nerve receives the chorda tympani nerve approximately 1 cm below the bifurcation of the lingual and inferior alveolar nerves. The pathway of the lingual nerve is in contact with the periosteum of the mandible just behind the internal oblique ridge. The lingual nerve crosses the submandibular duct at the interproximal space between the mandibular first and second molars. The submandibular ganglion is suspended from the lingual nerve at the distal area of the second mandibular molar. CONCLUSION: A zoning classification is another way to more accurately describe the lingual nerve based on close anatomic landmarks as seen in human cadaveric specimens. This system could identify particular areas of interest that might be at greater procedural risk.

Additional vascular compression of the brachial plexus in a cadaver with a cervical rib: case illustration.

Cervical ribs are uncommon and occur in approximately 0.5-1% of the population. The authors describe a cadaver found to have a cervical rib with further compression by the dorsal scapular artery. This vessel originated from the third portion of the subclavian artery. No other anomalies were found in this specimen. The authors speculate that some cases of symptomatic cervical rib may have an additional vector of compression from a dorsal scapular artery when it arises from the third portion of the subclavian artery. Additional studies aimed at the vascular system may be useful in diagnosis and operative planning for symptomatic patients.

An unusual case of a mediastinal mass in a cadaver.

Since 1975, only approximately 60 saphenous vein graft aneurysms have been reported in the medical literature. We now report this unusual finding in a male cadaver who had undergone a recent coronary artery bypass grafting procedure. Although aneurysm formation is an unusual complication of saphenous vein graft surgery, the diagnosis must be suspected particularly in the face of a mediastinal mass on chest radiography in patients who have undergone coronary artery bypass grafting. Needle biopsy in these cases may prove lethal. We believe this to be the first description of this complication in a cadaver.

Novel surgical approach to the carpal tunnel: cadaveric feasibility study.

Carpal tunnel syndrome is the most common entrapment neuropathy dealt with by the clinician. Multiple techniques have been used to surgically treat this pathological condition and all of these approach the carpal tunnel from the palmar surface of the hand or wrist. We have developed a novel endoscopic approach to the carpal tunnel utilizing a dorsal approach that necessitates a good appreciation of the anatomy of this region. This approach was carried out in 10 hands. Through a single dorsal incision we were able to transect the flexor retinaculum in all specimens without obvious damage to neural or vascular tissues. The microscissors used in our study were found to be too delicate for transection of the flexor retinaculum thus another cutting tool should be considered. Our dorsal approach with visualization of the internal aspect of the flexor retinaculum may obviate many of the complications that are seen with the current techniques used to surgically treat carpal tunnel syndrome such as injury to the median nerve and its branches. Clinical trials are now necessary with prospective randomized studies that will determine which techniques are most efficacious and minimize complications most effectively.

Landmarks for the greater petrosal nerve.

The anatomy of the greater petrosal nerve while within the middle cranial fossa is lacking in the English literature and must be well understood by the surgeon who operates in this area. Twenty-two sides from six female and five male cadavers were examined. Measurements were made between the greater petrosal nerve as it coursed through the middle cranial fossa and surrounding structures such as the arcuate eminence and lateral wall of the middle cranial fossa. Mean distances from the arcuate eminence to the hiatus of the greater petrosal nerve into the middle cranial fossa measured 17.5 mm (SD = 2.2). The length of this nerve within the middle fossa was approximately 10 mm (SD = 2). From the lateral wall of the middle fossa to a midpoint of the greater petrosal nerve mean distances measured 39 mm (SD = 2.4). The mean distance from the foramen spinosum to the exit of this nerve inferior to the trigeminal ganglion measured 7 mm (SD = 1.8). These measurements will hopefully aid the surgeon who wishes to expose or avoid the greater petrosal nerve within the middle cranial fossa.

Retroesophageal right subclavian artery with persistent ductus arteriosus.

We report an adult male cadaver with persistence of the ductus arteriosus and a right retroesophageal artery. The retroesophageal artery was first appreciated as a retropharyngeal mass during the dissection of this area. Both the left and right vertebral arteries originated in normal fashion. The thoracic duct of our specimen drained into the junction of the left internal jugular and left subclavian veins. We believe this to be the first report of simultaneous right retroesophageal subclavian artery and patent ductus arteriosus. The anatomy and embryology of these two anomalies in the same specimen are discussed.