Nihal Apaydin

Review of the surgical anatomy of the axillary nerve and the anatomic basis of its iatrogenic and traumatic injury

The axillary nerve is invariably reported to be one of the most commonly injured nerves during surgical procedures of the shoulder, and the importance of protecting it cannot be overemphasized. Many researchers have tried to identify safe regions, but the results vary among published studies. The axillary nerve may also be injured during acute trauma to the shoulder or by chronic repeated trauma as has been described in the quadrilateral space syndrome. The nerve injury may occur together with shoulder dislocation and rotator cuff tear, thus comprising the so-called “unhappy triad” of the shoulder joint. Simple attention to potential variations in the origin and course of the axillary nerve and its relationship to the shoulder capsule and having a precise knowledge of “safe zones” during operations can enhance clinical outcomes. The objective of this review, therefore, is to discuss the surgical anatomy of the axillary nerve and further emphasize the clinical importance of the its injury following shoulder trauma.

Mapping the axillary nerve within the deltoid muscle

Reports place the frequency of axillary nerve injury at 6% for all brachial plexus injuries, emphasizing the importance of an accurate anatomic description of this nerve within the deltoid in order to reduce iatrogenic injury. The aim of the present study was to explore the anatomic variations of the axillary nerve within the deltoid muscle. Fifty human cadavers were dissected, resulting in 100 nerve specimens. The anterior and posterior branches of the axillary nerve were identified and their length measured from their point of origin (split from the axillary nerve) to their termination in the deltoid muscle. In 65% of cases, the axillary nerve split into two branches (anterior and posterior) within the quadrangular space, and in the remaining 35% split within the deltoid muscle. The posterior branch of the deltoid muscle irrespectively of origin gave off a branch to the teres minor and the superior lateral brachial cutaneous nerve in 100% of cases. The branch to the posterior part of the deltoid muscle was present in 90% of cases, and the branch to the middle part of the deltoid was present in 38% of cases. The anterior branch of the deltoid muscle provided a branch to the joint capsule, a branch to the anterior part of the deltoid muscle and the middle part of the deltoid in 100% of cases. In 18% of the cases, the anterior branch of the axillary nerve provided a branch to the posterior part of the deltoid muscle. The middle part of the deltoid muscle received dual innervation in 38% of cases and the posterior part of the deltoid muscle in 8% of the cases.

Regional anatomic structures of the elbow that may potentially compress the ulnar nerve

HYPOTHESIS Traumatic injuries to the ulnar nerve at the elbow are a frequent problem as it is vulnerable to stretching and compression with motion of the upper limb. The aim of the present study was to explore the course of the ulnar nerve at the elbow and forearm and to determine possible anatomical structures that may cause compression of this structure. MATERIALS AND METHODS We examined 12 upper limbs from cadavers. The length of any fibrous bands, and if present, their distance to the medial epicondyle was recorded. RESULTS On 5 sides a fibrous band originating from the medial intermuscular septum was observed to cross over the ulnar nerve. The average length of the fibrous band was 5.7 cm, and it attached to the medial epicondyle. The mean length of the ulnar nerve as it coursed in the cubital tunnel was 3.8 cm. In 4 of the cases, the ulnar nerve was covered by muscle fibers originating from the flexor digitorum superficialis and extending to the flexor carpi ulnaris. On 5 sides we observed fibrous thickenings, and on 8 sides vascular structures were found crossing over the ulnar nerve. DISCUSSION The cubital tunnel is the most common site of compression of the ulnar nerve. Numerous surgical procedures are recommended for cubital tunnel syndrome. Simple decompression is used most commonly. Although surgical procedures are reported to provide efficient pain relief and functional recovery, residual or recurrent symptoms have been reported. Reasons for such recurrences may be more proximal or distal compression of the ulnar nerve as seen in our study. CONCLUSION Knowledge of possible compression sites of the ulnar nerve is important to the surgeon so that complications are avoided and postoperative recurrence is decreased. LEVEL OF EVIDENCE Basic science study.

Ossification of Ligaments Near the Foramen Ovale: An Anatomic Study With Potential Clinical Significance Regarding Transcutaneous Approaches to the Skull Base

OBJECTIVE There is paucity of information regarding the specific anatomy and clinical significance of ossified ligaments near the foramen ovale (e.g., pterygospinous and pterygoalar ligaments). The present study was undertaken to define this anatomy in more detail and to review the literature regarding these anatomic variations. METHODS One hundred fifty-four adult human dry skulls were analyzed for the presence of ossified ligaments of pterygospinous (ligament of Civinini) and pterygoalar (ligament of Hyrtl). Measurements were made of these bony structures and observations made of their relationships to the inferior aspect of the foramen ovale and neighboring structures. RESULTS Two ossifications each (2.6%) of the ligaments of Civinini and Hyrtl were found. One of each of these (1.3%) was completely ossified, thereby resulting in 2 complete foramina (i.e., 1 foramen of Civinini and 1 foramen of Hyrtl). A significant correlation was found between the left and right sides, with either complete or incomplete ossification of these ligaments being found on left sides (75%) (incomplete Civinini on right side and all others on left side). The complete foramen of Civinini was found to have an area of 16.7 mm2, and the complete foramen of Hyrtl was found to have an area of 9.42 mm2. CONCLUSION Such anomalous bony obstructions could interfere with transcutaneous needle placement into the foramen ovale or distort anatomic relationships during approaches to the cranial base.

The Annular Ligament An Anatomical Study

Background Despite documentations of ligamentous structures of the elbow, the anatomy and clinical and functional importance of the annular ligament has not been comprehensively defined in the orthopaedic literature. Hypothesis The annular ligament is an important component of both the proximal radioulnar and humeroradial joints, as well as an important component of the neighboring muscles and ligaments. Study Design Descriptive laboratory study. Materials and Methods To investigate the annular ligament and its relationship with neighboring structures, macroscopic and microscopic dissections were performed on both upper extremities of 30 cadavers (12 female and 18 male) fixed in 10% formaldehyde and on 1 upper extremity of a fresh cadaver (male). Results The distal ulnar insertion of discrete fibers on the supinator crest was defined as the inferior oblique band of the annular ligament, and the proximal insertion of the annular ligament was defined as the superior oblique band of the annular ligament. These patterns were noted in all specimens. It was difficult to distinguish the fibers of the supinator muscle in every specimen because they were intimately fused with the fibers of the annular ligament. Conclusions The superior and inferior oblique bands of the annular ligament attached proximally and distally onto the ulna, thus helping to secure the annular ligament in place.

Vertebral spinal osteophytes

Osteoarthritis is a common complication in the elderly and is often associated with osteophyte growth on vertebral bodies. The clinical presentation of vertebral osteophytes is related to anatomical structures adjacent to the spinal column. For instance, cervical osteophytes potentially involve the pharynx and esophagus, leading to dysphagic symptoms that may be accompanied by food aspiration, vocal fold paralysis and obstructive sleep apnea. In addition to anterior cervical osteophytes, posterior and uncinate process osteophytes may form, compressing the spinal cord and vertebral artery blood supply, respectively. Cervical osteophytes have also been shown to form an accessory median atlanto-occipital joint when the relationship between the atlas, dens and basiocciput is involved. In the thorax, the esophagus is often affected by osteophytes and may result in dysphagia. Traumatic and non-traumatic thoracic aorta pseudoaneurysm formation has been attributed to sharp osteophytes lacerating the aorta, a direct complication of the relationship between the aorta anterior vertebral column. Additionally, aspiration pneumonia was reported in patients with compression of a main stem bronchus, due to mechanical compression by thoracic osteophytes. In the lumbar spinal region, the two major structures in close proximity to the spine are the inferior vena cava and abdominal aorta, both of which have been reported to be affected by osteophytes. Treatment of osteophytes is initially conservative with anti-inflammatory medications, followed by surgical removal. Increasing obesity and geriatric populations will continue to result in an array of osteoarthritic degenerative changes such as osteophyte formation.

Relationships of the sural nerve with the calcaneal tendon: an anatomical study with surgical and clinical implications

The percutaneous repair of the calcaneal tendon (CT) places the sural nerve (SN) at high risk for injury up to 60%. The aim of our study, therefore, was to explore and describe the course of SN in relation to the CT and to provide an anatomical description of the area in which the SN resides in order to assist surgeons in avoiding iatrogenic injury during surgical procedures in the leg. Forty-four lower extremities of 22 adult cadavers were dissected and the course of the sural nerve investigated. The CT was divided into ten horizontal equal fractions. The widths of CT, and horizontal distances of the SN and small saphenous vein (SSV) to a vertical line connecting the midpoints of these fractions were measured. All the measurements were obtained using a computer-assisted image analysis system. In 95.5% of the specimens the sural nerve was medial to the lateral border of the CT proximally and was intersecting with the lateral border of the CT at the 55% of the mid-tendon line. The SN divided into its terminal branches at a mean of 90% of the mid-tendon line. Based on our results, the course of the sural nerve is quite variable and seems to have the highest risk of injury at its proximal portion. The sutures placed on the CT distal to the 55% of the mid-tendon line may decrease iatrogenic nerve injury.

Retropharyngeal space and lymph nodes: an anatomical guide for surgical dissection.

Conclusions Identification of the alar fascia is the key part of surgical dissection of the retropharyngeal lymph nodes (RPLNs). In cases where mandibulotomy is not performed for the removal of the primary tumor and/or the posterior pharyngeal wall is not incised, the medial or lateral approaches described in this paper can be performed. Objective Surgical dissection of the RPLNs may improve prognosis and locoregional control in oropharyngeal, hypopharyngeal and cervical esophageal carcinomas. There have been no previous anatomical studies concerning landmarks and approaches for the surgical dissection of the RPLNs. This study was designed to illustrate the fascial anatomy of the retropharyngeal region (RPR), provide anatomical guidelines for RPLN dissection and describe and compare approaches for surgical removal of the RPLNs. Material and methods Twelve fixed cadavers were used. Slices were obtained from the necks of the first three cadavers and the RPRs of the slices were dissected under an operating microscope. The other nine cadavers were dissected in a surgical position to expose the RPLNs and the fasciae of the RPR. Results In the coronal plane, the alar fascia divides the space between the buccopharyngeal and prevertebral fasciae into two compartments and constitutes the posterior border of the retropharyngeal space, which contains the RPLNs. The alar fascia, an important landmark for reaching the RPLNs, can be identified by the cervical sympathetic trunk, superior sympathetic ganglion and superior laryngeal nerve. Two approaches can be performed to remove the RPLNs, namely medial or lateral to the internal and external carotid arteries, internal jugular vein and vagus nerve.

The phrenico-esophageal ligament: an anatomical study

The phrenico-esophageal ligament (PEL), which is claimed by some to be an important anti-reflux barrier, has been accepted as an important structure by some surgeons dealing with the surgical treatment of hiatal hernias. However, the characteristics of its anatomical structure and the physiological importance of this ligament is still a subject of discussion. The aim of this study was to define this anatomic structure and to point out the clinical importance of the PEL. This study has been carried out on samples taken from 2 fresh and 12 fixed cadavers. The PEL was observed to be derived from the transversalis and endothoracic fascia attaching the esophagus to the diaphragmatic crura at the region of the esophageal hiatus. While the transversalis fascia covered the inferior surface of the diaphragm, it was observed to divide into upper and lower leaflets when it approached the esophageal hiatus. The endothoracic fascia turned superiorly at the level of esophageal hiatus and attached on to the esophagus by uniting with the upper leaflet of the transversalis fascia in 11 of the specimens. In three of the specimens, it attached on the esophagus at a higher level than the transversalis fascia. The histologic sections of our study revealed that the PEL is formed by collagen and elastic fibers composed of fibroblasts and blood vessels. Since the PEL is a strong structure that firmly attached to the esophageal wall and surrounded the upper part of the distal esophagus like a skirt, it is reasonable that it may play an important role in the gastroesophageal sphincteric mechanism. Histological evidence for decrease in collagen fibers with age and the loose arrangement of the elastic fibers due to this decrement might decrease the resistance and the elasticity of the PEL. This situation may explain the predisposition to hiatal hernias seen with increased in age.

The precise localization of distal motor branches of the tibial nerve in the deep posterior compartment of the leg

The tibial nerve has been reported to be often iatrogenically injured during fibular graft harvest, high tibial osteotomy and fascial release procedures. Despite this complication, there are limited data available in the literature concerning the surgical anatomy of tibial nerve branches in the deep posterior compartment of the leg. The aim of the present study was to quantitative and localize the motor nerve points for the flexor hallucis longus (FHL), tibialis posterior (TP) and flexor digitorum longus muscles (FDL) in relation to a regional bony landmark. The range for the number of branches of the tibial nerve and the terminal motor points of each muscle were identified and measurements were made with a digital caliper from these points to the apex of the head of fibula. Three particular types in the branching of tibial nerve were determined. In 55.6% of the cases there were separate branches to each of the muscles in the deep posterior compartment of the leg (Type I). In 30.6% of the cases there were two main branches of the tibial nerve that provided motor branches (Type II). Finally, the tibial nerve had one main branch, which gave rise to separate motor branches to each of the muscles in 13.8% (Type III). In 61.1% of the cases the FHL was innervated by proximal and distal branches of the tibial nerve. In 38.9% of the cases, it was innervated only by one proximal branch. In all of our cases, the TP was innervated by both proximal and distal branches and the FDL innervated only distally. This provided a detailed anatomical description of the tibial nerve in the deep posterior compartment of the leg. Knowledge of the variable peripheral course of the tibial nerve, as well as the detailed anatomy of its motor branches may decrease iatrogenic injuries and motor loss of the foot during surgical procedures.