Clinical anatomy : official journal of the American Association of Clinical Anatomists & the British Association of Clinical Anatomists
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The percutaneous placement of lateral distal humeral pins risks injury to the radial nerve. We aimed to provide a reliable and safe parameter for the insertion of lateral distal humeral pins. A secondary aim of this study was to investigate the effect of pin/screw placement in the intended zone of fixation at the lateral distal humerus. ⋯ The Pearson correlation coefficient between the lateral nerve height and the trans-epicondylar distance was r = 0.95. A relative dimension, the trans-epicondylar distance is both reliable and easily accessible to the operating surgeon. The absolute safe zone for pin entry into the lateral distal humerus is that area lying within the caudad 70% of a line, equivalent in length to the patient's own trans-epicondylar distance, when projected proximally from the lateral epicondyle.
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The wide anatomical variation of the brachial plexus and the axillary artery has been thoroughly explored in previous studies. However, there has been little information reported on the variation in the relationship between the brachial plexus and the axillary artery. The principal feature of this relationship is the passage of the axillary artery through the loop of the median nerve, which occurs in normal arteries derived from the seventh intersegmental artery. ⋯ In another five cases of this type, the lateral and medial cords merged and the axillary artery passed anteromedial to the plexus. The sixth intersegmental axillary artery pierced the musculocutaneous nerve which is from the unified lateral and medial cords. This study discussed the how the anomalous structure of the brachial plexus could involve the deterioration of the course of the axillary artery.
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The brachialis muscle is dually innervated by the musculocutaneous nerve running via the anterior division of the brachial plexus and the radial nerve running via the posterior division of the plexus. There have been inconsistent descriptions of the pathway of the radial nerve branch at the brachial plexus. ⋯ All the radial nerve branches innervating the muscle ran via the posterior cord, the posterior division, and the superior or middle trunk at the brachial plexus. The radial nerve branches arose from C5 in 5 cases, C6 in 11 cases, C5 and C6 in 3 cases, and C6 and C7 in 1 case.
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This study aimed to document the prevalence and morphology of the ceratocricoid muscle in a large sample of fetuses and adults and to explain its possible origin in a sample of embryos. Forty-five embryos, thirty-four fetuses, and ninety human larynges from adults with no known laryngeal pathology were studied. The muscle was observed in 23% of the fetal sample and in 14% of the adult sample. ⋯ The ceratocricoid muscle develops from tissue within the mesenchymal bridge which connects the external and internal laryngeal sphincters or rings from embryonic stages 15-20. The close relationship of the ceratocricoid muscle to the recurrent laryngeal nerve could mean that it can exert pressure on this nerve. This may be a possible explanation for the causation of certain idiopathic recurrent laryngeal nerve palsies.
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The petrous apex is a complex area surrounded by the cavernous sinus, Dorello's canal and Meckel's cave. The petrosphenoidal ligament (PSL) and the petrolingual ligament (PLL) are important structures located in the region. These two ligaments were examined under a surgical microscope in 10 specimens of five adult cadaveric heads fixed in formalin. ⋯ The PLL invariably surrounded part of the dorsal and lateral walls of the lacerum segment of the internal carotid artery (ICA), just under the anteroinferior portion of the anteromedial wall of Meckel's cave in all specimens. The PSL and PLL are valuable anatomical landmarks for identifying the ICA and the nerves in this region. A thorough understanding of the relationship of the two ligaments with neurovascular structures is a prerequisite for surgery in and around the petrous apex.