Clinical anatomy : official journal of the American Association of Clinical Anatomists & the British Association of Clinical Anatomists
-
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.
-
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.