Browsing by Subject "Anatomical variation"
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Item ANATOMICAL VARIATION OF THE LATERAL THORACIC ARTERY: WHAT THE TEXTBOOKS AREN'T TELLING YOU(2014-03) Miller, Kendall R.; Kirchhoff, Claire A.The lateral thoracic artery is the blood supply to the serratus anterior muscle and is typically described as arising directly from the second part of the axillary artery. Students expect to find this “normal” branching pattern, as variations are seldom mentioned. Variations are, however, relatively common, suggesting that they merit inclusion in regular anatomical instruction. Students at the Texas College of Osteopathic Medicine completed a standardized data sheet on the axillary artery branches during axillary dissection. All cadavers used in this study were acquired through the Willed Body Program at the University of North Texas Health Science Center (n=80; 20 males, 20 females). An observable lateral thoracic artery directly branching from the second part of the axillary artery was found in only 48% of the axillae observed. In 46% of axillae, an artery was observed traveling to the serratus anterior muscle branching from the thoracodorsal artery. In 25% of axillae, the lateral thoracic artery from the axillary artery was doubled by an artery branching from the thoracodorsal artery. In approximately half of all axillae, the lateral thoracic artery was observed to branch from the thoracodorsal artery rather than branching directly from the axillary artery, as “normally” expected. These results support previous work on variations of the lateral thoracic artery. Given the high frequency of anatomical variations, we also propose that information on variations ought to be incorporated into anatomical education.Item ANATOMICAL VARIATION OF THE STERNOCLEIDOMASTOID MUSCLE; A CASE REPORT(2013-04-12) Vice, LaurenPurpose: The sternocleidomastoid (SCM) muscle is a prominent neck muscle. It is the main flexor muscle of the neck and an accessory muscle during deep inspiration. Variations of the SCM have been widely recognized and described in medical literature. Supernumerary clavicular origins separating into individual bellies are a defined variant. However, the existence of a thyrohyoid insertion has not previously been described. Methods: Medical students performed a routine cadaver dissection in the University of North Texas Health Science Center's Gross Anatomy Lab. Results: A sternocleidomastoid muscle with four heads was identified on the left side of a 59 year old male cadaver whose cause of death is liver cancer. A typical SCM has origins on the sternal head and clavicular head, and an insertion on the mastoid process. This male cadaver however has two distinct abnormal findings. The SCM shows three clavicular origins separating into individual bellies. Additionally a unilateral thyrohyoid insertion is present, originating from the distal end of the sterno-mastoid belly. While the supernumerary SCM bellies can be explained by abnormal mesodermal splitting, the thyrohyoid insertion presents as a genetic abnormality not previously reported. Conclusions: Surgical awareness of abnormalities is significant, especially in regards to the existence of supernumerary posterior triangles and the additional thyrohyoid head. Furthermore, the clinical implications suggest possible tension headaches, torticollis and even infringement on the thyroid cartilage during swallowing and speech.