Musculocutaneous nerve as a branch from median nerve: A case report

The brachial plexus is the most variable part of the peripheral nervous system. The Musculocutaneous nerve is a terminal branch of the lateral cord of the brachial plexus in a normal individual. It is not uncommon for variations in the origin, branching termination, and connection patterns. During routine dissection in the Anatomy Department, College of Medicine, King Saud University, we found the lateral cord after giving a small branch to the coracobrachialis muscle join the medial root of the medial cord to form the median nerve. Knowledge of these variations is essential for anatomists, orthopedics, neurologists, and anesthesiologists.

A Case Report of a Rare Variation in the Lateral Cord of the Brachial Plexus

The brachial plexus is the largest and most complex neural plexus in the body located in the neck and axilla. So far, there have been many reports of various variations in the brachial plexus that are of clinical significance. In the present study, while dissecting the upper limb of a 54-year-old man in the dissection room of Shahid Sadoughi University of Medical Sciences in Yazd, a rare variation was observed in the lateral cord branches of the plexus. In this case, the medial pectoral nerve, which normally separates from the medial cord, originated from the lateral cord. Awareness of this variation is important for anatomists, surgeons, anesthesiologists and radiologists to interpret the graphs, etc., and can help to reduce clinical complications during surgery and better interpret and diagnose the graphs.

Variations in formation of median nerve: a cadaveric study

Background: Median nerve is generally formed in axilla, as one of the branch of brachial plexus. It is formed by the union of medial and lateral roots which are the branches of me­dial and lateral cord respectively. The knowledge of origin, course and area of distribution of median nerve is important for the anatomist, the neurologist and also for correction of traumatic injuries that are related to brachial plexus. The main objective of this study is to observe different variations in median nerve formation in cadavers. Methods: A descriptive cross-sectional study was conducted in 25 formalin fixed adult human ca­davers in the Department of Anatomy, KIST Medical College and Teaching Hospital, Lalitpur Ethical approval was taken. Altogether, 50 specimens were enrolled in the study by convenient sampling method. The calculation was done using Statistical Package for Social Sciences version 20 (SPSS). Results: In this study the formation of median nerve was observed to be normal in 78% of the cases. In 20% cases three roots were forming the median nerve and in 2% cases four roots were present. Among these variations in 18% cases the additional roots were observed to be given by the lateral cord of the brachial plexus. Conclusions: This study concludes that most of the median nerve forms in axilla by the union of two roots with few variations.

Axial MRI biomarkers of spinal cord damage to predict future walking and motor function: a retrospective study

Study design Retrospective. Objectives Primary: to assess if axial damage ratios are predictors of future walking after spinal cord injury (SCI), and if they add any predictive value if initial neurological impairment grades are available. Secondary: to determine if lateral spinal cord regions are predictors of future lower extremity motor scores (LEMS). Setting University/hospital. Methods Axial T2-weighted MRIs were used. Axial damage ratios and non-damaged lateral cord volumes were calculated. Each participant answered at 1 year after SCI, “Are you able to walk for 150 feet? (45.72 meters)” For the secondary aim, right and left LEMS were used. Results In total, 145 participants were selected. Individuals that could walk had smaller ratios than those that were unable. Walking and axial damage ratios were negatively correlated. A 0.374 ratio cut-off showed optimal sensitivity/specificity. When initial neurological grades were used, axial damage ratios did not add predictive value. Forty-two participants had LEMS available and were included for the secondary aim. Right cord regions and right LEMS were positively correlated and left regions and left LEMS, but these variables were also correlated with each other. Conclusions Axial damage ratios were significant predictors of walking ability 1 year after SCI. However, this measure did not add predictive value over initial neurological grades. Lateral cord regions correlated with same-side LEMS, but the opposite was also found, calling this biomarker’s specificity into question. Axial damage ratios may be useful in predicting walking after SCI if initial neurological grades are unavailable. Sponsorship This research was funded by a National Institutes of Health award, National Institute of Child Health and Development—NIH R03HD094577.

The Rare Five Finger Pectoralis Nerves: A Case Report

The brachial plexus is a complex network of nerve tissue in the human body that has been reported to vary from person to person. We describe a very rare variation of the brachial plexus found on a routine cadaveric dissection. On the left side of the chest, we identified two lateral pectoral nerves arising from the lateral cord and innervating the pectoralis major muscle; two medial pectoral nerves (MPNs) arising from the medial cord that innervates both pectoral muscles and a communicating branch that connects the lateral and MPN. In addition, this communicating branch had a nerve that innervated the pectoralis minor muscle. Knowing the variations of branching of the pectoral nerves is critical when performing any medical procedure in the pectoral region, such as plastic breast reconstruction surgery after modified radical mastectomy in breast cancer, removal of the pectoral muscles, anesthetizing the brachial plexus, or axillary dissection.

The 2-Dimensional and 3-Dimensional Anatomy of the Adult Brachial Plexus Divisions and Cords

Background: The objective of this work was to perform a critical review of the 2-dimensional and 3-dimensional anatomy of the adult brachial plexus divisions and cords. Methods: Twelve adult brachial plexuses from fresh cadavers were dissected. All were male and aged between 30 and 50 years. Only corpses without brachial plexus injuries were selected. The purpose of the dissections was to identify the origin of the anterior and posterior divisions of the adult brachial plexus in their respective trunks, as well as the positioning of the posterior, lateral, and medial cords. Results: The posterior division of all trunks had a cranial and dorsal origin, while the anterior division of all trunks had a caudal and ventral origin. The posterior cord was the most cranial of all, the lateral cord was central, and the medial cord was the most caudal of all cords. The posterior division of the superior trunk was always between the suprascapular nerve and the anterior division. Conclusions: Brachial plexus diagrams in most textbooks and papers are different from what was found in our dissections. Contrary to the known diagram, the posterior divisions always had a cranial origin in the superior, middle, and inferior trunks.