Cleidocervical muscle: a mini literature survey of a human muscle variation.

Cleidocervical muscles (CCM) or levator claviculae muscles in humans can be found as supernumerary unilaterally or bilaterally on the neck attached proximally to the clavicle and distally to the transverse process of cervical vertebrae at various levels. Altogether 20 case reports from year 1994 till present including 25 subjects related to CCM were found and analysed where parameters such as cervical insertion level, clavicular insertion at the middle vs. lateral third, unilateral vs. bilateral presence of the muscle, study type, reported gender of the subjects were extracted. Our literature survey shows that the prevalence of CCM in male and female was equally presented in radiological studies whereas almost 3-fold higher prevalence of males was found in cadaver reports. Since body donor system worldwide is male dominant, a 1:1 proportion of male and female in radiological studies could show more reality-based distribution of this muscle. Nevertheless, the presentation of this muscle was found in over 90% of the case reports unilaterally with higher left sided dominance. Even though the attachment points of CCM varied from case to case, the proximal attachment was found slightly more frequent on the middle third of the clavicle whereas the distal insertion was present more often on the superior cervical vertebrae than the lower ones. With prevalence of CCM in the population around 2.0-2.5%, the clinical, radiological and surgical relevance of this variation has to be highlighted to avoid potential misleading diagnostics in the neck.

A unilateral sternopharyngeal branch of the sternocleidomastoid muscle in an aged Caucasian male: a unique cadaveric report.

The sternocleidomastoid muscle (SCM) consists of a sternal and a clavicular head which merge together and inserts distally posterolateral on the mastoid process and superior nuchal line, hence separating the anterior from the posterior triangle of the neck. Many types of structural variations in SCM have already been reported before. A unique variation of this muscle was discovered in an aged Caucasian male cadaver during an anatomical dissection at the Paracelsus Medical University in Nuremberg, Germany. This study reports a right unilateral accessory muscular branch at the sternal head of the SCM which formed a tendon on the level of omohyoid muscle before dividing into anterior and posterior fascicles. The posterior fascicle attached to the external carotid artery at the site where a common trunk for lingual and facial artery branched off, drawing external carotid artery inferiorly to build an inferior loop, whereas the anterior fascicle passed further superior and broadened to form a muscular belly. This superior muscular belly extended to the posterior and lateral side of the pharynx to ultimately merge into the superior constrictor pharyngeal muscle. Such anatomical variation has never been reported before. Therefore, we propose the nomenclature of this variational structure as a sternopharyngeal branch of the SCM. This report helps not only to inform the clinicians regarding the possible variation of this muscle during surgical procedures or radiological diagnostics but also encourage developmental researches in the future.

The sternocleidomastoid muscle variations: a mini literature review.

The sternocleidomastoid muscles (SCM) are prominent paired muscles of the neck connecting proximally the manubrium sterni and the clavicle to the mastoid process and the occipital bone distally. Following their points of attachment sternomastoid, sternooccipital, cleidomastoid and cleidooccipital portions of this muscle have been described. Altogether 23 case reports from year 2000 till 2020 with 29 subjects related to the SCM supernumerary variations were searched and analysed where parameters such as supernumerary proximal variation types (sternal vs. clavicular), insertional variation, unilaterality/bilaterality of the variation, study type, reported gender of the subjects and the country of research were extracted. The research shows that 48.3% of the subjects had bilateral presentation of SCM variations. If present unilaterally, three quarters of the cases were on the left side. The most frequent variation is located at the clavicular side of the proximal SCM head whereas isolated sternal sided proximal head variation or an insertional variation alone are very rare. Interestingly, with 96.6%, most of cases in the literature were discovered in cadavers during anatomical dissections. Male gender represented with 82.8% higher prevalence than females. The higher male prevalence in the body donor system, predominantly in the Asian continent could play a decisive role in the outcome as more than half of the reported cases stemmed from India in this period. Importantly, the knowledge of different anatomical variations of the SCM is highly relevant for surgical, clinical or radiological approaches in the neck.

Rare malformations associated with partial anomalous pulmonary venous return: a cadaveric case report.

A unique partial anomalous pulmonary venous return in combination with other rare malformations such as annular pancreas and a persistent umbilical vein was discovered in a female Caucasian cadaver during an anatomical dissection at the Paracelsus Medical University in Nuremberg, Germany. The pulmonary anomaly comprised the aberrant left superior pulmonary vein connecting the superior lobe of the left lung with the left brachiocephalic vein resulting in a left to right shunt. An annular pancreas without any signs causing duodenal compression was additionally found. To complete the constellation of malformations, a persistent umbilical vein within the round ligament fissure of the liver was also observed, connecting to an inferior branch of the extrahepatic left ramus of the portal vein. This rare constellation of malformations has been illustrated and thoroughly discussed with the currently available literature to develop a hypothesis for the genetic and developmental background.