CONGENITAL FORAMEN IN THE BODY OF STERNUM

Background:The knowledge of sternal variations is important as this bone is usually chosen for bone marrow aspiration.One such developmental anomaly is the presence of foramina, of varying dimensions, in manubrium or body or xiphisternum.Usually, the defect occurs in the lower third of sternum,in the body, as a single midline foramen (oval or round) and is usually asymptomatic and can be demonstrated only by CT scanning. The observation and knowledge of these foramina are of utmost importance in clinical, forensic and acupuncture techniques.Hence, this observation could be a useful one. Materials and methods: During a routine osteology class in the Department of Anatomy,Kanyakumari Government Medical College,an adult sternum of unknown sex and age was found to have a foramen in the lower part of body at the level of articular facets for fifth costal cartilages. Results:The following observations were made: (1)The sternum presented an oval foramen in the lower part of the body. (2) It was located in midline at the junction between third and fourth sternebrae.(3) Its margins were smooth and measured 5mm×6mm. Conclusion:Embryologically,sternum is formed by the craniocaudal fusion of two sternal bars,which are condensations of mesenchymal tissue which get converted to pre-cartilage before fusion. Any defect in this fusion may cause cleft sternum or sternal foramina(single or multiple). The single sternal foramen presented here could have clinical implications. Its knowledge helps in preventing fatal cardiac tamponade following needle insertion during bone marrow biopsy or acupuncture performed in this region. Forensic misinterpretation of this defect is also possible.