The Pterygospinous foramen and pterygoalar foramen (crotaphitico-buccinatorius) are variant and atavic formations of the skull base and arise respectively from complete or incomplete idiopathic ossifications of the pterygospinous and pterygoalar ligaments. By proximity with areas of relevance for diagnosis and surgery, such as access pathways to the parapharyngeal and retropharyngeal spaces, it is necessary to be aware of these conditions due to the difficulties generated in surgical maneuvers and the promotion of compressive syndromes of mandibular nerve branches. This study was conducted on 45 samples of dry skulls and disarticulated sphenoid bones belonging to the collection of the

The caroticoclinoid (CF) and the interclinoid (IF) foramina are variant formations of the middle cranial fossa, which result from idiopathic and possibly atavistic ossifications of the caroticoclinoid and interclinoid ligaments, respectively. Topographically, these foramina are intimately associated, to varying degrees, depending on their conformations, with the neurovascular elements of the paraclinoid region and have important clinical and surgical significance. Thus, this study, conducted from 38 dry skulls belonging to the shared collection of the Federal University of Juiz de Fora, Governador Valadares campus, revealed 11 skulls (28.95 %) with one of the two complete formations -the caroticoclinoid or the interclinoid, and in 6 skulls the caroticoclinoid foramen occurred uni or bilaterally. As a result, 50 % of these skulls presented the CF exclusively on the right (or 62.5 % of the total number of variant foramina), with an average transverse diameter of 4.91 mm and 5.8 mm AP (anteroposterior) diameter and an average area of 22.5 mm 2 . Concerning the IF, the findings occurred in 5 skulls with variable distributions between the clinoid processes and lateralities. The average length of the bone bridges in the IF was 7.7 mm. In conclusion, detailed anatomical knowledge of the caroticoclinoid and the interclinoid foramina is fundamental to the practice of neurosurgical procedures, since they have intimate relationships at a location of high structural complexity.

The anatomical variations are a chapter of major importance in the practice of human macroscopy due to their high clinical and surgical implications. Many of these variations, in all body segments, are biological atavisms or phylogenetic remnants and result from narrow osteofibrous formations in association with neurovascular structures -in part of their pathways.In the skull, due to its structural and developmental complexities, one notices several foraminal formations, complete or incomplete, which originate, in great part, from idiopathic calcifications of ligaments or fibrous laminae in the exocranium as well as in the endocranium. These foramen, sometimes denominated canals, are formed from ossifications or calcifications of ligaments and are intimately related to neurovascular structures, causing, on the one hand, compressive neuropathies and, on the other hand, making surgical access difficult. Thus, we indicate as relevant the following variant foramina in their completely ossified presentations: petrosphenoidal, pterygoalar, pterygospinous, caroticoclinoid, and interclinoid.The petrosphenoidal foramen (or the Dorello's canal) is a generally osteofibrous formation delimited by the superior petrosphenoidal ligament (or the Gruber's ligament) between the apex of the petrous part of the temporal bone (petrous tubercle) and the occipital clivus. Therefore, connecting the posterior and middle cranial fossae. The superior petroesphenoidal ligament constitutes one of the limits of the inferomedial paraclival triangle and can ossify to varying degrees, forming a completely osseous passage in rare cases (figures 01 and 02). The petrosphenoidal foramen is responsible for the transition of structures -the abducens nerve, the inferior petrosal sinus, and the dorsal meningeal branch of the meningohypophyseal trunk. Historically, what justifies the eponym, is considered the first description of the foramen by the Italian anatomist Primo Dorello in the work "Considerazioni sopra la causa della paralisi transitoria dell'abducente nelle flogosi dell'orecchio medio" [1]. The foramen pterigoalar (porus crotaphitico-buccinatorius or the foramen ofHyrtl) is a resistant osteofibrous formation and, evolutionarily, atavistic. Thus, the foramen is formed, in part, by the homonymous ligament of the skull base -the pterygoalar ligament. However, this ligament can, to varying degrees, and for unknown reasons, be ossified and, when completely mineralized, becomes a relatively dense bony bar (Figures 03 and 04) that interposes between the foramen ovale and the infratemporal fossa. This complicates the course of mandibular nerve branches and extracranial surgical access to the foramen ovale and the parapharyngeal

Many of the musculofascial and osteofibrous structures of the upper limbs, and which are of the normal human structural constituent (pattern), are notably neglected in general anatomical descriptions. Their complex structures, and sometimes controversial or incomplete descriptions, have significant implications in important neurovascular conditions, such as compressive trauma, and those of orthopedic reconstructions. Thus, we objective a detailed study, structural and historical, of the literature, on two of the most important osteofibrous formations - the retrocondylar retinaculum (Osborne's ligament), together with the aponeurosis of the flexor carpi ulnar muscle (Osborne's fascia), and the Struther's ligament in association with the supracondylar process and foramen homonym.