UPDATED: The word [glenoid] is composed of the root term [-glen-] which arises from the Greek [γλήνη] (glíni), meaning “a shallow socket”, and the suffix [-oid], also Greek, meaning “similar to”. Similar to a shallow socket.

The etymology of the word is not clear, as some authors contend that it means “eyeball” or just the “pupil” of the eye. The earliest known use of the term by Homer was referring to a “mirror”. All of these meanings carry the reference to reflection of an image.

The term [glenoid cavity] is the smooth, slightly concave surface of the glenoid process of the scapula that forms part of the shoulder joint. Being so shallow, the glenoid cavity is supplemented by a fibrocartilaginous ring called the [glenoid labrum]. There are other uses of the term [glenoid] in human anatomy.

Original image courtesy of www.ancienttouch.com

The Ponticulus Posticus (PP), also known as the pons arcuatus, foramen arcuale, and  arcuate foramen, is a bony bridge that connects the retroglenoid tubercle with the posterior arch of the C1 vertebra, also known as the Atlas.

It substitutes the lateral segment of the posterior atlantooccipital ligament or joint capsule (1) on the area which stabilizes the vertebral artery on its emergency of the transverse foramen of the Atlas (2). This bridge or arch could be thick, thin or even incomplete (2). The importance of this calcification relies on the fact that it has been linked with cervicogenic headache (1,3) chronic tension-type headaches, sensorineural hearing loss (4), shoulder and arm pain, neck pain, and vertigo (1, 5).

The presence of a ponticulus posticus could also impact the planning of high cervical surgeries associated with the Atlas [C1] (6). A recent meta-analysis of the prevalence of this condition worldwide found an overall prevalence of a complete PP of 9.1% versus an incomplete PP, which was 13.6%. In males (10.4%) the complete PP was more common than in females (7.3%), but an incomplete PP was more commonly seen in females (18.5%) than in males (16.7%) (7).

Despite the fact that this calcification has been associated with different painful disorders, some other authors consider it an anatomical condition destined to protect the vertebral artery and not a pathological condition (8). PP is visible on lateral cervical spine and cranial lateral radiographs as thin bony arch on the shape of a ring crossing from the retroglenoid tubercle to the posterior arch of C1, being either partially of fully calcified (Figures C and D).

Note 1: For the etymology of the term glenoid, click here.
Note 2: Figures C and D can be found at the bottom of the article

Sources:
1. Ross JS, Moore KR, editors. Diagnostic Imaging: Spine E-Book. 3rd ed. Philadeplphia: Elsevier; 2015. 31 p.
2. Torres Cueco R. La Columna Cervical: Evaluación Clínica y Aproximaciones Terapéuticas. Principios anatómicos, funcionales, exploración clínica y técnicas de tratamiento. Tomo I. 1° Ed. Madrid: Medica Panamericana; 2008. 124 p.
3. Tambawala SS, Karjodkar FR, Sansare K, Motghare D, Mishra I, Gaikwad S, Dora AC. Prevalence of Ponticulus Posticus on Lateral Cephalometric Radiographs, its Association with Cervicogenic Headache and a Review of Literature. World Neurosurg [Internet]. 2017 Apr 17(cited 02 Jun 2017). pii: S1878-8750(17)30525-9. Available at: doi: 10.1016/j.wneu.2017.04.030. [Epub ahead of print]
4. Koutsouraki E, Avdelidi E, Michmizos D, Kapsali SE, Costa V, Baloyannis S. Kimmerle's anomaly as a possible causative factor of chronic tension-type headaches and neurosensory hearing loss: Case report and literature review. Int J Neurosci. 2010; 120:236-9

Figure A: Incomplete PP viewed from the posterior aspect of the articular fossa related to the retroglenoid tubercle.
Click on the image for a larger depiction

  Figure B: Complete PP on a C1 sample. It crosses from the retroglenoid tubercle down to the posterior arch.
Click on the image for a larger depiction

Acknowledgments: The Atlas [C1] specimens shown on figures A and B belong to the Anatomy department of the Medical College of the Finis Terrae University, Santiago, Chile and are used to show two examples of PP. With permission.
Article written by Prof. M. Fernanda Cortes, DDS, MsC.

  Figure C: Complete PP shown on a lateral radiographic view.                               Figure D: Partial PP shown on a lateral radiographic view.
Click on the image for a larger depiction

Friends of Medical Terminology Daily:

As you know, we are part of an incredible quest to find the body of Andreas Vesalius, recognized worldwide as the Father of Modern Anatomy. His life and the story and legends about his death are part now of scientific fact and folklore.

The quest for the lost grave of Andreas Vesalius has been published in this blog several times. Many of the members of this group, such as Pascale Pollier, Theo Dirix, Dr. Sylvianne Déderix, Dr. Maurits Biesbrouck, etc. are contributors to Medical Terminology Daily.

The project has had several stages and you are welcome to follow the above links to the authors to read their contributions which clarify the scope and objectives of this quest, including Theo Dirix's article : "To put it in another way: where do we have to look for Vesalius's grave?"

Wax bust of Andreas Vesalius by Pascale Pollier. Click on the image for a larger depiction

The project next step is to perform a detailed research on the area where we suspect (actually know with a high degree of certainty) where the cemetery of the Church of Santa Maria delle Grazie used to be.

"The Belgian School of Archaeology)in Athens (EBSA) just obtained the permission for a new archaeological project at Zakynthos in collaboration with the local Ephorate and Dr Merkouri, as well as the IMS in Rethymnon (Dr A. Sarris). The project, initiated and coordinated by Theo Dirix and Pascale Pollier, concerns the quest for the tomb of the Belgian anatomist, father of modern anatomy, Andreas Vesalius who died and was buried in the island."

Needless to say, we are all excited. Now we have to fund this research, and you can all help by contributing as little or as much as you can to the GoFundMe page. We are very close to our objective and this will allow us to pay the permits, rent the equipment and finally get a little closer to finding Andreas Vesalius.

Original photograph of the Church of Santa Maria delle Grazie in Zakynthos, Greece. Click on the image for a larger depiction

Personal note: Click on the following link to collaborate with this incredible quest. I already did. Dr. Miranda

GoFundMe Campaign for the next stage of the project

The mandibular canal is a long, bilateral canal which runs along and within the mandible. This canal transports the inferior alveolar neurovascular bundle. The mandible is known vernacularly as the “jawbone” or “lower jaw”.

The mandibular canal starts on the medial surface of the mandibular ramus at the mandibular foramen (Figure A, arrow) descends anteroinferiorly through the body of the mandible until it ends in the mental foramen at the buccal (anterior) surface of the mandible, usually in the area between the premolars (Figure B, arrow).

Before exiting, the canal forms an “anterior loop” projected anterior to the mental foramen prior to changing its direction back and outwards in direction to the buccal plate (Figure C, red line). This last portion of the canal is called the “mental canal”.

A frequent anatomical variation is the presence of a bifid mandibular canal (recent studies indicate it has a prevalence of around 16%).

Different anatomical studies show that the mandibular canal not only finishes at the mental foramen, but it could divide itself giving an incisive canal which runs anteriorly onto the incisal region (Figure C, yellow line). When it doesn’t continue as an incisal canal, the neurovascular elements go anteriorly through the cells of the spongy bone tissue.

The presence of this Incisal canal has surgical relevance, and knowledge of its exact location and anatomical parameters has a high importance on reducing complications of surgical procedures in the mental area such as dental implants, bone lesions removal and bone harvesting among others, all which could damage the incisal canal and the neurovascular bundle inside it.

With the latest use of CBCT (Cone Beam Computed Tomography) technology to evaluate anatomical structures, the presence of this canal has showed to be high (92-100%) and its length can vary from reaching only the premolar area or even the central mandibular incisors in the least of cases.

Click on the image for a larger depiction

This word originates from the root terms [-lith-], which arises from the Greek word [λίθος] meaning “stone” and the term [-pedion-] (or [pædion]) which is also Greek [παιδί] meaning “child”. In simple terms this would mean a “stone child”.

Strangely enough, “stone children” or lithopædia are rare cases found in nature, and have been described in humans since early times, the first one by Abū al-Qāsim (Abulcasis) in the 10th century.

When found, it is usually a fetus of more than 12 weeks of estimated age. This is because a younger fetus, if it dies, will usually be reabsorbed by the mother’s body. Usually they are ectopic pregnancies where the fetus dies and is calcified, turning into “stone”.

Technically there are three types of lithopaedia:

1. Lithokelyphos: Only the surrounding fetal membranes calcify. The fetus decomposes and is absorbed, while the calcified membranes protect the mother from the effects of necrosis.

2. Lithokelyphopaedion: Where the membranes and the fetus calcify.

3. True lithopedion, also known as “lithopedion proper”, or lithotecnon. The most common presentation when found, only the fetus is calcified.

The incidence of lithopedia is estimated close to 1.8% of ectopic pregnancies. The following images are of a lithopedion case described by Bainbridge in 1911 and include an X-Ray of the lithopedion.

Lithopedion Clark,JG 1897
Click on the image for a larger depiction

Sources:
1. “A rare case of Lithopedion” Clark, JG John Hopkins Hospital Bulletin Volume 8 (1897) 221-228
2. “Lithopedion, Report of a case with a review of the literature” Bainbridge, WS. Am J Obstr V65 (1911) 31 – 52
3. “Chilean woman carried calcified foetus for 50 years” BBC News
4. Blog: James Edwards Hughes “The Lithopedion”