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Journal of the Anatomical Society of India

Bilateral Foramen Clinoideo-Caroticum & Interclinoid Bars-A Report of 2 Cases

Author(s): Patnaik, V.V.G; *Singla, Rajan, K.; *Bala Sanju.

Vol. 52, No. 1 (2003-01 - 2003-12)

Department of Anatomy, Govt. Medical College, Patiala, "Department of Anatomy Govt. Medical College, Amritsar, ** Department of Oral & Maxillofacial Surgery, SGRD Dental College, Amritsar. INDIA.


In the present paper, the authors have reported two skulls, in one of which, a bilatera: foramen clinoideo caroticum is seen as a consequence of fusion of anterior & middle clinoid processes. In the other one anterior & posterior clinoid processes are fused bilaterally forming interclinoid bars. Further a note is added on the ontogeny & clinical significance of the conditions whereever applicable.

Key words: Foramen Clinoideo Caroticum, Interclinoid bar, Clinoid process


For the purpose of study, cranial cavity can be divided into 3 fossae viz. anterior, middle and posterior cranial fossae. The anterior cranial fossa, extending from frontal bone anteriorly to lesser wing of sphenoid posteriorly lodges the frontal lobe of cerebral hemispheres. The lesser wings of the sphenoid which form the posterior border of this fossa end medially to form eminences termed as anterior clinoid processes. To these are attached anterior end of free margin of tentorium cerebelli. The middle cranial fossa is butterfly shaped & formed in the centre by superior or cerebral surface of body of the sphenoid. Anteriorly this surface is smooth & is termed jugum sphenoidale. Traced posteriorly, it presents, sulcus chiasmaticus, tuberculum sellae, sella turcica & dorsum sellae. Anterior boundary of sella turcica is completed laterally by 2 small eminences, the middle clinoid processes. It also forms the anterior end of the medial boundary of the groove for internal carotid artery. The superoiateral angles of dorsum sellae end in 2 tubercles of varying size, the posterior clinoid processes which give attachment to the fixed margin of tentorium cerebelli.

The posterior cranial fossa is deep lying posterior to petrous part of temporal bone, formed greatly by squamous part of occipital bone & lodges the cerebellar hemispheres. (Williams et al, 1999)

Material & Methods:

The material consisted of 2 dry skulls which belonged to the students of MBBS 1st year. These were studied and scrutinised for any other variation & photographed.


Skull No. 1: In 1st skull, anterior & middle clinoid processes were linked by a bony bridge between the two on both sides thus forming a foramen termed foramen clinoideo-caroticum on both sides. (Photograph-1) There was no tendency of fusion between anterior and posterior or between middle and posterior clinoid processes on either side.

Skull No. 2: In 2nd skull, anterior & posterior clinoid processes were joined to each other by thick bone on both right & left sides. This bar of bone is known as interclinoid bar (Dubrul, 1996) On both sides, from the middle of this bony bar, a bony spicule was projecting medially and inferiorly towards a similar one arising from middle clinoid process. However both of these failed to fuse with each other on either side though there was an attempt to fusion. Thus an incomplete foramen clenoideo-carotium was formed on both sides (Photograph 2)


Skull No. 1: Anterior & middle clinoid processes in the living are normally linked by a ligament which is not seen in the dry skulls. However, sometimes if this ligament ossifies a foramen is formed through which internal carotid artery passes as it courses upwards medial to the anterior clinoid process to supply the brain. This foramen is known as "Foramen Clinoideo Caroticum." This is the only mention made by Dubrul, 1996 & Williams et al, 1999. No other text book of anatomy (Anson, 1950; Thorek, 1951; Hamilton, 1956; Lockhart et al 1959, or Me Minn, 1994) has even touched this topic. Even Dubrul, 1996 & Williams et al, 1999 are silent about its prevalence & about its bilateral presentation. A bilateral complete foramen clinoideo-Caroticum observed in 1st skull seems to be extremely rare & merits reporting. Clinical importance : The internal carotid artery passes through the foramen ciinoideo-caroticum as it turns upwards to supply brain. While on one hand, the foramen gives a safety cover to the artery, on the other hand, it may confuse the radiologist doing carotid arteriogram. So one should be aware of this uncommon anomaly.

Skull No. 2: The interclinoid bar of bone present between anterior & posterior clinoid processes as observed in 2nd skull may be a sequalae of ossification in duramator extending between these two processes. (Dubrul, 1996). Again on reviewing the literature (Anson, 1950, Thorek, 1951; Hamilton, 1956; Lockhart et al, 1959; Me Minn, 1994, Williams et al, 1999) no reference to this entity, its prevelance or bilateral presentation couid be traced. So a need was felt to report this rare bilateral presentation of interclinoid bar.


  1. Anson B.J. : An Atlas of human anatomy In : The skull. W.B. Saunders Co. Philadelphia : pp 7-8 (1950).
  2. Dubrul, E. L. Oral Anatomy In : The skull. AITBS Publishers & Distributors, Delhi. PP 13. (1996)
  3. Hamiliton, W.J. Textbook of Human Anatomy In : The skull. Mai Millon & Co, London : pp : 133-4 (1956).
  4. Lockhart R.D.; Hamilton, G.F. Fyfe., F.W. : Anatomy of the human body In : Bones & joints- skull. Faber & Faber Ltd. London. : pp 34-35 & 40-41, (1959).
  5. Me. Minn, R.M.H. Last's Antomy; Regional & Applied In : Osteology of skull. 9th Edn. Churchill Livingstone, Edinburgh, London : pp 643-66 (1994).
  6. Thorek, P : Anatomy in Surgery In: Skull 2nd Edn. J.B. Lippincot Co. Philadelphia, London : pp. 9-28 (1951).
  7. Williams P. L. Bannister, L.H.; Berry M.M; Collins P; Dyson, M.; Dussek, J. E.; Ferguson, M.W.J. Gray's Anatomy. In : Skeletal System. Soames, R. W.; Edr 38th Edn. Churchill living stone, Edinburgh, London : pp 547-612. (1999)

Missing Image


Photograph showing the skull with bilateral Foramen clinoideo- caroticun. (FCC) [ACP-Anterior clinoid process; MCP-middle clinoid process ; BB- Bony bar between ACP & MCP completing FCC]

Missing Image


Photograph showing the skull with Bilateral Fusion of Anterior clinoid process (ACP) with Posterior clinoid process. (PCP). There is an attempt to form foramen clinoideo-Caroticum (FCC) on both sides.

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