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Home , Foramen rotundum

Original/Research Articles An Accessory Foramen Adjacent to The Foramen Rotundum in Dried

Bindu Aggarwal, Madhur Gupta, Harsh Kumar

Abstract The and an emissary vein pass through foramen rotundum to reach the . An accessory foramen was observed adjacent to the foramen rotundum in dried skulls. 134 sides of adult dried skulls were selected from the archives of the Department of Anatomy, Gian Sagar Medical and Dental College, Banur and were studied for presence of an accessory foramen adjacent to foramen rotundum. The accessory foramen was observed in 12 sides of skulls that varied in its shape and all opened into the pterygopalatine fossa. In patients of trigeminal neuralgia the maxillary nerve infiltration is done through the foramen rotundum. Failure of maxillary nerve block has been reported in about 16% of cases suggesting that the failure of nerve block may be due to a branch of the maxillary nerve which passes through the accessory foramen adjacent to the foramen rotundum.

Introduction The maxillary nerve is involved in cases he foramen rotundum is a round of trigeminal neuralgia. Maxillary nerve T foramen present in the middle cranial block is approached through the foramen fossa. It lies medially on the upper surface rotundum but failure of the nerve block 8, 9 of the greater wing of sphenoid. The have been reported. foramen is located posterior to the medial An accessory foramen was observed end of the and while teaching the under-graduates in the leads directly into the pterygopalatine adjacent to the fossa.1, 2, 3 foramen rotundum. Thus the present The foramen rotundum transmits the study was conducted to see its presence maxillary nerve (containing sensory fibres) thinking that failure of maxillary nerve and an emissary vein. The maxillary nerve, block could be because of some fibres a branch of the passes passing through the accessory foramen horizontally forwards and medially, below present adjacent to the foramen in the lateral wall of the to rotundum. traverse via the foramen rotundum into Material and Methods the pterygopalatine fossa. The maxillary In the present study, 134 sides of adult nerve supplies skin, teeth, gums, cheek, dried skulls of unknown sex were mucosa related to maxilla and the side of examined for the presence of an accessory 4, 5, 6, 7 nose. foramen, adjacent to the foramen Dept. of Anatomy, Gian Sagar Medical College and rotundum. The route of the accessory Hospital, Banur, Patiala, Punjab, India-140 601. foramen was confirmed by passing a

Bombay Hospital Journal, Vol. 53, Special Issue, 2011 317 colored fluid through it. It was confirmed that the accessory foramen opened into the pterygopalatine fossa and not into the or the infra-temporal fossa. The width of the bony bar which separated foramen rotundum from the superior orbital fissure was measured. The presence, shape, size and location of the accessory foramen were observed and noted. All the measurements were done with the help of a divider with a fixing device and digital Vernier calipers. Results The foramen rotundum was present bilaterally in all the skulls in the middle cranial fossa. It was round in shape and placed obliquely. It was separated from the superior orbital fissure by a bony bar. The mean width of the bony bar on the right side was 3.652 mm and the range was 0.32 - 6.91mm. On the left side the mean width

Fig. 2 : Showing a minute accessory foramen (AF) on the left side of , anterior to the foramen rotundum (FR) and opening into the pterygopalatine fossa, anterior clenoid process (ACP), (FO). of the bony bar was 3.444 mm and the range was 0.32 - 5.81 mm. An accessory foramen adjacent to foramen rotundum opening into the pterygopalatine fossa was observed in left side of skulls. The accessory foramen was either present on the right side or the left side, their difference being statistically insignificant. The accessory foramen varied in shape and size (Figs. 1-3). A Fig. 1 : Showing the round shaped groove could be clearly seen passing from accessory foramen (AF) opening into the the foramen rotundum to the accessory pterygopalatine fossa, lateral to the foramen rotundum (FR) on the left side with foramen suggesting that a small branch of a groove in between the two (G), anterior maxillary nerve passes through the clenoid process (ACP), foramen ovale (FO). accessory foramen too (Fig 1).

318 Bombay Hospital Journal, Vol. 53, Special Issue, 2011 The maxillary nerve, a small artery and emissary vein pass through foramen rotundum to reach the pterygopalatine fossa.17 In the present study a groove could be clearly seen passing from the foramen rotundum to the accessory foramen suggesting that a small branch of maxillary nerve passes through the accessory foramen too. A variant of the foramen rotundum was found in the form of a small opening which led to or the space 18 Fig. 3 : Showing the slit-shaped accessory between the pterygoid plates. The foramen (AF) on the right side of skull, adjacent opening was found in 5 out of 50 skulls to the foramen rotundum (FR) and opening into and suggested that it transmitted an the pterygopalatine fossa, anterior clenoid 19 process (ACP), foramen ovale (FO). emissary vein. In the present study an accessory foramen was observed adjacent Discussion to the foramen rotundum in left side of The foramen rotundum through which skull and opened into the pterygopalatine the maxillary nerve passes and opens into fossa. the pterygopalatine fossa, was present as a The foramen rotundum may be round foramen bilaterally in the middle doubled or absent (0.64% of 157 skulls) cranial fossa in all the skulls as described and may be continuous with the superior 1,10,11 in various text books of anatomy. The orbital fissure.16 In the present study, it foramen is oval-shaped in the foetal was named as accessory foramen. period, ring-shaped by 4th foetal month and 12 The maxillary nerve is involved most round- shaped after birth. The foramen frequently in trigeminal neuralgia and rotundum is confluent with the superior 8 atypical facial neuralgia. To treat this orbital fissure and during normal human condition, the nerve fibres are blocked embryogenesis; it can be identified as a 20 with a neurolytic or local anaesthetic. discrete separate orifice from the superior orbital fissure by the 12th week of foetal In order to block the maxillary nerve, 13,14 the infiltration of the nerve is approached life. The cartilages of the sphenoid are interrupted by pathway of maxillary through the foramen rotundum. In a high nerve to create the foramen rotundum.15 percentage of patients, the procedure of nerve block is successful but, in a few In the present study, the width of the cases, failure of nerve infiltration has been bony bar that separated foramen reported in spite of radiological guidance. 9 rotundum and superior orbital fissure varied and the mean width on the right The failure could be due to incomplete side was 3.652 mm and on the left it was infiltration as some fibres of the maxillary 3.444 mm. Usually, during ossification of nerve may pass through the accessory , a spur of bone develops foramen as previous studies have also from the greater wing of sphenoid described the presence of double foramen 16 separating the foramen rotundum and the rotundum. The infiltration probably will superior orbital fissure.16 be complete only if the fibres of the

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