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ORIGINAL ARTICLE
Year : 2013  |  Volume : 19  |  Issue : 1  |  Page : 20-22

Clinical anatomy of greater petrosal nerve and its surgical importance


Department of Anatomy, Goa Medical College, Bambolim, Goa, India

Date of Web Publication6-Mar-2013

Correspondence Address:
Prashant E Natekar
Department of Anatomy, Goa Medical College, Bambolim, Goa
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0971-7749.108157

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  Abstract 

Background: Surgical approach towards greater petrosal nerve has to be done with caution as many surgeons are unfamiliar with the anatomy of the facial nerve. The anatomical landmarks selected must be reliable and above all easy to identify for identification of the greater petrosal nerve so as to avoid injury to the structures in the middle cranial fossa. Observation and Results: The present study is carried out on 100 temporal bones by examining the following measurements of the right and the left sides a) length of the hiatus for grater petrosal superficial nerve b) distance from superior petrosal sinus c) distance from lateral margin of middle cranial fossa d) arcuate eminence and e) distance from exit to the foramen ovale. Discussion: The anatomical landmarks selected must be reliable and above all easy to identify. Bony structures are more suitable than soft tissue or cartilaginous landmarks because of their rigid and reliable location. These anatomical landmarks will definitely help the surgeon while performing vidian nerve neurectomy and also the anatomical relationship of the facial nerve in temporal bone. The middle fossa approach involves a temporal craniotomy in cases of perineural spread of adenoid cystic carcinomas hence these anatomical landmarks will serve as useful guide for the surgeons and radiologists.

Keywords: Foramen lacerum, Greater petrosal nerve, Middle cranial fossa, Superior petrosal sinus, Vidian nerve


How to cite this article:
Natekar PE, De Souza FM. Clinical anatomy of greater petrosal nerve and its surgical importance. Indian J Otol 2013;19:20-2

How to cite this URL:
Natekar PE, De Souza FM. Clinical anatomy of greater petrosal nerve and its surgical importance. Indian J Otol [serial online] 2013 [cited 2020 Feb 26];19:20-2. Available from: http://www.indianjotol.org/text.asp?2013/19/1/20/108157


  Introduction Top


The greater petrosal nerve is a branch of facial nerve which innervates the lacrimal gland, mucous membrane of the nasal cavity and palate. The fibers that form the greater petrosal nerve originate from the lower part of the pons. This nerve is a mixed nerve containing both sensory and parasympathetic. The bulks are sensory and are contained in the main facial nerve trunk. The parasympathetic fibers exit the brain stem as a part of a separate division of the seventh nerve known as nervous intermedius. At the geniculate ganglion, the greater petrosal nerve breaks away and courses anteromedially to exit the superior surface of the temporal bone via hiatus for the greater petrosal nerve. The nerve then continues anteromedially and slightly inferiorly and passes under Meckel's cave toward the foramen lacerum, at which point it joins the deep petrosal nerve from the carotid sympathetic plexus together forming the vidian nerve by post synaptic parasympathetic fibers and presynaptic sympathetic fibers. [1] This is also known as the "Nerve of pterygoid canal." Nerves that get involved in the formation of vidian nerve are greater petrosal nerve (preganglionic parasympathetic fibers), deep petrosal nerve (postganglionic sympathetic fibers), and ascending sphenoidal branch from otic ganglion. The vidian nerve exits its bony canal in the pterygopalatine fossa where it joins the pterygopalatine ganglion. The postganglionic parasympathetic fibers are distributed to the lacrimal gland and mucous membrane of the nose and palate providing secretory and vasomotor innervation. Surgical approach toward greater superficial petrosal nerve has to be done with caution as many surgeons are unfamiliar with the anatomy of this nerve. The present study is essential as bony structures are rigid and more suitable as anatomical guides so as to assess the anatomical relationship of the length of greater petrosal nerve, distance from superior petrosal sinus, distance from lateral margin of middle cranial fossa, from arcuate eminence, and its distance from exit to the foramen spinosum.

Since this nerve is mostly being unrecognized without a tailored high resolution approach, its anatomical knowledge is essential preoperatively wherein the surgical approach can be individually tailored minimizing the risk during surgical interventions.


  Materials and Methods Top


The present study is carried out on 100 temporal bones (dried and cadaveric) from the department of anatomy at Goa Medical College Bambolim, Goa, India, by examining the hiatus for the greater petrosal nerve of the right and the left sides of both the sexes. Each hiatus was carefully examined and its relation to the following important anatomical landmarks was measured in millimeters of both the sides.

  1. Length of the hiatus for the greater petrosal nerve (a) to (b)
  2. Distance from superior petrosal sinus (c) to hiatus for the greater petrosal nerve (d)
  3. Distance from lateral margin of middle cranial fossa (e) to hiatus for the greater petrosal nerve (d)
  4. Distance from arcuate eminence (f) to hiatus for the greater petrosal nerve (d)
  5. Distance from exit of hiatus for greater petrosal nerve (b) to the foramen spinosum (g).

  Observations and Results Top


From the above table, our present study reveals the distance in millimeters like length of the hiatus for greater petrosal nerve, distance between the hiatus for greater petrosal nerve to superior petrosal sinus, lateral margin of middle cranial fossa, arcuate eminence, and foramen spinosum. When our data were analyzed, it was found that the length of the hiatus for greater petrosal nerve was 24 mm, distance between the hiatus for greater petrosal nerve to superior petrosal sinus was 13 mm, distance from lateral margin of middle cranial fossa to the hiatus was 25 mm, distance from arcuate eminence to the hiatus for the greater petrosal nerve was 19 mm, and distance from exit of hiatus for greater petrosal nerve to the foramen spinosum was 13 mm. Our finding shows the difference in the above parameters when compared to the findings of Tubbs et al[2] as shown in [Table 1], [Figure 1].
Figure 1: Left temporal bone showing length of hiatus for greater petrosal nerve (a) to (b), superior petrosal sinus (c) to hiatus for greater petrosal nerve (d) lateral margin of middle cranial fossa (e) to hiatus for greater petrosal nerve (d) arcuate eminence (f) to hiatus for greater pertrosal nerve (d) and hiatus for greater petrosal nerve (d) to foramen spinosum (g).

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Table 1: Distance from hiatus for greater petrosal nerve to its important anatomical landmarks

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  Discussion Top


Bony structures are more suitable than soft tissue or cartilaginous landmarks because of their rigid and reliable location. [3] Vidian nerve is formed at the junction of greater petrosal and deep petrosal nerves. This area is located in the cartilaginous substance which fills the foramen lacerum. From this area, it passes forward through the pterygoid canal accompanied by artery of pterygoid canal.

Vasomotor rhinitis is a condition characterized by profuse rhinorrhea and sneezing, with or without nasal obstruction, occurring in attacks which may be either paroxysmal or perennial. The running of the nose and sneezing may be so severe as to even disable the patient.

Studies showed conclusively that stimulation of the parasympathetic or interruption of the sympathetic nerve supply to the nasal mucous membrane caused vasodilatation, hypersecretion, and sneezing. [4] These anatomical landmarks will definitely help the surgeon while performing vidian nerve neurectomy.

The anatomical relationship of the facial nerve in temporal bone is well known in surgical anatomy. [5],[6] Although no much study is being done regarding the bony anatomical landmarks, earlier study has revealed the distance from IAM to its neighboring normal anatomical structures. [7] Greater petrosal nerve is visible on MR in healthy subjects if it is sought if the radiologist is familiar with the anatomy. [8],[9],[10]

In our present study, we have measured the length of greater petrosal nerve, distance from superior petrosal sinus, distance from lateral margin of middle cranial fossa, from arcuate eminence and its distance from exit to the foramen spinosum.

The middle fossa approach involves a temporal craniotomy in cases of perineural spread of adenoid cystic carcinomas; hence, these anatomical landmarks will serve as useful guide for the surgeons and radiologists.

There may be variations in the distances from the landmarks in living as per the body compositions as this study was performed on fixed cadaver material and the same needs to be studied in vivo as thorough knowledge of the distance between the hiatus for greater petrosal nerve to important anatomical landmarks is basic and very important to the surgeons and radiologists before and during surgical intervention.

 
  References Top

1.Susan S. Clinically oriented anatomy. 6 th ed. Churchill Livingstone London: Lippincort Williams and Wilkins; 2010. p. 977.  Back to cited text no. 1
    
2.Tubbs SR, Curtis JW, E Geroge S, Sheetz J, Zehren S. Landmarks for the greater petrosal nerve. Clinical anatomy 2005;18:210-4.  Back to cited text no. 2
    
3.du Ru JA, van Benthem PP, Bleys RL, Lubsen H, Hordijk GJ. Landmarks for parotid gland surgery. J Laryngol Otol 2001;115:122-5.  Back to cited text no. 3
    
4.Malcomson KG. The vasomotor activities of the nasal mucous membrane. J Laryngol Otol 1959;73:73-98.  Back to cited text no. 4
[PUBMED]    
5.Donaldson J, Ducker L, Lambert P, Rubel E. Surgical anatomy of temporal bone. 4 th ed. New York: Raven Press; 1962.  Back to cited text no. 5
    
6.Schuknecht HF, Gulya J. Anatomy of the temporal bone with surgical implications. Philadelphia: Lea and Febiger; 1986.  Back to cited text no. 6
    
7.Natekar PE, De Souza FM. Anatomical landmarks: A surgical aid for identification of facial nerve to internal acoustic meatus. Indian J Otol 2011;17:117-9.  Back to cited text no. 7
  Medknow Journal  
8.Liu DP, Lo WM. Imaging of temporal bone. In: Som PM, Bergeron RT, editors. Head and Neck Imaging. St. Louis Mo: Mosby; 1991. p. 944-59.  Back to cited text no. 8
    
9.Gebarski SS, Telian SA, Niparko JK. Enhancement along the normal facial nerve in facial canal: MR imaging and anatomical correlation. Radiology 1992;183:391-4.  Back to cited text no. 9
[PUBMED]    
10.Tien R, Dillon WP, Jackler RK. Contrast MR imaging of facial nerve in 11 patients with Bell's palsy. AJNR Am J Neuroradiol 1990;11:735-41.  Back to cited text no. 10
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