Main page/Nerve anastomosis

Nerve anastomosis

Petrosal nerves

3 superficial petrosal nerve

Greater superficial petrosal nerve

  • Arises from geniculate ganglia (CN7)
  • Joins GSPN to form Vidian nerve
  • Contains parasympathetic afferents from superior salivatory nucleus → efferent division of the Nervous intermedius (CN7) → GSPN → vidian nerve → pterygopalatine ganglion → lacrimal gland
    • The preganglionic parasympathetic axons of this nerve synapse in the pterygopalatine ganglion.
    • Superior view of the right middle cranial fossa.
        • The GSPN constructs both Glasscock's and Kawase's triangles
          • The line through root of zygoma and foramen spinosum reaches the intersection of the GSPN and the trigeminal ganglion.
        • The midpoint of the line extended from midpoint of the arcuate eminence to the foramen spinosum is roughly the hiatus fallopii.
        notion image
    • 4 segments of the GSPN in a panoramic anterolateral view.
        • Intrapetrosal Segment
          • The intrapetrosal segment arose from the geniculate ganglion and penetrated through the petrous bone to the hiatus fallopii.
        • Suprapetrosal Segment
          • After the GSPN pierced the hiatus fallopii, the suprapetrosal segment coursed parallel to the lateral wall of the horizontal internal carotid artery (ICA), posteriorly to the mandibular branch of the trigeminal nerve, and anterointernally to the foramen lacerum in the middle cranial fossa.
          • The petrosal segment of ICA always coursed below the GSPN, with a thin bone lamella separating them; however, near the foramen lacerum
          • The sulcus for GSPN is a groove in the bone that is located in the surface of the petrous bone.
        • Segment of Foramen Lacerum
          • The segment of foramen lacerum extended from the point of entering foramen lacerum to its entrance into the pterygoid/vidian canal.
         
        notion image
        Vidian canal (VC) is well seen on the right passing to the pterygopalatine fossa (PPF). It contains the vidian artery, a branch from the internal carotid artery (ICA)
        Vidian canal (VC) is well seen on the right passing to the pterygopalatine fossa (PPF). It contains the vidian artery, a branch from the internal carotid artery (ICA)
  • Damage
    • Unilateral impairment of reflexive tearing

Lesser superficial petrosal nerve

  • Arises from the Tympanic plexus.
  • The geniculate ganglion sends parasympathetic afferents into the Tympanic plexus via the geniculotympanic nerve
    • Parasympathetic afferents from inferior salivatory nucleus → tympanic nerve (CN9) → Tympanic plexus → lesser superficial petrosal nerve (+ geniculotympanic nerve) → otic ganglion → parotid gland

External superficial petrosal nerve

  • Receives sympathetic fibers from the plexus surrounding the middle meningeal artery

1 deep petrosal nerve

  • Arises from the carotid plexus
  • Joins GSPN to form vidian nerve
  • Contains sympathetic afferents
  • Communicating branch of the geniculate ganglion of the facial nerve with the sympathetic plexus surrounding the middle meningeal artery.

The tympanic and internal carotid artery plexuses and their communications

notion image
  • Tympanic plexus (1) is formed by the
      • Afferents
      • Superior (3) and inferior (4) caroticotympanic nerves from the internal carotid artery sympathetic plexus (5)
      Efferent
      • Lesser petrosal nerve (6)
          • Derived from tympanic plexus
          • Is joined by a branch from the facial nerve
            • Aka
              • Communicating branch of facial nerve with tympanic plexus (7).
              • Geniculotympanic nerve.
                • Arises from the geniculate ganglion
          • Mainly contains preganglionic parasympathetic fibres of the CN9
          • Ultimately ends in the otic ganglion → Parotid gland
           
          Carotid plexus also communicates with Gasserian ganglion and abducens nerve (not shown here)
          Carotid plexus also communicates with Gasserian ganglion and abducens nerve (not shown here)
      Greater superficial petrosal nerve (8) GSPN
      • Branches from the geniculate ganglion
      • Contains preganglionic parasympathetic fibers of the facial nerve
      • Is joined by a branch from the carotid sympathetic plexus—known as the deep petrosal nerve (9)—to form the vidian nerve (10), which ultimately ends in the pterygopalatine (Meckel's) ganglion (11).

Images

Anastomosis of the auriculotemporal nerve with the temporofacial division of the facial nerve and anastomosis of the greater auricular nerve with the cervicofacial division of the facial nerve at the parotid and peri-parotid regions.
Anastomosis of the auriculotemporal nerve with the temporofacial division of the facial nerve and anastomosis of the greater auricular nerve with the cervicofacial division of the facial nerve at the parotid and peri-parotid regions.
Note that geniculate ganglion gives rise to the greater petrosal nerve, communicates with the lesser petrosal nerve and receives sympathetic fibers from the plexus surrounding the middle meningeal artery. The nerve connecting the latter with the geniculate ganglion is known as the external petrosal nerve. The greater, lesser and external petrosal nerves are superficial petrosal nerves.
Note that geniculate ganglion gives rise to the greater petrosal nerve, communicates with the lesser petrosal nerve and receives sympathetic fibers from the plexus surrounding the middle meningeal artery. The nerve connecting the latter with the geniculate ganglion is known as the external petrosal nerve. The greater, lesser and external petrosal nerves are superficial petrosal nerves.
This image is a bit wrong the lesser petrosal nerve does not arise from the geniculate ganglion but it comes from the tympanic plexus. The geniculate ganglion has a connection with the tympanic plexus via the geniculotympanic nerve
This image is a bit wrong the lesser petrosal nerve does not arise from the geniculate ganglion but it comes from the tympanic plexus. The geniculate ganglion has a connection with the tympanic plexus via the geniculotympanic nerve
Anastomosis between the lacrimal nerve and zygomaticotemporal branch of the zygomatic nerve (a branch of the maxillary nerve) within the orbit.
Anastomosis between the lacrimal nerve and zygomaticotemporal branch of the zygomatic nerve (a branch of the maxillary nerve) within the orbit.
Schematic drawing showing connections between cranial nerves VII, IX, and X and some of their branches. Notable here is the loop-shaped connection (black star) between the proximal portions of the facial and glossopharyngeal nerve trunks.
Schematic drawing showing connections between cranial nerves VII, IX, and X and some of their branches. Notable here is the loop-shaped connection (black star) between the proximal portions of the facial and glossopharyngeal nerve trunks.
Haller-Sappey ansa. Note the styloid branch of the facial nerve receives a communication from the glossopharyngeal nerve and then divides into the digastric and stylohyoid nerve branches to supply the posterior belly of the digastric muscle and stylohyoid muscle, respectively. Note the Y-shaped communication between the pharyngeal branches of the vagus and glossopharyngeal nerves as both branches join to form a single trunk before supplying the pharynx.
Haller-Sappey ansa. Note the styloid branch of the facial nerve receives a communication from the glossopharyngeal nerve and then divides into the digastric and stylohyoid nerve branches to supply the posterior belly of the digastric muscle and stylohyoid muscle, respectively. Note the Y-shaped communication between the pharyngeal branches of the vagus and glossopharyngeal nerves as both branches join to form a single trunk before supplying the pharynx.
The communication between the glossopharyngeal and facial nerves travelling through the posterior belly of the digastric muscle. Note that in this case, the ansa is continuous with a digastric branch of the facial nerve. Other communications are seen in this picture: (1) connection of the glossopharyngeal nerve with the jugular nerve of the superior cervical sympathetic ganglion and the nodose ganglion of the vagus nerve and (2) connection between the auricular nerve of the vagus nerve and the facial nerve trunk.
The communication between the glossopharyngeal and facial nerves travelling through the posterior belly of the digastric muscle. Note that in this case, the ansa is continuous with a digastric branch of the facial nerve. Other communications are seen in this picture:
(1) connection of the glossopharyngeal nerve with the jugular nerve of the superior cervical sympathetic ganglion and the nodose ganglion of the vagus nerve and
(2) connection between the auricular nerve of the vagus nerve and the facial nerve trunk.