CN IV Trochlear Nerve

Authors

Affiliations

Nate Yomogida, B.S., SPT

Doctor of Physical Therapy

B.S. in Kinesiology

Chloë Kerstein, B.S., SPT

Doctor of Physical Therapy

B.A. in Neuroscience

Nerves of the Orbit

Nerves of the orbit and ciliar ganglion (lateral view)¹

Oblique section through the right cavernous sinus¹

Dissection showing the origins of the right ocular muscles and the nerves entering the superior orbital fissure¹

Upper part of medulla spinalis, hindbrain, and midbrain (posterior view)¹

flowchart TB
  Lmidbrain[L Tegmentum of Midbrain] --> Decussate[Decussate]
  Decussate[Decussate] --> Ltrochlearnucleus[L Trochlear Nucleus]
  
  Ltrochlearnucleus --> LSOF[L Superior Orbital fissure]
  LSOF -- Somatic Motor --> LSOM{L Superior Oblique Muscle}
  

  RA[R tegmentum of the midbrain] --> Decussate[Decussate]
  Decussate --> Rtrochlearnucleus[R Trochlear Nucleus]
  Rtrochlearnucleus --> RSOF[R Superior Orbital fissure]
  RSOF -- somatic motor --> RSOM{R Superior Oblique Muscle}

Pathway

• Exits from the Tegmentum in the Dorsal Midbrain at the level of the inferior colliculus (Near midline & ventral to cerebral aqueduct)²
• Trochlear nucleus
• (Decussate) & exit Midbrain ->cavernous sinus -> Superior orbital fissure -> Superior oblique muscle

Axons leave nucleus & Travel dorsally -> Decussate & Exit midbrain on dorsal surface -> Enter cavernous sinus -> Travel through superior orbital fissure -> Superior oblique muscle

References

1.

Gray H. Anatomy of the Human Body. 20th ed. (Lewis WH, ed.). Lea & Febiger; 1918. https://www.bartleby.com/107/

2.

Blumenfeld H. Neuroanatomy Through Clinical Cases. 3rd ed. Oxford university press; 2022.