II. Physiology

  1. Innervates extraocular lateral rectus muscle
  2. Moves eye laterally
  3. Long thin nerve that is susceptible to compression (Cranial Nerve 4 and 6 are similar in this way)
    1. Paralysis (unilateral or bilateral) may occur even with generalized Increased Intracranial Pressure
    2. Contrast with the Cranial Nerve 3 which is a thick cable-like nerve requiring significant compression for paralysis

III. Anatomy

  1. Abducens Nucleus
    1. Abducens Nucleus lies beneath facial colliculus in the pons
  2. Course
    1. As with all other Cranial Nerves (except CN 4), fibers remain ipsilateral (do not cross over)
    2. Nerve crosses clivus (anterior aspect of the basal portion of the Occipital Bone)
    3. Nerve runs below clinoid process (Sphenoid Bone)
    4. Nerve passes through Cavernous Sinus
    5. Nerve enters orbit through superior orbital fissure

IV. Exam

  1. Normal function of the lateral rectus muscle
    1. Lateral eye movement (eye abduction)
  2. Paralysis of the lateral rectus muscle
    1. eye_eom.png
    2. See Cranial Nerve 6 Palsy
    3. Unilateral paralysis results in lateral Gaze Palsy (may present with horizontal Diplopia)

V. Causes: CN 6 Palsy

  1. Distinguish from Internuclear Ophthalmoplegia (Conjugate Gaze Palsy)
  2. Trauma, compression, inflammation or infection
    1. May occur anywhere along the CN 6 course (and nerve is thin, susceptible to injury)
    2. See Anatomy above
  3. Focal spread of infection at petrous apex of Temporal Bone (e.g. Otitis Media, Mastoiditis)
  4. Cavernous Sinus Thrombosis
  5. Cerebrovascular Accident affecting Pons
  6. Bilateral CN 6 Palsy Causes
    1. Wernicke's Encephalopathy (bilateral CN 6 Palsy)
    2. Botulism
    3. Increased Intracranial Pressure

VI. References

  1. Gilman (1989) Manter and Gatz Essentials of Neuroanatomy and Neurophysiology, Davis, p. 87-113
  2. Goldberg (2014) Clinical Neuroanatomy, p. 24-39
  3. Netter (1997) Atlas Human Anatomy, ICON Learning, p. 110-129

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Ontology: Abducens nerve structure (C0000741)

Definition (NCI_CDISC) The sixth cranial nerve.
Definition (NCI) A cranial nerve that supplies motor impulses to the lateral rectus muscle of the eye.
Definition (MSH) The 6th cranial nerve which originates in the ABDUCENS NUCLEUS of the PONS and sends motor fibers to the lateral rectus muscles of the EYE. Damage to the nerve or its nucleus disrupts horizontal eye movement control.
Concepts Body Part, Organ, or Organ Component (T023)
MSH D000010
SnomedCT 80622005
English Abducens Nerve, Abducent Nerve, Abducent Nerves, Nerve, Abducens, Nerve, Abducent, Cranial Nerve VI, Cranial Nerve, Sixth, Nerve VI, Cranial, Nerve, Sixth Cranial, Nerves, Sixth Cranial, Sixth Cranial Nerve, Sixth Cranial Nerves, cranial nerve VI, Abducent nerve [VI], Abducens nerve [VI], Nervus abducens [VI], Abducens nerve tree, abductor digiti minimi, Nerve VIs, Cranial, Cranial Nerve VIs, abducent nerve, 6n, abducens nerve, sixth cranial nerve, Nervus abducens, abducence nerve, ABDUCENS NERVE, Nervus Abducen, Abducens, Nervus, Abducen, Nervus, Nervus Abducens, Nerve VIs, Nerve VI, Sixth cranial nerve, Lateral rectus nerve, Abducens nerve, Abducens nerve (VI), Abducent nerve, Cranial nerve VI, Abductor digiti minimi, Abducens nerve structure (body structure), Abducens nerve structure, Abducens nerve, NOS, Nerve (Abducens)
French Nerf crânien 6, Sixième paire crânienne, Sixième nerf crânien, Nerf crânien VI, Nerf moteur oculaire externe, Nerf abducens
Swedish Abducensnerv
Czech nervus abducens, odtahovací nerv, VI. hlavový nerv
Finnish Loitontajahermo
Japanese 外転神経, 第6脳神経
German SECHSTER HIRNNERV, Hirnnerv VI, Nervus abducens, VI. Hirnnerv
Italian Sesto nervo cranico, Nervo cranico VI, Nervo abducente
Latvian Atvilcējmuskuļa nervs
Polish Nerw odwodzący, Nerw VI
Norwegian Abducens-nerve, Hjernenerve 6, 6. hjernenerve, Nervus abducens
Spanish Nervio Craneal VI, VI Par Craneal, VI par craneal, estructura del nervio motor ocular externo (estructura corporal), estructura del nervio motor ocular externo, nervio motor ocular externo, nervio recto lateral, sexto nervio craneal, sexto par craneal, sexto par craneano, Nervio Abducente, Sexto Nervio Craneal, VI Nervio Craneal
Portuguese VI Nervo Craniano, VI Par Craniano, Nervo Abducente, Nervo Craniano VI, Sexto Nervo Craniano
Dutch Nervus abducens, Nervus cranialis VI, VIe hersenzenuw

Ontology: Structure of abducens nucleus (C0152407)

Definition (NCI) The cranial nerve nucleus from which the abducens nerve originates from. It is located in the middle portion of the brain stem.
Definition (MSH) A region in the PONTINE TEGMENTUM that is the nucleus of the ABDUCENS NERVE.
Concepts Body Part, Organ, or Organ Component (T023)
MSH D065827
SnomedCT 31456003
English Abducens nerve nucleus, Nucleus of abducens nerve (VI), Abducent nucleus, Nucleus of abducens nerve, 6, nucleus of abducens nerve (VI), abducens nerve nucleus, abducens nucleus, abducens nucleus proper, Nucleus nervi abducentis, Nucleus abducens, Abducens Nucleus, Abducen, Nucleus, Abducentis, Nucleus Nervi, Nervi Abducentis, Nucleus, Nucleus Abducens, Nucleus Nervi Abducentis, Abducens Nerve Nucleus, Nucleus Abducen, Abducens, Nucleus, Abducenti, Nucleus Nervi, Nervi Abducenti, Nucleus, Nucleus Nervi Abducenti, Nucleus, Abducens Nerve, Nucleus, Abducens, Nerve Nucleus, Abducens, Abducens nucleus, Sixth cranial nerve nucleus, Structure of abducens nucleus (body structure), Structure of abducens nucleus, Sixth Cranial Nerve Nucleus
Spanish estructura del núcleo del nervio motor ocular externo (estructura corporal), estructura del núcleo del nervio motor ocular externo, núcleo del VI par craneal, núcleo del nervio motor ocular externo, núcleo del sexto nervio craneal, núcleo del sexto nervio craneano, núcleo del sexto par craneal