Anatomy of Cranial Nerves 5,7,8


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Gross Anatomy of Cranial Nerves 5, 7, 8

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Anatomy of Cranial Nerves 5,7,8

  1. 1. DR. DIBAKOR BHATDR. DIBAKOR BHAT HMO, Department of NeurologyHMO, Department of Neurology Dhaka Medical College HospitalDhaka Medical College Hospital 05.04.2014
  2. 2. DEVELOPMENT Trigeminal nerve: Metencephalon, Mesencephalon Facial nerve: Metencephalon, Myelencephalon Vestibulocochlear nerve: Myelencephalon
  5. 5. TRIGEMINAL NERVE Largest cranial nerve Nuclei 1.The main sensory nucleus 2.The spinal nucleus 3.The mesencephalic nucleus 4.The motor nucleus
  6. 6. The main sensory nucleus: It lies in the posterior part of the Pons, lateral to the motor nucleus. It is continuous below with the spinal nucleus The spinal nucleus: It is continuous superiorly with the main sensory nucleus in the Pons and extends inferiorly through the whole length of the medulla oblongata and into the upper part of the spinal cord as far as the second cervical segments
  7. 7. The mesencephalic nucleus: It is composed of a column of unipolar nerve cells in the lateral part of grey matter around the cerebral aqueduct, extends inferiorly into the pons as far as the main sensory nucleus The motor nucleus: It is situated in the pons medial to the main sensory nucleus
  8. 8. Sensory branches of the trigeminal nerve The ophthalmic, maxillary and mandibular branches leave the skull through three separate foramina: superior orbital fissure, foramen rotundum and foramen ovale  The ophthalmic nerve carries sensory information from the scalp and forehead, the upper eyelid, the conjunctiva and cornea of the eye, the nose (including the tip of the nose), the nasal mucosa, the frontal sinuses and part of the meninges (the dura and blood vessels).  The maxillary nerve carries sensory information from the lower eyelid and cheek, the nares and upper lip, upper teeth and gums, nasal mucosa, the palate and roof of pharynx, the maxillary, ethmoid and sphenoid sinuses and part of the meninges.  The mandibular nerve carries sensory information from the lower lip, the lower teeth and gums, the chin and jaw (except the angle of the jaw, which is supplied by C2-C3), part of the external ear and part of the meninges.
  9. 9. Sensory branches of the trigeminal nerve  Touch & Pressure terminates into main sensory nucleus  Pain & Touch terminates into spinal nucleus  Ophthalmic division terminates into inferior part of spinal nucleus  Maxillary division terminates into medial part of spinal nucleus  Mandibular division terminates into inferior part of spinal nucleus
  10. 10. Motor branches of the trigeminal nerve  Motor branches are distributed in the mandibular nerve, originate in motor nucleus  The motor branches of the trigeminal nerve control the movement of eight muscles, including the four muscles of mastication Muscles of mastication masseter temporalis medial pterygoid lateral pterygoid Other tensor veli palatini mylohyoid anterior belly of digastric tensor tympani  All have bilateral cortical representation. A central lesion (e.g. stroke) is unlikely to produce any observable deficit. However, injury to the peripheral nerve can cause paralysis of muscles on one side of the jaw.
  11. 11. Course The trigeminal nerve leave the anterior aspect of the pons as a small motor root and a large sensory root. The nerve passes forward out of the posterior cranial fossa and rests on the upper surface of the apex of the petrous part of the temporal bone in the middle cranial fossa. The large sensory root now expand to form the crescent shaped trigeminal ganglion, which lies within a pouch of dura mater called the trigeminal or meckel’s cave.
  12. 12. Function The sensory function of the trigeminal nerve is to provide the tactile, proprioceptive and nociceptive afferent of the face and mouth. The posterior scalp and the neck are innervated by C2-C3, not by the trigeminal nerve. The motor function activates the muscles of the mastication, the tensor tympani, tensor veli palatini, mylohyoid, and anterior belly of the digastric.
  13. 13. FACIAL NERVE
  14. 14. FACIAL NERVE Facial nerve is a Mixed nerve Nuclei The main motor nucleus This lies deep in the reticular formation of the lower part of the pons. The upper part of the nucleus that supplies the muscles of the upper part of the face receives corticonuclear fibers from both cerebral hemisphere. The part of the nucleus supplies the lower part of the face receives corticonuclear fibers only from the opposite cerebral hemisphere.
  15. 15. The parasympathetic nuclei: These lies posterlateral to the main motor nucleus, they are: 1. Superior salivatory nucleus 2. Lacrimal nucleus The sensory nucleus: This is the upper part of the nucleus of the tractus solitarius and lies close to the motor nucleus.
  16. 16. Intracranial Course & Relation
  17. 17. Intracranial Course & Relation
  18. 18. Intracranial Course & Relation
  19. 19. Intracranial Course & Relation
  20. 20. Intracranial Course & Relation
  21. 21. Intracranial Course & Relation
  22. 22. Branches of VII nerve
  23. 23. Branches of VII nerve
  24. 24. Terminal Branches
  25. 25. Ganglia Associations  Geniculate ganglia  Submandibular ganglia  Pterygopalatine ganglia
  26. 26. Ganglia Associations
  27. 27. Ganglia Associations
  28. 28. Function Efferent 1. Motor control of most of the muscles of facial expression, innervates the posterior belly of the digastric, stylohyoid and stapedius muscle of the middle ear 2. The facial also supplies parasympathetic fibers to the submandibular gland and sublingual glands via chorda tympani. Parasympathetic innervation serves to increase the flow of saliva from these glands. It also supplies parasympathetic innervation to the nasal mucosa and the lacrimal gland via the pterygopalatine ganglion 3. Efferent limb of the corneal reflex
  29. 29. Function Afferent It receives taste sensations from the anterior two-thirds of the tongue and sends them to the nucleus of solitary tract
  31. 31. Vestibular nerve nuclei 1. Lateral vestibular nucleus 2. Superior vestibular nucleus 3. Medial vestibular nucleus 4. Inferior vestibular nucleus Cochlear nerve nuclei 1. Anterior cochlear nuclei 2. Posterior cochlear nuclei
  32. 32. Course It emerges from the anterior surface of the brain between the lower border of the pons and medulla oblongata and enters the inner skull via the internal acoustic meatus in the temporal bone, along with the facial nerve.
  33. 33. Function The vestibular nerve conducts nerve impulse from Utricle and saccule: position of head Semicircular canals: movement of head The cochlear nerve conducts nerve impulse concerned with sound from the organ of corti