Facial nerve

The facial nerve (Latin, facial nerve, of Facies = face ) is the seventh cranial nerve. After its topography in the embryo, he is also known as 2 Kiemenbogennerv. The facial nerve has sensitive, sensory, motor, and parasympathetic fibers innervate large parts of the head. The sensitive / sensory and parasympathetic part is also called nervus intermedius, the entire seventh cranial nerve nerve then intermediofacialis.

Origin

The motor nuclei ( nuclei motorii facial nerve ) are located in the pons, ie in the metencephalon ( hindbrain ). Before the motor fibers which connect the other qualities, they rotate the motor nucleus of the nervus abducens, which is referred to as the "inner Fazialisknie ".

The parasympathetic origin core, superior salivatory nucleus, located in the Myelencephalon ( hindbrain ).

The sensory fibers projecting from the periphery to the nucleus probably spinal trigeminal nucleus and the pontine trigeminal nucleus, while the sensory fibers are routed to the nucleus of the solitary tract.

The facial nerve enters the cerebellopontine angle together with the vestibulocochlear nerve to the brain surface and draws on the internal acoustic meatus in the temporal bone, a portion of the temporal bone, in which the inner and middle ear are located. Within the temporal bone, it runs in a bony canal, which is therefore called Fazialiskanal ( canal of the facial nerve ). In this channel, the nerve takes a sharp turn from front to back. This bend is referred to as " outer Fazialisknie ". At this point, a ganglion is turned on, geniculate ganglion. Of the sensitive and sensory pseudounipolar nerve cell bodies of the facial nerve in him. It is comparable to the dorsal root ganglion of a Spinalnervens.

Separates Even within the facial canal of the facial nerve Intermediusanteil. In addition, the nerve is released stapedius. The rest of the facial nerve exits through the stylomastoid foramen in the petrous bone.

Nervus intermedius

The intermedius (the " Intermediate ", according to its spatial location on the surface of the brain between the facial nerve itself and the eighth cranial nerve ) has two main branches, which also attach to his first main branch some motor fibers.

Petrosal nerve

The greater petrosal nerve ( "big petrous nerve" ) comes from the geniculate ganglion and parasympathetic, motor and sensory. It connects with the sympathetic fibers of the nerve deep petrosal nerve of the pterygoid canal and pulls as the pterygopalatine ganglion. In this ganglion, the preganglionic parasympathetic fibers are switched to post-ganglionic fibers and get together with the sympathetic fibers mostly with the use of branches of the maxillary nerve to its target organs:

  • Lachrymal gland
  • Glands of the nasal mucosa, nasal glands
  • Glands of the palate
  • Glands of the nasopharynx

The sensory fibers innervating the taste buds of the soft palate.

Chorda tympani

The chorda tympani ( "Surprise string " ) runs through the middle ear, leaves the skull at the fissure sphenopetrosa and has parasympathetic fibers, which stimulate the secretion of lower salivary glands ( submaxillary and sublingual gland ) and the tongue glands ( efferent ). It directs sensory taste stimuli from the anterior two thirds of the tongue.

Nervus stapedius

The stapedius nerve innervates the stapedius muscle ( stapedius ) in the middle ear. This small muscle is one of the two muscles that affect the chain of ossicles in their vibration behavior, the air conduction of sound - for example, when a great noise - reduce. The facial nerve is thus efferent limb of the stapedius reflex. An increased sensitivity to sound ( hyperacusis ) may occur in a facial nerve damage and thus of N. stapedius.

Facial branches

After exiting the stylomastoid foramen the facial nerve passes below the parotid gland forward and occurs at the posterior border of the mandible to the surface. There he lies just under the skin. Thus it is not completely protected and can easily be damaged by external influences. This can lead to peripheral facial paralysis.

Specifically, the following branches are specified:

  • Posterior auricular nerve ( auricular nerve in animals caudalis ): innervates the posterior ear muscles; has some sensory fibers that innervate the Huntsche zone
  • Auricular nerve internus: supplied in animals the inside of the ear
  • (Posterior Venter ) for the posterior belly of the digastric muscle: Ramus digastric
  • Ramus stylohyoideus: for the musculus stylohyoideus

The following branches innervating motor mimic facial muscles and are considered as disposals from the parotid plexus, a nerve network in the parotid gland:

  • Rami frontal and zygomatici ( in animals as nerve auriculopalpebralis referred to ): Provide front ear muscles, musculus frontalis and some other ciliary muscles ( orbicularis oculi muscle, musculus retractor anguli oculi lateralis, levator anguli oculi medialis) and musculus zygomaticus
  • Rami buccales: provide the bulk of the perioral facial muscles
  • Ramus marginalis mandibulae: the lower facial muscles
  • Ramus colli: the platysma
  • Rami temporal: innervate the orbicularis oculi, procerus muscle and the musculi epicranii
Motor neuron Malleus Nucleus (neuroanatomy) Facial motor nucleus Petrous part of the temporal bone Acoustic reflex
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