Which of the marked structures A, B, C, or D in the Illustration represents vagus nerve?
Ans. C. CVagus nerveVagus nerve is the nerve of 4th and 6th pharyngeal arches. It is a mixed nerve containing approximately 80% of sensory fibers and 20% of motor fibers.Branches of vagus nerveA. In jugular foramen, the superior ganglion gives off:1. Meningeal branch for dura of posterior cranial fossa;2. Auricular branch (Arnold's nerve or Alderman's nerve for auricle, external meatus and tympanic membrane. Superior ganglion is connected to glossopharyngeal (IX) and cranial part of accessory (XII) nerves through communicating branches.B. Inferior ganglion gives following branches: -1. Pharyngeal branch: It contains fibers of cranial accessory nerve and takes part in forming pharyngeal plexus to supply muscles of pharynx (except stylopharyngeus) and soft palate (except tensor veli palatini).2. Carotid branch: for carotid body.3. Superior laryngeal nerve: It divides into two branches: -a. External laryngeal nerve: - It is motor branch and supplies cricothyroid muscle. It accompanies superior thyroid artery). To avoid damage to this nerve, the superior thyroid artery is ligated close to the gland.b. Internal laryngeal nerve: - it is sensory branch which supplies mucous membrane of larynx above vocal folds and carries taste sensations from posterior most part of tongue (Valleculae) and epiglottis.4. Recurrent laryngeal nerve: -5. Cardiac branches: - These are superior and inferior. Out of four cardiac branches of vagi (two on each side), the left inferior goes to superficial cardiac plexus. The other three go to deep cardiac plexus.6. Other branches: - Pulmonary branches, esophageal branches, gastric branches, hepatic branches, coeliac branches.
A
B
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D
Head & Neck