Which of the following not derived from the 6th branchial arch?
Correct Answer: Cricothyroid
Description: ANSWER: (D) Cricothyroid REF: Grays anatomy 40th ed chapter 35 See APPENDIX-6 below BRANCHIAL ARCHES APPENDIX - 6 Brachial Arches There are six pharyngeal arches, but in humans the fifth arch only exists transiently during embryologic growth and development. Since no human structures result from the fifth arch, the arches in humans are I, II, III, IV, and VI. The first three contribute to structures above the larynx, while the last two contribute to the larynx and trachea Pharyngeal Arch Muscular Contributions Skeletal Contributions Nerve Artery Corresponding Pouch Structures 1st (mandibular arch) Muscles of mastication, Anterior belly of the digastric, Mylohyoid, Tensor tympani, Tensor veli palatini Maxilla, mandible (only as a model for mandible not actual formation of mandible), Incus and Malleus, Meckel's cartilage, Ant. ligament of malleus, Sphenomandibular ligament Trigeminal nerve (V2 and V3) Maxillary artery, external carotid artery Eustachian tube, middle ear, mastoid antrum, and inner layer of the tympanic membrane. 2nd (hyoid arch) Muscles of facial expression. Buccinator, Platysma, Stapedius, Stylohyoid, Posterior belly of the digastric Stapes, Styloid process, hyoid (lesser horn and upper part of body), Reichert's cartilage, Stylohyoid ligament Facial nerve (VII) Stapedial Artery middle ear, palatine tonsils 3rd Stylopharyngeus Hyoid (greater horn and lower part of body), thymus Glossopharyngeal nerve (IX) Common carotid/ Internal carotid Inferior parathyroid, Thymus 4th Cricothyroid muscle, all intrinsic muscles of soft palate including levator veli palatini Thyroid cartilage, epiglottic cartilage Vagus nerve (X) Superior laryngeal nerve Right 4th aortic arch: subclavian artery Left 4th aortic arch: aortic arch Superior parathyroid, ultimobranchial body (which forms the Para follicular C-Cells of thyroid gland) 6th All intrinsic muscles of larynx except the cricothyroid muscle Cricoid cartilage, arytenoid cartilages, corniculate cartilage Vagus nerve (X) Recurrent laryngeal nerve Right 6th aortic arch: pulmonary artery Left 6th aortic arch: Pulmonary artery and ductus arteriosus Rudimentary structure, becomes part of the fourth pouch contributing to thyroid C-celts.
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Anatomy
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