Semester 2 - Endocrine - Pharyngeal Apparatus

During the tonsillectomy procedure, the glossopharyngeal nerve may have been damaged, resulting in the loss of sensation over the posterior third of the tongue. The glossopharyngeal nerve is responsible for providing sensory innervation to the posterior third of the tongue, as well as other structures in the throat and pharynx. Damage to this nerve can lead to a loss of taste sensation, difficulty swallowing, and a sensation of a lump in the throat.

The space described in the question is located between the buccopharyngeal fascia anteriorly and the prevertebral fascia posteriorly. This space is known as the retropharyngeal space.

The correct answer is the auricular nerve (of Arnold). This nerve is responsible for providing sensory innervation to the posterior side of the external ear canal. It is a derivative branch of the cranial nerve of the fourth pharyngeal arch.

The styloglossus muscle is not derived from a pharyngeal arch. The styloglossus muscle is a muscle of the tongue that helps to retract and elevate the tongue. It is derived from the occipital somites, not from a pharyngeal arch. The other muscles mentioned in the question (stylopharyngeus, stylohyoid, levator veli palatine, and tensor veli palatini) are all derived from pharyngeal arches.

The most likely diagnosis in this case is a lateral cervical cyst. The patient's symptoms of a painless swelling on the right side of her neck, along with the CT scan findings of a well-defined cystic mass at the angle of the mandible just anterior to the sternocleidomastoid muscle, are consistent with a lateral cervical cyst. This type of cyst typically occurs in the lateral neck and is often asymptomatic. Thyroglossal duct cyst, dermoid cyst, swollen lymph node, and accessory thyroid tissue are less likely diagnoses based on the given information.

The correct answer is that neuroectoderm gives rise to the neurohypophysis. The neurohypophysis, also known as the posterior pituitary, is derived from neuroectoderm during embryonic development. This is in contrast to the anterior pituitary, which is derived from the oral ectoderm. The neurohypophysis is responsible for the storage and release of hormones produced by the hypothalamus, while the anterior pituitary produces and releases its own hormones.

The parietal bone of the skull is formed by intramembranous ossification. This type of ossification occurs when bone tissue forms directly from mesenchymal cells, without the need for a cartilage precursor. In the case of the parietal bone, the mesenchymal cells differentiate into osteoblasts, which then secrete bone matrix that eventually mineralizes to form mature bone. This process allows for the formation of flat bones, such as the parietal bone, which provide protection and support for the brain.

The correct answer is that the oral ectoderm gives rise to the anterior pituitary. This means that during embryonic development, the cells from the oral ectoderm differentiate and form the anterior pituitary gland. This process is known as oral ectodermal placode invagination. The other statements provided in the options are incorrect. The diencephalon pouch is not derived from the posterior pituitary, Rathke's pouch is derived from the ectoderm, the infundibular stem is not derived from the anterior pituitary, and the neuroectoderm gives rise to the pars tuberalis, not the anterior pituitary.