Semester 2 Week 2 Embryo - Neuroembryology

The pons and cerebellum are derived from the walls of the metencephalon. The metencephalon is one of the five primary vesicles of the developing brain and is responsible for the formation of various structures, including the pons and cerebellum. The pons is a part of the brainstem that plays a role in relaying signals between different parts of the brain, while the cerebellum is involved in motor control, coordination, and balance.

The pyramids are formed by nerve tracts running through the caudal medulla, which develop ventral to the sulcus limitans. This indicates that the functional association of the pyramids is motor.

Schwann cells are responsible for forming the myelin sheaths surrounding cranial and spinal nerves. Myelin sheaths are important for insulating and protecting nerve fibers, allowing for faster and more efficient transmission of nerve impulses. Astrocytes, microglial cells, neuroglial cells, and oligodendrocytes are all types of glial cells, but they do not form myelin sheaths around cranial and spinal nerves.

Meroanencephaly is a serious congenital malformation that occurs when the cranial neuropore fails to close properly. This results in incomplete development and closure of the brain and skull. It is a severe form of neural tube defect that leads to significant brain abnormalities and is often fatal.

The correct answer is the basal plate of the mesencephalon. The fourth cranial nerve, also known as the trochlear nerve, is a motor nerve that controls the superior oblique muscle of the eyeball. During embryonic development, the nucleus of this nerve is derived from the basal plate of the mesencephalon, which is a region in the midbrain.

The primary embryological cause of DiGeorge Syndrome is the lack of normal development and migration of neural crest cells. Neural crest cells are a group of cells that arise from the neural tube during embryonic development and migrate to various parts of the body, including the thymus gland, parathyroid glands, and facial structures. In DiGeorge Syndrome, there is a failure in the normal development and migration of these cells, leading to the craniofacial malformations, immunological defects, and calcium metabolic defects associated with the syndrome.

The epaxial musculature refers to the muscles located on the dorsal side of the body, specifically the muscles that run along the vertebral column. The rectus capitis posterior minor is a small muscle located in the posterior neck region, which is part of the epaxial musculature. Therefore, it is a derivative of the epaxial musculature. The other options, such as the rectus femoris, biceps brachii, trapezius, and innermost intercostal, are not derivatives of the epaxial musculature.

Blockage of the arachnoid villi is the most common cause of communicating or non-obstructive hydrocephalus. The arachnoid villi are responsible for absorbing cerebrospinal fluid (CSF) and maintaining the balance of fluid in the brain. When these villi become blocked, the CSF cannot be properly absorbed, leading to an accumulation of fluid and subsequent hydrocephalus. This condition is often seen in young children and can result in symptoms such as enlarged head size, developmental delays, and neurological problems.