3D Pons Embryology (Metencephalon) - Rhombencephalon Embryology Part 3 - Neuroembryology Part 6

The lecture focuses on the development of the pons, which is part of the rhombencephalon. The development begins with the formation of the pontine flexure, where the roof plate widens and splays open, creating the floor of the fourth ventricle. This process leads to a specific arrangement of the basal and alar plates.

In the pons region, a unique structure called the rhombic lip forms. The rhombic lip is a thickened dorsolateral part of the alar plate that will eventually develop into the cerebellum. The rest of the structures in this region will form various nuclei of the pons and medulla.

The lecture then delves into the specific types of nuclei found in the pons:

1. General Somatic Efferent (GSE): The abducens nucleus, which supplies the lateral rectus muscle via the sixth cranial nerve.
2. General Visceral Efferent (GVE): The superior salivatory nucleus, which is part of the seventh cranial nerve. It supplies the submandibular, sublingual, and lacrimal glands.
3. Special Visceral Efferent (SVE): The facial nerve motor nucleus, which supplies muscles derived from the second pharyngeal arch via the seventh cranial nerve.
4. General Visceral Afferent (GVA) and Special Visceral Afferent (SVA): The nucleus of tractus solitarius, which extends from the lower part of the pons to the upper part of the medulla.
5. General Somatic Afferent (GSA): The trigeminal sensory nuclear complex, consisting of the principal, mesencephalic, and spinal nuclei.
6. Special Somatic Afferent (SSA): The vestibulocochlear nuclear complex, including cochlear and vestibular nuclei.
7. Motor nucleus of the trigeminal nerve: A special visceral efferent nucleus supplying muscles of mastication via the fifth cranial nerve.

The lecture emphasizes the columnar arrangement of these nuclei, which is similar to the arrangement in the medulla. This arrangement follows a specific pattern from medial to lateral: general somatic efferent, general visceral efferent, special visceral efferent, and then the afferent nuclei.

The reticular formation, derived mainly from the basal plate with some contribution from the alar plate, is also present in the pons. Additionally, pontine nuclei develop from the alar plate or its dorsolateral extension (rhombic lip) and migrate ventrally. These nuclei play a crucial role in connecting the cerebrum, cerebellum, and spinal cord.

The lecture concludes with a brief overview of cranial nerve origins in the brainstem, which helps in understanding the placement of nuclei:

Midbrain: 3rd and 4th cranial nerves
Pons: 5th (mid-pons), 6th, 7th, and 8th (near pontomedullary junction)
Medulla: 9th, 10th, 11th (lateral to olive), and 12th (most medial)

This arrangement corresponds to the placement of their respective nuclei within the brainstem.

Understanding this organization of nuclei and cranial nerve origins is crucial for grasping the complex anatomy and embryology of the brainstem, particularly the pons and medulla oblongata. This knowledge forms the foundation for further study in neuroanatomy, neuroembryology, and neurophysiology.

[vincentpinto]

Stunning work and modelling, with your explanation! Wow!

[unsaali]

Sir have u uploaded lectures of development of GIT? My GIT module is starting from tomorrow and I am worried about my embryology, no matter how many lectures I watch on YouTube about embryo, I am not satisfied unless I watch your animated videos