Second arch is also called:

 # Second arch is also called:

A. Hyoid arch 

B. Mandibular arch

C. Maxillary arch 

D. Pharyngeal arch

The correct answer is A. Hyoid arch. 

The second arch in embryonic development is indeed referred to as the Hyoid arch. The hyoid arch, also known as the second pharyngeal arch, is one of the series of pharyngeal arches that contribute to the development of structures in the head and neck.

The hyoid arch gives rise to important structures such as the lower part of the hyoid bone (a bone in the neck), the muscles of facial expression, muscles involved in swallowing, and certain muscles in the throat. Nerves and blood vessels associated with this arch also develop within it.

Each pharyngeal arch has its specific developmental contributions and plays a role in the formation of different structures. The hyoid arch, or second arch, is significant in the development of various structures in the head and neck region during embryonic development.

First arch is also called:

 # First arch is also called:

A. Hyoid arch 

B. Mandibular arch

C. Maxillary arch 

D. Pharyngeal arch

The correct answer is B. Mandibular arch.

The first arch in embryonic development is often referred to as the Mandibular arch. During the early stages of embryonic development, several structures form in a series of arches known as pharyngeal arches. These arches play a crucial role in the development of the face and neck.

The Mandibular arch, also known as the first pharyngeal arch, is the most anterior of the pharyngeal arches. It gives rise to various structures including the lower jaw (mandible), certain muscles of mastication (chewing), and some muscles of facial expression. The nerves and blood vessels associated with this arch also develop within it.

Each pharyngeal arch has a specific set of components that contribute to the formation of different structures. In the case of the Mandibular arch, it primarily gives rise to the lower jaw, muscles involved in chewing, and some facial muscles. The arches undergo complex growth, fusion, and differentiation processes to form the various structures of the face and neck during embryonic development.

Bilaminar disc is formed during which period of embryonic events?

 # Bilaminar disc is formed during which period of embryonic events?

A. 1st week

B. 3rd week

C. 2nd week

D. 4th week

The correct answer is C. 2nd Week. 

The bilaminar disc is formed during the second week of embryonic development. This period is known as the second week because it follows the first week of embryonic development, which primarily involves the formation of the blastocyst. During the second week, the blastocyst undergoes implantation into the uterine wall, and the embryonic bilaminar disc forms. The bilaminar disc consists of two layers called the epiblast and the hypoblast, which are important for the subsequent development of the embryo.

During which period of human prenatal development does the congenital defects occur?

 # During which period of human prenatal development does the congenital defects occur?

A. Period of ovum

B. Period of embryo

C. Period of morula

D. Period of fetus

The correct answer is B. Period of embryo.

Congenital defects can occur during the period of embryo development. This period typically spans from the third to the eighth week after fertilization. It is during this time that the major organs and body systems begin to form, making the embryo particularly susceptible to external factors that can interfere with normal development and result in congenital defects.