Block 1 Mini1 Pt 2 Neuroembryology

1. Which of the following is a derivative of the epaxial musculature?

Rectus abdominis

Pectoralis major

Sternocleidomastoid

Inner intercostal

Rectus capitis posterior minor

The rectus capitis posterior minor is a derivative of the epaxial musculature. This muscle is located at the back of the neck and is involved in the movement and stabilization of the head. It is derived from the epaxial muscles, which are the muscles that develop along the back of the body during embryonic development. The other options listed, such as the rectus abdominis, pectoralis major, sternocleidomastoid, and inner intercostal muscles, are not derivatives of the epaxial musculature.

Explanation

The rectus capitis posterior minor is a derivative of the epaxial musculature. This muscle is located at the back of the neck and is involved in the movement and stabilization of the head. It is derived from the epaxial muscles, which are the muscles that develop along the back of the body during embryonic development. The other options listed, such as the rectus abdominis, pectoralis major, sternocleidomastoid, and inner intercostal muscles, are not derivatives of the epaxial musculature.

2. Failure of closure of the cranial neuropore causes this serious congenital malformation.

Meroanencephaly

Rachischisis

Myelocele

Spina bifida occulta

Spina bifida cystica

Meroanencephaly is a serious congenital malformation that occurs when the cranial neuropore fails to close properly. This results in incomplete development of the brain and skull. The condition is characterized by a lack of cerebral hemispheres and a thin layer of brain tissue covering the base of the skull. Meroanencephaly is a severe form of neural tube defect and is typically incompatible with life.

Explanation

Meroanencephaly is a serious congenital malformation that occurs when the cranial neuropore fails to close properly. This results in incomplete development of the brain and skull. The condition is characterized by a lack of cerebral hemispheres and a thin layer of brain tissue covering the base of the skull. Meroanencephaly is a severe form of neural tube defect and is typically incompatible with life.

3. DiGeorge Syndrome is a suite of congenital craniofacial malformations associated with immunological defects due to failure of the thymus gland to differentiate and calcium metabolic defects related to failed parathyroid gland development. A primary embryological cause is

Failure of development of Rathke’s pouch

Lack of migration of ectoderm through the primitive streak

Lack of normal development and migration of neural crest cells

Failure of descent of the thyroid gland primordium

Lack of normal closure of the cervical sinus

The correct answer is lack of normal development and migration of neural crest cells. DiGeorge Syndrome is a congenital disorder that is caused by the abnormal development of neural crest cells, which are a group of cells that play a crucial role in the formation of various tissues and organs in the body. These cells are responsible for the development of the thymus gland, parathyroid gland, and other structures in the craniofacial region. When there is a lack of normal development and migration of neural crest cells, it can result in the malformations and defects seen in DiGeorge Syndrome, including craniofacial malformations, immunological defects, and calcium metabolic defects.

Explanation

The correct answer is lack of normal development and migration of neural crest cells. DiGeorge Syndrome is a congenital disorder that is caused by the abnormal development of neural crest cells, which are a group of cells that play a crucial role in the formation of various tissues and organs in the body. These cells are responsible for the development of the thymus gland, parathyroid gland, and other structures in the craniofacial region. When there is a lack of normal development and migration of neural crest cells, it can result in the malformations and defects seen in DiGeorge Syndrome, including craniofacial malformations, immunological defects, and calcium metabolic defects.

4. Nerve tracts running through the caudal medulla develop ventral to the sulcus limitans and eventually form the pyramids. Based on the position of their embryological development, the functional association of the pyramids is

Somatic sensory

Visceral sensory

Special sensory

Motor

Sympathetic

The pyramids develop ventral to the sulcus limitans in the caudal medulla, indicating their embryological position. This suggests that the functional association of the pyramids is motor, as they are responsible for carrying motor information from the brain to the spinal cord and ultimately to the muscles.

Explanation

The pyramids develop ventral to the sulcus limitans in the caudal medulla, indicating their embryological position. This suggests that the functional association of the pyramids is motor, as they are responsible for carrying motor information from the brain to the spinal cord and ultimately to the muscles.

5. The embryonic location of the nucleus of the fourth cranial nerve, an exclusively motor nerve which exits from the dorsum of the brainstem and innervates a muscle that moves the eyeball, is

Alar plate of the metencephalon

Alar plate of the myelencephalon

Basal plate of the mesencephalon

Basal plate of the diencephalon

Intermediolateral position near the sulcus limitans of the rhombencephalon

The correct answer is basal plate of the mesencephalon because the fourth cranial nerve, also known as the trochlear nerve, is an exclusively motor nerve that innervates the superior oblique muscle of the eye. The basal plate of the mesencephalon is responsible for the development of motor neurons, making it the embryonic location of the nucleus of the fourth cranial nerve.

Explanation

The correct answer is basal plate of the mesencephalon because the fourth cranial nerve, also known as the trochlear nerve, is an exclusively motor nerve that innervates the superior oblique muscle of the eye. The basal plate of the mesencephalon is responsible for the development of motor neurons, making it the embryonic location of the nucleus of the fourth cranial nerve.

6. Which of the following is a derivative of the epaxial musculature?

Rectus femoris

Biceps brachii

Trapezius

Innermost intercostal

Rectus capitis posterior minor

The rectus capitis posterior minor is a derivative of the epaxial musculature. The term "epaxial" refers to the muscles that lie dorsal to the transverse processes of the vertebrae, and the rectus capitis posterior minor is one of these muscles. It is a small muscle located in the back of the neck, and it helps to extend and rotate the head. The other options listed are not derivatives of the epaxial musculature.

Explanation

The rectus capitis posterior minor is a derivative of the epaxial musculature. The term "epaxial" refers to the muscles that lie dorsal to the transverse processes of the vertebrae, and the rectus capitis posterior minor is one of these muscles. It is a small muscle located in the back of the neck, and it helps to extend and rotate the head. The other options listed are not derivatives of the epaxial musculature.