1. Nerves of Branchial arch derived from:
a) Mesoderm
b) Endoderm
c) Neural crest
d) Neuroectoderm
Correct Answer - C
Answer -C. Neural crest
Branchial or pharyngeal arches are masses of mesoderm covered
by ectoderm and lined by endoderm. Within these masses, muscular
and skeletal components develop, as well as aortic arches and
nerve networks. The arches are separated by grooves, visible on
the surface of the embryo as pharyngeal clefts and in the interior as
the pharyngeal pouches
In the human embryo, the arches are first seen during the 4th week
of development.
They appear as a series of outpouchings of mesoderm on both
sides of developing pharynx.
The neural crest are bilaterally paired strips of cells arising in the
ectoderm at the margins of the neural tube. These cells migrate to
many different locations and differentiate into many cell types within
the embryo.
Neural Crest Derivatives
A key feature of neural crest is the migration into other embryonic
tissues to form specific neural and non-neural populations and
structures.
Cranial neural crest
migration - dorsolaterally and into pharyngeal arches
craniofacial mesenchyme - cartilage, bone, cranial neurons, glia,
,and connective tissues of the face
pharyngeal arches and pouches - thymic cells, tooth odontoblasts,
middle ear bones (ossicles), stria vascularis cells, and jaw
(mandible)
In the body region, neural crest cells also contribute the peripheral
nervous system (both neurons and glia) consisting of sensory
ganglia (dorsal root ganglia), sympathetic and parasympathetic
ganglia and neural plexuses within specific tissues/organs.
In the head region, neural crest cells migrate into the pharyngeal
arches forming ectomesenchyme contributing tissues which in the
body region are typically derived from mesoderm (cartilage, bone,
and connective tissue).
Neural Crest Origin
System Cell Type
PeripheralNervous Neurons - sensory ganglia, sympathetic and
System parasympathetic ganglia, enteric nervous
(PNS) system, and plexuses
Neuroglial cells, olfactory ensheathing cells
Schwann cells
Endocrine Adrenal medulla
Calcitonin-secreting cells
Carotid body type I cells
Integumentary Epidermal pigment cells
Facial cartilage Facial and anterior ventral skull cartilage and
and bone bones
Sensory Inner ear, corneal endothelium and stroma
Connective tissue Tooth papillae
smooth muscle, and adipose tissue of skin of
head and neck
Connective tissue of meninges, salivary,
lacrimal, thymus, thyroid, and pituitary glands
Connective tissue and smooth muscle in arteries
of aortic arch origin
,2. Hard palate contains:
a) Keratinised, submucosa, minor salivary gland
b) Keratinised, absent submucosal layer, minor salivary gland
c) Non keratinised, submucosal layer, minor salivary gland
d) Non keratinised, absent submucosa, minor salivary gland
Correct Answer - A
Answer - A. Keratinised, submucosa, minor salivary gland
The hard palate is located on the roof of the oral cavity, posterior
and medial to the alveolar process of the maxilla.
The bony structure is formed by the palatine processes of the
maxilla and the horizontal plates of the palatine bones.
The periosteum is covered by a firmly attached mucosa centrally,
although a submucosa is apparent laterally containing vessels. The
hard palate is continuous with the soft palate posteriorly.
Macroscopic Features
The hard palate is typically a pale pink colour and may have an
orange peel appearance from the palatine salivary glands (more
common posteriorly).
Microscopic Features
The hard palate is lined with a keratinising stratified squamous
epithelium, tightly bound to the underlying periosteum of the
palatine bone/maxilla. There is minimal submucosa, which
becomes more prominent posteriorly.
,
a) Mesoderm
b) Endoderm
c) Neural crest
d) Neuroectoderm
Correct Answer - C
Answer -C. Neural crest
Branchial or pharyngeal arches are masses of mesoderm covered
by ectoderm and lined by endoderm. Within these masses, muscular
and skeletal components develop, as well as aortic arches and
nerve networks. The arches are separated by grooves, visible on
the surface of the embryo as pharyngeal clefts and in the interior as
the pharyngeal pouches
In the human embryo, the arches are first seen during the 4th week
of development.
They appear as a series of outpouchings of mesoderm on both
sides of developing pharynx.
The neural crest are bilaterally paired strips of cells arising in the
ectoderm at the margins of the neural tube. These cells migrate to
many different locations and differentiate into many cell types within
the embryo.
Neural Crest Derivatives
A key feature of neural crest is the migration into other embryonic
tissues to form specific neural and non-neural populations and
structures.
Cranial neural crest
migration - dorsolaterally and into pharyngeal arches
craniofacial mesenchyme - cartilage, bone, cranial neurons, glia,
,and connective tissues of the face
pharyngeal arches and pouches - thymic cells, tooth odontoblasts,
middle ear bones (ossicles), stria vascularis cells, and jaw
(mandible)
In the body region, neural crest cells also contribute the peripheral
nervous system (both neurons and glia) consisting of sensory
ganglia (dorsal root ganglia), sympathetic and parasympathetic
ganglia and neural plexuses within specific tissues/organs.
In the head region, neural crest cells migrate into the pharyngeal
arches forming ectomesenchyme contributing tissues which in the
body region are typically derived from mesoderm (cartilage, bone,
and connective tissue).
Neural Crest Origin
System Cell Type
PeripheralNervous Neurons - sensory ganglia, sympathetic and
System parasympathetic ganglia, enteric nervous
(PNS) system, and plexuses
Neuroglial cells, olfactory ensheathing cells
Schwann cells
Endocrine Adrenal medulla
Calcitonin-secreting cells
Carotid body type I cells
Integumentary Epidermal pigment cells
Facial cartilage Facial and anterior ventral skull cartilage and
and bone bones
Sensory Inner ear, corneal endothelium and stroma
Connective tissue Tooth papillae
smooth muscle, and adipose tissue of skin of
head and neck
Connective tissue of meninges, salivary,
lacrimal, thymus, thyroid, and pituitary glands
Connective tissue and smooth muscle in arteries
of aortic arch origin
,2. Hard palate contains:
a) Keratinised, submucosa, minor salivary gland
b) Keratinised, absent submucosal layer, minor salivary gland
c) Non keratinised, submucosal layer, minor salivary gland
d) Non keratinised, absent submucosa, minor salivary gland
Correct Answer - A
Answer - A. Keratinised, submucosa, minor salivary gland
The hard palate is located on the roof of the oral cavity, posterior
and medial to the alveolar process of the maxilla.
The bony structure is formed by the palatine processes of the
maxilla and the horizontal plates of the palatine bones.
The periosteum is covered by a firmly attached mucosa centrally,
although a submucosa is apparent laterally containing vessels. The
hard palate is continuous with the soft palate posteriorly.
Macroscopic Features
The hard palate is typically a pale pink colour and may have an
orange peel appearance from the palatine salivary glands (more
common posteriorly).
Microscopic Features
The hard palate is lined with a keratinising stratified squamous
epithelium, tightly bound to the underlying periosteum of the
palatine bone/maxilla. There is minimal submucosa, which
becomes more prominent posteriorly.
,
