This document provides an overview of pharyngeal arch derivatives. It defines key terms and describes the development of the pharyngeal arches, pouches, and clefts during the fourth and fifth weeks of embryological development. The pharyngeal arches give rise to many structures in the head and neck, including muscles, bones, arteries and nerves. Derivatives of the arches include parts of the jaw, ear bones, hyoid bone and laryngeal cartilages. Persistence of pharyngeal pouches and clefts can lead to clinical issues such as branchial fistulae or cysts.
The ear develops from three germ layers into three main structures - the inner, middle, and outer ear. The outer ear develops from hillocks in the mandibular and hyoid arches, which fuse to form the pinna. The external auditory canal develops from the first branchial groove. The middle ear cavities develop from outpouchings of the first and second pharyngeal pouches. Ossicles develop from the first and second branchial arches. The inner ear develops from the otic placode, forming the fluid-filled cochlea and vestibular system. The facial and acoustic nerves also develop during this period to innervate the ear structures.
The document discusses the development of the pharyngeal apparatus during the 4th week of intrauterine development. It notes that there are initially six pharyngeal arches that develop in the lateral wall of the primitive pharynx, although the 6th arch is small and disappears, leaving five arches. Between the arches are four pharyngeal clefts lined by ectoderm and four pharyngeal pouches lined by endoderm. The derivatives of the pharyngeal arches include muscles, nerves, skeletal elements, and other structures. Clinical syndromes can result from abnormalities in development of the pharyngeal arches and clefts.
External ear,tympanic membrane and auditory tube Dr.N.Mugunthan.M.S.,mgmcri1234
External ear,tympanic membrane and auditory tube - Lecture by Dr.N.Mugunthan.M.S.,Associate Professor, Mahatma Gandhi Medical College & Research Institute, Pondicherry,
Sri Balaji Vidyapeeth University.
This document discusses the pharyngeal arches and pouches, which are structures that form early in human embryonic development. It notes that the pharyngeal pouches form inner endodermal pouches off the primitive foregut and each pouch contributes to specific derivatives. It also mentions that pharyngeal clefts form outer ectodermal grooves, with the first cleft contributing to structures of the face. The document lists some conditions that can occur when development of these structures goes wrong, such as ectopic thyroid or parathyroid tissue, branchial cysts and fistulae, and craniofacial defects.
Nasolabial cysts are soft tissue masses located under the ala nasi that contain fluid and are lined with epithelial tissue. They most commonly occur in females and are always extraosseous. Historically, Klestadt first proposed the inclusion theory that these cysts arise from entrapped tissue within nasolabial fissures. Imaging such as CT scans can identify nasolabial cysts without displacement of upper teeth. Surgical excision via sublabial approach is the ideal treatment.
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.for more details please visit
www.indiandentalacademy.com
This document describes the anatomy and physiology of the nose and paranasal sinuses. It discusses the development, external anatomy, internal anatomy including the nasal septum and lateral nasal wall, blood supply, nerve supply, paranasal sinuses, and physiology of the nose. Key structures mentioned include the nasal valve, osteomeatal complex, turbinates, and mucociliary clearance mechanism that protects the lower airways.
The ear develops from three germ layers into three main structures - the inner, middle, and outer ear. The outer ear develops from hillocks in the mandibular and hyoid arches, which fuse to form the pinna. The external auditory canal develops from the first branchial groove. The middle ear cavities develop from outpouchings of the first and second pharyngeal pouches. Ossicles develop from the first and second branchial arches. The inner ear develops from the otic placode, forming the fluid-filled cochlea and vestibular system. The facial and acoustic nerves also develop during this period to innervate the ear structures.
The document discusses the development of the pharyngeal apparatus during the 4th week of intrauterine development. It notes that there are initially six pharyngeal arches that develop in the lateral wall of the primitive pharynx, although the 6th arch is small and disappears, leaving five arches. Between the arches are four pharyngeal clefts lined by ectoderm and four pharyngeal pouches lined by endoderm. The derivatives of the pharyngeal arches include muscles, nerves, skeletal elements, and other structures. Clinical syndromes can result from abnormalities in development of the pharyngeal arches and clefts.
External ear,tympanic membrane and auditory tube Dr.N.Mugunthan.M.S.,mgmcri1234
External ear,tympanic membrane and auditory tube - Lecture by Dr.N.Mugunthan.M.S.,Associate Professor, Mahatma Gandhi Medical College & Research Institute, Pondicherry,
Sri Balaji Vidyapeeth University.
This document discusses the pharyngeal arches and pouches, which are structures that form early in human embryonic development. It notes that the pharyngeal pouches form inner endodermal pouches off the primitive foregut and each pouch contributes to specific derivatives. It also mentions that pharyngeal clefts form outer ectodermal grooves, with the first cleft contributing to structures of the face. The document lists some conditions that can occur when development of these structures goes wrong, such as ectopic thyroid or parathyroid tissue, branchial cysts and fistulae, and craniofacial defects.
Nasolabial cysts are soft tissue masses located under the ala nasi that contain fluid and are lined with epithelial tissue. They most commonly occur in females and are always extraosseous. Historically, Klestadt first proposed the inclusion theory that these cysts arise from entrapped tissue within nasolabial fissures. Imaging such as CT scans can identify nasolabial cysts without displacement of upper teeth. Surgical excision via sublabial approach is the ideal treatment.
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.for more details please visit
www.indiandentalacademy.com
This document describes the anatomy and physiology of the nose and paranasal sinuses. It discusses the development, external anatomy, internal anatomy including the nasal septum and lateral nasal wall, blood supply, nerve supply, paranasal sinuses, and physiology of the nose. Key structures mentioned include the nasal valve, osteomeatal complex, turbinates, and mucociliary clearance mechanism that protects the lower airways.
The document discusses the facial artery, which arises from the external carotid artery. It has both cervical and facial parts. The cervical part runs upwards in the neck, allowing movement of neck structures. It gives off branches like the ascending palatine and tonsillar arteries. The facial part enters the face by piercing the mandible. In the face, it gives branches like the inferior and superior labial arteries and terminates by anastomosing with the ophthalmic artery. The document also discusses the common carotid artery and its branches.
The tympanic membrane (TM) receives its arterial blood supply from both the deep auricular artery and first part of the maxillary artery on its outer surface, and the anterior and posterior tympanic arteries which branch from the first part of the maxillary artery and stylomastoid artery on its inner surface. The TM's nerve supply originates from the auriculotemporal nerve on its anterior half, the auricular branch of the vagus nerve on its posterior half, and the tympanic branch of the glossopharyngeal nerve through the tympanic plexus on its medial surface. The document provides an overview of examining the TM and various pathological conditions that can affect it including retraction, bul
The maxillary nerve is the second division of the trigeminal nerve. It originates in the lateral wall of the cavernous sinus and passes through the foramen rotundum into the pterygopalatine fossa. It gives off several branches in the pterygopalatine fossa and infratemporal fossa, including the posterior superior alveolar nerve, zygomatic nerve, and anterior and middle superior alveolar nerves. The maxillary nerve terminates by innervating structures in the face, providing sensation to the maxillary region. A maxillary nerve block can provide anesthesia for dental procedures involving the maxillary area, such as when a large canine space abscess is
The parotid bed is an irregular space located in the face that houses the parotid gland. Several nerves and blood vessels pass through the substance of the parotid gland as it is molded into the parotid bed, including the facial nerve, trigeminal nerve, external carotid artery, and tributaries of the external jugular vein. The parotid gland is the largest of the three major salivary glands and is enclosed in a capsule within the parotid bed. It has an irregular shape and lobes that extend into adjacent spaces.
This document outlines the anatomy of the nose, beginning with its external features such as the nasal bones, cartilages, skin and muscles. It then details the internal nasal septum formed by bone and cartilage. The lateral nasal wall contains three turbinates and their air passages. Sensory innervation is provided by the trigeminal and facial nerves. Arterial blood supply originates from the ophthalmic, maxillary and facial arteries, and veins drain to the angular and ophthalmic veins. Precise knowledge of nasal anatomy guides surgical procedures like rhinoplasty and septoplasty.
The document discusses the anatomy of the anterior triangle of the neck. It begins by outlining the boundaries and contents of the anterior triangle. It then describes how the triangle is divided into four smaller triangles - the submental, submandibular, carotid, and muscular triangles - by the digastric and omohyoid muscles. Each smaller triangle's boundaries, floor, contents, and structures are defined in detail. Key structures discussed include the thyroid gland, carotid sheath, carotid sinus, and carotid body. Blood supply and lymphatic drainage of the thyroid gland are also summarized.
This document discusses the anatomy and development of the nose and paranasal sinuses. It begins with the embryonic development of the nose from 4-7 weeks of gestation. It then describes the development of the paranasal sinuses from 25-28 weeks of gestation onward. Next, it covers the anatomy of the external nose, nasal cavity, paranasal sinuses and related structures. It concludes with brief sections on the functions, blood supply, innervation and common conditions like sinusitis that can affect the nose and sinuses.
Maxillary sinus is the largest of the paranasal sinuses. It develops from a shallow groove in the maxilla and reaches its maximum size by age 18. It has multiple walls and communicates with the nasal cavity via the osteum. Maxillary sinusitis can result from dental issues like periapical abscesses, cysts, foreign bodies or trauma. Odontogenic tumors and cysts can also involve the maxillary sinus. Care must be taken during dental procedures near the maxillary sinus to prevent oroantral communications.
The posterior belly of the digastric muscle originates from the mastoid notch of the temporal bone and inserts on the intermediate tendon which connects to the hyoid bone. It has relationships superiorly with the external carotid artery branches and inferiorly with the internal carotid artery, internal jugular vein and cranial nerves IX, X, XI, XII. The posterior belly is supplied by the posterior auricular and occipital arteries and innervated by the facial nerve.
The lateral wall of the nose is formed by several bones and cartilages. It consists of seven bones: the nasal bone, frontal process of maxilla, lacrimal bone, conchae and labyrinth of ethmoid, inferior nasal concha, perpendicular plate of palatine, and medial pterygoid plate of sphenoid. It also consists of three cartilages: the lateral nasal cartilage, major alar cartilage, and three to four minor alar cartilages. The lateral wall is divided into three areas - the anterior vestibule, middle atrium of the middle meatus, and posterior conchae. The conchae are curved bony projections that separate the meatuses
The infratemporal fossa is located below the temporal fossa. It is bounded by the ramus of the mandible laterally, the maxilla anteriorly, and the lateral pterygoid plate medially. The infratemporal fossa contains the mandibular nerve, maxillary artery, pterygoid venous plexus, and the medial and lateral pterygoid muscles. The maxillary artery passes through the infratemporal fossa and gives off several branches including the middle meningeal artery, accessory meningeal artery, inferior alveolar artery, and infraorbital artery. It communicates with surrounding areas through gaps in bones and openings in the skull.
The scalp consists of 5 layers - skin, connective tissue, aponeurosis, loose areolar tissue, and pericranium. The clinically important layer is the aponeurosis, as lacerations through this layer can cause gaping of the wound requiring suturing. The scalp receives innervation from the trigeminal and cervical nerves and is supplied by the supratrochlear, supraorbital, zygomaticotemporal, auriculotemporal, lesser occipital, and greater occipital nerves.
The infratemporal fossa is a complex space located deep to the mandible containing neurovascular structures. It has boundaries of the maxilla anteriorly, styloid process posteriorly, and lateral pterygoid plate medially. Contents include the lateral and medial pterygoid muscles, fat pad, buccal lymph node, mandibular nerve and its branches, maxillary artery, and otic ganglion. The fossa communicates superiorly with the cranial cavity and medially with the pterygopalatine fossa. Anatomy of this region is important for spread of infection, tumors, and trauma.
This document summarizes the anatomy of the external ear. It describes the pinna (auricle), which is made of elastic cartilage covered in skin. It is attached to the skull by ligaments and muscles supplied by the facial nerve. The external auditory canal extends from the bottom of the concha to the tympanic membrane. The outer third is cartilaginous while the inner two thirds are bony. The tympanic membrane separates the external ear from the middle ear. It consists of the pars tensa and pars flaccida and is innervated by the auriculotemporal, vagus, and glossopharyngeal nerves.
The parotid gland is the largest of the three pairs of major salivary glands. It is located below the external acoustic meatus, between the ramus of the mandible and sternocleidomastoid muscle. The parotid gland develops from an ectodermal furrow during the 6th week of gestation and begins secreting saliva through the parotid duct at 18 weeks gestation.
The face develops from the third to eighth week of gestation as the pharyngeal arches, pouches and clefts form. The pharyngeal arches contribute mesenchymal tissue that gives rise to structures of the head and neck. Neural crest cells migrate into the arches and determine the skeletal structures that develop. Each arch is associated with a cranial nerve and blood vessel. Structures of the face, ears, tongue, larynx and thyroid develop from the differentiation and fusion of the pharyngeal arches and clefts.
The soft palate contains five muscles that are important for swallowing and breathing. The muscles are the tensor veli palatini, levator veli palatini, palatoglossus, palatopharyngeus, and musculus uvulae. Each muscle has a specific origin, insertion point, and action. For example, the levator veli palatini originates from the base of the skull and curves downward and forward to enter the palate, contracting to lift the soft palate upwards and backwards during swallowing. The muscles receive their nerve supply from either the trigeminal or accessory cranial nerves and are supplied by arteries including the facial and maxillary arteries.
This document provides an overview of the facial nerve (cranial nerve VII). It begins with definitions of nerves and nerve conduction. It then discusses the classification of the nervous system and provides an introduction to the facial nerve. The remainder of the document details the embryology, nuclei of origin, functional components, course, branches and distribution, ganglia, blood supply, surgical anatomy, applied aspects, and conclusion of the facial nerve. It provides diagrams and explanations of these various aspects of the facial nerve's anatomy and function.
phayrangeal apparatus By Dr.Aisha Sadaf IBMS -KMU-peshawarAisha Sadaf
The document describes the development of the pharyngeal arches, pouches, and clefts in early human embryogenesis. It states that the pharyngeal arches develop as six curved mesenchymal thickenings on each side of the primitive pharynx. Each arch gives rise to specific skeletal, muscular, vascular and nervous derivatives. The pharyngeal pouches form as outpocketings between the arches and give rise to structures such as the tonsils and parathyroid glands. Pharyngeal clefts form between the pouches and contribute to structures like the external auditory meatus. Congenital anomalies can result if development of the arches, pouches or clefts is disrupted.
The ear develops from three parts - the external, middle, and inner ear. The inner ear develops from thickenings in the ectoderm called otic placodes around 22 days. These placodes invaginate to form the otic vesicles which divide into dorsal and ventral components forming the structures of the inner ear. The middle ear develops from the first pharyngeal pouch and cleft, giving rise to the tympanic cavity and auditory tube. The ossicles develop from the surrounding cartilage. The external ear develops from swellings near the pharyngeal arches which fuse to form the auricle and the external auditory meatus develops from the dorsal cleft.
The document discusses the facial artery, which arises from the external carotid artery. It has both cervical and facial parts. The cervical part runs upwards in the neck, allowing movement of neck structures. It gives off branches like the ascending palatine and tonsillar arteries. The facial part enters the face by piercing the mandible. In the face, it gives branches like the inferior and superior labial arteries and terminates by anastomosing with the ophthalmic artery. The document also discusses the common carotid artery and its branches.
The tympanic membrane (TM) receives its arterial blood supply from both the deep auricular artery and first part of the maxillary artery on its outer surface, and the anterior and posterior tympanic arteries which branch from the first part of the maxillary artery and stylomastoid artery on its inner surface. The TM's nerve supply originates from the auriculotemporal nerve on its anterior half, the auricular branch of the vagus nerve on its posterior half, and the tympanic branch of the glossopharyngeal nerve through the tympanic plexus on its medial surface. The document provides an overview of examining the TM and various pathological conditions that can affect it including retraction, bul
The maxillary nerve is the second division of the trigeminal nerve. It originates in the lateral wall of the cavernous sinus and passes through the foramen rotundum into the pterygopalatine fossa. It gives off several branches in the pterygopalatine fossa and infratemporal fossa, including the posterior superior alveolar nerve, zygomatic nerve, and anterior and middle superior alveolar nerves. The maxillary nerve terminates by innervating structures in the face, providing sensation to the maxillary region. A maxillary nerve block can provide anesthesia for dental procedures involving the maxillary area, such as when a large canine space abscess is
The parotid bed is an irregular space located in the face that houses the parotid gland. Several nerves and blood vessels pass through the substance of the parotid gland as it is molded into the parotid bed, including the facial nerve, trigeminal nerve, external carotid artery, and tributaries of the external jugular vein. The parotid gland is the largest of the three major salivary glands and is enclosed in a capsule within the parotid bed. It has an irregular shape and lobes that extend into adjacent spaces.
This document outlines the anatomy of the nose, beginning with its external features such as the nasal bones, cartilages, skin and muscles. It then details the internal nasal septum formed by bone and cartilage. The lateral nasal wall contains three turbinates and their air passages. Sensory innervation is provided by the trigeminal and facial nerves. Arterial blood supply originates from the ophthalmic, maxillary and facial arteries, and veins drain to the angular and ophthalmic veins. Precise knowledge of nasal anatomy guides surgical procedures like rhinoplasty and septoplasty.
The document discusses the anatomy of the anterior triangle of the neck. It begins by outlining the boundaries and contents of the anterior triangle. It then describes how the triangle is divided into four smaller triangles - the submental, submandibular, carotid, and muscular triangles - by the digastric and omohyoid muscles. Each smaller triangle's boundaries, floor, contents, and structures are defined in detail. Key structures discussed include the thyroid gland, carotid sheath, carotid sinus, and carotid body. Blood supply and lymphatic drainage of the thyroid gland are also summarized.
This document discusses the anatomy and development of the nose and paranasal sinuses. It begins with the embryonic development of the nose from 4-7 weeks of gestation. It then describes the development of the paranasal sinuses from 25-28 weeks of gestation onward. Next, it covers the anatomy of the external nose, nasal cavity, paranasal sinuses and related structures. It concludes with brief sections on the functions, blood supply, innervation and common conditions like sinusitis that can affect the nose and sinuses.
Maxillary sinus is the largest of the paranasal sinuses. It develops from a shallow groove in the maxilla and reaches its maximum size by age 18. It has multiple walls and communicates with the nasal cavity via the osteum. Maxillary sinusitis can result from dental issues like periapical abscesses, cysts, foreign bodies or trauma. Odontogenic tumors and cysts can also involve the maxillary sinus. Care must be taken during dental procedures near the maxillary sinus to prevent oroantral communications.
The posterior belly of the digastric muscle originates from the mastoid notch of the temporal bone and inserts on the intermediate tendon which connects to the hyoid bone. It has relationships superiorly with the external carotid artery branches and inferiorly with the internal carotid artery, internal jugular vein and cranial nerves IX, X, XI, XII. The posterior belly is supplied by the posterior auricular and occipital arteries and innervated by the facial nerve.
The lateral wall of the nose is formed by several bones and cartilages. It consists of seven bones: the nasal bone, frontal process of maxilla, lacrimal bone, conchae and labyrinth of ethmoid, inferior nasal concha, perpendicular plate of palatine, and medial pterygoid plate of sphenoid. It also consists of three cartilages: the lateral nasal cartilage, major alar cartilage, and three to four minor alar cartilages. The lateral wall is divided into three areas - the anterior vestibule, middle atrium of the middle meatus, and posterior conchae. The conchae are curved bony projections that separate the meatuses
The infratemporal fossa is located below the temporal fossa. It is bounded by the ramus of the mandible laterally, the maxilla anteriorly, and the lateral pterygoid plate medially. The infratemporal fossa contains the mandibular nerve, maxillary artery, pterygoid venous plexus, and the medial and lateral pterygoid muscles. The maxillary artery passes through the infratemporal fossa and gives off several branches including the middle meningeal artery, accessory meningeal artery, inferior alveolar artery, and infraorbital artery. It communicates with surrounding areas through gaps in bones and openings in the skull.
The scalp consists of 5 layers - skin, connective tissue, aponeurosis, loose areolar tissue, and pericranium. The clinically important layer is the aponeurosis, as lacerations through this layer can cause gaping of the wound requiring suturing. The scalp receives innervation from the trigeminal and cervical nerves and is supplied by the supratrochlear, supraorbital, zygomaticotemporal, auriculotemporal, lesser occipital, and greater occipital nerves.
The infratemporal fossa is a complex space located deep to the mandible containing neurovascular structures. It has boundaries of the maxilla anteriorly, styloid process posteriorly, and lateral pterygoid plate medially. Contents include the lateral and medial pterygoid muscles, fat pad, buccal lymph node, mandibular nerve and its branches, maxillary artery, and otic ganglion. The fossa communicates superiorly with the cranial cavity and medially with the pterygopalatine fossa. Anatomy of this region is important for spread of infection, tumors, and trauma.
This document summarizes the anatomy of the external ear. It describes the pinna (auricle), which is made of elastic cartilage covered in skin. It is attached to the skull by ligaments and muscles supplied by the facial nerve. The external auditory canal extends from the bottom of the concha to the tympanic membrane. The outer third is cartilaginous while the inner two thirds are bony. The tympanic membrane separates the external ear from the middle ear. It consists of the pars tensa and pars flaccida and is innervated by the auriculotemporal, vagus, and glossopharyngeal nerves.
The parotid gland is the largest of the three pairs of major salivary glands. It is located below the external acoustic meatus, between the ramus of the mandible and sternocleidomastoid muscle. The parotid gland develops from an ectodermal furrow during the 6th week of gestation and begins secreting saliva through the parotid duct at 18 weeks gestation.
The face develops from the third to eighth week of gestation as the pharyngeal arches, pouches and clefts form. The pharyngeal arches contribute mesenchymal tissue that gives rise to structures of the head and neck. Neural crest cells migrate into the arches and determine the skeletal structures that develop. Each arch is associated with a cranial nerve and blood vessel. Structures of the face, ears, tongue, larynx and thyroid develop from the differentiation and fusion of the pharyngeal arches and clefts.
The soft palate contains five muscles that are important for swallowing and breathing. The muscles are the tensor veli palatini, levator veli palatini, palatoglossus, palatopharyngeus, and musculus uvulae. Each muscle has a specific origin, insertion point, and action. For example, the levator veli palatini originates from the base of the skull and curves downward and forward to enter the palate, contracting to lift the soft palate upwards and backwards during swallowing. The muscles receive their nerve supply from either the trigeminal or accessory cranial nerves and are supplied by arteries including the facial and maxillary arteries.
This document provides an overview of the facial nerve (cranial nerve VII). It begins with definitions of nerves and nerve conduction. It then discusses the classification of the nervous system and provides an introduction to the facial nerve. The remainder of the document details the embryology, nuclei of origin, functional components, course, branches and distribution, ganglia, blood supply, surgical anatomy, applied aspects, and conclusion of the facial nerve. It provides diagrams and explanations of these various aspects of the facial nerve's anatomy and function.
phayrangeal apparatus By Dr.Aisha Sadaf IBMS -KMU-peshawarAisha Sadaf
The document describes the development of the pharyngeal arches, pouches, and clefts in early human embryogenesis. It states that the pharyngeal arches develop as six curved mesenchymal thickenings on each side of the primitive pharynx. Each arch gives rise to specific skeletal, muscular, vascular and nervous derivatives. The pharyngeal pouches form as outpocketings between the arches and give rise to structures such as the tonsils and parathyroid glands. Pharyngeal clefts form between the pouches and contribute to structures like the external auditory meatus. Congenital anomalies can result if development of the arches, pouches or clefts is disrupted.
The ear develops from three parts - the external, middle, and inner ear. The inner ear develops from thickenings in the ectoderm called otic placodes around 22 days. These placodes invaginate to form the otic vesicles which divide into dorsal and ventral components forming the structures of the inner ear. The middle ear develops from the first pharyngeal pouch and cleft, giving rise to the tympanic cavity and auditory tube. The ossicles develop from the surrounding cartilage. The external ear develops from swellings near the pharyngeal arches which fuse to form the auricle and the external auditory meatus develops from the dorsal cleft.
Embryology of branchial arches applied anatomy by osama elhamzawyOsama Elhamzawy
This document discusses the embryology of branchial arches and their nerve supply. It begins by introducing the three germ layers and their derivatives. It then describes the development of the pharyngeal arches, pouches, and grooves during the fourth week of development. The fate of each pharyngeal arch is outlined, including the cartilage, muscles, and nerves derived from each arch. The derivatives of the pharyngeal pouches are also summarized, focusing on structures like the tonsils, thymus, and parathyroid glands. Finally, some common birth defects involving the pharyngeal region are briefly mentioned.
The nasopharynx is located behind the nasal cavities and above the soft palate. Its roof is formed by the base of the skull, and its walls connect it to surrounding structures like the Eustachian tubes. It continues below into the oropharynx. During swallowing, the soft palate and palatopharyngeal sphincter close off the nasopharynx from the oropharynx. Mucosal folds in the nasopharynx mark locations like the openings of the Eustachian tubes.
The tongue develops from the floor of the pharynx beginning in the 4th week of gestation. The anterior two-thirds develops from swellings in the first pharyngeal arch, while the posterior one-third develops from the second, third, and part of the fourth arches. The thyroid gland develops as an epithelial proliferation in the floor of the pharynx between the fifth and seventh weeks and descends to its final location in front of the trachea by the seventh week. The development of the tongue, thyroid gland, and associated structures can result in congenital anomalies if development is disrupted.
The development of the head and neck is characterized by the formation of pharyngeal arches and pouches. The pharyngeal arches give rise to muscles, bones and cartilage in the head and neck region. Neural crest cells migrate into the arches and contribute to skeletal development. The pharyngeal pouches form important structures such as the ears, tonsils, thyroid and parathyroid glands. Congenital defects can occur if development of the arches, pouches or neural crest cells is disrupted.
Birth defect system according to System wise in that Respiratory System Birth...sonal patel
Birth defect system according to System wise in that Respiratory System Birth defect, Cardiovascular System Birth defect,Digestive System Birth defect, Extremity Birth defect made by sonal Patel
The document summarizes the development of the ear from the early stages of formation through maturation. It describes:
- The formation of the otic placode from surface ectoderm, which then invaginates to form the otic vesicle.
- How the otic vesicle develops into the inner, middle, and outer ear structures. The inner ear forms from regionalization of the vesicle directed by homeobox genes.
- The development of the middle ear bones and structures from the pharyngeal arches. The external ear develops from auricular hillocks that fuse to form the pinna.
- Key processes like differentiation of hair cells and formation of the bony labyrinth that
The pharyngeal apparatus in a 4 week old human embryo consists of pharyngeal arches, pouches, grooves, and membranes. The arches contribute to structures of the face, mouth, larynx and neck. Each arch contains mesenchyme, blood vessels, cartilage that ossifies into bones, and muscles. The pouches form structures such as the tonsils, thymus, and parathyroid and thyroid glands. The grooves separate the arches and membranes form at their floors, with only the first becoming the eardrum. By the end of development, most grooves and membranes disappear as the neck forms.
The document summarizes the development of the pharyngeal arches and pouches in humans. It discusses that the pharyngeal arches develop as thickenings in the foregut wall to support the primitive pharynx. Originally six arches form, though the fifth is small and disappears. Between the arches are endodermal pouches and ectodermal clefts. The structures that derive from each arch are described, including muscles, arteries, nerves and skeletal elements. The fate of the endodermal pouches is also outlined, many contributing to structures of the ear, throat and thyroid gland.
The tongue develops from swellings that arise in the first, third, and fourth pharyngeal arches. The anterior two-thirds is derived from the first arch and the posterior one-third from the third and fourth arches. The muscles develop from occipital somites and are innervated by the hypoglossal nerve. The development results in the anterior two-thirds receiving sensory innervation from the trigeminal nerve and the posterior part from the glossopharyngeal nerve. Congenital anomalies can occur if development is incomplete, such as ankyloglossia from failure of the alveolar ridge to separate the tongue.
Development of the Face, Tongue, Palate, Thyroid gland profgoodnewszion
The tongue develops from endodermal and ectodermal tissues originating from the pharyngeal arches. The thyroid gland develops from an endodermal diverticulum that descends in the neck and remains connected to the tongue via the thyroglossal duct. The face develops from five prominences, with the nose forming from the frontal prominence and medial and lateral nasal prominences. The palate develops as the palatine shelves rotate and fuse in the midline. Congenital anomalies can affect structures developing from the pharyngeal arches, including cleft lip/palate and thyroglossal duct cysts.
1. The respiratory system develops from lung buds that arise from the foregut and connective tissue from the splanchnic mesoderm. During the 4th week, the laryngotracheal groove appears and deepens to form the laryngotracheal tube, which bifurcates to form the right and left lung buds.
2. The proximal part of the laryngotracheal tube forms the larynx, and the distal part forms the trachea. The lung buds form the primordium of the bronchial tree and lungs. The splanchnic mesoderm forms the surrounding connective tissue.
3. Components of the trachea, including the lining epithe
The ear develops from three parts - the external ear, middle ear, and inner ear. The external ear develops from swellings around the first pharyngeal cleft. The middle ear develops from the first pharyngeal pouch. The inner ear develops from thickenings of surface ectoderm that invaginate to form the otic vesicles. These vesicles give rise to the membranous labyrinth containing the saccule, utricle, semicircular canals and cochlear duct. The ossicles of the middle ear develop from cartilage of the pharyngeal arches. Congenital deafness and abnormalities of the external ear can result from abnormal development and are often associated with other malformations
The document summarizes the development of the face from the 4th week of embryonic development. It discusses how the frontonasal process, maxillary processes, and mandibular processes form the structures of the face, including the lips, nose, eyes, ears, and palate. It also describes the development of branchial arches and how they contribute to specific muscles, nerves, arteries, and bones. The formation and differentiation of the pharyngeal pouches and clefts that form parts of the ear, thyroid, parathyroid glands and thymus are also outlined.
The document discusses the development of the pharyngeal arches and their derivatives. There are 6 pharyngeal arches that develop around the pharynx in successive order. Each arch consists of an outer ectoderm layer, inner endoderm layer, and middle mesoderm layer. The 5 pairs of pharyngeal arches give rise to many important structures of the head and neck, including muscles, bones, arteries and nerves. Derivatives of each arch are listed, such as how the first arch forms parts of the mandible and maxilla. Between the arches are pharyngeal grooves externally and pouches internally that form other structures like the palatine tonsil.
The ear and nose develop from thickenings of ectoderm that invaginate to form early structures. The ear develops from the otic placode which forms the otic vesicle containing early structures of the inner ear. Structures like the cochlea, semicircular canals, and organs develop further. The nose develops from facial prominences that grow and fuse to form the nasal cavity and structures within it like the septum. The ear structures like the ossicles, auditory tube and external ear develop from the pharyngeal arches and clefts. Congenital anomalies can occur if development of these intricate structures is disrupted.
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3. Definition
Groove --- invagination of ectoderm.
Pouch ---- evagination of endoderm.
Arch – bulge/ swelling
Diverticuli --- evagination through a wall of a tubular organ.
4. GENERAL EMBRYOLOGY
Development begins with fertilization when the sperm and oocyte, each haploid
with 23 chromosomes, unite to form the diploid zygote containing 46
chromosomes.
The zygote divides, producing a morula which cavitates to form a blastocyst
that implants in the endometrium during the second week.
Initially the inner cell mass forms a bilaminar germ disc which then, by
gastrulation, leads to a trilaminar disc comprised of ecto-, meso- and endoderm
layers in week 3
Weeks 3-8 comprise the embryonic period
7. PHARYNGEAL ARCHES
Arches of mesenchyme derived from paraxial and lateral plate
mesoderm and neural crest cells appear in the fourth and
fifth weeks of development.
They are covered externally by ectoderm, which forms clefts
between successive arches, and internally by endoderm
which forms pouches between arches.
8. Providence of Pharyngeal Arches
A typical pharyngeal arch contains ;
A pharyngeal arch artery
A cartilaginous rod
A muscular component
Sensory and motor nerves
9. First pharyngeal arch
The first arch has a dorsal maxillary process and a ventral
mandibular process.
The maxillary process gives rise to the premaxilla, maxilla,
zygomatic bone, the zygomatic process and squamous part of the
temporal bone by intramembranous ossification.
The mandibular process / Meckel's cartilage which persists as the
malleus, anterior ligament of malleus, incus and
sphenomandibular ligament.
10. Cont…
The trigeminal (V) nerve supplies sensation to the first arch
connective tissues via its ophthalmic, maxillary and
mandibular branches.
Only the mandibular division has a motor root and supplies
eight first arch muscles:
Four muscles of mastication (temporalis, masseter, medial and lateral
pterygoid),
Two tensors (tympani and palati), mylohyoid and the anterior belly of
digastric.
11.
12. Second pharyngeal /Hyoid Arch/Reichert’s
cartilage
The second arch gives rise to the
Dorsal Part -- stapes, styloid process of the temporal bone,
Middle -- stylohyoid ligament,
Ventral -- lesser cornu and upper body of the hyoid bone.
The facial (VII) nerve supplies sensation to second arch connective
tissue in the external auditory canal, but is mainly motor supplying:
stapedius, stylohyoid, posterior belly of digastric, occipitofrontalis and the
muscles of facial expression.
13. Third pharyngeal arch
The third arch gives rise to the greater cornu and lower body
of the hyoid bone.
The glossopharyngeal (IX) nerve supplies sensation to third
arch connective tissues in the posterior third of the tongue
and is motor to glossopharyngeus.
14. Fourth and sixth pharyngeal arches
The cartilagenous components of the fourth and sixth arches fuse to form the
laryngeal cartilages: thyroid, cricoid, arytenoid, corniculate and cuneiform.
The superior laryngeal branch of the vagus (X) supplies sensation to fourth arch
connective tissue from the valleculae and epiglottis to the true vocal cords and
is motor to levator palati, pharyngeal constrictors (partially) and cricothyroid.
The recurrent laryngeal branch of the vagus supplies sensation to sixth arch
derivatives, notably the infraglottic larynx:, and is motor to the other muscles of the
larynx.
15.
16. Derivatives of pharyngeal arch arteries
1st Arch – Maxillary Artery
2nd Arch – Stapedial A. + Ext.
Carotid
3rd Arch – CCA and Proximal ICA
4th Arch -- Left – part of arch of
Aorta
Right –proximal part of
Subclavian a.
6th Arch – Left – Ductus Arteriosus
Right – Pulmonary Artery
22. PHARYNGEAL POUCHES
On each side, between the six arches, lie five pharyngeal pouches lined by
endoderm
The first pouch extends laterally to form the Eustachian tube, the middle ear
cavity and the tubotympanic recess, which extends as far as the tympanic
membrane.
Distal portion of tubotympanic recess expands upward to become middle ear
cavity or tympanic cavity
Proximal part becomes eustachian (auditory, pharyngotympanic) tube
23.
24. Cont…
The second pouch forms the bed of the palatine tonsil.
The third pouch forms ventral and dorsal wings.
The epithelium of the ventral wing differentiates into the
thymus, while that of the dorsal wing forms the inferior
parathyroid gland.
25. Cont,,,
The dorsal wing of the fourth pouch differentiates into parathyroid tissue
which descends to lie posterior to the superior pole of the ipsilateral
thyroid lobe.
The ventral wing of the fourth(fifth pouch) forms the ultimobranchial
body, which is incorporated into the thyroid gland· and gives rise to
parafollicular calcitonin secreting cells.
28. Pharyngeal diverticulum
The structural weakness between thyropharyngeus and
cricopharyngeus, Killian's dehiscence, may be the site of an
acquired pulsion diverticulum which may be described
erroneously as a 'pharyngeal pouch'.
29. PHARYNGEAL CLEFTS
The 5-week embryo is characterized by the presence of four pharyngeal
clefts
On each side, between the first five arches, lie four pharyngeal clefts lined by
ectoderm.
Normally, only the first cleft persists and its dorsal end gives rise to the external
auditory meatus, separated from the first pouch by the tympanic membrane.
the second, third, and fourth clefts lose contact with the outside
The clefts form a cavity lined with ectodermal epithelium, the cervical sinus,
but with further development, this sinus disappears.
30. Clinical correlate
The second arch overgrows the second, third and fourth clefts, forming the
cervical sinus which then resorbs.
However, if this sinus persists, it gives rise to cervical cysts along the anterior
border of sternocleidomastoid.
If the cysts communicate with the skin, they form external branchial fistulae.
31. Branchial Fistula
An abnormal canal that opens internally into the tonsillar sinus and externally in the
side of the neck
This canal results from persistence of parts of the second pharyngeal groove and
second pharyngeal pouch
The fistula passes between the internal and
external carotid arteries and opens into the tonsillar sinus.
32. Pharyngeal membranes
Pharyngeal membranes appear in the floor of the pharyngeal grooves
These membranes form where the epithelia of the grooves and pouches approach
each other
The endoderm of the pouches and ectoderm of the grooves are soon separated by
mesenchyme
Only first pharyngeal membrane becomes the tympanic membrane, others
obliterate.
33. Tongue
The tongue appears in embryos of approximately 4 weeks in the form of
two lateral lingual swellings and one medial swelling, the tuberculum
impar
These three swellings origínate from the first pharyngeal arch.
As the lateral lingual swellings increase in size, they overgrow the
tuberculum impar and merge, forming the anterior two-thirds, or body,
of the tongue
34. Cont,,,
Because the mucosa covering the body of the tongue
originates from the first pharyngeal arch, sensory
innervation to this area is by the mandibular branch of the
trigeminal nerve.
The body of the tongue is separated from the posterior
third by a V-shaped groove, the terminal sulcus
35. Cont…
The posterior part, or root, of the tongue originates from the
second, third, and parts of the fourth pharyngeal arch.
The fact that sensory innervation to this part of the tongue is
supplied by the glossopharyngeal nerve indicates that tissue of the
third arch overgrows that of the second.
The epiglottis and the extreme posterior part of the tongue are
innervated by the superior laryngeal nerve, reflecting their develop-
ment from the fourth arch.
36. Cont…
Some of the tongue muscles probably differentiate in situ, but most are derived
from myoblasts originating in occipital somites. Thus, tongue musculature is
innervated by the hypoglossal nerve.
37. Clinical correlates
Tongue-Tie / Ankyloglossia/
Frenulum extends to the tip of the tongue.
Normally extensive cell degeneration occurs, and the frenulum is the only tissue
that anchors the tongue to the floor of the mouth.
38. THYROID GLAND
The thyroid gland appears as an epithelial proliferation in the floor of
the pharynx between the tuberculum impar and the copula at a point
later indicated by the foramen cecum.
Subsequently, the thyroid descends in front of the pharyngeal gut as a
bilobed diverticulum.
During this migration, the thyroid remains connected to the tongue by a
narrow canal, the thyroglossal duct. This duct later disappears.
39. Cont…
With further development, the thyroid gland descends in
front of the hyoid bone and the laryngeal cartilages. It reaches
its final position in front of the trachea in the seventh week.
The thyroid begins to function at approximately the end
of the third month.
40.
41. Clinical correlates
Thyroglossal cyst
it is a cystic remnant of the thyroglossal duct.
50 % - close to or just inferior to the Hyoid bone.
May also be found at the base of the tongue.
Aberrant thyroid tissue
Any where along path of descent.
Ectoderm gives rise to tissues and organs which maintain contact with the outside world - the nervous system, skin, the sensory epithelium of the ear, nose and eye, and tooth enamel.
Neurulation is the process by which ectoderm forms a neural plate that folds to form the neural tube, giving rise to the brain and spinal cord, and the neural crest.
Neural crest changes into mesenchyme and contributes to the connective tissue and bones of the face and skull.
Lateral to the neural tube, paraxial mesoderm forms pairs of somites each of which give rise to its own sclerotome (bone and cartilage), myotome (muscle) and dermatome (dermis) component. The occipital bone and cervical vertebrae are derived from sclerotomes,
Endoderm provides the epithelial lining of the gastrointestinal and respiratory tracts, including the tympanic cavity and auditory tube, and the parenchyma of the thyroid and parathyroid glands.
Showing position of primordial germ cells
Cross sectional view
The fifth and sixth arches are rudimentary and are not visible on the surface of the embryo
The thymus separates from the pharyngeal wall and descends inferomedially to unite with contralateral thymic tissue
behind the sternum.
The inferior parathyroid descends to lie posterior to the inferior pole of the ipsilateral thyroid lobe.
the first cleft ---The ventral end is normally obliterated, but may persist as a sinus, cyst or fistula. Such a fistula extends from below the auricle, through the parotid gland and opens into the external auditory meatus. It has a variable relationship with the facial (VII) nerve.
The cervical sinus may also communicate with the second pouch in the bed of the palatine tonsil to form an internal branchial fistula. Such fistulae pass over the glossopharyngeal (IX) and hypoglossal (XII) nerves and run between the external and internal carotid arteries
Active proliferation of mesenchymal tissue in the second arch causes it to overlap the third and fourth arches.
Branchial cysts do not usually become apparent until late childhood or early adulthood
A second median swelling, the copula, or hypobranchial eminence, is formed by mesoderm of the second, third, and part of the fourth arch.
The general sensory innervation of the tongue is easy to understand. The body is supplied by the trigeminal nerve, the nerve of the first arch; that of the root is supplied by the glossopharyngeal and vagus nerves, the nerves of the third and fourth arches, respectively. Special sensory innervation (taste) to the anterior two-thirds of the tongue is provided by the chorda tympanic branch of the facial nerve, whereas the posterior third is supplied by the glossopharyngeal nerve.
Follicular cells produce the colloid that serves as a source of thyroxine and triiodothyronine. Parafollicular, or C, cells de- rived from the ultimobranchial body serve as a source of calcitonin.