Pterygoid processes of the sphenoid
The pterygoid processes of the sphenoid, one on either side, descend perpendicularly from the regions where the body and the greater wings of the sphenoid bone unite. Each process consists of a medial pterygoid plate and a lateral pterygoid plate, the latter of which serve as the origins of the medial and lateral pterygoid muscles; the medial pterygoid, along with the masseter allows the jaw to move in a vertical direction as it contracts and relaxes. The lateral pterygoid allows the jaw to move in a horizontal direction during mastication. Fracture of either plate are used in clinical medicine to distinguish the Le Fort fracture classification for high impact injuries to the sphenoid and maxillary bones; the superior portion of the pterygoid processes are fused anteriorly. The plates are separated below by an angular cleft, the pterygoid notch, the margins of which are rough for articulation with the pyramidal process of the palatine bone; the two plates diverge behind and enclose between them a V-shaped fossa, the pterygoid fossa, which contains the medial pterygoid muscle and the tensor veli palatini.
Above this fossa is a small, shallow depression, the scaphoid fossa, which gives origin to the tensor veli palatini. The anterior surface of the pterygoid process is broad and triangular near its root, where it forms the posterior wall of the pterygopalatine fossa and presents the anterior orifice of the pterygoid canal. In many mammals it remains, its name is Greek from its shape. The medial pterygoid plate of the sphenoid bone is a horse-shoe shaped process that arises from its underside, it is narrower and longer than the lateral pterygoid plate and curves lateralward at its lower extremity into a hook-like process, the pterygoid hamulus, around which the tendon of the tensor veli palatini glides. The lateral surface of this plate forms part of the pterygoid fossa, the medial surface constitutes the lateral boundary of the choana or posterior aperture of the corresponding nasal cavity. Superiorly the medial plate is prolonged on to the under surface of the body as a thin lamina, named the vaginal process, which articulates in front with the sphenoidal process of the palatine and behind this with the ala of the vomer.
The angular prominence between the posterior margin of the vaginal process and the medial border of the scaphoid fossa is named the pterygoid tubercle, above this is the posterior opening of the pterygoid canal. On the under surface of the vaginal process is a furrow, converted into a canal by the sphenoidal process of the palatine bone, for the transmission of the pharyngeal branch of the internal maxillary artery and the pharyngeal nerve from the sphenopalatine ganglion; the pharyngeal aponeurosis is attached to the entire length of the posterior edge of the medial plate, the constrictor pharyngis superior takes origin from its lower third. Projecting backward from near the middle of the posterior edge of this plate is an angular process, the processus tubarius, which supports the pharyngeal end of the auditory tube; the anterior margin of the plate articulates with the posterior border of the vertical part of the palatine bone. In many animals it is a separate bone called the pterygoid bone.
The lateral pterygoid plate of the sphenoid is broad and everted and forms the lateral part of a horseshoe like process that extends from the inferior aspect of the sphenoid bone, serves as the origin of the lateral pterygoid muscle, which functions in allowing the mandible to move in a lateral and medial direction, or from side-to-side. Its lateral surface forms part of the medial wall of the infratemporal fossa, gives attachment to the lateral pterygoid muscle. Posterior edge is sharp, has sharp projection - pterygospinous process; this article incorporates text in the public domain from page 151 of the 20th edition of Gray's Anatomy "Anatomy diagram: 34257.000-1". Roche Lexicon - illustrated navigator. Elsevier. Archived from the original on 2014-01-01. Anatomy figure: 22:4b-05 at Human Anatomy Online, SUNY Downstate Medical Center "Anatomy diagram: 25420.000-1". Roche Lexicon - illustrated navigator. Elsevier. Archived from the original on 2014-01-01
Embryology is the branch of biology that studies the prenatal development of gametes and development of embryos and fetuses. Additionally, embryology encompasses the study of congenital disorders that occur before birth, known as teratology. Embryology has a long history. Aristotle proposed the accepted theory of epigenesis, that organisms develop from seed or egg in a sequence of steps; the alternative theory, that organisms develop from pre-existing miniature versions of themselves, held sway until the 18th century. Modern embryology developed from the work of von Baer, though accurate observations had been made in Italy by anatomists such as Aldrovandi and Leonardo da Vinci in the Renaissance. After cleavage, the dividing cells, or morula, becomes a hollow ball, or blastula, which develops a hole or pore at one end. In bilateral animals, the blastula develops in one of two ways that divide the whole animal kingdom into two halves. If in the blastula the first pore becomes the mouth of the animal, it is a protostome.
The protostomes include most invertebrate animals, such as insects and molluscs, while the deuterostomes include the vertebrates. In due course, the blastula changes into a more differentiated structure called the gastrula; the gastrula with its blastopore soon develops three distinct layers of cells from which all the bodily organs and tissues develop: The innermost layer, or endoderm, give rise to the digestive organs, the gills, lungs or swim bladder if present, kidneys or nephrites. The middle layer, or mesoderm, gives rise to the muscles, skeleton if any, blood system; the outer layer of cells, or ectoderm, gives rise to the nervous system, including the brain, skin or carapace and hair, bristles, or scales. Embryos in many species appear similar to one another in early developmental stages; the reason for this similarity is. These similarities among species are called homologous structures, which are structures that have the same or similar function and mechanism, having evolved from a common ancestor.
Drosophila melanogaster, a fruit fly, is a model organism in biology on which much research into embryology has been done. Before fertilization, the female gamete produces an abundance of mRNA - transcribed from the genes that encode bicoid protein and nanos protein; these mRNA molecules are stored to be used in what will become the developing embryo. The male and female Drosophila gametes exhibit anisogamy; the female gamete is larger than the male gamete because it harbors more cytoplasm and, within the cytoplasm, the female gamete contains an abundance of the mRNA mentioned. At fertilization, the male and female gametes fuse and the nucleus of the male gamete fuses with the nucleus of the female gamete. Note that before the gametes' nuclei fuse, they are known as pronuclei. A series of nuclear divisions will occur without cytokinesis in the zygote to form a multi-nucleated cell known as a syncytium. All the nuclei in the syncytium are identical, just as all the nuclei in every somatic cell of any multicellular organism are identical in terms of the DNA sequence of the genome.
Before the nuclei can differentiate in transcriptional activity, the embryo must be divided into segments. In each segment, a unique set of regulatory proteins will cause specific genes in the nuclei to be transcribed; the resulting combination of proteins will transform clusters of cells into early embryo tissues that will each develop into multiple fetal and adult tissues in development. Outlined below is the process that leads to tissue differentiation. Maternal-effect genes - subject to Maternal inheritance Egg-polarity genes establish the Anteroposterior axis. Zygotic-effect genes - subject to Mendelian inheritance Segmentation genes establish 14 segments of the embryo using the anteroposterior axis as a guide. Gap genes establish 3 broad segments of the embryo. Pair-rule genes define 7 segments of the embryo within the confines of the second broad segment, defined by the gap genes. Segment-polarity genes define another 7 segments by dividing each of the pre-existing 7 segments into anterior and posterior halves.
Homeotic genes use the 14 segments as pinpoints for specific types of cell differentiation and the histological developments that correspond to each cell type. Humans are deuterostomes. In humans, the term embryo refers to the ball of dividing cells from the moment the zygote implants itself in the uterus wall until the end of the eighth week after conception. Beyond the eighth week after conception, the developing human is called a fetus; as as the 18th century, the prevailing notion in western human embryology was preformation: the idea that semen contains an embryo – a preformed, miniature infant, or homunculus – that becomes larger during development. Until the birth of modern embryology through observation of the mammalian ovum by von Baer in 1827, there was no clear scientific understanding of embryology. Only in the late 1950s when ultrasound was first used for uterine scanning, was the true developmental chronology of human fetus available; the competing explanation of embryonic development was epigenesis proposed 2,000 years earlier by
The infratemporal fossa is an irregularly shaped cavity, situated below and medial to the zygomatic arch. It is not enclosed by bone in all directions, it contains superficial muscles that are visible during dissection after removing skin and fascia: namely, the lower part of the temporalis muscle, the lateral pterygoid, the medial pterygoid, its boundaries may be defined by: anteriorly, by the infratemporal surface of the maxilla and the ridge which descends from its zygomatic process posteriorly, by the articular tubercle of the temporal and the spina angularis of the sphenoid superiorly, by the greater wing of the sphenoid below the infratemporal crest, by the under surface of the temporal squama, containing the foramen ovale, which transmits the mandibular branch of the trigeminal nerve, the foramen spinosum, which transmits the middle meningeal artery inferiorly, by the medial pterygoid muscle attaching to the mandible medially, by the lateral pterygoid plate laterally, by the ramus of mandible, which contains the mandibular foramen, leading to the mandibular canal through which the inferior alveolar nerve passes.
This contains the lingula, a triangular piece of bone that overlies the mandibular foramen antero-medially. The mylohyoid groove descends obliquely transmitting the mylohyoid nerve the only motor branch of the posterior division of the trigeminal nerve. Lower part of the Temporalis and masseter muscles Lateral and medial pterygoid muscles The internal maxillary vessels, consisting of the maxillary artery originating from the external carotid artery and its branches. Internal maxillary branches found within the infratemporal fossa including the middle meningeal artery inferior alveolar artery deep temporal artery buccal artery pterygoid venous plexus retromandibular vein Mandibular nerve, inferior alveolar nerve, lingual nerve, buccal nerve, chorda tympani nerve, otic ganglion. Mandibular nerve, the third branch of the trigeminal nerve known as the "inferior maxillary nerve" or nervus mandibularis, enters infratemporal fossa from middle cranial fossa through foramen ovale. Motor branches: masseteric nerve deep temporal nerve lateral pterygoid nerve and medial pterygoid nerveIts motor fibers innervate all the muscles of mastication plus the mylohyoid, anterior belly of the digastric, the tensores veli palati and tympani Sensory innervation: meningeal nerve buccal nerve auriculotemporal nerve lingual nerve inferior alveolar nerve auricle external acoustic meatus tympanic membrane temporal region cheek skin overlying the mandible floor of mouth lower teeth gingiva Middle cranial fossa.
Temporal fossa. Pterygopalatine fossa. Orbit. Parapharyngeal space; the foramen ovale and foramen spinosum open on its roof, the alveolar canals on its anterior wall. At its upper and medial part are two fissures, which together form a T-shaped fissure, the horizontal limb being named the inferior orbital, the vertical one the pterygomaxillary; this article incorporates text in the public domain from page 184 of the 20th edition of Gray's Anatomy
Anatomical terms of bone
Many anatomical terms descriptive of bone are defined in anatomical terminology, are derived from Greek and Latin. A long bone is one, cylindrical in shape, being longer than it is wide. However, the term describes the shape of a bone, not its size, relative. Long bones are found in the legs, as well as in the fingers and toes. Long bones function as levers, they are responsible for the body's height. A short bone is one, cube-like in shape, being equal in length and thickness; the only short bones in the human skeleton are in the carpals of the wrists and the tarsals of the ankles. Short bones provide support as well as some limited motion; the term “flat bone” is something of a misnomer because, although a flat bone is thin, it is often curved. Examples include the cranial bones, the scapulae, the sternum, the ribs. Flat bones serve as points of attachment for muscles and protect internal organs. Flat bones do not have a medullary cavity. An irregular bone is one that does not have an classified shape and defies description.
These bones tend to have more complex shapes, like the vertebrae that support the spinal cord and protect it from compressive forces. Many facial bones the ones containing sinuses, are classified as irregular bones. A sesamoid bone is a round bone that, as the name suggests, is shaped like a sesame seed; these bones form in tendons. The sesamoid bones protect tendons by helping them overcome compressive forces. Sesamoid bones vary in number and placement from person to person but are found in tendons associated with the feet and knees; the only type of sesamoid bone, common to everybody is the kneecap, the largest of the sesamoid bones. A condyle is the round prominence at the end of a bone, most part of a joint – an articulation with another bone; the epicondyle refers to a projection near a condyle the medial epicondyle of the humerus. These terms derive from Greek. An eminence refers to a small projection or bump of bone, such as the medial eminence. A process refers to a large projection or prominent bump, as does a promontory such as the sacral promontory.
Both tubercle and tuberosity refer to a projection or bump with a roughened surface, with a "tubercle" smaller than a "tuberosity". These terms are derived from Tuber. A ramus refers to an extension of bone, such as the ramus of the mandible in the jaw or Superior pubic ramus. Ramus may be used to refer to nerves, such as the ramus communicans. A facet refers to a flattened articular surface. A line refers to a long, thin projection with a rough surface. Ridge and crest refer to a narrow line. Unlike many words used to describe anatomical terms, the word ridge is derived from Old English. A spine, as well as referring to the spinal cord, may be used to describe a long, thin projection or bump; these terms are used to describe bony protuberances in specific parts of the body. The Malleolus is the bony prominence on each side of the ankle; these are known as the lateral malleolus. Each leg is supported by two bones, the tibia on the inner side of the leg and the fibula on the outer side of the leg; the medial malleolus is the prominence on the inner side of the ankle, formed by the lower end of the tibia.
The lateral malleolus is the prominence on the outer side of the ankle, formed by the lower end of the fibula. The trochanters are parts of the femur, it may refer to the greater, lesser, or third trochanter The following terms are used to describe cavities that connect to other areas: A foramen is any opening referring to those in bone. Foramina inside the body of humans and other animals allow muscles, arteries, veins, or other structures to connect one part of the body with another. A canal is a long, tunnel-like foramen a passage for notable nerves or blood vessels; the following terms are used to describe cavities that do not connect to other areas: A fossa is a depression or hollow in a bone, such as the hypophyseal fossa, the depression in the sphenoid bone. A meatus is a short canal. A fovea is a small pit on the head of a bone. An example of a fovea is the fovea capitis of the head of the femur; the following terms are used to describe the walls of a cavity: A labyrinth refers to the bony labyrinth and membranous labyrinth, components of the inner ear, due to their fine and complex structure.
A sinus refers to a bony cavity within the skull. A joint, or articulation is the region where adjacent bones contact each other, for example the elbow, shoulder, or costovertebral joint. Terms that refer to joints include: articular process, referring to a projection that contacts an adjacent bone. Suture, referring to an articulation between cranial bones. Bones are described with the terms head, shaft and base The head of a bone refers to the proximal end of the bone; the shaft refers to the elongated sections of long bone, the neck the segment between the head and shaft. The end of the long bone opposite to the head is known as the base; the cortex of a bone is used to refer to its outer layers, medulla used to
Anterior nasal spine
The anterior nasal spine, or anterior nasal spine of maxilla, is a bony projection in the skull that serves as a cephalometric landmark. The anterior nasal spine is the projection formed by the fusion of the two maxillary bones at the intermaxillary suture, it is placed at the level of the nostrils, at the uppermost part of the philtrum and fractures. Posterior nasal spine This article incorporates text in the public domain from page 158 of the 20th edition of Gray's Anatomy Diagram at upstate.edu - side Diagram at upstate.edu - front Anatomy photo:22:os-1911 at the SUNY Downstate Medical Center - "Osteology of the Skull: The Maxilla" "Anatomy diagram: 34256.000-1". Roche Lexicon - illustrated navigator. Elsevier. Archived from the original on 2014-01-01. "Anatomy diagram: 34256.000-2". Roche Lexicon - illustrated navigator. Elsevier. Archived from the original on 2014-01-01
In animal anatomy, the mouth known as the oral cavity, buccal cavity, or in Latin cavum oris, is the opening through which many animals take in food and issue vocal sounds. It is the cavity lying at the upper end of the alimentary canal, bounded on the outside by the lips and inside by the pharynx and containing in higher vertebrates the tongue and teeth; this cavity is known as the buccal cavity, from the Latin bucca. Some animal phyla, including vertebrates, have a complete digestive system, with a mouth at one end and an anus at the other. Which end forms first in ontogeny is a criterion used to classify animals into protostomes and deuterostomes. In the first multicellular animals, there was no mouth or gut and food particles were engulfed by the cells on the exterior surface by a process known as endocytosis; the particles became enclosed in vacuoles into which enzymes were secreted and digestion took place intracellularly. The digestive products were diffused into other cells; this form of digestion is used nowadays by simple organisms such as Amoeba and Paramecium and by sponges which, despite their large size, have no mouth or gut and capture their food by endocytosis.
The vast majority of other multicellular organisms have a mouth and a gut, the lining of, continuous with the epithelial cells on the surface of the body. A few animals which live parasitically had guts but have secondarily lost these structures; the original gut of multicellular organisms consisted of a simple sac with a single opening, the mouth. Many modern invertebrates have such a system, food being ingested through the mouth broken down by enzymes secreted in the gut, the resulting particles engulfed by the other cells in the gut lining. Indigestible waste is ejected through the mouth. In animals at least as complex as an earthworm, the embryo forms a dent on one side, the blastopore, which deepens to become the archenteron, the first phase in the formation of the gut. In deuterostomes, the blastopore becomes the anus while the gut tunnels through to make another opening, which forms the mouth. In the protostomes, it used to be thought that the blastopore formed the mouth while the anus formed as an opening made by the other end of the gut.
More recent research, shows that in protostomes the edges of the slit-like blastopore close up in the middle, leaving openings at both ends that become the mouth and anus. Apart from sponges and placozoans all animals have an internal gut cavity, lined with gastrodermal cells. In less advanced invertebrates such as the sea anemone, the mouth acts as an anus. Circular muscles around the mouth are able to contract in order to open or close it. A fringe of tentacles thrusts food into the cavity and it can gape enough to accommodate large prey items. Food passes first into a pharynx and digestion occurs extracellularly in the gastrovascular cavity. Annelids have simple tube-like gets and the possession of an anus allows them to separate the digestion of their foodstuffs from the absorption of the nutrients. Many molluscs have a radula, used to scrape microscopic particles off surfaces. In invertebrates with hard exoskeletons, various mouthparts may be involved in feeding behaviour. Insects have a range of mouthparts suited to their mode of feeding.
These include mandibles and labium and can be modified into suitable appendages for chewing, piercing and sucking. Decapods have six pairs of mouth appendages, one pair of mandibles, two pairs of maxillae and three of maxillipeds. Sea urchins have a set of five sharp calcareous plates which are used as jaws and are known as Aristotle's lantern. In vertebrates, the first part of the digestive system is the buccal cavity known as the mouth; the buccal cavity of a fish is separated from the opercular cavity by the gills. Water flows in through passes over the gills and exits via the operculum or gill slits. Nearly all fish have jaws and may seize food with them but most feed by opening their jaws, expanding their pharynx and sucking in food items; the food may be held or chewed by teeth located in the jaws, on the roof of the mouth, on the pharynx or on the gill arches. Nearly all amphibians are carnivorous as adults. Many catch their prey by flicking out an elongated tongue with a sticky tip and drawing it back into the mouth where they hold the prey with their jaws.
They swallow their food whole without much chewing. They have many small hinged pedicellate teeth, the bases of which are attached to the jaws while the crowns break off at intervals and are replaced. Most amphibians have one or two rows of teeth in both jaws but some frogs lack teeth in the lower jaw. In many amphibians there are vomerine teeth attached to the bone in the roof of the mouth; the mouths of reptiles are similar to those of mammals. The crocodilians are the only reptiles to have teeth anchored in sockets in their jaws, they are able to replace each of their 80 teeth up to 50 times during their lives. Most reptiles are either carnivorous or insectivorous but turtles are herbivorous. Lacking teeth that are suitable for efficiently chewing of their food, turtles have gastroliths in their stomach to further grind the plant material. Snakes have a flexible lower jaw, the two halves of which are not rigidly attached, numerous other joints in their skull; these modifications allow them to open their mouths wide enough to swallow their prey whole if it is wider than they are.
Birds do not have teeth, macerating their food. Their beaks have a range of sizes and shapes according to their diet and are compose
Franklin P. Mall
Franklin Paine Mall was an American anatomist and pathologist known for his research and literature in the fields of anatomy and embryology. Mall was granted a fellowship for the Department of Pathology at the Johns Hopkins University and after positions at other universities returned to be the head of the first Anatomy Department at the Johns Hopkins School of Medicine. There, he reformed the field of its educational curriculum. Mall was the founder and the first chief of the Department of Embryology at the Carnegie Institution for Science, he donated his collection of human embryos that he started as a postgraduate student to the Carnegie Institution for Science. Franklin Mall was born to German immigrants Franz Mall and Louise Christine Miller, on a farm in Belle Plaine, Iowa. At the age of ten, Mall's mother died, his stepmother showed no affection towards him. Mall was unhappy in his childhood, he had little opportunity to challenge his intellect both at home and in school. Mall met John McCarthy, a teacher at the local academy who impacted Mall's learning experience and life.
Mall, in a personal correspondence, wrote that while he hated history as a child, Mr. McCarthy "showed he liked it." In addition, Mall had the support of his father. With this newfound appreciation of academic pursuit, Mall was able to attain higher education. Mall was accepted into the Department of Medicine at the University of Michigan, the school where his family physician had received his training. During his time at Ann Arbor, Mall was drawn to three of his professors: Corydon Ford, Victor Vaughn, Henry Sewall. Mall was impressed by their pedagogical approach and their extensive knowledge in their respective fields, their lectures were objective. Mall noted that the majority of the students in his class favored rote memorization as a means to academic success; this was in contrast to his own preference for critical thinking and reasoning, a difference that emerged in his subsequent educational reforms. Mall graduated in June 1883 and went to Germany to further his education in 1884, he spent his first year abroad in Heidelberg to study ophthalmology.
In Germany, Mall found his peers to be driven and better educated. Mall valued the freedom of choice and the liberty afforded to him while studying in Germany. In 1885, Mall went to Leipzig to begin his career in research under the guidance of Wilhelm His. Mall's first project resulted in evidence that contradicted his mentor's position on the origin of the thymus, concluding that it develops from the endoderm instead of the ectoderm, his revisited the issue and acknowledged the validity of Mall's work. During his time with His, Mall started a collection of human embryos that he would continue to expand for the rest of his career. With His' recommendation, Mall moved to Carl Ludwig's laboratory that year, where he was assigned to study the blood vessels and lymphatics of the intestinal villus. Under Ludwig's tutelage, Mall learned methods of injecting blood lymphatics. Mall took apart the layers of the intestine to examine the blood supply of each layer and the organ as a whole. Using this knowledge, he constructed a model that demonstrated the circulatory relationship in the intestinal organ.
Mall's strong relationships with his mentors grew his curiosity and his affinity to scientific research. He spread his focus on laboratory research to the American education system; as described by a student, Mall was shy on outward appearance. He was known to have a good sense of humor among his friends. Mall was immersed in his research focused on solving any complications that were presented during the course of his work. Deep in thought, Mall would sometimes be seen wandering around the hospital building and the city of Baltimore. Otherwise, he was known to be engrossed with work for long periods in his laboratory. Mall first met Mabel Glover while teaching his first class at Johns Hopkins, they got married in 1894 and had two daughters and Mary Louise Mall. Mall fell ill after complications from a second operation for the removal of gallstones, he died while being treated at the Johns Hopkins Hospital in November 1917. In 1886, Mall returned to the United States to undertake a fellowship in pathology at the Johns Hopkins University.
Training under William H. Welch, Mall studied the anatomy of the stomach, he expressed interest in bacteriology and connective tissue, discovering the ability of certain bacteria to digest connective tissue. Mall's collaboration with William Halstead on connective tissue led to the development of a new method of surgical suturing for the intestine. In 1888, Mall became a professor of Pathology. After a three year stay in Baltimore, Mall accepted an offer from Stanley Hall for the position of adjunct professor of anatomy at Clark University. While at Clark, Mall used the Born wax-plate method to create the first model of a human embryo in the United States. Furthermore, Mall discovered the vasomotor nerves of the portal vein and founded an embryological research program at the university. In 1892, Mall followed Charles Otis Whitman to Chicago, becoming the professor of Anatomy at the University of Chicago. After a year in Chicago, Mall accepted a professorship at the newly opened Johns Hopkins School of Medicine.
Accepting a personal request from William H. Welch