Anatomic sciences 272-313 (tooth tooth hist veins)

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Anatomic sciences 272-313 (tooth tooth hist veins)
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2014-09-26 10:21:07
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272-313
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  1. Cementum is the closest in composition to which of the following?

    - Bone
    - Enamel
    - Dentin
    - Dental pulp
    • Bone
    • Cementum is a bone-like mineral tissue whose primary function is to attach to Sharpey's fibers.
    • It is formed by cementoblasts in the PDL, as opposed to dentin which is formed by odontoblasts in the pulp and develops from the dental follicle (dental sac).
    • Resembles bone moreso than Dentin except, No innervation or blood vessels
    • Organic portion (50%) made from collagen and protein, inorganic (45%) made from calcium and hydroxyapatite.
    • Thickest portion at root apex, thinnest at the CEJ.
    • Two types of cementum (functionally with NO difference): Acellular (no cementocytes, predominates at coronal 2/3rds) and Cellular (called secondary, frequent at apical 3rd)
    • Bone: 50% inorganic, 25% water and 25% collagen.
  2. When using a high speed handpiece to remove caries from a tooth, the dentist must drill past the enamel into dentin. The first layer of dentin (at the DEJ) is called:

    - Intratubular dentin
    - Intertubular dentin
    - Mantle dentin
    - Circumpulpal dentin
    - Interglobular dentin
    • Mantle dentin, is the first predentin that forms and matures within the tooth. Mantle dentin shows a difference in the direction of the mineralized collagen fibers compared to the rest of the dentin, with the fibers perpendicular to the DEJ and has higher levels of mineralization.
    • Dentin that surrounds the pulpal wall is called circumpulpal dentin. This dentin makes up the bulk of the dentin in the tooth.
    • Primary dentin: formed before the completion of the apical foramen, more mineralized than 
    • Secondary dentin: formed after the completion of the apical foramen, less mineralized than first
    • Tertiary dentin: formed as a result of injury.
    • Each dental tubule contains the cytoplasmic cell process Tomes' fiber of an odontoblast
    • Fibrous matrix that odontoblasts secrete into dentin is mostly type 1 collagen.
  3. Sensory nerve fibers that originate from the inferior and superior alveolar nerves innervate the odontoblastic layer of the pulp cavity. These nerves enter the tooth through the apical foramen as myelinated nerve bundles. They branch to form the sub-odontoblastic nerve plexus of Raschkow which is separated from the odontoblasts by a:

    - Cell rich zone
    - Cell free zone (zone of Weil)
    - Fibroblastic later
    • Cell free zone (zone of Weil)
    • The pulp is the innermost tissue of the tooth formed from the central cells of the dental papilla.
    • Accessory canals: form when Hertwigs epithelial root sheath encounters a blood vessel during root formation, the root structure forms around the vessel.
    • Peripheral aspect of the dental pulp is referred to as the odontogenic zone, subadjacent to this zone is the cell-free zone (of Weil). This region contains bundles of reticular (Korff's) fibers.
    • Just under the cell free zone (of Weil) is a cell rich zone containing numerous fibroblasts (the predominant cell type of the pulp)
    • Medial to the cell rich zone is the deep pulp cavity that contains subodontoblastic plexus of Raschkow.
  4. Amelogenesis (the formation of enamel) begins at the:

    - Cementoenamel junction (CEJ)
    - Dentinoenamel junction (DEJ)
    - Cementodentinal junction (CDJ)
    - Mucogingival junction (MGJ)
    • Dentinoenamel junction (DEJ)
    • Amelogenesis occurs during the appositional stage of tooth development and is produces by ameloblast cells and is secreted by their Tomes' process, which faces the DEJ.
    • Odontoblasts begin dentin formation immediately before enamel formation by the ameloblasts. Dentinogenesis starts by laying dentin matrix moving toward the DEJ inward toward the pulp, adjacent to the pulpal surface.
    • DEJ is the area where tooth calcification begins.
    • Morphology of the DEJ is determined at the Bell stage.
    • Oldest enamel in a tooth is at the DEJ underlying a cusp.
  5. Pulpal involvement of a carious lesion in a young child is much more likely because:

    - Caries progress faster in primary teeth
    - Caries can enter primary teeth from the enlarged apical foramen
    - The pulp chamber is larger in primary teeth compared to permanent teeth
    - Reparative dentin is not as functional in primary teeth as it is in permanent teeth
    • The pulp chamber is larger in primary teeth compared to permanent teeth
    • Cells found in the pulp: Fibroblasts (most numerous), Odontoblasts (only cell bodies are located in the pulp), Undifferentiated mesenchymal cells, Lymphocytes, plasma cells and eosinophils
    • Pulp has two types of nerve fibers: Autonomic nerve fibers (unmyelinated) and afferent (sensory) fibers (myelinated)
    • Pulp capping is more successful in young teeth because:
    • Contains more cells (odontoblastic)
    • Large apical foramen
    • Very vascular
    • More tissue fluid
    • Fewer fibrous elements
  6. The main function of cementum is to provide rough surface anchorage for attachment of:

    - Transseptal fibers
    - Sharpey's fibers
    - Oblique fibers
    - Alveolar crest fibers
    • Sharpey's fibers
    • Cementum is composed of mineralized fibrous matrix cells (cementocytes). The fibrous matrix consists of both Sharpey's fibers and intrinsic nonperioseal fibers. Sharpey's fibers are the terminal portions of the principal fibers of the PDL.
    • Other functions of cementum: Compensates, for bone loss of tooth surface due to occlusal wear by apical cementum deposits throughout life. Protects, the root surface from resorption during vertical eruption and tooth movement.
    • Cementum differs from enamel because it contains collagen fibers and cellular components.
    • Cementoids are immature and uncalcified, and cementocytes get trapped within the cementum they prodouce (like bone)
  7. An irritating or painful response to cold, hot or pressure stimuli is usually caused by sensitivity of which oral tissue?

    - Dentin
    - Cementum
    - Pulp
    - Enamel
    • Dentin
  8. Generally, as the dental pulp ages, the number of cells ______, and the number of collagen fibers ______.

    - Decreases, decreases
    - Decreases, increases
    - Increases, decreases
    - Increases, increases
    • Decreases, increases
    • Decrease: water, cells and number of undifferentiated cells. Decrease in regenerative capability. Size of the pulp cavity due to the addition of secondary or tertiary dentin.
    • Increase: number of collagen fibers, and calcifications within the pulp.
    • The only type of nerve ending found in the pulp is free nerve ending, which is a specific receptor for pain (no matter the source of stimulation, heat, cold, pressure, the response will be PAIN)
    • Pulp contains both myelinated (sensory) and unmyelinated (sympathetic) nerve fibers that are afferent.
    • Proprioeptors are not found in the pulp.
  9. Topical application of fluoride and more recently amorphous calcium phosphate (ACP) are both treatments to remineralize incipient carious lesions in which tissue?

    - Bone
    - Dentin
    - Enamel
    - Cementum
    • Enamel, hardest calcified tissue and richest in calcium. 96% inorganic, of ectodermal origin. Organic proteins rich in proline.
    • Fundemental morphological unit of enamel is the enamel rod or prism. Each is formed in increments by a single ameloblast, perpendicular to the DEJ, shape is determined by the Tomes' process.
    • Enamel facts:
    • Good thermal insulator
    • Acid solubility reduced by fluoride
    • No capacity for regeneration, lose functional ability after crown has erupted.
  10. What percent of enamel is NOT inorganic hydroxyapatite?

    - 4%
    - 10%
    - 16%
    - 25%
    • 4%
    • 1% organic maxtrix
    • 3% water
    • Due to high inorganic content, appears clear on histologic sections.
    • Enamel is a selectively permeable membrane, allowing water and certain ions to pass via osmosis.
  11. Which of the following lines would be present in all deciduous teeth and in permanent first molars, but not in the rest of the permanent dentition? 

    - Hunter-Schreger bands
    - Lines of retzius
    - Perikymata
    - Neonatal line
    • Neonatal line
    • Since enamel formation begins at the top of the cusp, the ameloblasts create an artifact called Lines of retzius. Where these lines terminate on the surface they create tiny vallyes around the tooth circumference called Perikymata or imbrication lines of pickerill.
    • The neonatal line marks the division between enamel made before and after birth.
    • Enamel tufts: fan-shaped, hypocalcifed enamel rods that project from the DEJ to the enamel proper.
    • Enamel spindles: short dentinal tubes near the DEJ, they may serve as pain receptors.
    • Enamel lamellae: partially calcified vertival defects in enamel resembling cracks or fractures that traverse the entire length of the crown and surface to the DEJ.
    • Hunter-Schreger bands: alternating light and dark lines seen in dental enamel that begin at DEJ and end before they reach enamel surface.
  12. Where you you expect to see the incremental lines of von Ebner?

    - Alveolar bone
    - Enamel
    - Dentin
    - Cementum
    • Dentin
    • The incremental lines of von Ebner, in dentin can be likened to the growth rings or incremental lines of Retzius in enamel.
    • Contour lines of Owen: adjoining parallel imbrication lines that are present in stained dentin.
    • Most pronounced contour line is the neonatal line ocurrs during the trauma of birth. Other contour lines occur with tetracycline staining of teeth where the antibiotic becomes chemically bound to dentin.
    • Tomes' granular layer: most often found in the peripheral portion of the dentin beneath the root's cementum adjacent to the DCJ.
  13. Which type of collagen is likely not to be found in the organic component of dentin?

    - Type 1
    - Type III
    - Type IV
    - Type V
    • Type IV
    • Dentin is a specialized connective tissue that makes up the bulk of the tooth, hard and elastic. 70% inorganic, 20% organic and 10% water. Inorganic component consists of mainly calcium hydroxyapetite.
    • Dental pulp and dentin are made of dental papilla
    • Main type of cell in dentin is odontoblast, which is derived from the ectomesenchyme.
    • Major organic component of dentin is Type 1 collagen fibers (91%), Type 3 fibers in mantle dentin, Type 5 and 6 found in traces.
  14. In orthodontic tooth movement, bone remodeling is forced. The bands , wires, or appliances put pressure on one side of the tooth and adjacent alveolar bone, creating a zone of ______ in the PDL. This leads to _______ of bone. On the opposite side of the tooth and bone, a _____ zone develops in the PDL and causes the _____ of bone.

    - Tension; deposition; compression; resorption
    - Compression; resorption; tension, deposition
    - Compression; deposition; tension, resorption
    - Tension; resorption; compression; deposition
    • Compression; resorption; tension, deposition
    • The new alveolar bone deposited during orthodontic movement is best described as intramembranous.
    • Osteoblasts (derived from mesenchyme): bone forming cells that secrete collagen, when they have been trapped in the osteoid they are osteocytes
    • Osteoclasts (derived from stem cells in bone marrow): Essential for bone remodeling and modeling, resorptive activity allows for permanent renewing of bone.
    • During active tooth eruption, there is an apposition of bone on all surfaces of the alveolar crest and walls of bony socket.
    • Permanent teeth move occlusally and bucally when erupting.
  15. Apical abscesses of which teeth have a marked tendency to produce cervical spread of infection most rapidly?

    - Mandibular central and lateral incisors
    - Mandibular canine and first premolar
    - Maxillary first and second molars
    - Mandibular second and third molars
    • Mandibular second and third molars
    • Certain anatomic features determine to a large extent the actual direction that an infection may take. The attachment of muscles may determine the route that an infection will take, channeling the infection into certain tissue spaces
  16. The lamina dura is a radiopaque layer of bone surrounding the periodontal ligament along the roots teeth. Histologically, the lamina dura is comprised of which type of bone?

    - Bundle bone
    - Cancellous bone
    - Osteid
    - Trabecular bone
    • Bundle bone
    • Alveolar process is that part of the maxilla and mandible that forms and supports the sockets of the teeth. Consists of 2 parts
    • 1. Alveolar bone proper: thin layer of compact bone that is a specialized continuation of cortical plate and forms the tooth socket or alveolus. Lamina dura, is a horse shoe shaped white line that corresponds to alveolar bone proper. composed of bundle bone, which provides a course surface for ligament fiber attachment.
    • 2. Supporting alveolar bone: bone that surrounds the alveolar bone proper and gives support to the socket. Made up of Cortical plate, composed of lingual and facial plates of compact bone and Spongy bone, fills in area between cortical plates and alveolar bone proper.
  17. A newly erupted tooth has a membranous covering. It is derived from which structure?

    - Perikymata
    - Dental papilla
    - Dental follice
    - Oral epithelium
    • Oral epithelium
    • Also known as Nasmyth's membrane, the secondary enamel cuticle is the thin membrane covering newly erupted teeth. Ectodermally derived, produced by the ameloblast cell after it produces the enamel rods.
    • This membrane is abraded by mastication and cleaning. Eventually replaced by an organic deposit called the pellicle, that if not removed causes caries and periodontal disease.
  18. A physician determines that a patient with acromegaly will develop a skeletal class III occlusion due to excessive growth of the mandible. What causes the formation of resting lines as seen in the cortical bone of the mandible?

    - Growth of mandible by appositional growth
    - Growth of mandible by interstitial growth
    - Growth of mandible by both interstitial and appositional growth
    • Growth of mandible by appositional growth
    • Bone apposition is the deposition of successive layers of bone on those already present.
    • Due to its rigid structure, bone can grow only by appositional growth. Cartilage can grow by both appositional and interstitial growth.
    • Both maxilla and mandible form from tissues of the first branchial arch (mandibular), both start out as small centers of intramembranous ossificaiton.
  19. Dentin is considered a living tissue because of odontoblastic cell processes known as:

    - Triacetate fiber
    - Tomes' fiber
    - Tag fiber
    - Korff's fiber
    • Tomes' fiber
    • These odontoblastic processes (Tomes' fibers) occupy the dental tubules (one per odontoblast)
    • It is because of these cell processes that dentin is considered a living tissue and produces stimuli (fluid movement), sclerotic and reparative dentin.
    • * Odontoblasts begin dentin formation immediately before ameloblasts begin enamel formation. They lay down a dentin matrix moving from the DEJ inward toward the pulp.
    • * Amelogenesis is process of enamel matrix that occurs during the appositional stage of tooth development. Enamel matrix is secreted from each ameloblast from its Tomes' process.
    • Cell body of odontoblast lies in pulp cavity.
  20. Which of the following us produced in reaction to various stimuli such as attrition, caries, or a restorative dental procedure?

    - Primary dentin
    - Secondary dentin
    - Tertiary dentin
    - Mantle dentin
    • Tertiary dentin, produced rapidly in response to localized injury to exposed dentin. It tries to seal off the area, this the term reparative.
    • Primary dentin: dentin formed in a tooth before the completion of the apical foramen of the root.
    • Secondary dentin: is the dentin formed after completion of apical foramen of the tooth.
    • Sclerotic dentin: fills blind tracts with mineral, appears shiny, dark and smooth. Seals off dental tubules to prevent bacteria from entering pulp cavity
  21. The dental lamina, a thickening of the oral epithelium that produces the swellings of the enamel organs, is first seen histologically around the:

    - Second week in utero
    - 6th week in utero
    - 10th week in utero
    - 4th week in utero
    • 6th week in utero
    • By the 3rd week after conception, the stomodeum is formed. Over the next few weeks the tongue, jaws and palate develop. During the 6th to 7th week, the formation of the teeth commences. By the 8th wee all of the primary incisors, canines and molars are discernible.
    • Tooth development is initiated by the mesenchyme's inductive influence on the overlying ectoderm. Early in the 6th week, there is a thickening of the oral epithelium, as u-shaped bands are called the dental lamina, they follow the curvature of the jaws.
    • On the dental lamina, swellins called enamel organ, are produced, inside this organ condensed mesenchyme becomes the dental papilla. Surrounding both the enamel organ and the dental papilla is a capsule-like structure of the mesenchyme called the dental-sac.
    • The enamel organ separated from the dental lamina after the first layer of dentin is deposited.
  22. The reduced enamel epithelium forms as the collapse of what structure?

    - Cervical loop
    - Hertwig's epithelial sheath
    - Enamel organ
    - Dental lamina
    • Enamel organ
    • Following the formation of the crown, the enamel organ collapses to form the reduced enamel epithelium that covers the tooth through eruption
    • The reduced enamel epithelium is important in the formation of the dentogingival junction, which is the area where the enamel and the oral epithelium come together as the tooth erupts in the mouth. This forms the initial junctional epithelium, which later migrates down the tooth to assume its normal position.
    • The junctional epithelium attaches to the tooth by using hemidesmosomes. The apical extent of the junctional epithelium is usually the cementoenamel junction.
  23. Which structure functions to shape the root (or roots) and to induce dentin formation in the root area so that it is continuous with coronal dentin?

    - Dental papilla
    - Dental lamina
    - Dental sac
    - Hertwig's sheath
    - Enamel
    • Hertwig's sheath
    • Structure responsible for root development is the cervical loop. It is a bilayer rim at the most cervical part of the enamel, it grows deeper into the surrounding mesenchyme of the dental sac, moving away from the newly completed crown area to enclose more of the dental papilla tissue and form the Hertwig's epithelial root sheath (HERS).
    • Hertwig's sheath is an epithelial diaphragm that is derived from the inner and outer enamel epithelium of the enamel organ, produces the shaped of the roots and induces formation of root dentin.
    • Accessory root canals are formed by a break or perforation in the root sheath before the root dentin is deposited.
  24. Just before the first layer of dentin forms (mantle dentin), differentiating inner enamel epithelium cells (ameloblasts) secrete some enamel proteins, which do not accumulate as a layer.

    These first proteins, together with growth factors, may play a role in the epithelial-mesenchymal signaling that leads to the terminal differentiation of odontoblasts, possibly by interacting with components of the basal lamina that separates them.

    - Which statements are true and false?
    • Both statements are true.
    • Although enamel protein secretion occurs before mantle dentin is visible on the crown, these proteins do not assemble as a layer until dntin is formed.
    • Histiogenesis of a tooth:
    • 1: Elongation of the inner enamel epithelial cells of the enamel organ; this influences mesenchymal cells on the periphery of the dental papilla to differentiate into odontoblasts
    • 2: Differentiation into odontoblasts
    • 3: Deposition of the first layer of dentin
    • 4: Deposition of the first layer of enamel
    • * Tooth development is dependent on a series of sequential cellular interactions between epithelial and mesenchymal components of the tooth germ. Once the extomesenchyme influences the oral epithelium to grow down into the ectomesenchyme and become a tooth germ, the above events occur.
  25. The four distinct layers of the enamel organ include all of the following EXCEPT?

    - Outer enamel epithelium
    - Inner enamel epithelium
    - Stratum granulosum
    - Stratum intermedium
    - Stellate reticulum
    • Stratum granulosum
    • Four layers of enamel organ (OEE): the outer layer of the organ (very thin) outlines the shape of the future developing enamel organ
    • Inner enamel epithelium (IEE): innermost cellular layer of the enamel organ (very thin), In this layer the cells will become ameloblasts and produce enamel.
    • Stratum intermedium: this area lies immediately lateral to the inner enamel epithelium (ticker), seems to be essential to enamel formation (prepares nutrients for the IEE).
    • Stellate reticulum: central core and fills the bulk of enamel organ. Contains a lot of intercellular fluid (rich in albumin) that is lost just before enamel deposition.
    • *After enamel formation is completed, all of these structures become one and form the reduced enamel epithelium. It is important for the Dentogingival junction and forms the initial junctional epithelium.
  26. Important developmental changes begin late in the cap stage and continue during the transition of the tooth germ cap to bell. Through these changes, termed _____, a mass of epithelial cells transforms itsself into morphologically and functionally distinct components.

    - Initiation
    - Apposition
    - Histodifferentiation
    - Reflexion
    • Histodifferentiation
    • Initiation (6-7 weeks): ectoderm lining the stomodeum gives rise to oral epithelium and then to dental lamina. Induction is the main process involved (congenital absence of teeth is due to interruption in this phase)
    • Bud stage (8th week): growth of dental lamina into bud that penetrates growing ectomesenchyme, Proliferation is the main process invovlved
    • Cap stage (9-10 weeks): enamel organ turns into a cap, surrounding the mass of the dental papilla and surrounded by the mass of the dental sac, thus forming the tooth germ. proliferation, differentiation and morphogenesis are the proceses involved. Dens in dente, germination, fusion and tubercle formation occur here.
    • Bell stage (11-12 weeks): final shaping of the tooth, cells differntiate into diff tissue forming cells (ameloblasts, odontoblasts, cementoblasts and fibroblasts) Histdifferentiation and morphodifferentiation (macrodontia and microdontia, amelo/dentino-genesis imperfecta) occur here.
    • Apposition (varies per tooth): differentiated cells begin to deposit dental tissues where they belong (enamel, dentin, etc..) conscrescence, enamel pearls occur here
  27. A cementicle is a spherical, calcified body that lies in the periodontal ligament or fused to the cementum of a tooth. Which developmental remnant is the most likely site of ectopic cementum nucleation.

    - Junctional epithelium
    - Cervical enamel extensions
    - Cementoenamel junction
    - Epithelial rests of malassez
    • Epithelial rests of malassez, are the remnants of Hertqig's epithelial root sheath and can be found as groups of epithelial cells in the periodontal ligament. Some of these rests can degenerate and others become calcified and form cementicles.
    • Purpose of Hertwig's sheath is to shape the root (or roots) and induce dentin formation in the root area so it is continuous with the coronal dentin.
    • * The continuuity of Hertwig's epithelial root sheath must be broken in order for cementum to be deposited during the tooth development (cementogenesis)
  28. Histologically, the dentin of the root is distingushed from the dentin of the crown by the presence of?

    - Incremental lines of Retzius
    - Rete pegs
    - Granular layer of Tomes
    - Sharpey's fibers
    • Granular layer of Tomes, found in the root dentin.
    • Globular dentin: refers to areas of both primary and secondary mineralization in dentin
    • Interglobular dentin: areas of unmineralized or hypomineralized dentin where globular zones of mineralization have failed to fuse with mature dentin. Seen frequently in circumpulpal dental.
  29. Which of the following products is not ectodermal in origin?

    - Junctional epithelium
    - Enamel
    - Hertwig's epithelial root sheath
    - Pulp
    - Ameloblasts
    • Pulp
    • Components of tooth germ
    • 1 - Enamel organ: formed from oral epithelium, derived from ectoderm, has 4 cells layers; Outer and Inner enamel epithelium, Stratum intermedium and Stallate reticulum
    • 2 - Dental follicle (sac): which is formed by the mesenchyme, which is derived from neural crest cells (cementum, PDL alveolar bone proper)
    • 3 - Dental papilla: also formed from the mesenchyme, derived from neural crest cells. Dental papilla will give rise to dentin and dental pulp.
  30. The portal vein is about 2 inches long and is formed behind the neck of the pancreas by the union of the :

    - Left gastric and the left colic veins
    - Appendicular and the inferior mesenteric veins
    - Superior mesenteric and splenic veins
    - Right gastric and the right colic veins
    • Superior mesenteric and splenic veins
    • Portal veins is commonly known as the the hepatic portal vein) it is a major vein that drains blood from the abdominal part of the gastrointestinal tract, spleen, pancreas and gallbladder.
    • Almost all of the blood coming from the digestive system drains into a special venous circulation called the portal circulation.
    • Tributaries of the portal vein are:
    • Splenic vein
    • Inferior mesenteric vein
    • Superior mesenteric vein
    • Gastric vein
    • * Portal vein carries twice as much blood as the hepatic artery. blood is returned to the heart via the inferior vena cava.
  31. The difference between most posterior intercostal veins and the left superior intercostal vein is that most posterior intercostal veins drain directly into the azygos venous system, while the left superior intercostal vein drains directly into which vein?

    - Superior vena cava
    - Inferior vena cava
    - Left brachiocephalic vein
    - Left subclavian vein
    • Left brachiocephalic vein
    • An intercostal vein runs alongside each intercostal artery, each side has 11 intercostal vein and one subcostal vein. poster posterior intercostal veins empty into the azygos venous system, which in turn empties into the superior vena cava at T4.
    • Azygos veins consist of the main azygos vein, the inferior hemiazygos vein and the superior hemiazygos vein.
    • The right brachiocephalic vein is formed at the root of the neck by the union of the right subclavian and the right internal jugular veins. The left brachiocephalic vein has a similar origin, it joins the right brachiocephalic vein to form the superior vena cava.
  32. The subclavian vein begins at the outer border of the first rib as a continuation of the:

    - Brachial vein
    - Brachiocephalic vein
    - Internal jugular vein
    - Axillary vein
    • Axillary vein
    • The subclavian veins are two large veins, one on either side of the body, each one begins at the outer border of the first rib as a continuation of the axillary vein. Anterior to the scalenus muscle, it joins the internal jugular vein and forms the brachiocephalic vein.
    • Inferior vena cava is larger than the superior.
  33. Oxygenated blood leaves the placenta and enters the fetus through:

    - Foramen ovale
    - Ductus venosus
    - Umbilical arteries
    - Ductus arteriosum
    - Umbilical vein
    • Umbilical vein
    • It is the only fetal vessel to carry blood that is rich in oxygen and nutrients. All of the other vessels carry a mixture of arterial and venous blood. After circulation in the fetus the blood returns to the placenta through the umbilical arteries.
    • Foramen ovale: opening between the left and right atria in fetus, that closes at birth and becomes a depression known as the interatrial septum.
  34. Exchange of gases in peripheral tissue occurs in:

    - Alveoli
    - Arterioles
    - Arteries
    - Capillaries
    - Venules
    • Capillaries, composed of a single layer of epithelial cell, exchange of carbon dioxide and oxygen takes place through this cell wall. Blood vessels pass in single line.
    • Capillaries pass deoxygenated blood back through venules then back to veins.
  35. All of the following nerves are embedded in the lateral wall of the cavernous sinuses EXCEPT:

    - Trochlear nerve (CN IV)
    - Ophthalmic nerve (CN V-1)
    - Oculomotor nerve (CN III)
    - Maxillary nerve ( CN V-2)
    - Mandibular nerve (CN V-3)
    • Mandibular nerve (CN V-3)
    • The two cavernous sinuses are large veins lying within the skull cavity, immediately behind each eye socket and on the other side of the pituitary gland.
    • These sinuses empty by the way of the superior petrosal sinuses into the transverse sinuses that continue as the sigmoid sinuses.
    • A cavernous sinus thrombosis is a blood clot within the cavernous sinus that causes cavernous sinus syndrome, causes edema of the eyelids and the conjunctivae of the eyes as well as paralysis of the cranial nerves that course through the sinus.
    • The orbital cavity is drained by superior and inferior ophthalmic veins. The superior ophthalmic vein communicates in front with the facial vein, the inferior with the inferior orbital fissure with the pterygoid venous plexus. Both pass backward and drain into the cavernous sinus.
  36. The veins of the brain are direct tributaries of the:

    - Internal jugular vein
    - Dural sinuses
    - Diploic veins
    - Emissary veins
    - Pterygoid venous plexus
    • Dural sinuses
    • Large, endothelium lined channels situated between the two layers of dura matter, the endosteal and meningeal layers.
    • Emissary veins: which are valveless, connect the dural venous sinuses with the veins of the scalp.
    • An emissary vein: found in the foramen ovale, is the means of communication between the pterygoid plexus and the cavernous sinus.
    • The internal jugular vein begins in the jugular foramen as a continuation of the sigmoid sinus, receives blood from the brain, face, and the neck.
    • Generally, the veins of the head and neck DO NOT have valves.
  37. Which vein provides the primary superficial drainage of the face?

    - Supratrochlear
    - Superficial temporal
    - Retromandibular
    - Facial
    Facial, valveless veins that provide the primary superficial drainage of the face. Tributaries include the deep facial vein, which drains the pterygoid venous plexus of the intratemporal fossa.
  38. Which of the following are considered to be primary resistance vessels?

    - Large arteries
    - Arterioles
    - Capillaries
    - Large veins
    • Arterioles
    • Veins: have thinner walls than arteries but have larger diameters because of the low blood pressures required for venous return to the heart.
    • Valves in the veins of the neck, arms and legs prevent venous backflow.
    • Arteries carry oxygenated blood and veins carry deoxygenated blood, with the exception of the pulmonary vessels and some fetal vessels.
  39. At the level of the inferior border of the 1st right costal cartilage, the branchiocephalic veins unite to form the:

    - External jugular vein
    - Internal jugular vein
    - Retromandibular vein
    - Superior vena cava
    • Superior vena cava
    • Three main veins of the neck
    • External jugular vein: begins near the angle of the mandible, descends and terminates in the subclavian vein. drains most of the scalp and side of the face. Internal jugular foramen in the posterior cranial fossa as the direct continuation of the sigmoid sinus, merges with the subclavian vein to form the brachiocephalic vein.
    • Anterior jugular vein, smallest of the jugular vein, arises near the hyoid from the suberficial mandibular veins.
    • Brachial, basilic and cephalic all drain the upper limbs into the axillary vein at the level of the border of the 1st rib to form the subclavian vein.
    • Femoral, internal and external iliac become the common iliac vein.
    • Inferior vena cava begins at L5
  40. At the medial angle of the eye, the facial vein communicates with the ______, which drains into the cavernous sinus.

    - Occipital vein
    - Posterior auricular vein
    - Superficial temporal vein
    - Superior ophthalmic vein
    • Superior ophthalmic vein , communicates with the facial vein in front. The inferior ophthalmic communicates through the inferior orbital fissue with the pterygoid venous plexus. BOTH pass backward through the superior orbital fissure and drain into the cavernous sinus.
    • Danger tirangle of the face, because of no valve and backflow, the dural sinuses may become infected through the deep facial vein and the superior ophthalmic vein.
  41. Which dural venous sinus lies in the convex attached border of the falx cerebri?

    - Cavernous sinus
    - Transverse sinus
    - Superior sagittal sinus
    - straight sinus
    • Superior sagittal sinus
    • The dural venous sinuses are endothelial-lines spaces between the periosteal and the meningeal layers of the dura. Large veins from the surface of the brain empty into these sinuses and most of the blood from the brain ultimately drains through them into the internal jugular veins.
  42. All of the following are characteristic features of veins EXCEPT:

    - Muscular tunica media
    - Thick tunica adventitia
    - Larger lumen
    - Valves
    - Vasa vasorum
    • Muscular tunica media, veins have a thin tunica media with few muscle fibers/
    • Arteries: Large (elastic), Small (muscular). Arteries have a very thick tunica media, that contains a lot of elastic fibers (some smooth muscle fibers)
    • Arterioles: small vessels, small lumen, thicker tunica media with a lot of smooth muscle fibers.
    • Capillaries: small vessels, walls have endothelial layer only.
    • Venules: Small vessels, walls have endothelium and very thin tunica adventitia, larger venules have a thicker tunica adventitia.
    • Veins: Thin tunica media with a few smooth muscle fibers, thick tunica adventitia with little elastic tissue. some contain valves and vasa vasorum.

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