Week 10 - Thorax, Nasal Cavity, Salivary Glands

no photos

What are the three main functions of the nasal cavity?

• Air conduction, conditioning, and filtration

• Sense of smell

• Regulation of immune response to inhaled antigens

What type of epithelium is olfactory epithelium?

Pseudostratified columnar epithelium

What are the 4 cell types in olfactory epithelium?

1. Olfactory receptor cells

2. Sustentacular cells

3. Brush cells

4. Basal cells

What structures are found in the lamina propria of the olfactory epithelium?

Connective tissue, olfactory nerve fibers, blood and lymphatic vessels, serous-mucous glands

What is the function of olfactory bipolar neurons?

Smell

Describe the structure of olfactory bipolar neurons.

• Apical dendrite with ~20 cilia (200μm long, limited motility)

• Basal axonal process leaves the cell to enter lamina propria and form CN I

What are sustentacular cells?

• Most common olfactory epithelial cell

• Provide metabolic and physical support

• Secrete odorant-binding proteins

• Columnar with apical nucleus and microvilli

What are basal cells in the olfactory epithelium?

• Small, round stem cells

• Differentiate into sustentacular cells

What are brush cells in olfactory epithelium?

• Columnar with large blunt microvilli

• Nucleus in basal position

• Synapse with CN V

• Function: Sensation

What type of epithelium is respiratory epithelium?

Ciliated pseudostratified columnar epithelium

What are the 4 cell types in respiratory epithelium?

1. Ciliated cells

2. Goblet cells

3. Brush cells

4. Basal cells

What supports the respiratory epithelium?

A thick basement membrane

What are the three major salivary glands and their secretion types?

• Parotid: Serous (contains lots of adipose tissue)

• Submandibular: Mixed (mostly serous in humans)

• Sublingual: Mixed (mostly mucous in humans)

What are the four types of minor salivary glands and their locations?

• Buccal (mouth)

• Labial (lip)

• Lingual (tongue)

• Palatine (back of mouth)

Describe the developmental origin of salivary glands.

• Develop from oral epithelium as solid cords that enter mesenchyme

• Cords become branched with bulbous ends

• Canalization occurs as inner cells degenerate → form ducts

• Bulbous ends become secretory acini

• Minor glands are found in submucosa

What is an acinus?

A blind sac composed of secretory cells (acinar cells)

What are the types of acinar cells?

• Serous cells (protein-secreting, spherical acini)

• Mucous cells (mucin-secreting, tubular acini)

• Mixed acini with serous demilunes (artefact of fixation)

What are serous demilunes?

Caps of serous cells on mucous acini; appear as half-moons due to fixation artefact

What structures surround salivary glands?

A connective tissue capsule with septa dividing the gland into lobules containing blood vessels and excretory ducts

What are myoepithelial cells?

Contractile cells between epithelial secretory cells and basal lamina; they move secretion toward the excretory duct

What are the types of salivary ducts and their epithelial linings?

• Intercalated ducts: Simple cuboidal epithelium

• Striated (intralobular) ducts: Columnar epithelium with basal infoldings

• Excretory ducts: Stratified or pseudostratified

What is the function of basal infoldings in striated ducts?

Resorption of electrolytes and fluid (morphological specialization)

What is saliva composed of?

Water, proteins, glycoproteins (enzymes and antibodies), electrolytes; it is highly bicarbonate

What are the functions of saliva?

Protective and digestive; lubricates, moistens, and initiates digestion

What supports the thorax?

The thoracic cage, made of horizontally positioned ribs that articulate with the vertically positioned sternum and thoracic vertebrae.

What fills the spaces between the ribs in the thorax?

Tissues that contribute to the thoracic wall.

What are the functions of the thorax?

• Protect vital thoracic and abdominal organs

• Act as a conduit for structures passing between head/neck and abdomen

• Provide mechanics for breathing (inspiration and expiration)

What are the 3 compartments of the thoracic cavity?

• Pulmonary cavities (lateral, contain lungs, lined with parietal pleura)

• Mediastinum (central, contains heart, vessels, trachea, etc.)

What are the divisions of the mediastinum?

• Superior mediastinum: Above sternal angle (transverse thoracic plane)

• Inferior mediastinum: Below sternal angle

  • Anterior

  • Middle

  • Posterior

What does the superior mediastinum contain?

Thymus, brachiocephalic veins, SVC, aortic arch + branches, trachea, oesophagus, thoracic duct, vagus & phrenic nerves.

What does the anterior inferior mediastinum contain?

Thymus (children), fat (adults), lymph nodes, pericardial-sternal ligaments.

What does the middle inferior mediastinum contain?

Heart, roots of great vessels, pericardium, phrenic nerves.

What does the posterior inferior mediastinum contain?

Bronchi, thoracic aorta, oesophagus, vagal and sympathetic trunks, thoracic duct, azygos and hemiazygos veins.

What are the components of the thoracic cage?

• Sternum

• 12 thoracic vertebrae and intervertebral discs

• 12 pairs of ribs + costal cartilages

What joints form at the sternum?

• Manubriosternal joint (TV4/5) = sternal angle

• Xiphisternal joint = inferior thoracic cavity limit, inferior heart border, diaphragm central tendon, superior liver limit

What are the articulations on the sternum?

• Manubrium: suprasternal notch, clavicular notches, synchondroses (1st ribs), half-notch (2nd ribs)

• Body: notches for ribs 2–7

• Xiphoid: half-notch for 7th ribs

What are key features of thoracic vertebrae?

• Heart-shaped body with costal facets

• Long downward-sloping spinous process

• Transverse processes with facets

• Vertebral canal, lamina, pedicle

What forms a zygapophysial joint?

Superior and inferior articular processes and facets.

What are the articulations for ribs on vertebrae?

• Rib head with vertebral body

• Rib tubercle with transverse process

What ribs are typical, and what features do they have?

Ribs 3–9; features: head, neck, tubercle, angle, body, costal groove

What ribs are atypical?

Ribs 1, 2, 10, 11, 12

What is the classification of ribs by attachment?

• True ribs (1–7): attach directly to sternum

• False ribs (8–10): attach via cartilage of rib above

• Floating ribs (11–12): don’t attach to sternum

What joints do ribs form?

• Sternocostal (sternum + cartilage)

• Costovertebral

• Costocorporeal (rib head + vertebral body)

• Costotransverse (tubercle + transverse process)

How are intercostal spaces labeled?

By the number of the rib immediately above the space.

What components fill the intercostal spaces?

Muscles, membranes, blood vessels, nerves (same number as rib above)

What are the intercostal muscles from superficial to deep?

• External intercostals

• Internal intercostals

• Innermost intercostals

What do intercostal muscles do?

Support the thoracic wall, assist in breathing, resist paradoxical motion, protect neurovascular bundle.

What is the VAN arrangement?

• Vein (superior)

• Artery (middle)

• Nerve (inferior)
  Located in the costal groove of each rib.

What bounds the thoracic inlet?

• Superior border of manubrium

• 1st ribs and cartilages

• TV1

What bounds the thoracic outlet?

• Xiphisternal joint

• Ribs 7–10 cartilages, 11th ribs ends, 12th ribs borders

• TV12

• Diaphragm

What passes through the thoracic inlet?

Brachiocephalic veins, subclavian veins and arteries, internal jugular veins, vagus and phrenic nerves, trachea, apex of lungs, oesophagus

What fills the thoracic outlet?

The diaphragm

What is the diaphragm?

A double-domed musculotendinous sheet, chief muscle of respiration, separating thorax and abdomen.

What happens during inspiration and expiration in the diaphragm?

• Inspiration: central tendon descends

• Expiration: tendon ascends

What spinal levels do structures pass through the diaphragm?

• IVC: TV8

• Oesophagus: TV10

• Aorta: TV12

What are the diaphragm attachments?

• Xiphoid process

• Costal margin (ribs 7–10)

• Ends of ribs 11–12

• Lumbar vertebrae:

  • Right crus (LV1–3)

  • Left crus (LV1–2)

What are the diaphragm ligaments?

• Lateral arcuate (quadratus lumborum)

• Medial arcuate (psoas major)

• Median arcuate (over aorta)

What are the diaphragm openings (inferior view)?

• Central tendon

• Caval opening (IVC)

• Oesophageal hiatus

• Aortic hiatus

• Crus (R & L)

• Arcuate ligaments