Thyroid gland, Pharynx & esophagus, & Larynx & Trachea Flashcards
cervical visceral layers
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Endocrine layer: thyroid and parathyroid
- Thyroid gland: secretes thyroid hormone (regulation of metabolism) and calcitonin ( Ca concentration in blood)
- Parathyroid gland: parathormone (PTH: Ca concentration in blood)
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Respiratory layer: larynx and trachea
- Conducts air to respiratory tract
- Directs food into alimentary tract
- Producing voice
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Alimentary layer: pharynx and esophagus
- Conducts air to respiratory tract
- Directs food into alimentary tract
- Involved in food propulsion (esophagus)
thyroid gland
Thyroid gland
Location: anterior portion of neck, deep to sternothyroid and sternohyoid muscles, at the level of C5 – T1 vertebrae
Parts
- Lobes (R & L): anterolateral to larynx and trachea
- Isthmus: unites lobes over trachea (anterior to 2-4 tracheal rings)
- Pyramidal lobe: projects superiorly towards thyroid cartilage (not always present)
- Thyroid capsule: fibrous tissue surrounding the gland
Arteries
- Superior thyroid a.: branch of ECA, supply superior portion of the gland
- Inferior thyroid a.: branch of subclavian a., supply inferior portion of gland
Veins
- Superior and middle thyroid vv.: tributary of IJV
- Inferior thyroid v.: tributary of brachiocephalic v.
parathyroid gland
Parathyroid glands
- Location: external to thyroid capsule, on the posterior surface of each lobe of the thyroid gland
- Superior parathyroid glands: lie ~ 1cm superior to point of entry of inferior thyroid a. into thyroid gland
- Inferior thyroid gland: lie ~ 1cm inferior to point of entry of inferior thyroid a. into the thyroid gland
larynx (respiratory layer)
Organ of voice production, and guard air passages during swallowing
Location: in anterior portion of neck, at the level of C3 – C6 vertebral bodies
Boundaries: superoposterior with laryngopharynx and inferiorly is continuous with trachea
thyroid cartilage of the larynx
Thyroid (1): largest laryngeal cartilage
- Laminae: plates that fuse anteriorly and form the laryngeal prominence (Adam’s apple)
- Superior and inferior horns
- Thyrohyoid membrane: attach thyroid cartilage superiorly to the hyoid bone
cricoid cartilage of the larynx
Cricoid (1): complete ring, narrower anteriorly than posteriorly. Lower border (at the level of C6) marks the inferior limit of the larynx
- Cricothyroid ligament: attaches cricoid and thyroid cartilages. The lateral cricothyroid ligament forms the conus elasticus and vocals folds
- Clinical relevance: cricothyrotomy is conducted by performing an incision through the skin and this membrane to create a patent airway
epiglottic cartilage of the larynx
Epiglottic (1): elastic cartilage, attached inferiorly to the junction of the laminae of the thyroid cartilage and with a free superior end
- Epiglottis: epiglottic cartilage covered with mucous membrane, located posterior to root of tongue and hyoid bone and anterior to laryngeal inlet (entry to the larynx from the laryngopharynx)
- Thyroepiglottic ligament: attaches epiglottic cartilage to laminae of thyroid cartilage
arytenoid cartilage of the larynx
Arytenoid (2): pyramidal cartilages that articulate with the superior border of the cricoid cartilage
- Apex: superior portion that bears the corniculate cartilage
- Vocal process: anterior portion that serves as the posterior attachment for the vocal ligament
- Vocal ligaments: extend from the junction of the laminae of thyroid cartilage anteriorly to the vocal process of the arytenoid cartilages posteriorly. Makes up the submucosal skeleton of the vocal folds and is the superior free margin of the conus elasticus
- Quadrangular membrane: sheet of connective tissue extending between the epiglottic and arytenoid cartilages
- Vestibular ligament: inferior free margin of the quadrangular membrane. Makes up the submucosal skeleton of the vestibular fold
- Ary-epiglottic ligament: superior free margin of the quadrangular membrane. Makes up the submucosal skeleton of the ary-epiglottic fold
corniculate cartilage of the larynx
Corniculate (2): connect to the apex of the arytenoid cartilages
cuneiform cartilage
Cuneiform (2): no directly attached to other cartilages
*laryngeal cavity
Laryngeal inlet
communicates posteriorly with the laryngopharynx
Vestibule
between laryngeal inlet and vestibular folds
Vestibular folds
on the lateral wall of larynx, at the lower end of vestibule. Inferior free margin of quadrangular membrane
Infraglottic cavity
between vocal folds and inferior border of cricoid cartilage. It’s continuous with trachea