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How many lobes does the thyroid gland have?
2 (right and left)
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What connects the right and left lobes of the thyroid gland?
isthmus
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What is the pyramidal lobe of the thyroid gland?
- seen in few people
- extends superiorly from isthmus near midline of neck
- remnant of embryonic thyroglossal duct
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Where is the thyroid gland located?
- anterior to trachea with isthmus lying just inferior to cricoid cartilage on second and third tracheal rings
- right and left lobes extend superiorly on each side of trachea to level of laryngeal cartilage and inferirly to sixth tracheal ring
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What are the important cell types of the thyroid gland?
follicular cells and C-cells
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The thyroid gland receives blood from which two primary sources?
- superior thyroid artery
- inferior thyroid artery
- thyroid ima artery
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What is the superior thyroid artery a branch of?
external carotid
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What is the inferior thyroid artery a branch of?
thyrocervical trunk
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When present, what is the thyroid ima artery a branch of?
subclavian artery
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What drains blood from thyoid gland?
internal jugular via superior and middle thyroid vv. and into brachiocephalic vein via inferior thyroid v.
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Which three veins drain the thyroid?
superior, middle, and inferir thyroid vv.
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What do the follicular cells of the thyroid gland produce?
thyroid hormone under control of anterior pituitary gland
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What is the function of thyroid hormone?
works in conjunction with growth hormone to stimulate basal cellular metabolism
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What do C cells of the thyroid gland produce?
homone calcitonin
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What does calcitonin do?
reduce blood calcium levels by stimulating osteoblasts to lay down new bone
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Typically, how many parathyroid glands are there?
4
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Where are the parahyroid glands?
posterior surface of thyroid gland and within the thyroid capsule
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Where might the lower parathyroids occassionally be found?
outside of pretracheal fascia (thyroid capsule) or in superior mediastinum
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What do the parathyroid glands secrete?
parathyroid hormone
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What is parathyroid hormone?
an antagonist to calcitonin
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What does parathyroid hormone do?
regulates release of calcium into bloodstream by stimulating bone degradation
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Where is the trachea?
begins at inferior border of cricoid cartilage and extends to level of the sternal angle where it branches into right and left primary bronchi
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How many cartilage rings are in the trachea?
15-20
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What are the shapes of the cartilage rings?
C-shaped
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Where is the open portion of the C of the cartilage rings on the trachea?
posterior surface of trachea
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What is the purpose of the open portion of the C of the cartilage rins on the trachea?
to allow for expansion of esophagus as a bolus of food passes throught the thoracic cavity
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What closes the posterior surface of the trachea?
fibroelastic tissue and smooth muscle
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What is the esophagus?
muscular tube that transports ingested material from oral cavity, through thoracic cavity, to stomach
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The superior 1/3 of the esophagus is under what kind of control?
voluntary
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The middle 1/3 of the esophagus is made up of what kind of muscle?
mixture of skeletal and smooth m.
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The inferior 1/3 of the esophagus is made of what kind of muscle?
smooth muscle controlled by ANS
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The smooth muscle of the inferior 1/3 of the esophagus is controlled by which system?
ANS
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Where is the hyoid bone?
located at level C3
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What is the shape of the hyoid bone?
U shaped
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How is the hyoid bone attached to the rest of the body?
suspended by muscle that onnect to the mandible, styloid processes, thyroid cartilage, manubrium, and scapula
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Does the hyoid bone articulate with other bones?
no
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What are the parts of the hyoid bone?
body, paired greater horns, paired lesser horns
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How many laryngeal cartilages are there?
9
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How is thyroid cartilage formed?
by two laminae that join anteriorly
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What is the laryngeal prominence?
- Adam's apple
- prominent bump of the anterior thyroid cartilage
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What is the chief cartilage of the larynx?
thyroid cartilage
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How does the thyroid cartilage attach to the hyoid bone?
via the thyrohyoid membrane
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What is the shape of the cricoid cartilage?
signet ring
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Which is bigger, the cricoid or thyroid cartilage?
thyroid cartilage
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Which is stronger, the cricoid or thyroid cartilage?
cricoid
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What is the most inferior of the laryngeal cartilages?
cricoid cartilage
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How does the cricoid cartilage connect to the thyroid cartilage?
via cricothyroid membrane
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Where can an emergency tracheotomy be done?
through the cricothyroid membrane
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How does the cricoid cartilage connect to the first tracheal ring?
via cricotracheal ligament
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What is the roof of the cervical triangles?
investing layer of deep cervical fascia
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What is the floor of the cervical triangles?
muscles coveredc by prevertebral layer of deep fascia
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Which nerve supplies the carotid sinus and the carotid body?
CN IX, X
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All veins in the cervical region drain to which vein?
internal jugular
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What happens when the pyramidal lobe becomes infected?
thyroglossal cyst
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How many arteries supply the anterior cervical triangle?
- 2 (sometimes 3)
- superior, inferior, and thyroid ima
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How many veins supply the anterior cervical triangle?
- 3
- superior, middle, and inferior
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What is the function of thyroid hormone?
- regulate (increase) basil metabolic rate
- important in body growth and crucia in normal development of nervous system
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What is the function of the parathyroid glands?
increase blood calcium
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Hyperthyroidism
skinny, jittery, nervous, dry skin
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Hypothyroidism
fat, sluggish, tired
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