Thyroid Gland

Front 1

Thyroid has 2 lobes. What structure unite them?

Back 1

the isthmus.

Front 2

where is isthmus located?

Back 2

-anterior of trachea.

-2nd and 3rd level of tracheal cartilages.

-lies deep in the sternohyoid and sternothyroid muscles.

Front 3

Pyramidal lobe present in almost 40% of population.
what are the characteristics of pyramidal lobe?

Back 3

-ascend from isthmus (usually left) towards the hyoid bone.

-may be attached to hyoid bone by a fibrous band or muscular slip called: levator glandulae thyroidae

Front 4

what are the coverings of the thyroid gland?

Back 4

-surrounded by thin fibrous tissue.
-external to that, a false capsule formed by a sheath of pretracheal fascia; derived of deep cervical fascia.

Front 5

where does the false capsule of thyroid gland attached to?

Back 5

-arch of cricoid cartilage
-oblique line of thyroid cartilage.
-so it moves along during swallowing and speaking.

Front 6

what are the thyroid gland arterial blood supply and their origin?

Back 6

-superior thyroid artery. (from external carotid a)

-inferior thyroid artery.
(from thyrocervical trunk)

anastomose with each other, but little anastomosis across the median plane.

Front 7

where do the thyroid arteries lie?

Back 7

in between the capsule and pretracheal fascia.

Front 8

tell the route of thyroid arteries.

Back 8

-sup thy a: descend to the superior pole of the gland. run close to ext laryngeal nerve.
-inf thy a: runs superomedially to the carotid sheath > reach post aspect of gland > supply inf pole. closely related to the recurrent laryngeal nerve.

Front 9

what is thyrois ima artery?

Back 9

-small, unpaired artery.
-usually arise of the (any): >brachiocephalic trunk
>aorta
>right common carotid
>right subclavian
>internal thoracic a

-ascend on anterior surface of trachea.
-supply isthmus.

Front 10

what are the venous drainage of thyroid gland?

Back 10

superior pole: sup thyroid v
lateral parts: mid thyroid v
inferior pole: inf thyroid v

Front 11

where do the thyroid veins empty into?

Back 11

superior thyroid vein & middle thyroid vein: IJV

inferior tyroid vein: brachiocephalic vein

Front 12

what are the lymphatic drainage of the thyroid gland?

Back 12

-pretracheal lymph nodes.
-paratracheal lymph nodes.
-deep cervical nodes.

Front 13

what are the nerve supply for thyroid gland?

Back 13

postganglionics.
affect gland indirectly thru action on blood vessels.

sympathetic: sup,mid,inf cervical sympathetic ganglia.

parasympathetic: cardiac and laryngeal branch of vagus nerve.

Front 14

what is the structural unit of the thyroid gland?

Back 14

-thyroid follicle.
-spherical cyst-like compartment, various diameter.

Front 15

what is the composition of the folllicular epithelium?

Back 15

-a simple squamous,
-simple cuboidal,
or
-low columnar epithelium.

Front 16

what does the gland's lumen contain?

Back 16

pink-staining gel-like mass: called colloid (glycoprotein complex)

Front 17

what are the interfollicular connective tissue.

Back 17

-extensive network of capillaries.
-fibroblast.
-lymphocytes.

Front 18

what are the thyroid gland follicular epithelium?

Back 18

2 types:

-principal cell
-parafollicular cell

Front 19

what are the characteristics of the thyroid gland's principal cell?

Back 19

-shape and size depend on functional state of the gland.
-squamous: inactive
-low columnar: active
-slightly basophilic cytop.
-spherical nuclei (1/more)
-function:produce thyroid hormone

Front 20

what are the characteristics of the parafollicular cell of thyroid gland?

Back 20

-in periphery of principal cell
-within basal lamina
-pale staining
-larger than principal cell
-solitary/ small clusters.
-function: secrete calcitonin