Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Thyroid gland By Dr. Adel Sahib Al-Mayaly دعاء الصباح Blood supply • Thyroid is a vascular organ rich in blood supply. • Two main sources of arterial supply:• 1- External carotid artery;- sup. Thyroid artery. • 2- Subclavian artery;- inferior thyroid A. • 3- Thyroideae ima A. ;- brachiocephalic art. Blood supply Superior Thyroid Artery • the first branch from the anterior aspect of the external carotid. • It descends downward for a short distance it pierces the pretracheal fascia & divides into ant. & post. Branches. • The external laryngeal n. lies behind the art, & it leaves the art. just above the upper pole to supply cricothyroid muscle Inferior thyroid artery • from the thyrocervical trunk. • arches upwards and medially behind the carotid sheath arches upwards and medially behind the carotid sheath. • It divides outside the pretracheal fascia into • branches that pierce the fascia. • The recurrent laryngeal nerve has a variable relationship to the artery • Relation of RLN to IThA Venous Drainage • 1-Superior thyroid vein:• follows the superior thyroid artery and enters drains to the internal jugular vein. • 2- Middle thyroid vein:• Crosses anterior to the common carotid artery to drain into the internal jugular vein. • The inferior thyroid vein:• Drain into brachiocephalic vein. Parathyroid glands Overview • Parathyroid glands normally lie behind the lobes of the thyroid gland. • There are usually four glands two on each side. • Each weighs about 50 mg. • They are brownish-yellow, which helps to distinguish them from the deep red of the thyroid gland. • Superior Gland • It is the more constant in position. • it is usually within the thyroid’s pretracheal fascial capsule. • At the middle of the back of the thyroid lobe, level with the first tracheal ring and above the inferior thyroid artery. • • Inferior Gland • is less constant in position. • It is usually within the pretracheal fascial sheath behind the lower pole but it may. • be in the gland itself. Blood Supply • Both upper and lower parathyroid by an anastomosis between the superior and inferior arteries. • Their minute veins join thyroid veins. Lymph drainage • As for lymph drainage of the thyroid gland Cervical plexus Cervical plexus • It is formed by the ventral primary divisions of the first four cervical nerves. • Each nerve, except the first, divides into the superior branch and the inferior branch. • C1 joins the upper branch of C2 • the adjacent upper and lower branches of C2 and C3 fuse • Each nerve receives a gray ramus communicans from the superior cervical ganglion. Cervical plexus • The loops lie on the surfaces of the levator scapulae and the scalenus medius muscles • It is covered by the upper part of SCM muscle. • The plexus lies behind the prevertebral layer • of deep cervical fascia. • The plexus supplies the skin and the muscles of the head, the neck, and the shoulders. • Branches Cutaneous branches • 1- The lesser occipital nerve (C2), which supplies the back of the scalp and the auricle • 2- The great auricular nerve (C2 and 3), which supplies the skin over the angle of the mandible • 3- The transverse cervical nerve (C2 and 3), which supplies the skin over the front of the neck • 4-The supraclavicular nerves (C3 and 4). • The medial, and intermediate, and lateral branches • supply the skin over the shoulder region. Muscular (Deep) branches • 1- Communicating branch:- from C1 to the hypoglossal nerve. • It carries motor fibres to genniohyoid & thyrohyoid muscles & to remaining infrahyoid muscles. • 2- Muscular branches:- from all roots to prevertebral muscles. Cervical plexus • 3- proprioceptive branches:- from C2,3 to SCM & C3,4 to trapezius m. • 4- Descending cervicalis ( descending root of ansa). • 5- Phrenic nerve:- C3,4,5 • It runs vertically downward over scalenus anterior m. behind subclavian v. to enter mediastinum to supply diaphragm.