thyroid gland parathyroid trachea esophagus by prof. saeed abuel makarem
TRANSCRIPT
Thyroid Gland
Parathyroid Trachea Esophagus By Prof . Saeed Abuel Makarem
The deep cervical fascia of the neck is divided into 3 layers:
1- Investing layer.
2- Pretracheal layer.
3- Prevertebral layer.
Endocrine gland. Consists of right & left
lobes. The 2 lobes are
connected to each other by a narrow isthmus, which overlies the 2nd 3rd & 4th rings of the trache.
It is surrounded by a sheath derived from the pretracheal layer of cervical fascia.
Thyroid gland
Each lobe is pear shaped, with its apex reaches up to the oblique line of the thyroid cartilage.
Its base lies at the level of 4th or 5th tracheal rings.
Inside the pretracheal facial capsule, there is another capsule.
Each lobe is pear shaped, with its apex directed upward as for as the oblique line of the thyroid cartilage; its base is at the 4th or 5th tracheal ring.
The isthmus extends across the midline in front of the 2nd 3rd & 4th tracheal rings.
A small pyramidal lobe is often present which projects from the upper border of the isthmus usually to left of middle line.
Pyramidal lobe is connected to hyoid bone by a fibrous or muscular band called levator glandulae thyroideae.
This represents the fibrosed & obliterated thyroglossal duct.
Anterolaterally: Anterolaterally: Sternothyroid.Sternothyroid. Superior belly of Superior belly of
OmohyoidOmohyoid Sternohyoid.Sternohyoid. Sternomastoid.Sternomastoid. Posterolaterally:Posterolaterally: Carotid sheath & its Carotid sheath & its
contents.contents. MediallyMedially: : AboveAbove:: Larynx & pharynx .Larynx & pharynx . Below:Below: Trachea & esophagus.Trachea & esophagus. Recurrent laryngeal Recurrent laryngeal
nerve in betweennerve in between.. Cricothyroid muscle & Cricothyroid muscle &
external laryngeal external laryngeal nerve.nerve.
Relation of the isthmus
Anteriorly: sternothyroid,
sternohyoid, anterior jugular vein,
fascia & skin. Posteriorly: 2nd,3rd,&4th tracheal
rings. Terminal branches of
the 2 superior thyroid thyroid arteriesarteries which anastomosis along the upper border.
The rounded posterior border is related to the superior & inferior Parathyroid glands.
It is also related to the anastomosis between superior & inferior thyroid arteries.
:
Superior thyroid artery
From external carotid artery It descends to the upper pole of the lobe, with the external
laryngeal nerve. It runs along the upper border of
the isthmus to anastomosis with its fellow.
Thyroidea ima artery
If present, it arises from aortic arch or from brachiocephalic artery.
It ascends in front of trachea to reach isthmus.
Inferior thyroid artery
From thyrocervical trunk of 1st part of subclavian artery, ascends behind the gland to the level of cricoid cartilage.
Then it turns medially behind the carotid sheath.
The it reaches the posterior border of the gland & descends downwards.
The recurrent laryngeal nerve crosses either in front or behind the artery.
1- Superior thyroid vein internal jugular 2- Middle thyroid vein internal jugular3- Inferior thyroid vein left brachiocephalic
Veins of Thyroid Gland
Lymph Of the Thyroid Gland:
Deep cervical & paratracheal
Goiter
GOITER A non-neoplastic & non-inflammatory enlargement of the thyroid gland.
The thyroid glands develops high up close to foramen cecum of the developing tongue.
Then it descends along the thyroglossal duct to reach its final position by the 7th week.
Descent of the thyroid could be arrested at any point, or extends down to thorax.
Parathyroid glands Four small ovoid bodies,
about 6mm. Long. They lie within the facial
capsule of the gland. 2 superior parathyroid
has a constant position at the middle of posterior border of the gland.
2 inferior parathyroid usually at the level of the inferior pole.
They lie within the thyroid tissue or sometimes outside the facial capsule.
They are supplied by They are supplied by superior & inferior thyroid superior & inferior thyroid arteries.arteries.
Their veins are drained to Their veins are drained to superior, middle and superior, middle and inferior thyroid veinsinferior thyroid veins..
Lymph nodes:Lymph nodes: Deep cervical & Deep cervical &
paratracheal lymph nodes.paratracheal lymph nodes. Nerve supplyNerve supply:: Superior & middle cervical Superior & middle cervical
sympathetic ganglia.sympathetic ganglia.
10 to 15 cm long mobile tube.
Formed of cartilage & membrane.
Its diameter is about 2 cm in adult male.
It begins at lower border of cricoid cartilage (C 6).
It descends in the midline of the neck.
It ends at the level of the disc between T4 & T5.
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The trachea has a fibro -elastic wall which is supported by series of U-shaped bars of hyaline cartilage that keep the lumen patent.
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The posterior free ends of the cartilage are connected by smooth muscle, called the trachealis muscle.
Anteriorly: Skin, Superficial fascia,
investing cervical fascia
isthmus of thyroid gland,
Inferior thyroid veins jugular arch, thyroidea ima artery, left brachiocephalic
vein, sternothyroid &
sternohyoid
Posteriorly esophagus, recurrent laryngeal nerves (in between trachea and
esophagus) vertebral column. Laterally: Lobes of the thyroid gland
& carotid sheath. Blood supply: Inferior thyroid artery. Nerve : vagi, sympathetic trunk &
recurrent laryngeal Lymph: Pretracheal & Para
tracheal lymph nodes.
Muscular tube 25 cm or 10 inches long.
Extends from pharynx to stomach.
It begins at lower border of cricoid cartilage (C 6).
It begins in midline, but inclines to the left.
It descends in superior then posterior mediastinum of thorax.
Anteriorly trachea and recurrent
laryngeal nerves.
Posteriorly Prevertebral layer of
cervical fascia, longus coli muscle & vertebral column. Laterally: Lobe of thyroid gland, carotid sheath. Thoracic duct on left
side. BloodBlood: : Inferior thyroid artery. Lymph: deep cervical lymph nodes. Nerves: Recurrent
laryngeal and sympathetic trunk.