Module 4 Flashcards
(149 cards)
1
Q
- Hypophysis cerebra
- Master of Endocrine Glands
- 13x8mm in size; 0.5gm in weight
- covered by the dura mater
- Protected by the Sphenoid bone
A
Pituitary gland
2
Q
Boundaries of Pituitary Gland
A
● Anterior: Sphenoid sinus
● Posterior: Dorsum sella, Basilar artery and Pons
● Superior: Diaphragma sellae, Optic chiasma
● Lateral: Cavernous sinus and its contents
(ICA, Abducens nerve)
3
Q
Two functional lobes of the Pituitary Gland
A
Anterior pituitary – glandular tissue
Posterior pituitary – nervous tissue
4
Q
- Anterior Pituitary gland
- Buccal/ glandular portion
- Derived from an upgrowth (Rathke’s pouch) from the roof of the primitive pharynx (Stomodeum)
- Stalk connecting to the lobe and roof of mouth disappears
- may persist as Craniopharyngeal Canal
A
Adenohypophysis
5
Q
- Nervous in origin
- Derived from the brain
- From the floor of the 3rd ventricle and forms the infundibulum
A
Neurohypophysis
6
Q
(Lobes of the Pituitary Gland)
- constitute 80% of the gland
- pars anterior (pars distalis) – largest subdivision
- pars intermedia
- pars tuberalis
A
Adenohypophysis (Anterior lobe)
7
Q
Pars Distalis
A
- Acidophils (alpha cells)
- Somatotropes - Somatotropin
- Lactotropes/Mammotropes – Prolactin/ luteotropic H/ lactogenic H - Basophils (beta cells)
- Thyrotropes – TSH
- Corticotropes – Adrenocorticotropic H (ACTH), POMC, lipotropins, endorphins - Delta Basophils
- Gonadotropes – FSH, LH, ICSH - Chromophobes
8
Q
- contains small masses of colloid material, and some finely granulated cells
- produces melanocyte stimulating hormone
- relatively avascular zone
A
pars intermedia
9
Q
- projection from pars anterior
- most vascular part of the gland
- no hormone
A
pars tuberalis
10
Q
(Lobes of the Pituitary Gland)
- No nerve cells
- Has numerous neuroglial cells and fibers and small collection of colloid materials
- Cell bodies are located in the hypothalamus
- supraoptic nuclei – vasopressin (pitresin, ADH)
- paraventricular nuclei – oxytocin (pitocin)
- Pars nervosa
A
Neurohypophysis (Posterior lobe)
11
Q
Artery (branches from the Internal Carotid Artery) of the Pituitary Gland
A
- Superior hypophyseal artery
- Supplies the infundibulum
- Forms the capillary that forms the hypothalamic-hypophyseal portal system - Inferior hypophyseal artery
- Supplies the posterior lobe
12
Q
Venous Blood supply of the Pituitary Gland
A
- cavernous sinus
- intercavernous sinus
13
Q
Dwarfism vs Gigantism vs Acromegaly
A
Dwarfism: hyposecretion of the growth hormone in children
Gigantism: hypersecretion of growth hormone in children
Acromegaly: hypersecretion of growth hormone in adult. Results in exaggerated features esp in facial bone.
14
Q
produced by anti insulin effects of excessive growth hormone
A
pituitary diabetes
15
Q
(Anterior Pituitary Hormone)
- Stimulates breast development and maintains milk production following childbirth
- Secreted in response to high Estrogen and Progesterone levels in pregnancy
- Control is from PRH and PIH from the Hypothalamus
- Function in males is unknown
A
Prolactin (PRL)
16
Q
(Anterior Pituitary Hormone)
- Stimulates the release of Corticosteroids from the Adrenal Cortex. Released in response to CRH
- Binds to melanocytes in the skin and increase skin pigmentation
A
Adrenocorticotropic hormone (ACTH)
17
Q
(Anterior Pituitary Hormone)
- Influences growth and activity of the thyroid
- Secreted in response to TRH from the Hypothalamus
- Causes the Thyroid to secrete T4 and T3
A
Thyroid-stimulating hormone (TSH)
18
Q
Regulate hormonal activity of the gonads
A
Gonadotropic hormones
19
Q
(Gonadotropic hormones)
- stimulates follicle development in ovaries and sperm development in testes
A
Follicle-stimulating hormone (FSH)
20
Q
(Gonadotropic hormones)
- triggers ovulation
- causes ruptured follicle to become the corpus luteum
- Stimulates testosterone production in males > Referred to as interstitial cell-stimulating hormone (ICSH)
A
Luteinizing hormone (LH)
21
Q
(Hormones of the Posterior Pituitary)
- Stimulates contractions of the uterus during labor
- Causes milk ejection
- Can be stimulated by infant suckling and physical and chemical stimuli at the end of pregnancy
A
Oxytocin
22
Q
(Hormones of the Posterior Pituitary)
- Inhibits urine production in response to increasing blood osmolarity
- In large amounts, causes vasoconstriction leading to increased blood pressure (vasopressin)
- Destruction of cells resulting in decrease __ secretion causes Diabetes Insipidus a medical condition with production of large volume of diluted urine
A
Antidiuretic hormone (ADH)
23
Q
- is a surgical procedure performed through the nose and sphenoid sinus to remove pituitary tumors.
- can be performed with a microscope, endoscope, or both
A
Endoscopic Transsphenoidal Approach
24
Q
Hormones released from the Hypothalamus
A
- Thyroid-stimulating hormone releasing hormone (TRH)
- Corticotropin-releasing hormone (CRH)
- Growth hormone releasing hormone (GHRH)
- Growth hormone inhibitory hormone (GHIH) - somatostatin
- Gonadotropin-releasing hormone (GnRH)
- Prolactin inhibitory factor (PIH)
25
- Also called Epiphysis, derived from the roof of Diencephalon
- Pinecone-shaped organ
- 100-180 grams
- Located between the superior colliculi
- Composed of pinealocyte/ chief cells (produce melatonin-Antigonadropic effect)
- Calcify during adult age
Pineal gland
26
Exocrine and Endocrine Function of Pancreas
exocrine portion - enzymes hydrolyzing proteins, fats, and carbohydrates.
Endocrine portion - pancreatic islets (islets of Langerhans)
- produces insulin and glucagon
27
- elongated structure that lies in epigastrium and left upper quadrant.
- soft and lobulated and situated on the posterior abdominal wall
- crosses the transpyloric plane
Pancreas
28
Pancreas divided into a
head, neck, body, and tail
29
Head and Uncinate process of the pancreas
Head - disc shaped and lies within concavity of duodenum
Uncinate process - part of head extends to the left behind the superior mesenteric vessels
30
- is the constricted portion of the pancreas
- in front of the beginning of the portal vein
- in front of origin of the superior mesenteric artery
neck of the pancreas
31
Body and Tail of the Pancreas
body runs upward and to the left across the
- somewhat triangular in cross section.
The tail passes forward in the splenicorenal ligament
- comes in contact with the hilum of the spleen
32
Relation of the Pancreas Anteriorly
From right to left: transverse colon, attachment of transverse mesocolon, lesser sac, and stomach
33
Relation of the Pancreas Posteriorly
:From right to left: bile duct, portal and splenic veins, inferior vena cava, aorta, origin of the superior mesenteric artery, left psoas muscle, left suprarenal gland, left kidney, and hilum of the spleen
34
(pancreatic duct)
- begins in the tail and runs the length of the gland
- opens into the second part of the duodenum with the bile duct on the major duodenal papilla
- Sometimes drains separately into the duodenum.
The main duct (Wirsung)
35
- drains the upper part of head
- opens into the duodenum above the main duct on minor duodenal papilla
- communicates frequently with the main duct.
accessory duct (Santorini)
36
Arteries that supply the pancreas
- splenic artery
| - superior and inferior pancreaticoduodenal arteries
37
Veins of the Pancreas
- corresponding veins drain into the portal system.
38
Lymph Drainage and Nerve Supply of the Pancreas
Lymph Drainage
- along the arteries
- drain into celiac and superior mesenteric lymph nodes.
Nerve Supply
- Sympathetic and parasympathetic (vagal) nerve fibers
39
Arterial Suppy of the Pancreas: Celiac
gastroduodenal artery >> superior pancreaticoduodenal artery >> anterior and posterior >> superior pancreaticoduodenal arteries.
40
- passes behind the neck, it gives off the inferior pancreaticoduodenal artery
- divides into the anterior and posterior inferior pancreaticoduodenal arteries.
Superior Mesenteric Artery
41
Arterial supply from the Splenic Artery
1. Dorsal Pancreatic artery,
2. Great Pancreatic artery
3. Caudal pancreatic artery,
42
Development of Pancreas
- from dorsal and ventral bud from the foregut.
Dorsal bud - originates above the ventral bud
- grows into the dorsal mesentery.
Ventral bud - arises in common with the hepatic bud
Rotation of stomach and duodenum + rapid growth of left side of the duodenum -> ventral bud's coming into contact with the dorsal bud, and fusion occurs
43
Development of Pancreas: Ducts
Fusion occurs between the ducts
Main pancreatic duct - derived from entire ventral pancreatic duct and distal part of dorsal pancreatic duct.
Accessory duct - proximal part of the dorsal pancreatic duct
44
- arise as small buds from the developing ducts.
| - form isolated groups of cells that secrete insulin and glucagon at about the fifth month.
pancreatic islets
45
- form a common dilatation, the hepatopancreatic ampulla (ampulla of Vater)
- pass obliquely through the wall of the second part of the duodenum
- open on the summit of the major duodenal papilla, which is surrounded by the sphincter of Oddi
- sometimes open separately on the summit of the duodenal papilla.
bile duct and the main pancreatic duct
46
- ventral pancreatic bud becomes fixed
- when the stomach and duodenum rotate -> ventral bud is pulled around the right side of the duodenum to fuse with the dorsal bud of the pancreas ->encircling the duodenum
- may cause obstruction of the duodenum
Anular Pancreas
47
- may be found in the submucosa of the stomach, duodenum, small intestine (including Meckel's diverticulum), and gallbladder, and in the spleen.
- may protrude into the lumen of the gut and be responsible for causing intussusception.
Ectopic Pancreas
48
- caused by an abnormality in the secretion of mucus
- mucus produced is excessively viscid and obstructs the pancreatic duct which leads to pancreatitis with subsequent fibrosis
- also involves the lungs, kidneys, and liver.
Congenital Fibrocystic Disease
49
- consists of 2 lobes connected by isthmus.
| - surrounded by sheath derived from pretracheal layer of deep fascia.
thyroid gland
50
- attaches thyroid gland to larynx and trachea.
Ligament of Berry
51
(thyroid gland)
- muscular band connects the pyramidal lobe to the hyoid bone
levator glandulae thyroideae
52
(thyroid gland)
- projects upward from isthmus, to the left
pyramidal lobe
53
Relations to the Lobe: Anterolateral and Posterolateral (Thyroid)
Anterolaterally: sternothyroid, superior belly of the omohyoid, the sternohyoid, anterior border of sternocleidomastoid
Posterolaterally: carotid sheath (common carotid artery, internal jugular vein, vagus nerve
54
Relations to the Lobe: Medially and Posteriorly (Thyroid)
Medially: larynx, trachea, pharynx, esophagus. Cricothyroid and external laryngeal nerve. recurrent laryngeal nerve
Posteriorly: superior and inferior parathyroid glands
55
Relation to the Isthmus: Anteriorly and Posteriorly
Anteriorly: sternothyroids, sternohyoids, anterior jugular veins, fascia, and skin
Posteriorly: second, third, and fourth rings of the trachea
56
Blood Supply of the Thyroid gland
arteries anastomose profusely with one another over surface of the gland.
1. superior thyroid artery
2. inferior thyroid artery
3. thyroidea ima - arise from brachiocephalic artery or arch of the aorta
57
- a branch of the external carotid artery
| - accompanied by the external laryngeal nerve
superior thyroid artery
58
- a branch of the thyrocervical trunk
| - recurrent laryngeal nerve crosses either in front of or behind the artery
inferior thyroid artery
59
- arise from brachiocephalic artery or arch of the aorta
thyroidea ima
60
Thyroid Gland: Vein
1. superior thyroid vein - drains into the internal jugular vein
2. middle thyroid vein - drains into the internal jugular vein
3. inferior thyroid vein - anastomose with one another from both sides; drain into the left brachiocephalic vein.
61
Thyroid Gland: Lymph Drainage
- drains mainly laterally into the deep cervical lymph nodes.
- A few lymph vessels descend to the paratracheal nodes.
- Lymphatics is located in the level VI (Central compartment) and Level VII (Suprasternal compartment)
62
Nerve supply of the Thyroid Gland
Superior, middle, and inferior cervical sympathetic ganglia
63
Function of Thyroid Gland
1. Secrete Thyroid hormones
2. Thyroid hormones: thyroxine and triiodothyronine
- increase the metabolic activity of most cells in the body.
3. Parafollicular cells - produce Thyrocalcitonin
- Lowers the level of blood calcium
64
Swellings of the Thyroid Gland and Movement on Swallowing
- Any pathologic neck swelling that is part of the thyroid gland will move upward when the patient is asked to swallow.
65
The Thyroid Gland and the Airway
- Exerts pressure on the trachea in patients with pathologic enlargement of the thyroid.
66
- Sternothyroid muscles - binds down the thyroid gland to the larynx (limits upward expansion of the gland)
- Not uncommon that enlarged thyroid gland to extend downward behind the sternum.
- compress the trachea
- can cause severe venous compression
Retrosternal Goiter
67
Superior thyroid artery is related to the external laryngeal nerve, which supplies the cricothyroid muscle. Damage result to __
inability to tense the vocal fold
68
Inferior thyroid artery is related to the recurrent laryngeal nerve which supplies the intrinsic laryngeal muscles. Damage result to __
hoarseness
69
Thyroidectomy and the Parathyroid Glands
- In Total Thyroidectomy, all the parathyroid may be inadvertently removed -> cause hypocalcemia
- In partial thyroidectomy, posterior part of thyroid gland is undisturbed ->parathyroid glands spared
- Development of inferior parathyroid glands is closely associated with the thymus ->surgeon may find inferior parathyroid glands in superior mediastinum (because of pulling down into the thorax by the thymus)
70
Development of the Thyroid Gland
- begins to develop during the third week
- between the tuberculum impar and the copula
- grows inferiorly into the underlying mesenchyme and is called the thyroglossal duct
- distal end becomes bilobed and expand to form the thyroid gland.
71
Development of the Thyroid Gland 2
- thyroid gland migrates passes the body of the hyoid bone.
- seventh week, it reaches its final position
- origin of the thyroglossal duct on the tongue remains as a pit called the foramen cecum
- By third month - follicles are formed.
- Ultimobranchial bodies (5th pharyngeal pouch) and neural crest cells incorporated into the thyroid "parafollicular cells”
72
- Failure of development of the thyroid gland
| - most common cause of cretinism
Agenesis of the Thyroid
73
(Incomplete Descent of the Thyroid)
- most common form of incomplete descent - mass of tissue found just beneath the foramen cecum
- may obstruct swallowing in the infant
Lingual thyroid
74
- found in the thorax in relation to trachea, bronchi, or esophagus.
- displaced during formation of laryngotracheal tube
Ectopic Thyroid Tissue
75
- condition appear in childhood, in adolescence, or in young adults
Persistent Thyroglossal Duct
76
- may occur at any point along the thyroglossal tract
- most commonly midline below the hyoid bone.
- persistence of a small amount of epithelium that continues to secrete mucus
- prone to infection
- Tx: Sistrunk procedure.
Thyroglossal Cyst
77
- thyroglossal cyst ruptures spontaneously, producing a sinus - result of an infection of a cyst.
Thyroglossal Sinus (Fistula)
78
- ovoid bodies 6 mm long in their greatest diameter.
- four in number
- closely related to the posterior border of the thyroid gland, lying within its fascial capsule
Parathyroid Gland
79
- more constant in position
| - lie at middle of posterior border of thyroid gland
superior parathyroid glands
80
- lie close to the inferior poles of the thyroid gland.
- may lie within or outside the fascial sheath
- may be found caudal to thyroid gland, associated with inferior thyroid veins
- may reside in the superior mediastinum
inferior parathyroid glands
81
Parathyroid Gland: Artery and Vein
arterial supply from the superior and inferior thyroid arteries.
Venous drainage is the superior, middle, and inferior thyroid veins
82
Parathyroid Gland: Lymph Drainage and Nerve Supply
Lymph drainage to Deep cervical and paratracheal lymph nodes
Nerve Supply is superior or middle cervical sympathetic ganglia
83
- stimulates osteoclastic activity in bones
- mobilize bone calcium and increasing calcium levels in blood.
- stimulates absorption of dietary calcium from SI
- stimulate reabsorption of calcium in the PCT of kidney
- diminishes reabsorption of phosphate in PCT
- secretion controlled by calcium levels in the blood.
Chief cells produce parathyroid hormone
84
Development of the Parathyroid Glands
1. Inferior parathyroid glands (parathyroid III)
- result of proliferation in the 3rd pharyngeal pouch
* thymic diverticulum pulls the inferior parathyroid
2. Superior parathyroid glands (parathyroid IV)
- proliferation in the fourth pharyngeal pouch
- final position on posterior aspect of lateral lobe
85
Embryology Notes: Parathyroid Gland
In the earliest stage - consists of a solid mass of clear cells, the chief cells.
In late childhood, acidophilic cells, the oxyphil cells, appear.
- oxyphil cells - are thought to be nonfunctioning chief cells.
86
- Agenesis ->idiopathic hypoparathyroidism.
Absence and Hypoplasia of the Parathyroid Glands
87
- close relationship between parathyroid III and thymus
- parathyroid in superior mediastinum of the thorax
- variable position of the inferior parathyroid gland
Ectopic Parathyroid Glands
88
- Yellowish in color
- Weighs 4 gm each
- Retroperitoneal organ; lies on the upper pole of kidney
- Surrounded by Gerota’s fascia but separated from the kidney by Perirenal fat
Adrenal Gland
89
Adrenal Cortex is __ in origin
mesodermal
90
Embryology: Adrenal Cortex
- Week 4 – 6 : start from coelomic mesoderm adjacent to
urogenital ridge
- Week 8 : differentiate into thin definite outer cortex and thick inner fetal cortex
- Fetal cortex produce steroid during gestation and involutes at birth
- Definite cortex develop into functional adrenal cortex
91
Embryology: Adenal Medulla
- Medulla derived from neural crest cells
- Develop with sympathetic nervous system
- Week 5 : neural crest cell migrate to Para-aortic and Para-vertebral region towards medial aspect of adrenal cortex
92
(embryology)
| Extra adrenal chromaffin cells located to the left of aortic bifurcation near the __
origin of IMA
93
Parts of the Adrenal Gland
CORTEX - Outer bright yellowish, Inner reddish brown
1. Mineral corticoids- Concern with fluid and electrolyte balance
2. Glucocorticoids - Concern with metabolism of carbohydrates, fats and proteins
3. Sex Hormones - Plays a role in the prepubertal development of the sex organs
MEDULLA - Thin and gray in color
Catecholamines- Autonomic nervous system
Epinephrine, Norepinephrine
94
Parts of the Adrenal Cortex
1. Zona glomerulosa – thin outer portion; Present at birth
- Aldosterone, Deoxycorticosterone
2. Zona fasciculata – thick middle zone; Present at birth
- Cortisone, Cortisol
3. Zona reticularis – inner zone; Develop during first year of life
- Testosterone, Estrogen, Progesterone
95
- primary adrenal insufficiency that results in hyposecretion of glucocorticoids. Clinical manifestations include lethargy, weight loss and hypoglycemia, which leads to muscular weakness
Addison’s disease
96
hypersecretion of glucocorticoids, especially cortisol and cortisone. Clinical manifestations include moon face, buffalo hump on the back and pendulous abdomen
Cushing’syndrome
97
tumor of the chromaffin cells of the adrenal medulla, causes hypersecretion of the medullary hormones
Pheochromocytoma
98
- Pyramidal in shape
- Behind the right lobe of liver and IVC
- Rest posteriorly in the diaphragm
Right Suprarenal gland
99
- Crescentic in shape
- Rest posteriorly in the diaphragm
- Behind the pancreas, lesser sac and stomach
Left Suprarenal gland
100
Arterial Blood supply of the Adrenal Gland
- Suprarenal branch of inferior phrenic artery
- Suprarenal branch of Aorta
- Suprarenal branch of Renal artery
101
Adrenal Gland: Vein
Adrenal vein
- Right drains to inferior vena cava
- Left drains to left renal vein
102
Adrenal Gland: Lymph Drainage and Nerve Supply
Lymph drainage: Lateral aortic nodes
Nerve supply
Preganglionic symphatetic fibers
Majority ends in the medulla
103
- findings are non specific
| - May be helpful in detecting mass in adrenal area Calcification in adrenal
Plain Abdominal X-ray
104
Ultrasound: Adult vs Newborn (Adrenal)
Adult appearance
- Entirely hypo echoic
- Concave with straight margin
Newborn
- Cortex hypoechoic, Medulla hyper echoic
- Cortex>>medulla thickness
- Convex border
105
- Investigation of first choice in infant , children and pregnant women
- Indication: adrenal masses ( larger than 2 cm)
Ultrasound
106
- On precontrast scan adrenal have soft tissue density similar to that of liver
- Normal adrenal appear inverted V or Y shape within retroperitoneal fat
- Consist of body , medial limb and lateral limb
CT scan
107
Indication of CT scan
1. masses (adenoma and cancer)
2. Cyst
3. abscess
4. metastasis
108
- Equally effective as CT in imaging adrenal disorder
MRI
109
- Selective injection of contrast into the adrenal vein with an angiographic catheter
- Indication
* For localization of hormone active tumor
* For adrenal hyperplasia and adrenal adenoma
* Cushing’s diseases
Adrenal venogram
110
- Procedure in which contrast is injected into adrenal arteries to detect any vascular pathology
- Indication
* Adrenal tumor
* Adrenal hyperplasia
* CONN syndrome
Arteriography
111
Usual role of __ is to clarify inconclusive result of imaging
Scintigraphy
112
Indication of Scintigraphy
1. Functional status of adrenal nodule
2. Assess contralateral adrenal function
3. Detect functional metastasis
4. Detect recurrence after surgery
5. Detect ectopic site of hormone production
113
Adrenocortical imaging agent vs sympathoadrenal imaging agent
Adrenocortical imaging agent
NP-59 ( 6-B-iodomethyl-19-norcholesterol )
Selenium-75 6-B-selenomethylnorcholesterol
Sympathoadrenal imaging agent
MIBG ( metaiodobenzylguanidine )
114
Indication for MIBG
Pheochromocytoma
| Neuroblastoma, carcinoid, adrenal metastasis
115
Indication for NP-59
Adrenocortical carcinoma
Adenoma
Adrenal hyperplasia
116
- Shape: oval
- AP diameter: 8 mm
- Transverse diameter: 12 mm
- Weight: 0.5 g
- Master gland of the endocrine system
- Lies in the hypophyseal fossa (sella turcica)
- Fossa is roofed by diaphragma sell
- Stalk of the hypophysis cerebri pierces the diaphragm sellae and is attached above to the floor of the third ventricle
PITUITARY GLAND
117
Pars Nervosa connected to hypothalamus by Median eminence. If it is >1.5cm in any dimension, suspect a small lobule. If 2 cm suspect some __.
adenoma
118
Pituitary Gland: Relations
Superior
- Diaphragma selle
- Optic chiasma
- Tuber cinereum
- Infundibular recess of 3rd ventricle
Inferior
- Sphenoidal air sinuses
- Hypophyseal fossa and irregular venous channels between the 2 layers of dura covering it
On each side
- Cavernous sinus with its contents
119
It (pituitary gland) rests in hypophyseal fossa of Sphenoid Bone, surrounded by Sella Turcica and above it crossing of the Optic nerves also known as Optic Chiasm. So if there’s any pituitary lesions that will compress the optic chiasm you will have unique symptoms of __
Bitemporal Hemianopsia
120
Pituitary Gland: Subdivision
1. Adenohypophysis
Anterior lobe
Intermediate lobe
Tuberal lobe
2. Neurohypophysis
Posterior lobe
Infundibular stem
Median eminence of the tuber cinerum
121
Pituitary Gland: BLOOD SUPPLY AND VENOUS DRAINAGE
BS: Branches of Internal carotid artery (ICA)
VD: Short veins emerge on the surface of the gland and drain into the neighboring venous sinuses
122
Functions of the Pituitary Gland
1. Anterior Pituitary Gland / Adenohypophysis
- Regulates stress, growth, reproduction, and lactation
- Secretes ACTH, FSH, LH, GH, PRL, and TSH
2. Intermediate Lobe
- Synthesizes and secretes Melanocyte-stimulating hormone (MSH)
3. Posterior Pituitary Gland / Neurohypophysis
- Secretes oxytocin and ADH
123
RADIOIMAGING OF PITUITARY GLAND
- Not visualized on Plain X-ray of the skull
- Visualized on:
o CT Scan of brain
o MRI of brain
o PET Scan of brain
124
Radioimaging: Notes
- In normal conditions, it is not visualized in radiographs unless calcified
- In child, it is not usually calcified. It is found at the base of the skull that is covered with lots of bone so it’s hard to visualize.
- For adults, we have thick cranium so it’s even harder.
- In CT Scan, it can cause streaks, because of the difference in density of Pituitary which is a soft tissue, so it’s better to see it on MRI.
- On PET Scan, it’s fuzzy on Nuclear Imaging Studies.
125
- 2 lobes joined by the isthmus
- Lies against eh C5-T1 vertebrae clasping the upper part of
trachea
- Each lobe extends from the middle of the thyroid cartilage
to the 4th/5th tracheal ring
- Isthmus extends from 2nd – 3rd tracheal rings
- Lobes measurement: 5 cm x 2.5 cm x 2.5 cm
- Isthmus measurement: 1.2 cm x 1.2 cm
- Large in females than in males
- Increases in size during menstruation and pregnancy
THYROID GLAND
126
Thyroid Gland: Notes
Thyroid gland at the anterior part of the neck is surrounded by 2 muscles: STERNOTHYROID and STERNOHYOID with 2 lobes connected by ISTHMUS
Yung measurement para sa lobes and isthmus ay pang Caucasian. Generally for Asians or Filipinos the thickness of lobes, it is not more than 2cm. If it’s more than 2cm it’s a little bit enlarged.
For the length it’s usually 5 or 6cm. Kahit nga 6cm (length) at 1.5cm (width) nakakakaba na kasi pwedeng Hyperplasia.
127
- Peripheral condensation of connective tissue of the gland
- A dense capillary plexus is present deep to the true
capsule
- Because of the rich capillary plexus of the Thyroid, in
surgical operations it will be bloody
True capsule
128
- Derived from pretracheal layers of deep cervical fascia
- Forms the suspensory ligament of Berry, which
connects the lobe to the cricoid cartilage
False capsule
129
Functions of the Thyroid Gland
- Regulates basal metabolic rate (BMR)
- Stimulates somatic and psychic growth
- Plays important role in calcium metabolism
130
Thyroid Gland: RELATIONS
```
- Lobes are conical in shape and have:
o Apex – directed upwards
o Base
o 3 surfaces: Lateral, medial, and posterolateral
o 2 borders: Anterior, posterior
```
- At the level of 4th or 5th tracheal ring
131
Thyroid Gland: Lateral Surface
- Convex
- Covered by:
o Sternothyroid
o Sternohyoid
o Superior belly of omohyoid
o Anterior border of SCM
132
Thyroid Gland: Medial Surface
2 tubes: Trachea, esophagus
2 muscles: Inferior constrictor; Cricothyroid
2 nerves: External laryngeal nerve; Recurrent laryngeal nerve
133
Thyroid Gland: Posterolateral Surface
- Carotid sheath
| - Overlaps Common carotid artery
134
Thyroid Gland: Anterior Border
- Thin
| - Anterior branch of Superior thyroid artery
135
Thyroid Gland: Posterior Border
- Thick
- Inferior thyroid artery
- Anastomosis between Superior and inferior thyroid arteries
- Parathyroid gland
- Thoracic duct (left side)
136
- Connects the lower parts of the lobes
- 2 surfaces: Anterior and posterior
- 2 borders: Superior and inferior
Isthmus
137
2 surfaces: Anterior and posterior (Isthmus)
```
o Anterior surface is covered by:
Sternothyroid
Sternohyoid
Anterior jugular veins
Fascia and skin
```
o Posterior surface is related to: 2nd and 3rd tracheal rings
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2 borders: Superior and inferior (Isthmus)
o Superior border anastomosis between right and left
Superior thyroid arteries
o Inferior thyroid veins leave the gland at the inferior
border
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Thyroid Gland: BLOOD SUPPLY AND VENOUS DRAINAGE
BS:
o Superior thyroid artery – from External carotid artery
o Inferior thyroid artery – from Thyrocervical trunk
VD:
o Superior thyroid vein
o Inferior thyroid vein
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RADIOIMAGING OF THYROID GLAND
- Not visualized on Plain X-ray unless calcified
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Visualized on:
o Ultrasound
o CT Scan
o MRI
o Nuclear Medicine study (aka Thyroid scan
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Thyroid Gland
- Thyroid gland can be only seen in radiographs if it’s enlarged with the following signs: compress the trachea but can’t fully block it and deviate it, for the lobes one can be bigger than the other side, for the lesions thyroid lobules will tend to populate in asymmetric path and additional soft tissue density because of increased mass
- Can visualize in ultrasound because of superficial location
142
Instances where Ultrasound is preferred
Fetal Exam (Pregnancy), Gallbladder, Ovaries and prostate imaging are other examples where Ultrasound is best used.
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- 2 pairs: Superior and inferior
- Lie on the posterior border of thyroid gland within the thyroid capsule
- Shape: Oval or lentiform
- Measurement: 6 x 4 x 2 mm
- Weight: 50 mg
- Anastomotic artery between superior and inferior thyroid
artery is a good marker because they lie close to it
- Superior thyroid artery is more consistent in location near the middle of the posterior border of the thyroid lobe
PARATHYROID GLAND
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Parathyroid Gland: BLOOD SUPPLY AND VENOUS DRAINAGE
BS:
o Inferior thyroid artery
o Anastomotic artery between superior and inferior thyroid
arteries
VD: Thyroid veins
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RADIOIMAGING OF PARATHYROID GLAND
- Not visualized on normal studies
- Seen mostly when there is adenoma
- Sometimes may be ectopic in location
- Best modality to find Parathyroid is through ultrasound
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- Nuclear imaging is similar to Thyroid scan except in thyroid scan the optics flood the entire thyroid gland and you need to wait for a day to see the small part of the parathyroid.
* Delayed image shows a retention of the radioactive material at the inferior pole of the left thyroid – parathyroid adenoma
Parathyroid Scan
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- A pair of glands
- Lie in the epigastrium at the upper pole of the kidneys
- In front of crus of diaphragm
- Opposite the vertebral end of the 11th intercostal space and 12th rib
- Right adrenal gland: Triangular / pyramidal
- Left adrenal gland: Semilunar
- Measurement: 50 mm in height, 30 mm in breadth, and 10
mm in thickness
- 1/3 the size of kidneys in children and 1/30th the size in adults
- Weight: 5 g
Adrenal Gland
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Adrenal Gland: BLOOD SUPPLY AND VENOUS DRAINAGE
BS:
o Superior adrenal artery – from Inferior phrenic artery
o Middle adrenal artery – from Abdominal aorta
o Inferior adrenal artery – from Renal artery
VD:
o Each gland drained by one vein
o Right adrenal vein – drains into IVC
o Left adrenal vein – drains into Left renal vein
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RADIOIMAGING OF ADRENAL GLANDS
- Not seen on plain X-ray unless calcifications are present
- Visualized by:
o CT Scan
o MRI
o Ultrasonography – seen better in children than in adults
- Located in the perirenal space near the upper pole of each kidney
- They may be shaped like the letters H, L, Y, T, or V
- They are less than 4 cm in length and less than 1.0 cm in
thickness
