Abdominal Vascular System Week 1 Review

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Questions and Answers

What is the outermost layer of a blood vessel called?

Basement membrane

Tunica adventitia (correct)

Tunica intima

Tunica media

What are the tiny veins and arteries that supply the blood vessel itself called?

Vasa vasorum

The internal layer of the tunica intima is called __________.

Endothelium

Match the following abdominal arteries with their organs:

Common hepatic artery = Liver Splenic artery = Spleen Left gastric artery = Stomach and small intestines Superior mesenteric artery = Small intestine, cecum, colon Signup and view all the answers

The right renal artery is often seen inferior to the inferior vena cava.

False Signup and view all the answers

How many types of veins are mentioned in the content?

3 Signup and view all the answers

Name two deep veins of the upper extremity.

Subclavian vein, axillary vein Signup and view all the answers

There are __ veins for every one artery.

two Signup and view all the answers

Match the following arteries with their location in the body:

Subclavian artery = Upper extremity Brachial artery = Upper extremity Common iliac artery = Lower extremity External carotid artery = Head and neck Signup and view all the answers

Vertebral arteries pass through the thoracic vertebrae.

False Signup and view all the answers

What is the sonographic appearance of the appendix?

SAG = finger-like projection, TRV = bullseye Signup and view all the answers

Which veins lie posterior and lateral to the thyroid?

Both A and B Signup and view all the answers

The thyroid gland is located within the superior portion of the neck.

True Signup and view all the answers

The appendix typically appears as a _ _ _ _ _ _ _-like projection on a sagittal view.

finger Signup and view all the answers

Match the following thyroid hormones with their functions:

Triiodothyronin (T3) = Regulates metabolic rate Thyroxine (T4) = Regulates metabolic rate Calcitonin = Lowers blood calcium levels Thyroid-stimulating hormone (TSH) = Regulates T3 and T4 Signup and view all the answers

What is the primary function of the parathyroid hormone (PTH)?

Triggers bones to release calcium back into the bloodstream when levels are too low Signup and view all the answers

Study Notes

Abdominal Vasculature

3 layers of a blood vessel:
- Tunica adventitia: outermost layer with vasa vasorum and nerves
- Tunica media: middle layer with external elastic membrane, smooth muscle, and internal elastic membrane
- Tunica intima: innermost layer with internal elastic membrane, lamina propria, basement membrane, and endothelium

Abdominal Arteries

Abdominal aorta (AO):
- Located in retroperitoneal cavity, anterior and left of IVC and spine
- Originates from left ventricle of heart
- Posterior to diaphragm
- Bifurcates at umbilicus into right and left iliac arteries
- Tapers into a narrower diameter as it descends, normally ≤ 3 cm
Branches of AO arch (thoracic cavity):
- Right innominate artery/Brachiocephalic trunk
- Left common carotid artery (CCA)
- Left subclavian artery
Branches of abdominal AO:
- Celiac trunk: 1st branch of abdominal AO, originates from anterior AO, 1-3 cm below diaphragm
- Superior mesenteric artery: 2nd branch of abdominal AO, originates from anterior AO, 1-2 cm below celiac trunk
- Right and left renal arteries: branches of abdominal AO, supply kidneys respectively
- Gonadal arteries: branches of abdominal AO, supply reproductive organs
- Inferior mesenteric artery: last branch of abdominal AO before bifurcation into right and left iliac arteries

Celiac Trunk

3 branches:
- Common hepatic artery (CHA): right side of celiac trunk, borders superior surface of pancreas head
  - Branches: gastroduodenal artery, right gastric artery, proper hepatic artery (further divided into right and left hepatic arteries)
- Splenic artery (SA): left side of celiac trunk, borders superior surface of pancreas body and tail
  - Tortuous in nature, numerous branches
- Left gastric artery: limited visualization with ultrasound due to small size

Superior Mesenteric Artery

Originates from anterior AO, 1-2 cm below celiac trunk
Runs parallel to anterior AO and posterior to pancreas
Normally 6 mm in diameter
Doppler waveform depends on fasting state
Objective: supplies blood to small intestine, cecum, and ascending and transverse colon

Renal Arteries

Right and left renal arteries: branches of abdominal AO, supply kidneys respectively
Right renal artery is often seen superior to IVC
Left renal artery is more superior than right
Normally 4-5 mm in diameter
Branches into 4 or 5 smaller arteries prior to reaching hilum of kidney
Low resistance Doppler waveform

Gonadal Arteries

Difficult to visualize with ultrasound due to small size
Arise from anterior lateral aspect of AO, inferior to renal arteries, following psoas muscle

Inferior Mesenteric Artery

Last branch of abdominal AO before bifurcation into right and left iliac arteries
Originates from anterior lateral side of AO, 4 cm away from bifurcation
Limited visualization on ultrasound due to small size
Normally 3 mm in diameter
High resistance Doppler waveform
Objective: supplies blood to descending colon, sigmoid colon, and rectum

Abdominal Veins

Inferior vena cava (IVC):
- Located in retroperitoneal cavity, anterior to spine, posterior to intestines and caudate lobe of liver, and to right of AO
- Passes through diaphragm and terminates in right atrium of heart
- Formed by convergence of common iliac veins
Branches of abdominal IVC:
- Hepatic veins: 1st branches of IVC from heart
  - 3 branches: right, middle/intermediate, and left
  - Normally 4-7 mm in diameter
  - Pulsatile Doppler waveforms
- Renal veins: 2nd branches of IVC from heart
  - Right renal vein: shorter than left renal vein
  - Normally 4-6 mm in diameter
  - No pulsatility in Doppler waveforms
- Superior mesenteric vein (SMV): joins with splenic vein to form portal vein
  - Drains proximal portion of large intestine and portions of small intestine
- Splenic vein (SV): joins with SMV to form portal vein
  - Runs along posterior border of pancreas
- Gonadal veins: next branches of abdominal IVC after renal veins
  - Right gonadal vein: located lateral and inferior to right renal vein
  - Left gonadal vein: technically a branch of LRV, doesn’t drain directly into IVC

Portal Venous System

Main portal vein (MPV or PV): originates from junction of SMV and SV, posterior to pancreas and just to right of midline
Bifurcates at porta hepatis into right and left portal veins
Normally < 13 mm in diameter
Portal veins have hyperechoic borders, allowing distinction from hepatic veins### Bile Duct and Portal Vein
Right portal vein (RPV):
- Runs centrally and horizontally in the right lobe of the liver
- Bifurcates into anterior and posterior branches, dividing the right lobe into anterior and posterior segments
- Larger than the left portal vein
Left portal vein (LPV):
- Runs in the left lobe of the liver
- Branches divide the left lobe into medial and lateral segments
Sonographic appearance of the appendix:
- Sagittal view: finger-like projection
- Transverse view: bullseye

Thyroid and Neck

Anatomy of the thyroid:
- Consists of two lateral lobes and a connecting isthmus
- Lies within the inferior portion of the neck
- Anterior to the trachea
- Trachea is medial to both thyroid lobes
Muscles of the neck:
- Strap muscles: group of muscles in the neck, including sternohyoid, sternothyroid, omohyoid, and sternocleidomastoid
Dimensions of the thyroid:
- Length: 4-6 cm
- A/P: 2-3 cm
- Width: 1.5-2 cm
- Isthmus A/P: 2-6 mm (most narrow portion of the thyroid, always measured A/P)
Physiology of the thyroid:
- Regulates metabolism by synthesizing, storing, and secreting thyroid hormones (T3, T4, and calcitonin)
- TSH (thyroid-stimulating hormone) regulates T3 and T4
Sonographic appearance of the thyroid:
- Homogeneous with medium-level echoes
- Hyperechoic to surrounding muscles and vasculature
- Most to least echogenic: thyroid > muscles > blood vessels

Parathyroid

Location:
- Posterior to the thyroid gland
- Anterior to the longus colli muscle
- Superior parathyroid glands are more posterior and medial
- Inferior parathyroid glands are more anterior and may be embedded in the thyroid tissue
Dimensions:
- Length: 5-7 mm
- A/P: 1-2 mm
- Width: 3-4 mm
Physiology of the parathyroids:
- Maintains homeostasis of blood calcium by secreting parathyroid hormone
- PTH triggers bones to release calcium back into the bloodstream when levels are too low

Female Pelvis

Anatomy of the female pelvis:
- Located in the RT/LT iliac regions and the hypogastric region
- Linea terminalis: circular line that separates the true and false pelvis
- Pelvic girdle: the bones that comprise the pelvis, including sacrum, coccyx, and innominate bones
Muscles of the pelvis:
- False pelvis: iliopsoas, rectus abdominus, and iliaca
- True pelvis: obturator internus, piriformis, and pelvic diaphragm (including levator ani, pubococcygeus, and iliococcygeus)
Ligaments of the pelvis:
- Broad ligament: double folds of peritoneum, containing the fallopian tube, round ligament, ovarian ligament, vessels, and nerves of the uterus and ovaries
- Uterine ligaments: sits within the broad ligament
- Ovarian ligaments: part of the broad ligament
Blood supply of the female pelvis:
- Uterine blood vessels: uterine artery and branches
- Vaginal blood vessels: vaginal artery (branch of the uterine artery)
- Ovarian blood vessels: uterine artery and ovarian artery
Potential spaces of the female pelvis:
- Anterior cul-de-sac/Morison’s pouch/Vesicouterine pouch: located between the anterior uterus and bladder
- Posterior cul-de-sac/Pouch of Douglas/Rectouterine pouch: located between the uterus and rectum
- Space of Retzius/Prevesical space/Retropubic space: located between the anterior bladder wall and the pubic symphysis
Organs of the female pelvis:
- Vagina:
  - Extends from the external genitalia to the cervix of the uterus
  - Size: 7-10 cm
  - Fornices: pockets around the base of the cervix
  - 3 layers: mucosal lining, muscle wall, and adventitia
  - Sonographic appearance: isoechoic to the uterus with a central linear echogenic stripe
- Uterus:
  - A pear-shaped, muscular, hollow organ that nourishes the developing fetus during pregnancy
  - 3 layers: endometrium, myometrium, and serosa
  - 4 sections: fundus, body, isthmus, and cervix
  - Sonographic appearance: hyperechoic to the surrounding bowel
  - Dimensions: varies with age and parity
  - Positions: anteverted, anteflexed, retroverted, retroflexed, levoversio, and dextroversion
- Fallopian tubes:
  - Coiled muscular tubes that direct mature ovum from the ovaries to the uterus
  - Dimensions: length 7-12 cm, diameter 3 mm
  - 4 sections: interstitial, isthmus, ampulla, and infundibulum
  - Fimbriae: projections that direct ovum into the tube
- Ovaries:
  - A pair of almond-shaped organs that form ova
  - Dimensions: varies with age and parity
  - 2 layers: cortex and medulla
  - Location: lateral to the uterus, sometimes superiolateral to the uterus

Male Pelvis

Anatomy of the male pelvis:
- Scrotum: a pouch of skin continuous with the abdomen that supports the testes
- Testicles: a pair of organs where sperm is produced
- Location/Orientation:
  - Divided into sections called lobules which each contain 1-3 seminiferous tubules
  - Joined at the mediastinum to form the rete testis
- Vascularity:
  - RT gonadal vein branches directly from the IVC
  - LT gonadal vein branches from the LT renal vein
  - RT and LT gonadal arteries branch directly from the AO
- Dimensions:
  - Length: 3-5 cm
  - A/P measurement: 2-3 cm
  - Width: 2-3 cm
- Sonographic appearance: homogeneous, medium-level echoes
- Normal variants:
  - Appendix epididymis: an extension/flap coming off of the epididymis
  - Appendix testes: an accessory small piece of testicular tissue
Epididymis:
- An organ that lies along the posterolateral aspect of each testicle
- Divided into the head, body, and tail
- Ductus epididymis: the single convoluted tube that makes up the epididymis
- Size: 6-7 cm
- Turns into the vas Deferens, which turns into the ejaculatory duct
- Sonographic appearance: head is posterior and superior to the testicle, isoechoic/hyperechoic to the testicle

Vascularity

Lower extremity vasculature:
- Divided into 3 systems:
  - Aortoiliac (aka inflow): area from the iliac bifurcation to the inguinal ligament
  - Femoropopliteal (aka outflow): area from the inguinal ligament to the trifurcation of the popliteal artery
  - Tibioperoneal (aka runoff): area from the end of the popliteal artery to the ankle
- Arteries lie lateral to veins
- Order of lower extremity arteries: aorta, common iliac arteries, external iliac and internal iliac arteries, common femoral artery, deep femoral and superficial femoral arteries, popliteal artery, anterior tibial and posterior tibial arteries### Veins
There are three types of veins: deep veins, superficial veins, and perforating veins.
Deep veins include CIV, EIV, and IIV.
Superficial veins include CFV, GSV, FV, DFV, and are the longest veins.
Perforating veins connect the deep and superficial venous systems.
There are two veins for every one artery.
The order of lower extremity veins is: IVC, CIV, EIV, IIV, CFV, GSV, FV, DFV, POP, PV, ATV, and PTV.

Upper Extremity Vasculature

Arteries:
- The order of upper extremity arteries is: subclavian artery, axillary artery, brachial artery, ulnar artery, and radial artery.
Veins:
- Deep veins: the order of upper extremity deep veins is: subclavian vein, axillary vein, brachial veins, ulnar vein, and radial vein.
- Superficial veins: the order of upper extremity superficial veins is: axillary vein, cephalic vein, and basilic vein.

Cerebrovascularity

There are three main branches of the AO arch: brachiocephalic trunk/innominate artery, LT common carotid artery, and LT subclavian artery.
Brachiocephalic trunk/innominate artery branches into the RT common carotid artery and RT subclavian.
LT common carotid artery branches into LT external carotid and LT internal carotid.
Common carotid arteries:
- Located medial to the jugular veins and lateral to the thyroid.
- Internal carotids supply brain and eyes, while external carotids supply face, neck, and scalp.
- Internal carotids have low resistance waveforms and no visible branches, while external carotids have high resistance waveforms and branches.
Vertebral arteries:
- Pass through the cervical vertebrae to supply blood to the posterior aspect of the brain.
Circle of Willis:
- A collateral pathway in the brain that allows blood to flow to the brain if there is a blockage in one branch.

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Description

Review of the abdominal vascular system covering the 3 layers of a blood vessel, including tunica adventitia and tunica media. Learn about the structure and functions of blood vessels.