ANAT 3001 blood vessels

walls of blood vessels

3 layers common to arteries and veins

• tunica intima 

• tunica media

• tunica externa

tunica intima

inner layer

• simple squamous epithelium (endothelium)

tunica media

middle layer

• contains smooth muscle to control blood flow

• thicker in arteries than veins

tunica externa (“adventitia”)

outer layer

• connective tissue anchors vessels to other structures

vasoconstriction

• contract smooth muscle in tunica media

• decrease blood flow through lumen

vasodilation

• relax smooth muscle in tunica media

• increases blood flow through lumen

arteries

elastic arteries, muscular arteries, arterioles

• carry blood away from heart (oxygenated and deoxygenated)

elastic arteries

• largest (2.5-1cm)

• closest to heart, conduct blood away from heart

• elastic fibers allow expansion when blood is pumped

• ex. aorta, pulmonary, brachiocephalic, common carotid, subclavian, and common iliac arteries

• branch into muscular arteries

muscular arteries

• medium sized arteries distribute blood to organs and tissues

• less elastic tissue and relatively thicker tunica media

• control flow of blood with smooth muscle

• branch into arterioles

arterioles

• smallest arteries

• smallest arterioles have only endothelium and single layer of smooth muscle

• branch into capillaries

capillaries

• smallest blood vessels

  • only one RBC can pass through a capillary at a time

• form a bed or branching vessels for exchange of gases and nutrients

• composed of tunica intima (endothelium and basement membrane)

veins

venules, medium veins, large veins

• carry blood to the heart (oxygenated and deoxygenated)

• superficial veins travel in subcutaneous tissue

• deep veins travel between skeletal muscles

• open multiple veins per artery

venules

• smallest of veins, run with arterioles

• have thin layer of smooth muscle, little ability to vasoconstrict

• merge to form larger venules, then veins

medium veins

• ~1 cm in diameter

• have all 3 tunics, externa is thickest

• run with muscular arteries 

• low pressure in veins, need valves for one way flow

large veins

• up to 3 cm in diameter

• have all 3 tunics, externa is thickest

• run with elastic arteries

• lack valves

skeletal muscle pump

• skeletal muscle contraction and relaxation helps move venous blood

• muscles squeeze veins, push blood towards heart

• inactivity results in greater risk of clot formation

respiratory pump

• IVC ascends in abdomen and thorax

• does not have skeletal muscle pump, assist from diaphragm

• inhalation - diaphragm flattens

  • increases abdominal pressure 

  • lowers thoracic pressure 

  • blood in IVC pushed towards heart

aorta

• carries oxygenated blood away from the heart

• 3 parts

  • ascending aorta

  • aortic arch

  • descending aorta 

aortic arch

aortic arch gives off 3 branches that supply the head, neck, and upper limbs

1. brachiocephalic trunk

   1. right common carotid artery - supply head and neck

   2. right subclavian artery - supply upper limbs

2. left common carotid artery

3. left subclavian artery

arteries to head and neck

common carotid artery splits into…

• internal carotid artery - travels into cranial cavity supply brain

• external carotid artery - remains outside of skull to supply superficial structures of head and neck

branches of external carotid artery

• superior thyroid a. - supply thyroid gland

• lingual a. - supply tongue

• facial a. - supply face

• occipital a. - supply back of head

• maxillary a. - supply muscles of mastication and teeth

• superficial temporal a. - supply scalp

vertebral arteries

• branch from subclavian arteries

• travel superiorly in transverse foramina in cervical vertebrae

• enter cranium through foramen magnum

• left and right arteries join to form basilar artery

blood supply to the brain: internal carotid arteries

• branch into anterior and middle cerebral arteries

• anterior cerebral arteries connect via anterior communicating arteries

blood supply to the brain: vertebral arteries

• join to form basilar artery

• basilar artery gives off left & right posterior cerebral arteries

• posterior cerebral arteries connect to internal carotid arteries through posterior communicating arteries

circle of willis

• circle of arteries supplying the brain

• formed by posterior cerebral, posterior communicating, internal carotid, anterior cerebral, and anterior communicating arteries

blood supply to upper limbs

• subclavian artery

  • travels between first rib and under clavicle to become axillary artery

• axillary artery

  • becomes brachial artery

• brachial artery

  • after passing elbow, splits into radial and ulnar arteries

• radial & unlar arteries 

  • form palmer arches in the hand

blood supply to thorax

• thoracic aorta 

  • gives off posterior intercostal arteries

• internal thoracic arteries

  • either side of the sternum

  • branch from subclavian arteries

  • gives off anterior intercostal arteries which join with posterior intercostal arteries

blood supply to the abdomen

• thoracic aorta passes the diaphragm to become the abdominal aorta

  • 3 branches

• renal arteries supply the kidneys

• gonadol arteries supply gonads (testes or ovaries)

• abdominal artery splits into left and right common iliac arteries

3 unpaired, central branches of the abdominal aorta

1. celiac trunk

2. superior mesenteric artery

3. inferior mesenteric artery

celiac trunk

supplies stomach, liver, spleen, gallbladder, pancreas, and duodenum

superior mesenteric artery

supplies jejunum, ileum, appendix, ascending colon, and transverse colon

inferior mesenteric artery

supplies descending colon, sigmoid colon, and rectum

iliac arteries

• common iliac arteries enter pelvis and divide into internal and external iliac arteries

• internal iliacs supply pelvic organs, gluteal region, and external genitalia

• external iliacs leave pelvis to become femoral arteries in the thigh

arteries in lower limb

• femora artery - supplies the muscles of the thich

  • passes through the back of the knee to become the popliteal artery

• popliteal artery branches into

  • anterior tibial artery - supply anterior compartment of leg and dorsum of foot

  • posterior tibial artery - supply posterior compartment of leg and plantar foot

  • fibular artery - supply lateral compartment of leg

veins of the head and neck

• external jugular vein

• internal jugular vein

external jugular vein

• superficial to sternocleidomastoid

• carries blood from neck and superficial head

• joins with internal jugular vein or subclavian vein at base of neck

internal jugular vein

• begins at jugular foramen (base of skull)

• carries blood from brain (dural sinuses), orbit, and face

• deep to sternocleidomastoid

deep veins of upper limb

*run with arteries with the same name

• radial & ulnar veins

  • drain blood from hand and forearm

  • join near the elbow as the brachial vein

• brachial vein

  • drains blood from arm

  • becomes axillary vein in the axilla

• axillary vein

  • receives blood from shoulder, lateral thoracic wall, and upper extremity

  • becomes subclavian vein under clavicle

• subclavian vein

• joins with internal jugular vein to become the brachiocephalic vein

superficial veins of upper limb

*also called cutaneous veins (in hypodermis)

• basilic vein - medial side of arm and forearm, joins axillary vein

• cephalic vein - lateral side of arm and forearm, joins subclavian vein

• medial cubital vein - connects cephalic and

  • common site for venipuncture

veins of the thorax

• posterior intercostal veins drain blood from intercostal spaces

veins of the thorax - right side

• azygos vein collects blood from the posterior intercostals

• returns blood to the superior vena cava

veins of the thorax - left side

• lower left region - hemiazygos vein collects blood from posterior intercostals

• upper right region - accessory hemiazygos vein collects blood from posterior intercostals

• both return blood to the azygos vein

veins to the heart

• internal jugular veins & subclavian veins join to form brachiocephalic veins

• brachiocephalic veins join to form SVC

• azygos vein joins the back of SVC

• IVC returns blood from the abdomen, pelvis, and lower limbs

deep veins of lower limb

• posterior tibial vein drains blood from the foot and posterior compartment of the leg

• anterior tibial vein drains blood from the anterior compartment of the leg and foot

• fibular vein drains blood from the lateral compartment of the leg

• all 3 veins join to form the popliteal vein behind the knee

• popliteal vein moves around the medial side of the thigh to become the femoral vein that drains the thigh

superficial veins of lower limb

• located in the hypodermis

• great saphenous vein travels along medial leg and thigh collecting superficial blood of lower extremity

  • empties into femoral vein in upper thigh

• small saphenous vein travels along posterior leg collecting superficial blood from leg

  • empties into popliteal vein

iliac veins

• common iliac veins are formed from joining internal and external iliac vein

  • internal iliac - receives blood from pelvic organs, external genitalia, and gluteal region

  • external iliac - receives blood from lower extremity, becomes the femoral vein in thigh

portal vs caval drainage 

drainage of venous blood in the abdomen proceeds directly into the inferior vena cava (caval system) or the hepatic portal vein (portal vein)

caval system (IVC)

inferior vena cava receives blood from

• renal veins - draining blood from the kidneys

• gonadal veins - drain blood from the gonads

• common iliac veins

• liver

portal system

• hepatic portal vein receives blood from the digestive tract and accessory organs to be filtered by liver

  • nutrients and harmful agents are removed

  • filtered blood in the liver is sent to the IVC

• superior mesenteric, inferior mesenteric, and splenic veins empty in to the hepatic portal vein