Chapter 6: Vascular Supply

1. Chapter 6: Vascular Supply

2. Blood Distribution • 60% of blood volume at rest is in systemic veins and venules • function as blood reservoir • blood is diverted from it intimes of need • increased muscular activityproduces venoconstriction • hemorrhage causes venoconstriction to help maintain blood pressure • 15% of blood volume in arteries & arterioles

3. Cardiovascular System Blood vessels: Types A. Arteries -carry blood away from heart -thicker than veins -three layers: inner endothelium middle smooth muscle outer connective tissue -arteriole = small artery B. Veins -carry blood toward heart -same three layers as arteries (less SM and connective tissue) -thinner and more expansive than arteries -contain valves - to help the flow of blood back to heart -small vein = venule C. Capillaries -site of gas exchange with tissues -connect arterioles and venules -network of microscopic vessels (one cell thick) = capillary bed -site of exchange: gases, nutrients, wastes -can be closed off when not needed

4. Arteries • Tunica interna (intima) • simple squamous epithelium known as endothelium • basement membrane • internal elastic lamina • Tunica media • circular smooth muscle & elastic fibers • smooth muscle is innervated by sympathetic nervous system • decrease in stimulation or presence of certain chemicals causes vasodilation • increases diameter of vessel • nitric oxide, K+, H+ and lactic acid cause vasodilation • increase in stimulation causes muscle contraction or vasoconstriction • decreases diameter of vessel • Tunica externa • elastic & collagen fibers

5. Elastic Arteries • Largest-diameter arteries have lot of elastic fibers in tunica media • Help propel blood onward despite ventricular relaxation (stretch and recoil -- pressure reservoir) Muscular Arteries • Medium-sized arteries with more muscle than elastic fibers in tunica media • Capable of greater vasoconstriction and vasodilation to adjust rate of flow • walls are relatively thick • called distributing arteries because they direct blood flow

6. Veins • Proportionally thinner walls than same diameter artery • tunica media less muscle • lack external & internalelastic lamina • Still adaptable to variationsin volume & pressure • Valves are thin folds of tunica interna designed to prevent backflow • Venous sinus has no muscle at all • coronary sinus or dural venous sinuses • are large blood-filled spaces between two layers of tissue e.g. dural sinus – between the two layers of the dura mater meninges

7. Capillaries • Microscopic vessels that connect arterioles to venules • Found near every cell in the body but more extensive in highly active tissue (muscles, liver, kidneys & brain) • entire capillary bed fills with blood when tissue is active • lacking in epithelia, cornea and lens of eye & cartilage • Function is exchange of nutrients & wastes between blood and tissue fluid • Structure is single layer of simple squamous epithelium and its basement membrane

8. Common Carotid • -no branches as it travels up the neck • lateral to the trachea and larynx • beneath the sternocleidomastoid • wrapped in a sheath with the internal jugular and vagus nerve • ends in two divisions: • 1. internal carotid • 2. external carotid • just before the bifurcation – swelling = carotid sinus

9. Internal carotid • Internal carotid arteries (contribute to Circle of Willis) • lateral to the external carotid • branchless as it travels up the neck • at the base of the skull – forms the Circle • of Willis • supplies the brain • also gives off an opthalmic branch • supplies the eyes, orbits, and lacrimal gland

10. Common Carotid Branches • External carotid arteries • supplies structures external to skull as branches of maxillary and superficial temporal branches • 8 branches divided into four portions: • anterior portion • ascending portion • posterior portion • terminal portion

11. External carotid • 1. anterior portion: • Superior thyroid • Lingual • Facial (external maxillary) • 2. ascending portion • Ascending pharyngeal • 3. posterior portion • Occipital • Posterior auricular • 4. terminal portion • superficial temporal • maxillary (internal maxillary “Seven Little Fairies Ascended Over Polly’s Super Mums”

12. External Carotid artery 16 – infraorbital 17 – internal maxillary 10 – descending palatine 29 – superficial temporal 9 – deep lingual (lingual) 15 – inferior labial (facial) 24 – sublingual (lingual) 20 – middle meningeal (maxillary) 28 – superficial temporal 22 – posterior auricular 2 – ascending palatine (facial) 21 – occipital 18 – lingual 11 – facial 6 – carotid, external

13. Superior thyroid -supplies the infrahyoid region - muscles of the larynx, and the thyroid gland -branches: infrahyoid sternocleidomastoid superior laryngeal superior and inferior thyroid Lingual -supplies the suprahyoid region, floor of mouth and tongue -branches: deep lingual – apex of tongue dorsal lingual – base and body of tongue sublingual – mylohyoid, sublingual gland, mucous membranes of mouth floor suprahyoid - suprahyoid muscles

14. 9 – deep lingual 24 – sublingual 26 – submental 18 – lingual artery 6 – external carotid

15. Facial = external maxillary -can have a common trunk with the lingual -runs medial to the mandible -over the submandibular gland -over the lateral side of the mandible (under the platysma) -parallels the facial vein – separated by the posterior belly of the diagastric -divided into cervical and facial branches Cervical branches = supplies soft palate, roof of mouth, submandibular gland ascending palatine – soft palate and palatine muscles submandibular/glandular – glandular tissues submental – submandibular lymph nodes, submandibular salivary gland, mylohyoid and diagastric tonsillar – palate and roof of mouth Facial branches = supplies lips, nose, facial muscles inferior labial – lower lip and its muscles superior labial – upper lip and its muscles angular – side of nose, ends a medial commisure muscular

16. Facial artery (external maxillary) 16 – infraorbital 10 – descending palatine 27 – subnasal 29 – superior labial 15 – inferior labial 26 – submental 17 – internal maxillary 14 – inferior dental 25 – submandibular gland (glandular)

17. Ascending pharyngeal -ascending portion of external carotid -supplies throat, ear (tympanic region), cranial meninges -several small branches 1. palatine – may replace the ascending pharyngeal of the facial artery 2. pharyngeal – pharynx 3. meningeal – meninges 4. inferior tympanic – with the glossopharyngeal nerve, it enters the temporal bone to supply the tympanic region • Posterior auricular • -supplies internal ear, occipatalis muscle and scalp • auricular branch – internal ear • stylomastoid branch – mastoid air cells • occipitalis branch – occipitalis muscle and scalp at back of head • -may join with the occipital artery

18. Occipital -arises near the hypoglossal cranial nerve (XII) -travels to and supplies the posterior scalp, muscles of back of neck, nasal conchae -branches: 1. muscular – diagastric, stylohyoid splenius, and long. capitis 2. meningeal – through the jugular f. supplies the dura mater in the posterior fossa 3. SCM – may arise directly from the EC supplies the SCM 4. descending – largest branch, descends along the back of the neck, supplies the trapezius and semispinalis capitis 5. auricular – supplies the conchae and dura mater, enters via the stylomastoid foramen

19. Superficial temporal -supplies front of scalp, frontalis, temperoparietalis, temporalis, outer ear 1. transverse facial – runs along zygomatic arch -supplies the parotid gland, cheek bone and masseter 2. middle temporal – runs along the zygomatic arch, -supplies the temporalis 3. anterior auricular – supplies the outer ear structures 4. frontal – supplies the frontalis, front scalp 5. parietal – supplies muscles of the parietal region

20. Internal Maxillary -largest of the terminal branches of the external carotid -begins at neck of mandibular condyle -can be divided into three portions it arises from the EC 1. Mandibular 2. Pterygoid 3. Pterygopalatine

21. 1. Mandibular portion a. anterior tympanic b. middle meningeal – largest branch, supplies the dura mater, thru the foramen spinosum c. deep auricular – branch to the TMJ, supplies the tympanic membrane d. accessory meningeal – thru the foramen ovale, supplies the dura mater e. inferior alveolar – thru the mandibular f. with the inferior alveolar nerve, travels thru the mandibular canal -gives off four main branches 1. myloyoid branch– branches off before it enters the mandibular canal, supplies the floor or mouth and mylohyoid 2. lingual branch– supplies the mucus membranes of the mouth 3. mental branch– exits thru the mental f., supplies the chin 4. incisive branch– divides about the first premolar into dental and alveolar branches -dental = pulp tissue -alveolar = peridonteum + gingiva

22. 2. Pterygoid portion • -supplies muscles • -accompanies the trigeminal cranial • nerve (V) • -branches: • deep temporal – anterior and posterior • temporalis • 2. masseteric • 3. pterygoid – lateral & medial pterygoid m. • 4. buccinator

23. 3. Pterygopalatine portion • -branches: • posterior superior alveolar= post-dental • artery • -gives off dental and alveolar branches • -supplies the premolars and molars • -also the lining of the maxillary sinuses • b.artery of the pterygoid canal = vidian artery • -upper pharynx and auditory canal • c. infraorbital– thru the infraorbital f., supplies facial structures • -gives off an orbital branch and a superior alveolar branch (dental and alveolar branches) • d. pharyngeal – upper pharynx and auditory tube • e. sphenopalatine – thru the sphenopalatine f., enter the nasal cavity • -supplies the nasal conchae, the anterior part of the hard palate, the ethmoid, maxillary • and frontal sinuses (lateral nasal branch) • -also supplies the nasal septum (posterior septal branch)

24. -so dental and alveolar branches come from 1. the incisive branch of the inferior alveolar (mandibular portion) 2. posterior superior alveolar – pterygopalatine portion 3. anterior superior alveolar branch of the infraorbital (pterygopalatine portion) -supplies the upper incisors & canines -plus the maxillary sinus -dental branches supply the pulp of the teeth -alveolar branches supply the associated gingiva and peridontium

25. Veins of the Head and Neck • External and Internal jugular veins drain the head and neck into the superior vena cava • Dural venous sinuses empty into internal jugular vein

26. Veins of the Head and Neck • Frontal • Supraorbital • Angular • Superficial temporal • Maxillary • Posterior Facial • Posterior Auricular • Occipital • Facial - retromandibular

27. Facial Vein • drains lips, tongue, chin, orbit • drains into the internal jugular • begins at the medial corner of the eye • forms from the union of supratrochlear and supraorbital veins (drains the orbit) -also connects with the: -superior labial vein -inferior labial vein -submental vein – chin and submandibular region -lingual (dorsal, deep/ventral, sublingual branches) • two major branches: • retromandibular • superior thyroid -joins with the pterygoid plexus -union of the meningeal, posterior superior alveolar branches + branches from the nasal region and palate -drains the deep portions of the face & meninges

28. Retromandibular Vein -forms from the superficial temporal and maxillary veins -emerges from the parotid gland and travels down the neck -below the parotid – divides into two branches 1. anterior division – drains the facial region 2. posterior division – drains the facial region, travels down the SCM -the posterior division is joined by the posterior auricular vein = External Jugular

29. Superficial Temporal -drains the lateral scalp -joins up with the retromandibular vein • Maxillary • -drains the pterygoid plexus • -merges with the superficial temporal – into the retromandibular vein • -forms from the: • posterior superior alveolar– dental and alveolar branches (maxillary arch) • inferior alveolar– dental and alveolar branches (mandibular arch) • middle meningeal - meninges