Head and Neck: Chapter 6

Posterior branches of external carotid artery

Two branches: Occipital and posterior auricular arteries -Occipital artery: Supplies the SCM by way of the sternocleidomastoid branch and other muscles such as the suprahyoid muscles by way of the muscular branches. Also supplies auricular regions and meninges by way of the auricular and meningeal branches. Descending branches supply the trapezius muscle -Posterior auricular artery: supplies the internal ear by the auricular brand and the mastoid process by the stylomastoid artery

Terminal branches of external carotid artery

Two branches: Superficial temporal artery and maxillary arteries -Superficial temporal artery: has several branches (transverse facial artery, middle temporal artery, frontal branch, and parietal branch) Transverse facial artery: Supplies the parotid salivary gland and nearby facial area Middle temporal artery: Supplies the temporalis muscle Frontal and parietal branches: Supply parts of the scalp in the frontal and parietal regions -Maxillary artery: Largest terminal branch of the external carotid artery and has 3 parts First part: Mandibular part. Deep auricular artery and anterior tympanic artery which supply the auricular region and tympanic region respectively. Middle meningeal artery which supplies dura mater of the brain and cranial bones Accessory middle meningeal artery supplies the dura mater and cranial bones and structures in the infratemporal fossa Inferior alveolar artery which supplies the buccal periodontium and gingiva of the mandibular posterior teeth Mylohyoid artery which supplies the floor of mouth and mylohyoid muscle. Mental artery which supplies the chin. Incisive artery which supplies the pulp of the mandibular anterior teeth by each tooth's apical foramen Note: Both mental and incisive blocks have a high rate of positive aspiration due to nearness of mental artery and incisive artery Second part: Pterygoid part Deep temporal arteries supply the anterior and posterior parts of the temporalis muscle Pterygoid arteries supply the lateral and medial pterygoid muscles Masseteric artery supplies the masseter muscle Buccal artery supplies the buccinator muscle and buccal region Third part: Pterygopalatine part Posterior superior alveolar artery supply the pulp of the maxillary posterior teeth by way of each tooth's apical foramen. Alveolar branches of the posterior superior alveolar artery supply the buccal periodontium and gingiva of the maxillary posterior teeth. Infraorbital artery supplies the orbital and infraorbital region. Anterior superior alveolar artery supply the pulp of maxillary anterior teeth by way of the apical foramen. Alveolar branches supply the labial periodontium and gingiva of the maxillary anterior teeth. Middle superior alveolar artery supplies the buccal periodontium and gingiva of the maxillary premolars. Infraorbital artery terminal branches supply parts of the orbital and infraorbital branches of the face Descending palatine artery supply the posterior hard palate, palatal periodontium and gingiva of maxillary posterior teeth/soft palate Sphenopalatine artery main terminal branch supplies the nasal cavity within the nasal region. Nasopalatine branch supplies the anterior hard palate, palatal periodontium, and gingiva of the maxillary anterior teeth

Venous draining of head and neck

Veins of head and neck start as small venues and become larger near base of neck on the way to the heart -veins are symmetric on both sides of body. They are also larger and more numerous than arteries

Artery

blood vessel that carries blood away from the heart -starts as a large vessel and branches into smaller vessels of arterioles. Each arteriole branches into smaller vessels into a network of capillaries

Venous sinuses

blood-filled spaces between 2 layers of tissue

Blood vessels not only spread

cancer, but also can spread dental infections

Vein

carries blood towards the heart -veins are larger and more numerous than arteries

Anastomosis

connecting channel among blood vessels

Internal jugular vein

drains most structures of head and neck -originates in cranial cavity and leaves skull through jugular foramen

Retromandibular vein

drains the maxillary artery and the superficial temporal arteries. -divides into two parts: anterior division (joins facial vein) and posterior division (surface of SCM muscle). -Then joined together by the posterior auricular vein which drains the lateral scalp.

Venous sinuses

located within the meninges and are within the dura mater (dense connective tissue that lines the inner cranium) -dural sinuses: channels where blood is conveyed from cerebral veins into veins of the neck -Paired cavernous sinus (most important to dental care)- located on either side of the sella turcica. The sinus communicates with its contralateral sinus by anastomoses, pterygoid plexus of veins, and superior ophthalmic vein -internal carotid artery and cranial nerves pass through this blood filled space of the cavernous sinus (only anatomic location in which an artery passes through a venous structure. Important to dental professionals because the cavernous sinus can be involved with spread of dental infection)

Subclavian artery

major branch that supplies the intracranial and extra cranial structures as well as the upper extremity (arm)

Carotid pulse

palpation of the common carotid artery against the larynx (felt on either side) -used for monitoring; most reliable arterial pulse in the body because the common carotid is a major artery supplying the brain -dental personnel should used radial pulse to record patient's baseline pulse

Capillary

smallest blood vessel that caries blood to a larger area

Vascular system of the head and neck consists of

-arterial blood supply -capillary network -venous drain

narrowing and blockage of the arteries can cause pathologic changes that impact the head and neck with dental care.

-caused by buildup of fatty arterial plaque (contains mainly cholesterol as well as calcium, clotting proteins). -Results in atherosclerosis (narrowing/blockage of arteries) -Atherosclerosis results in cardiovascular disease. Lifestyle choices can reduce the onset/severity of coronary artery disease

Superior thyroid artery

-has 4 branches: infra hyoid artery, sternocleidomastoid branch, superior laryngeal artery, and cricothyroid branch. -Each branch supplies structures inferior to the hyoid bone (ex: infrahyoid muscles, SCM muscle, larynx muscles, thyroid gland) -Inferior thyroid artery anastomoses with the superior thyroid artery to help supply the thyroid gland and other structures like the thymus gland -Occasionally there is also thyroid ima artery present to supply the thyroids anterior surface and isthmus

Inferior alveolar vein

Forms from the merging of its dental branches, alveolar branches, and mental branches in the mandible, where they also drain into the pterygoid plexus -drains the periodontium and gingiva of mandibular teeth -mental branches enter the mental foramen after draining the mental regions with the chin on outer surface of the mandible

External carotid artery

Has 4 branches: anterior, medial, posterior, and terminal (named by location to the main artery) -SUPPLIES THE EXTRACRANIAL TISSUE OF THE HEAD AND NECK INCLUDING THE ORAL CAVITY

Vascular plexus

Large network of blood vessels

Blood vessels are

Less numerous than lymphatic vessels -venous blood vessels run parallel to lymphatic vessels and can spread cancer from a neoplasm to distant sites at a faster rate than lymphatic vessels

Arterial blood supply to the head and neckO

Major arteries include: -common carotid -subclavian arteries

External jugular vein

Posterior division of the retromandibular vein becomes the external jugular vein -anterior jugular vein drains into external jugular vein

Internal carotid artery

SOURCE OF THE OPHTHALMIC ARTERY: which supplies the eye, orbit, and lacrimal gland

Anterior branches of external carotid artery

Superior thyroid, lingual, facial

carotid sheath

The deep fascia of the neck that covers the common carotid artery, internal jugular vein, and the 10th cranial nerve (vagus nerve)

Origins to head and neck: Left side of body

Common carotid and subclavian arteries arise from the aorta

Origins to head and neck: Right side of body

Common carotid and subclavian arteries branch from the brachiocephalic artery

Brachiocephalic artery

Direct branch of the aorta (only on right side)

Pathways to heart from head and neck

External jugular vein joins the subclavian vein from the arm. Then internal jugular vein merges with the subclavian vein to form the brachiocephalic vein. Brachiocephalic vein unite to form the superior vena cava and then travel to the heart

Pterygoid plexus of veins

*Collection of small anastomosing vessels in the infratemporal fossa *Located around the pterygoid muscles & surrounding the maxillary artery on each side of the face *Anastomoses w/ facial & retromolar veins *Protects maxillary artery from compression during mastication by filling or emptying to accommodate changes in volume within the infratemporal fossa when mandible moves *Drain veins from deep parts of face *Drains into the maxillary vein *Possibility of piercing during PSA & causing a hematoma *Possibility of spreading infection along needle tract during PSA

Posterior superior alveolar vein

*Drains into pterygoid plexus formed by merging of dental & alveolar branches draining pulp & periodontium/gingiva of maxillary teeth

Superficial temporal vein

*Drains lateral scalp *Superficially located in skin covering the temporal region *Drains into the retromandibular vein

Lingual artery

*supplies blood to the tongue, supra hyoid muscles, and floor of mouth* -Dorsal lingual arteries and deep lingual arteries: Supply the tongue -Sublingual artery: supplies mylohyoid muscle, sublingual salivary gland, and oral mucosa of the floor of the mouth and lingual periodontium and gingiva of the mandibular teeth -Suprahyoid branch supplies the supra hyoid muscles

Maxillary vein

-Begins in infratemporal fossa which collects blood from pterygoid plexus -recieves the middle meningeal, posterior superior alveolar, inferior alveolar veins, etc. -Then merges with superficial temporal vein to drain into and form the retromandibular vein

Facial artery

-Branches include: Ascending palatine artery, tonsillar branches, submental artery, glandular branches, inferior labial artery, superior labial artery, and angular artery -Ascending palatine artery: supplies soft palate, palatine muscles, and palatine tonsils by way of the tonsillar branches. Can be result of serious blood loss or hemorrhage during a tonsillectomy -Submental artery: supplies the submandibular lymph nodes, mlyohyoid and digastric muscles, and submandibular salivary gland/nearby muscles. Also supplies the lingual periodontium and gingiva of mandibular teeth -Inferior labial artery: Supplies lower lip area including muscles of facial expression -Superior labial artery: Supplies upper lip area and muscles of facial expression -Angular artery: Supplies the lateral side of the naris of the nose

Common carotid artery

-Branchless -travels in the carotid sheath deep to the sternocleidomastoid muscle -common carotid artery ends by dividing into internal and external carotid arteries at the level of the pharynx. At point of division, the carotid sinus (swelling) is present

Facial vein

-Drains into internal jugular vein -Begins at medial canthus w/ the junction of supratrochlear & supraorbital veins from the frontal region *Supraorbital vein anastomoses w/ the ophthalmic vein to drain tissues of orbit *Provides communication w/ the cavernous venous sinus- communication and one way direction of blood flow may cause the cavernous sinus to become fatally infected through the spread of a dental infection *Receives branches from same areas of face supplied by facial artery *Anastomoses w/ the deep veins such as pterygoid plexus & retromandibular vein before joining the internal jugular vein at level of hyoid bone TRIBUTARIES IN ORAL REGION: 1. Superior labial vein: drains upper lip 2. Inferior labial vein drains lower lip 3. Submental vein: drains the chin & submandibular region 4. Lingual veins: A. Dorsal lingual vein- drains the dorsal surface of the tongue B. Deep lingual vein- drains the ventral surface of the tongue C. Sublingual vein- drains the floor of the mouth

Medial branch of external carotid artery

-One main branch: ascending pharyngeal artery -Ascending pharyngeal artery has many small branches: pharyngeal branch, meningeal branch, tonsillar branches. These branches supply pharyngeal walls, soft palate, meninges, and pharyngeal tonsils (can be another source of serious blood loss/hemorrhage during a tonsillectomy)

Thrombus

Blood clot -can dislodge from inner vessel wall and travel as an embolus -both thrombus and embolus can cause blockage of blood flow (stroke, heart attack, or tissue destruction). Can also be infected and spread infection -bacteria in blood (bacteremia) -If blood vessel is traumatized, a hemorrhage can occur -blood vessels can undergo temporary localize traumatic injury resulting in bruising (hematoma). Blood vessel is injured and small amount of blood escapes which then clots. Escaped blood causes tenderness, swelling, and discoloration