Vascularization of the Head and Neck

VASCULARIZATION OF THE HEAD AND NECK -pete

Off the SUBCLAVIAN ARTERY:

Thyrocervical Trunk: 3 branches: inferior thyroid (anterior cervical comes off of this), transverse cervical, suprascapular arteries

--inferior thyroid: runs superiomedially POSTERIOR to the carotid sheath to supply inferior thyroid (intimate relationship with recurrent laryngeal nerves!!!!!!!!!!!!!!!!!)

--transverse cervical: muscles in the scapular region; runs through the posterior cervical triangle

--suprascapular artery: supraspinatus, infraspinatus muscles (hopefully, this will be covered by vascularization of the upper limb! [if NOT, let me know cuz it’s important for anastomoses in the scapular region among other things!!!!!!!!!]

COMMON CAROTID: right: terminal branch of the brachiocephalic trunk (along with the subclavian): behind sternoclavicular joint while the left arises from aortic arch

--ascends in the carotid sheath medial to the internal jugular vein and anterior to the vagus nerve (X)

--divides into the internal and external carotid at the level of the laryngeal prominence (superior border of the thyroid cartilage)

External Carotid: blood supply to external of the skull; runs postero-superiorally between neck of the mandible and the auricle.

8 branches: (come off external carotid in the following order)

Superior thyroid: thyroid gland, larynx (via superior laryngeal); branches to sternocleidomastoid and to the

infrahyoid (strap) muscles [thyrohyoid, sternothyroid, omohyoid, sternohyoid]

--superior laryngeal runs with inferior laryngeal nerve, pierces thyrohyoid membrane and supplies larynx

Ascdending pharyngeal: smallest branch; ascends laterally to pharynx and base of skull, preveterbral

muscles, middle ear, and meninges

Lingual runs between genioglossus and hyoglossus muscles (lateral to genio and medial to hyo)

branches to the muscles of the tongue, sublingual glands, associated muscles

terminal (deep lingual artery) anastomoses with itself on the other side of the tongue

Facial: tonsillar branch, branches to palate and submandibular gland;

--in face: supra – and infra- labial and angular (terminal branch) which supplies the eyelids

--passes deep to the platysma, and in the face lies deep to the zygomaticus major and levator labii superioris muscles; very torturous route!!! (this is way to distinguish between artery and vein: artery is very torturous like the splenic artery)

Occipital: to posterior scalp

Posterior Auricular: ascends posterior to external acoustic meatus and supplies adjacent muscles, parotid

gland, facial nerve, auricle, scalp, temporal bone structures

Superficial Temporal: smaller of two teminal branches; begins deep to parotid, posterior to neck of

mandible and passes anterior to ear

-- gives off: transverse facial which supplies parotid gland/duct, masseter muscle, and skin of the face (anastomoses with facial artery)

Maxillary: other terminal branch of the external carotid; traverses the infratemporal fossa

Branches of the Maxillary: 3 groups of arteries, 17 all together (if don’t include greater palatine)

1st group: - deep auricular: to external acoustic meatus

-  anterior tympanic to tympanic membrane

-  middle meningeal: main artery to the calvaria and dura; passes between the two roots of the auriculotemporal nerve (from V3) and enters the skull via the foramen spinosum

-  accessory meningeal: passes through foramen ovale

-  inferior alveolar: mylohyoid, incisor, dental, lingual, and mental branches

2nd group: to muscles via

-  deep temporal

-  pterygoid,

-  masseteric, and buccal

3rd group: arise just before/after entering pterygopalatine fossa

- posterior superior alveolar

- middle superior alveolar

-  infraorbital

-  descending palatine

-  artery of the pterygoid canal

-  pharyngeal branch

-  sphenopalatine, (greater palatine?--- don’t know if this is a branch off of the sphenopalatine?))

-infraorbital: passes through the infraorbital foramen: facial, anterior superior alveolar,

and facial branches

-sphenopalatine: posterior lateral nasal and posterior septal branches (nasal mucosa); passes through the sphenopalatine foramen (branches to posterior lateral wall/nasal septum)

-greater palatine: enters nose through incisive foramen and supplies nasal septum

------these two anastomose in antero/inferior part of septum

Internal Carotid: blood supply to the interior of the skull: after branching from the external carotid, it rises vertically, before entering the carotid canal in the petrous part of the temporal bone. It then enters the middle cranial fossa through the foramen lacerum and then runs anteriorly into the cavernous sinus before taking a hairpin turn to enter into the subarachnoid space. Here it gives off the opthalmic artery; it then passes inferior to the optic nerve and then rises lateral to the optic chiasma before branching into the middle and anterior cerebral arteries at the medial end of the lateral sulcus.

---- forms circle of Willis with the basilar artery

--anterior cerebral: supplies medial and superior surfaces and the frontal pole of cerebrum

--middle cerebral: lateral surface and the temporal pole

------anastomoses with each other and with posterior cerebral

Opthalmic Arteries: pass through the optic foramen WITHIN the dural sheath of the optic nerve

--central artery: smallest but probably one of the more important branches off the opthalmic; comes off inferior to the optic nerve, runs within the dural sheath, PIERCES the optic nerve and runs within it (CENTRAL, pretty cool, eh? :) ) and emerges through the optic disk (supplies internal surface of the retina)

**** clinical thingee: it’s essentially an end artery (some anastomoses with the ciliary arteries) so if it’s blocked – results in instant/complete blindness in that eye

--Ciliary: supply sclera, choroid, cliary body, and iris (ahh, brings back memories of histo….)

-long posterior ciliary arteries supply ciliary body/iris

-short posterior ciliary arteries supply sclera and choroid

--Lacrimal: supplies the lacrimal gland, conjunctiva, eyelids; recurrent meningeal branch anastomoses with middle meningeal (anastomoses between external and internal carotid!!!!)

--Muscular branches: often accompany branches of the oculomotor nerve; they also give rise to anterior ciliary branches which give rise to conjunctiva and iris

from FRONTAL artery:

--supraorbital: anterior scalp/forehead (lateral to the supratrochlear): exit through the respective foramen

--supratrochlear: anterior scalp/forehead (medial to the supratrochlear): exits through its respective foramen

------these arteries freely anastomose with superficial temporal artery in CT (layer 2 of sCalp)

--dorsal nasal: dorsal part of the nose, eh?

--anterior and posterior ethmoidal arteries (which leave the orbit via the anterior/posterior ethmoid foramen); these arteries enter via foramen into the ethmoid air sinuses where they enter interior skull via an unnamed foramen, exit the skull through another unnamed foramen into the nasal passages to supply: anterosuperior mucosa of the lateral wall and the nasal septum

------travel along with anterior/posterior ethmoid nerves! And anastomose pretty freely with the palatine arteries from the maxillary (and from superior labial branch of the facial)

Opthalmic Veins:

--superior opthalmic vein: anastomoses with the facial vein; no valves so blood flow in either direction; ends in the cavernous sinus

--inferior opthalmic vein: ends in the superior opthalmic or cavernous sinus (communicates with pterygoid plexus)

--central vein: dumps into cavernous sinus

à since communication with facial vein, infections can enter these veins into the cavernous sinus…. BAD!!!! NOT GOOD!!!!! AVOID THAT!!

VERTEBRAL ARTERIES:

Branches off the first part of the subclavian: ascends through the transverse foramina of the cervical vertebrae; enters the cerebellomedullary cistern at the level of the foramen magnum; runs anteriorly on the anterolateral surface of the medulla; and joins with opposite one at caudal border of the pons to form basilar

--supply spine (give off anterior spinal)

Basilar Artery: gives off in order:

posterior inferior cerbellar

anterior inferior cerebellar (which gives off Labyrinthine arteries)

superior cerebellar

terminal branch is posterior cerebral artery

--posterior cerebral: supplied inferior and occiptial pole or cerebrum (anastomoses with other cerebral arteries)

--cerebellar: supply cerebellum!!!!

COMBINES with internal carotid to form Circle of Willis

Circle of Willis (aka the cerebral arterial circle): located at base of the brain in interpeduncular fossa; encircles the optic chiasma, infundibulum, mamillary bodies

---gives off two branches central and cortical branches from cerebral branches: central go deep, cortical go superficial!

--- consists of posterior cerebral connecting to internal carotid via posterior communicating branches

AND anterior cerebral arteries connected by an anterior communicating branch

------variety of clinical concerns with this circle: though the arteries anastomose, these connections are not really sufficient to adequately compensate for the loss of blood flow due to blockage; thus, one will suffer from a stroke: a variety of types thrombotic stroke: when embolus is dislodged and lodges into a smaller artery (ex: here!); Hemorrhagic stroke – often due to rupture of an aneurysm or arteriosclerotic artery. (Aneurysms can occur here as shown by the radiology lecture!)

Veins:

Anterior jugular: smallest of the jugulars; arises near hyoid bone from confluence of the submandibular veins (aka the submental venous plexus); dump into the subclavian (or external jugular); often connected to one another by a transverse trunk, thereby forming a jugular venous arch!

--no valves!

Internal jugular: largest vein in the neck; commences at the jugular foramen in the posterior cranial fossa where the sugmoid and inferior petrosal sinuses come together. Runs in the carotid sheath lateral to the internal carotid, anterior to the vagus. Joins the subclavian to form the brachiocephalic vein (at junction, it has a valve). RIGHT is usually bigger than left. Deep cervical lymph nodes run along its length usually posterior and lateral

--tributaries: facial, lingual, pharyngeal, superior and middle thyroid, occipital veins

------connected to anterior jugular via communicating branch

--facial vein: venous drainage for the face: begins with union of the supraorbital/supratrochlear veins

****--connections with cavernous sinus via superior ophthalmic vein and with the pterygoid plexus via the deep facial vein (since no valves, any infection can get from face to deep sinuses); LOOK above at opthalmic veins!

--receives a branch from the retromandibular vein; dumps into the internal jugular

External jugular: formed by joining of the retromandibular and posterior auricular veins; joined later by transverse cervical and suprascapular veins before it deposits into the subclavian (or internal jugular)

-- superficial temporal joins with maxillary to form the retromandibular vein

Inferior thyroid: drain into the brachiocephalic veins (often join and thus dump into only one of the brachiocephalics)

DURAL SINUSES: drain the brain! Into internal jugular for the most part….

Superior Sagittal: within the falx cerebri: flows into transverse sinus (blood from cerebrum and returns CSF via arachnoid villi)

Inferior Sagittal: falx cerebri along its inferior border (drains medial surfaces) flows into straight sinus

Straight: junction of falx cerebri and tentorium cerebelli; formed by union of inferior sagittal sinus and great cerebral vein; empties into transverse sinus (opposite to that into which the superior sagittal sinus dumps)

Transverse: at lateral margin of the tentorium (at posterolateral part of the petrous part of the temporal bone), they become sigmoid sinuses; they receive superior petrosal sinuses

Sigmoid: direct continuation of transverse sinuses -- terminate into internal jugular veins where they join with the inferior petrosal sinus

Occipital: between the transverse sinus and foramen magnum; drains iinto the sigmoid sinus near jugular foramen; communicates with internal vertebral venous plexus

Cavernous: on each side of the sphenoid bone. Communicates with veins in the orbit (usually flow is outwards, but because there are no valves, can come in….)

Superior Petrosal: drain cavernous sinus; dump into the transverse sinuses.

Basilar: commences near the clivus; connects inferior petrosal sinuses; communicates with the internal vertebral venous plexus

-----basilar and occipital sinuses can drain into the internal vertebral venous plexus; hence there is communication between the brain and the vertebrae (and thus the rest of the body); HERE is thus a means of communicating infection/tumors/etc…. from body to head/brain and vice versa…..

-----emissary veins: connect intracranial venous sinuses with veins external to the cranium. Usually flow is outwards (deep to superficial), but since they are valveless, infections can spread in this manner