Lecture 2: Arterial supply + venous drainage of face/head Flashcards
Common Carotid Artery
Ascends with neck to superior border of thyroid cartilage/C3-C4 vertebral level
- Birfucates –> internal/external carotid a
- As it ascends, positioned MEDIAL to IJV.
- Vagus n is POSTERIOR, between artery and vein
- All 3 in carotid sheath
Internal carotid artery
- Passes deep to posterior belly of digastric and stylohyoid muscles
- Crossed by hypoglossal n (passes superficial to both internal and external carotid arteries)
ICA p 2
- Ascends anterior to transverse process of C1-C3 to reach base of skull; passes into carotid canal (petrous temporal bone) to reach cranial cavity (middle cranial fossa)
- No branches in neck
- Major source of blood to brain and orbit
Four parts of ICA
- Cervical part: bifurcation of CCA to lower end of carotid canal
- Petrous part: pass through carotid canal (in petrous temporal bone)
- Cavernous: course through cavernous sinus (along body of sphenoid)
- Cerebral: after piercing dura (near anterior clinic process), ICA gives off ophthalmic a before terminating as anterior and middle cerebral arteries
Ophthalmic a
Emerges from internal carotid immediately upon leaving cavernous sinus
- Enters orbit via optic canal
- Several branches (lacrimal, ciliary, ethmoidal, muscular) + 2 to forehead: supraorbital and supratrochlear
External carotid a
Deep to posterior belly of digastric and stylohyoid muscles
- Posterior to ramus of mandible, embedded in parotid gland
Mainly supply structures external to skull
ECA branches
- Superior thyroid a
- Ascending pharyngeal a
- Lingual a
- Facial a
- Occipital a
- Posterior auricular a
- Superficial temporal a
- Maxillary a
Superior thyroid a
Passes anteroinferior, DEEP to infra hyoid muscles to reach thyroid gland
- Also gives off branches to local muscles – gives rise to superior laryngeal a (larynx)
Ascending pharyngeal a
Near origin of ECA and smallest branch
- Ascends between ICA and pharynx to base of skull
- Sends branches to pharynx
Lingual a
Arises from anteromedial aspect of ECA, between superior thyroid and facial arteries
- Crossed by hypoglossal n
- Passes deep to stylohyoid and posterior digastric muscles before disappearing deep to hyoglossus
- Passes to inferior aspect of tongue -> deep lingual and sublingual branches
- Primary blood supply to tongue and floor of oral cavity
Facial a
Deep to digastric and stylohyoid muscles and medial to ramus/angle of mandible
- Passes along lower border of mandible, where it has a close relationship to submandibular gland
- Prior to entering face, gives off submental a
- Hooks around inferior border of mandible and enters face
Facial branches of facial a
Inferior labial a
Superior labial a
Lateral nasal branch
Angular a
– terminal part of facial a as it travels to medial angle of eye
–Forms anastomosis with ophthalmic a (branch of ICA)
Occipital a
Arises from posterior aspect of ECA, opposite origin of facial a
- Passes posteriorly, parallel and deep to posterior belly of digastric as it courses to posterior scalp
- -Several branches that supply structures in area, scalp+muscles in the area
Posterior auricular a
Small posterior branch, ascends posteriorly between EAM and mastoid process
- several branches to structures in area, including posterior auricle and muscles in the area
Superficial temporal a
Originates within parotid gland
- Between neck of mandible and EAM, enters temporal fossa and terminates by dividing into frontal/parietal branches
- TRANSVERSE FACIAL A- superficial to masseter, inferior to zygomatic arch
Maxillary a
- Arises within parotid gland, posterior to neck of mandible
- Medial to mandible to enter infra temporal fossa
- Within infra temporal fossa, may pass superficial OR deep to lateral pterygoid muscle
- Divided into 3 parts by lateral pterygoid muscle
- Passes through pterygomaxillary fissure to enter pterygopalatine fossa
Maxillary a (1st or mandibular part)
- Deep auricular a - pierces wall of EAM, supplies lateral surface of tympanic membrane
- Anterior tympanic a - traverses petrotympanic fissure and supplies medial surface of tympanic membrane
- Middle meningeal a - traverses foramen spinosum to enter middle cranial cavity, blood supply: dura mater
- Accessory meningeal a - foramen ovale -> middle cranial cavity -> dura mater
- Inferior alveolar a: mandibular foramen -> mandibular canal; mandibular teeth and gingiva
Before passing into bone, gives off mylohyoid branch (travels with n)
2nd premolar: divides into incisor/incisive and mental branches
Incisive branch to midline–> anterior teeth/gingiva
Mental branch -> mental foramen -> muscles/skin of chin
Max artery 2nd or pterygoid part
- Masseteric a: superior to mandibular notch –> deep surface of masseter muscle
- Deep temporal a (anterior and posterior): ascends to supply temporal muscle
- Pterygoid arteries: supply pterygoid muscles
- Buccal a: buccinator
Max Artery 3rd or Pterygopalatine Part
- Posterior superior alveolar a: traverses alveolar foramen; supplies max molars, premolars, adjacent ging tissue as well as lining of maxillary sinus
- Infraorbital a: passes through inferior orbital fissure –> infraorbital groove –> infraorbital canal –> infraorbital foramen; supplies inferior eyelid, lateral nose and superior lip; along course gives rise to anterior alveolar a (max canine, incisors and adj gingival tissue)
BOTH supply max sinus - Descending palatine a: descends through greater palatine canal –> greater and lesser palatine arteries and pass through same named foramina; supply mucous membrane/glands of soft and hard palate and maxillary gingival tissue
- Artery of pterygoid canal: passes through pterygoid canal; supplies the nasopharynx, pharyngotymapnic tube and tympanic cavity
- Pharyngeal a: passes through palatovaginal canal; supplies nasopharynx
- Sphenopalatine a: terminal branch of maxillary a, passes through sphenopalatine foramen to reach nasal cavity; supplies portion of nasal cavity, including nasal septum and anterior hard palate
Venous Drainage: Cranial Cavity
Blood from brain empties into dural venous sinuses
- Blood from scalp may also communicate with dural venous sinuses via emissary veins, pass through openings in cranial wall
- — Emissary veins allow communication between veins outside skull and dural venous sinuses (inside skull) –> potential spread of infection
- Diploic veins occupy channels in diploe of cranial bones
Dural venous sinuses
Endothelial-lined spaces between periosteal and meningeal layers of dura
Superior sagittal sinus
Occupies convex superior attaches border of falx cerebri
-Begins near crest Galli and ends near internal occipital protuberance, at confluence of sinuses
Inferior sagittal sinus
Occupies concave inferior free border of falx cerebri
-Ends in straight sinus
Straight sinus
Formed by union of inferior sagittal sinus and great cerebral vein
- Joins confluence of sinuses
- Located at junction of falx cerebri and tentorium cerebelli
Occipital sinus
Occupies attached border of falx cerebelli and ends superiorly in confluence of sinuses
Confluence of sinuses
Union of superior sagittal, straight, occipital and transverse sinuses
Transverse sinus
- Passes from confluence of sinuses, laterally along attached margin of tentorium cerebelli
- Laterally, where sinus passes from tentorium cerebelli, it becomes sigmoid sinus
Sigmoid sinus
- Originates where transverse sinus leaves tentorium cerebelli
- S-shaped as it descends and passes through in posterior cranial fossa
- Continues inferiorly as IJV after traversing jugular foramen
Cavernous Sinus
Located on either side of sella turcic (sphenoid)
-Drains posteroinferiorly through superior and inferior petrosal sinuses
Superior petrosal sinus
- Located along anterior margin of tentorium cerebelli
- Passes from posterior end of cavernous sinus and terminates where it joins transverse sinus
Inferior petrosal sinus
Originates at posterior end of cavernous sinus, passes inferiorly and empties into proximal aspect of IJV
Cavernous sinus
Structures passing cavernous sinus include:
1. ICA
2. Internal carotid plexus (sympathetic nerves)
3. CN3
4. CN4
5. CN6
6. CNV1
7. CNV2
these structures separated from blood in sinus by endothelial cells
Superficial Temporal Vein
Begins from widespread network of veins in scalp
- Drains blood from scalp, anterior to auricle
- Near auricle, superficial temporal vein enters parotid gland
Maxillary Vein
Short trunk accompanying 1st part of maxillary artery
- Derived from union of veins of pterygoid venous plexus (deep network of vein in infra temporal fossa)
- Union of maxillary and superficial temporal veins occurs within parotid gland and forms retromandibular vein
Retromandibular vein
Courses posterior to ramus of mandible and descends through parotid gland, superficial to ECA and deep to facial n
Divides into anterior and posterior branches
Posterior branch of retromandibular vein
Joins posterior auricular vein –> external jugular vein (union occurs just after exiting parotid gland)
Anterior branch of retromandibular vein
Joins facial vein which drains into IJV (sometimes called common facial vein)
Facial Vein
Formed by union of supraorbital and supratrochlear veins at medial angle of eye
- Angular vein from its origin (medial eye) -> along lateral aspect of nose
- Receives several veins (superior, labial, inferior labial, submental veins) before uniting with anterior branch of retromandibular vein
- Communicates with pterygoid venous plexus
Deep Facial Veins and Pterygoid Venous Plexus
- Facial vein communicates with pterygoid venous plexus via deep facial veins and infraorbital vein
-From pterygoid venous plexus, blood can reach cavernous sinus
POTENTIAL SPREAD OF INFECTION
Routes for Spread of Infection of Embolism
- Facial vein –> deep facial vein –> pterygoid venous plexus –> emissary vein –> cavernous sinus
- Infraorbital vein –> pterygoid venous plexus –> emissary vein –> cavernous sinus
- Supraorbital vein –> ophthalmic vein –> cavernous sinus
