arterial supply of head and neck and face

ECA

1. ANATOMY OF EXTERNAL CAROTID ARTERY

2. INTRODUCTION External carotid artery is a terminal branch of common carotid artery and is the chief artery that supplies to the structures in front of neck and in the face

3. EMBRYOLOGY OF ECA During the fourth and fifth week of embryological development , when the pharyngeal arches form, the aortic sac gives rise to arteries- aortic arches. The aortic sac is the endothelial lined dilation, it is the primordial vascular channel from which the arteries arise. In the initial stage there are pair of aortic arches, which are numbered, I, II, III, IV, and V. This system becomes altered in further development. 3 rd arch: forms common carotid, first(cervical part of internal carotid artery(rest of the internal carotid artery arise from dorsal aorta) and external carotid artery.

4. CAROTID SHEATH LATERAL MEDIAL Its is derived from mesoderm . It arise in back of neck and terminate at skull base

5. BIFURCATION OF COMMON CAROTID ARTERY At the level of upper border of thyroid cartilage , artery ends by dividing into internal and external carotid artery and 2 structures of importance are found CAROTID SINUS CAROTID BODY LOCATION Termination of Common carotid artery or beginning of internal carotid artery Behind bifurcation of common carotid artery INNERVATION Glossopharyngeal and sympathetic nerves Glossopharyngeal, vagus and sympathetic nerves FUNCTION Baroreceptor / pressure receptor Chemoreceptor, responds to changes in Regulates blood pressure O2, CO2, ph of blood

6. CAROTID SINUS SYNDROME Loss of consciousness due to simple head movements H ypersensitivity of carotid sinus due to unknown etiology S udden slight pressure changes may cause stimulation of carotid sinus Impulse transmitted by sinus reduce blood pressure and may cause slowing of heart resulting in. Thus blood supply to brain and resulting in sudden loss of consciousness While supporting the mandible care should be taken not to apply pressure on carotid sinus

7. CAROTID BODY TUMOR/ CHEMODECTOMA It is a benign tumor that arises from chemoreceptors in carotid body Located at bifurcation of common carotid artery Its is seen at the level of hyoid bone, in the upper part of anterior triangle of neck beneath the anterior edge of sternocleidomastoid Pressure on tumor gives rise to syncopal attack due to decrease in pulse rate condition is called as carotid body syndrome

8. TREATMENT Transcatheter Embolization A transcatheter embolization is a procedure that reduces blood supply to the tumor. It is done two or three days before surgery. A catheter will be guided through your groin artery into the blood vessels that feed blood to the tumor. Then, medication and/or a blocking device, such as foam, plastic, metal coil, or glue is used to stop the blood flow to the tumor . Surgical removal( ressection )  a patch over a hole is created made during the tumor removal or replacing a section of the artery with a bypass graft (using another blood vessel to create a new pathway for the blood to flow).

9. COURSE OF EXTERNAL CAROTID ARTERY It begins in carotid triangle at the level of upper border of thyroid cartilage opposite c3 and c4 vertebrae . It runs upwards, slightly backwards and laterally and terminates behind neck of mandible, giving its terminal branches It has a slightly curved course and thus is anteromedial to internal carotid artery in lower part and anterolateral to internal carotid artery in upper part

10. RELATIONS OF EXTERNAL CAROTID ARTERY IN CAROTID TRIANGLE Superficial : Cervical branch of facial nerve : hypoglossal nerve :facial, lingual and superior thyroid vein Deep :Wall of pharynx :Superior laryngeal nerve :Ascending pharyngeal artery ABOVE CAROTID TRIANGLE Lies deep in substance of parotid gland, within gland it is related Superficially : Retromandibular vein and facial nerve Deep to external carotid artery are : Internal carotid artery

11. BRANCHES OF EXTERNAL CAROTID ARTERY THERE ARE TOTAL 8 BRANCHES ANTERIOR : FACIAL, :LINGUAL, :SUPERIOR THYROID POSTERIOR : OCCIPITAL :POSTERIOR AURICULAR MEDIAL : ASCENDING PHARYNGEAL TERMINAL : MAXILLARY :SUPERFICIAL TEMPORAL

12. SUPERIOR THYROID ARTERY ORIGIN : Below the level of greater cornua of hyoid bone COURSE : runs downwards and forwards parallel and just superficial to external laryngeal nerve. - It passes deep to omohyoid , sternohyoid and sternothyroid and reaches to upper pole of lateral lobe of thyroid gland and divides into its terminal branches BRANCHES: infrahyoid , sternocleidomastoid, superior laryngeal , cricothyroid, glandular branches SUPPLIES TO : Larynx and thyroid gland, infrahyoid muscles, sternocleidomastoid, cricothyroid

13. The superior thyroid artery and external laryngeal nerve are close to each other higher up but diverge slightly near the gland . Hence in thyroid surgery superior thyroid artery should be ligated close to gland to avoid injury to external laryngeal nerve Damage to external laryngeal nerve may cause some weakness in phonation due to loss of tightening effect of cricothyroid on the vocal cord. APPLIED ASPECT

14. LINGUAL ARTERY ORIGIN : opposite the tip of greater cornua of hyoid bone COURSE : divided in 3 parts First part : lies in carotid triangle, it forms a upward loop which is crossed by hypoglossal nerve and this loop allows for free movement of hyoid bone. Second part : lies deep to hyoglossus along the upper border of hyoid bone and is superficial to upper constrictor of pharynx Third part : is called as anterior profunda linguae or deep lingual artery . it runs upwards along upper border of hyoglossus and then horizontally forwards on the undersurface of tongues as fourth part and is accompanied by lingual nerve SUPPLIES TO : TONGUE, TONSIL

15. LIGATION OF LINGUAL ARTERY Incision circling the lower pole of submandibular gland Skin, platysma & deep fascia are incised & submandibular gland is exposed & lifted Tendon of digastric muscle is visible Free border of mylohyoid is seen, hypoglossal nerve identified Digastric tendon is pulled downwards , the digastric triangle is enlarged & hyoglossus muscle is visible Then the muscle are divided and between its vertical fibers the lingual artery is found and ligated APPLIED ASPECT : in surgical removal of tongue or tonsil the first part of artery is ligated before it gives any branches

16. FACIAL ARTERY Also called as anesthetists artery : can be palpated at anteroinferior surface of masseter against bony surface of mandible Origin : above the tip of greater cornua of hyoid bone Course : runs upward first in neck as cervical part and in face as facial part CERVICAL PART : - Its tortuosity allows free movement of pharynx during deglutition -It runs upwards on superior constrictor of pharynx deep to posterior belly of digastric -It grooves the posterior border of submandibular gland and makes an s band(2 loops) first winding down over submandibular gland and then up over base of mandible

17. FACIAL PART Its tortuosity allows free movement of mandible, lips and cheek during mastication and facial expressions The vessel enter the face at anteroinferior angle of masseter muscle, runs upwards 1.25 cm lateral to angle of mouth Then it ascends by side of the nose to the medial angle of eye where it terminates by anastomosing with dorsal nasal branch of ophthalmic artery

18. APPLIED ASPECT OF FACIAL ARTERY Facial artery compression It can be compressed at the lower border of mandible just anterior to angle thus leading to decreased blood flow in the area Facial artery can be injured during operative procedure on lower premolar and molars if instrument enters the cheek at inferior vestibular fornix, or in an attempt to remove buccal infection In cases of mandibular third molar impaction vertical incision should be made from vestibule in upward direction

19. LIGATION OF FACIAL ARTERY Closing in layers

20. OCCIPITAL ARTERY ORIGIN : Arises in carotid triangle from posterior aspect of external carotid artery opposite the origin of facial artery It is crossed by the hypoglossal nerve SUPPLIES TO : the back of the scalp and sternocleidomastoid muscles, and deep muscles in the back and neck Applied aspect Superficial branch of descending branch of occipital artery anastomoses with ascending branch of transverse cervical artery Deep branch of this anastomoses with deep cervical artery which should be taken care during neurosurgeries.

21. POSTERIOR AURICULAR ARTERY ORIGIN : Arises from posterior part of external carotid artery just above the posterior belly of digastric COURSE : it runs upwards and backwards deep to the parotid gland, but superficial to the styloid process. It crosses the base of mastoid process , and ascends behind the auricle SUPPLIES : back of auricle, the skin over mastoid process and back of scalp BRANCHES: Stylomastoid artery, posterior tympanic artery, auricular branch, occipital branch, parotid branch, perforating muscle branches 

22. ASCENDING PHARYNGEAL ARTERY ORIGIN: Is A small branch that arises from the medial side of external carotid artery. It arises very close to lower end of external carotid artery. COURSE: It runs vertically upwards between the side wall of the pharynx , and the tonsil , medial wall of the middle ear and auditory tube. BRANCHES : Pharyngeal branches, inferior tympanic artery, posterior meningeal artery

23. MAXILLARY ARTERY Origin : it is a larger terminal branch of external carotid artery given off behind the neck of mandible and is under cover of parotid gland Course : it is divided into 3 parts by lateral pterygoid muscle First part : mandibular part- runs horizontally forwards, first between neck of mandible and sphenomandibular ligament and then along lower border of lateral pterygoid Second part : pterygoid part- runs upwards and forwards superficial to lower head of lateral pterygoid Third part : pterygopalatine part- passes between the 2 heads of lateral pterygoid and through the pterygomaxillary fissure to enter pterygopalatine fossa

24. APPLIED ASPECT Second part is the most common site of hematoma after posterior superior alveolar nerve block Anteroposterior incisions must given during infection in palatal root of upper first molar parallel to artery Avoid injury to maxillary artery during surgeries involving condyle as artery lies medial to condyle Ankylotic mass of temporomandibular joint may encircle the artery hence the mass should be removed in pieces and not in toto Can be used as arterial donor in repair of internal carotid artery dissections and aneurysms due to close proximity of artery to cranial base If epistaxis is not controlled after nasal packing , it can be controlled by ligating IMA via endonasal , transantral or intraoral approach

25. SUPERFICIAL TEMPORAL ARTERY Origin : is a smaller terminal branch of external carotid artery, begins behind neck of mandible under cover of parotid gland Course : it runs vertically upwards , crossing the root of zygomatic arch or preauricular point, where its pulsations can be easily felt 5 cm above the arch it divides into anterior and posterior branches which supply temple and scalp

26. APPLIED ANATOMY Control of temporal hemorrhage Care should be taken in case of placement of incision in craniotomy In reduction of zygomatic arch fractures :gill’s approach A 2cm incision is placed in temporal region at an angle of 45  to zygomatic arch, between the 2 branches of superficial temporal artery and parallel to anterior branch

27. ECA LIGATION Can be done in carotid triangle or retromandibular fossa INDICATIONS: Bleeding from oral malignancies Diminishment of blood supply to the area of tumor bed as adjunctive procedure prior to the tumor resection Involvement of vessel or major branch in tumor Slipping of superior pedicle of thyroid gland Injuries causing carotid blow outs