EXTERNAL CAROTID ARTERY, BRANCHES AND LIGATION

R.Kavitha1st Yr PG

INTRODUCTION

• External carotid artery is the chief artery which supplies to structures in the front of the neck and in the face

EMBRYOLOGY OF ECA• During the fourth and

fifth weeks of embryological development, when the pharyngeal arches form, the aortic sac gives rise to arteries – the aortic arches.

• The aortic sac is the endothelial lined dilation, it is the primordial vascular channel from which the aortic arches arise.

• In the initial stage there are pairs of aortic arches, which are numbered I, II, III, IV, and V. This system becomes altered in further

development.

• 3rd Arch : forms common carotid artery, first (cervical) part of internal carotid artery (rest of internal carotid arises from dorsal aorta), and external carotid artery.

COMMON CAROTID ARTERIES

• Right common carotid artery is a branch of the brachiocephalic artery.It begins in the neck behind the right sternoclavicular joint.

• Left common carotid artery is a branch of the arch of aorta.It ascends to the back of the left sternoclavicular joint and enters the neck.

• In the neck,each artery runs upwards within the carotid sheath,under cover of the anterior border of the sternocleidomastoid muscle.

Carotid sheath• Carotid sheath is

condensation of the fibroareolar tissue around the main vessels of the neck.

• CONTENTS:It contains the common and internal carotid arteries,internal jugular vein and the vagus nerve.

• In the sheath,common carotid artery is medially placed.Vagus nerve lies in between.

RELATIONS• The ansa

cervicalis lies embedded in the anterior wall of the carotid sheath.

• The cervical sympathetic chain lies behind the sheath.

BIFURCATION OF COMMON CAROTID ARTERY

• Common carotid artery bifurcates into external and internal carotid arteries at the level of upper border of the thyroid cartilage.

• Two structures of importance at the bifurcation are

Carotid sinus Carotid body

CAROTID SINUS• Carotid sinus is slight dilatation at the

termination of the common carotid artery or the beginning of the internal carotid artery.

• It receives a rich innervation from the glossopharyngeal and sympathetic nerves.

FUNCTION: Carotid sinus acts as a baroreceptor or

pressure receptor and regulates pressure.

CAROTID BODY• Carotid body is a small,oval reddish-brown

structure situated behind the bifurcation.• It receives nerve supply mainly from the

glossopharyngeal nerve, but also from the vagus and sympathetic nerves.

FUNCTION: Carotid body acts as a chemoreceptor and

responds to changes in the oxygen and carbon dioxide and Ph content of the blood.

External carotid artery

• Generally,it lies anterior to the internal carotid artery.

• It is the chief artery of supply to structures in the front of the neck and in the face.

SURFACE MARKING• ECA is marked by joining

the following two points. -A) point on the anterior

border of the sternocleidomastoid muscle at the level of the upper border of the thyroid cartilage.

-B) second point on the posterior border of the neck of the mandible.

The artery is slightly convex forwards in its lower half and slightly concave forwards in its upper half.

B

A

COURSE• ECA begins in the carotid

triangle at the level of upper border of thyriod cartilage opposite the disc between the third and fourth cervical vertibrae.

• In the carotid triangle,it lies under cover of the anterior border of the sternocleidomastiod muscle

• As the artery ascends ,it passes deep to the post. Belly of digastric and stylohyoid muscle and terminates behind the neck of the mandible by dividing into the maxillary and superficial temporal arteries.

relationsIN THE CAROTID TRIANGLE Superficially—Cervical branch of facial nerve Hypoglossal nerve Facial,lingual,and superior thyriod veins Deep to the artery— Wall of pharynx Superior laryngeal nerve Ascending pharyngeal artery

ABOVE THE CAROTID TRIANGLE

Lies deep in the substance of the parotid triangle.

Within the gland, it is relatedSuperficially—Retromandibular vein Facial nerveDeep to the artery—ICAStructures passing between ECA and

ICA Styloglossus Stylopharyngeus IXth nerve Pharyngeal branch of Xth nerve Styloid process

BRANCHES

Total of 8 branches• ANTERIOR— Superior thyroid Lingual Facial• POSTERIOR-- Occipital Posterior auricular• MEDIAL— Ascending pharyngeal• TERMINAL— Maxillary Superficial

temporal

ANTERIOR BRANCHES

Superior thyriod arteryORIGIN:Arises from the front of ECA

below the tip of greater cornua of hyoid bone.

COURSE: Runs downwards and forwards parallel and just superficial to the extenal laryngeal nerve.

- It passes deep to omohyoid ,sternohyoid, sternothyroid and reaches the upper pole of lateral lobe of thyroid and divides into its terminal branches.

• It is accompanied by same-named vein.

BRANCHES: INFRAHYOID ARTERY STERNOCLEIDOMASTOID ARTERY SUPERIOR LARYNGEAL ARTERY CRICOTHYROID ARTERYGLANDULAR BRANCHES

LINGUAL ARTERYORIGIN:Arises from ECA opposite the

tip of the greater cornua of hyoid bone.

-It may arise in common with the facial artery, then becoming the linguofacial trunk.

COURSE:Divided into three parts by hypoglossus muscle.

FIRST PART – In carotid triangle, extends from origin to the posterior border of hyoglossus.

- Rests on the middle constrictor,forms a upward loop which is crossed by hypoglossal nerve. This loop permits the free movements of the hyiod bone.

SECOND PART – Deep to hyoglossus, runs horizontally forward along the upper border of hyoid bone between hyoglossus laterally and middle constrictor, stylohyoid ligament medially.

THIRD PART [ ‘arteria profunda linguae’ ]—Also called as deep lingual artery.

-It runs upwards along the anterior Border of hyoglossus, then horizontally forwards on the undersurface of tongue on each side of frenum linguae.

-In vertical course,it lies b/t the genioglossus medially & inferior longitudinal muscle of tongue laterally. Horizontal part is accompanied by lingual nerve.

BRANCHES

• SUPRAHYOID ARTERY• DORSAL LINGUAL ARTERY• SUBLINGUAL ARTERY• DEEP LINGUAL ARTERY

APPLIED ANATOMY

• In surgical removal of tongue , first part of artery is ligated before it gives any branches to the tongue or tonsil.

 LIGATION OF LINGUAL ARTERY : Incision – circling the lower pole of

submandibular gland.

- Skin, platysma, deep fascia incised, submandibular gland exposed , lifted, tendon of diagastric visible.

-Free border of mylohyoid muscle seen, hypoglossal nerve identified. Digastric tendon pulled downwards –enlarges the lingual triangle, hyoglossus muscle visible.

- Muscle divided bluntly, in the gap of its vertical fibers lingual artery found & ligated.

FACIAL ARTERY

ORIGIN: Arises from the ECA just above the tip of greater cornua of hyoid bone.

COURSE: Runs upwards in -- neck as cervical part ; face -- facial part.

Tortuous course—In neck allows free movements of pharynx during deglutition,

on face -- free movements of mandible , lips, & cheek during mastication & facial expressions, escapes traction & pressure during movements.  

.    

Cervical part : Cervical part Runs upwards on superior constrictor of pharynx deep to the posterior belly of digastric.

-It grooves the posterior border of submandibular gland, makes S-bend [2 loops] 1st winding down over submandibular gland & then up over the base of mandible.

Facial part:The vessel enters the face by winding around the base of the mandible, and by piercing the deep cervical fascia,at the anteroinferior angle of the masseter muscle.

• It runs upwards and forwards deep to the

risorus, to a point 1.25cm lateral to the angle of the mouth.

• Then it ascends by the side of the nose upto the medial angle of the eye where it terminates by anastomosing with the dorsal nasal branch of the ophthalmic artery.

BRANCHES

CERVICAL PART: ASCENDING PALATINE ARTERYTONSILLAR A RTERYGLANDULAR ARTERIES SUBMENTAL ARTERY

FACIAL PART:INFERIOR LABIAL ARTERY SUPERIOR LABIAL ARTERY LATERAL NASAL ARTERY ANGULAR ARTERY

• Facial Artery Compression:

Applying pressure to the facial artery as it passes over the inferior border of the mandible just anterior to the angle will diminish blood flow to that side.

LIGATION OF FACIAL ARTERY.

• Exposed --at the point crossing the lower border of mandible .

• Using contracted masseter as a landmark,

pulse of facial artery felt at point situated anterior to the attachment of masseter.

,

• Incision - at least half inch below the border of mandible & parallel to it.

Skin,platysma and deep cervical fascia cut

Artery is accompanied by facial vein & crossed superficially by marginal mandibular branch of facial nerve

Pulse of facial artery felt. Artery- isolated, tied & cut

POSTERIOR BRANCHES

OCCIPITAL ARTERYORIGIN:Arises in carotid

triangle from posterior aspect of ECA ,opposite the origin of facial artery.

-It is crossed at its origin by hypoglossal nerve.

COURSE: Passes backwards and upwards along & under cover of lower border of post. Belly of diagastric , crossing carotid sheath, hypoglossal & accessory nerves.

Then it runs deep to the mastiod process and muscles attached to it i.e.,sternocleidomastiod,

digastric etc.

Then crosses the rectus capitus lateralis,superior oblique,and semispinalis capitus muscle at the apex of the posterior triangle.

Finally it pierces the trapezius muscle and ascends in a tortuous course in the superficial fascia of the scalp.

Its terminal portion comes to lie along the greater occipital nerve.

 

BRANCHES

• STERNOMASTOID BRANCHES• AURICULAR BRANCH• MASTOID BRANCH• MENINGEAL BRANCH • MUSCULAR BRANCH

POSTERIOR AURICULAR ARTERYORIGIN: Arises from the

posterior aspect of the external carotid artery just above the posterior belly of the digastric.

COURSE:It runs upwards and backwards deep to parotid gland, but superficial to the styloid process.It crosses the base of the mastiod process and ascends behind the auricle.

BRANCHES

Stylomastoid. Auricular Occipital.

MEDIAL BRANCH

ASCENDING PHARYNGEAL ARTERY

ORIGIN:The smallest branch arising from the medial side of the external carotid artery, near its commencement.

COURSE: Ascends vertically between the internal carotid and the side of the pharynx, to the under surface of the base of the skull, lying on the Longus capitis.

BRANCHES

• PHARYNGEAL BRANCHES • PALATINE BRANCH•  PREVERTEBRAL BRANCHES• INFERIOR TYMPANIC ARTERY• MENINGEAL BRANCHES

TERMINAL BRANCHES

MAXILLARY ARTERYORIGIN:Large terminal branch

given off behind the neck of the mandible.

COURSE:  Divided into three parts by lateral pterygiod muscle.

• The first or mandibular portion passes horizontally forward, between the ramus of the mandible and the sphenomandibular ligament, where it lies parallel to and a little below the auriculotemporal nerve; it crosses the inferior alveolar nerve, and runs along the lower border of the lateral pterygiod.

  

• The second or pterygoid portion runs obliquely forward and upward superficial to the lower head of the lateral pterygiod.

•   The third or pterygopalatine portion passes between the two heads of the lateral pterygiod and pterygomaxillary fissure,to enter into the pterygopalatine fossa where it lies in front of the sphenopalatine ganglion.

BRANCHES First or Mandibular

Portion• Deep Auricular.• Anterior Tympanic.• Middle Meningeal• Accessory Meningeal• Inferior Alveolar.

Second or Pterygoid Portion

• Deep Temporal.• Masseteric.• Pterygoid.• Buccinator.

Third or Pterygopalatine Portion•Posterior Superior Alveolar.•Infraorbital.•Greater palatine artery•Pharyngeal.•Aretry of pterygiod canal•Sphenopalatine.

SUPERFICIAL TEMPORAL ARTERY

ORIGIN: The smaller of the two terminal branches of the external carotid, appears, to be the continuation of ECA. It begins in the substance of the parotid gland, behind the neck of the mandible.

COURSE: It runs vertically upwards crossing over the root of the zygomatic process

-about 5 cm. above this process it divides into two branches, a frontal and a parietal.

• Relations.—As it crosses the zygomatic process, it is covered by the Auricularis anterior muscle, and by a dense fascia; it is crossed by the temporal and zygomatic branches of the facial nerve and one or two veins, and is accompanied by the auriculotemporal nerve, which lies immediately behind it.

BRANCHES Besides some twigs to the parotid gland, to the

temporomandibular joint, and to the Masseter muscle, its branches are:• Transverse Facial.• Anterior Auricular.• Middle Temporal.• Frontal.• Parietal

INDICATIONS OF LIGATION• Uncontrolled

haemorrhage from Mouth Tongue Tonsils Maxillary sinus

• Acute massive epistaxis• Hereditary teliangectiasis• Nasopharyngeal

angiofibroma• Aneurysms( traumatic

aneurysms, of head and neck, parotid gland)

SURGICAL APPROACHES

• THERE ARE TWO SURGICAL EXPOSURES TO LIGATE THE ECA

» CAROTID TRIANGLE

» RETROMANDIBULAR FOSSA

PATIENT POSITION:

Supine position with shoulder on roll, neck extended and turned to opposite side.

LANDMARKS1)Upper border of

thyriod cartilage

2)Carotid bulb3)Internal jugular vein4)Anterior jugular vein-lower border of

mandible-Anterior border of

sternocleidomastiod muscle

Ligation in carotid triangle:KEY POINTS:-ICA doesn’t branch in the neck,except for

rare exceptions.

-ECA is usually anterior and superficial to ICA but not always.

-Follow the ECA to its 2nd branch,atleast.

Incision of skin at level of angle , behind anterior border of SCM, downwards parallel to the anterior border of the muscle to the level of cricoid

• Dissection is carried through skin,platysma,then anterior border of SCM is identified and retracted posteriorly.

• A clamp is used to dissect anterior to the muscle parallel to great vessels ,to identify carotid sheath.

• The CCA is carefully separated from other contents of sheath.

• The IJV, vagus nerve and ansa hypoglossi are retracted posteriorly.

• Usually at this place,a vesicular loop is placed loosely around CCA to obtain control.

• Then dissection is carried up along the CCA to the bifurcation area.

• At this point hypoglossal nerve is identified crossing the branches,it should be preserved.

-ICA doesn’t branch in the neck,except for rare exceptions.

-ECA is usually anterior and superficial to ICA but not always.

-Follow the ECA to its 2nd branch,atleast

-A 2-0 silk tie is placed between the superior thyriod and lingual arteries.

-The wound is closed in layers after the removal of vesicular loop from CCA .

COMPLICATIONS:-Damage to vital structures.

-Retrograde thrombus formation.

-Persistence of bleeding due to collateral flow.

.

LIGATION IN RETROMANDIBULAR FOSSA:

Done when there are maxillary artery injuries.

• Skin incision--- at line starting at the tip of mastoid process , circling the mandibular angle, continuing forward below the mandible one inch.

• Skin & posterior fibers of platysma are cut, the retromandibular vein or EJV is located, tied & cut.

• Branches of great auricular nerve cut -- permit mobilization of cervical lobe of parotid gland.  

• Attachment of parotid capsule to the anterior border of sternomastoid severed with scalpel. Parotid gland retracted .

• post. Belly of digastric ,stylohyoid muscle is visible. Above this stylomandibular ligament can be palpated if lower jaw of the patient is pulled forward.

• This movement--- widens the entrance into retromandibular fossa , tenses the stylomandibular ligament.

• Pulsations of ECA are felt , isolated & tied.

CONCLUSION

• After ligation of the external carotid artery the circulation is later re-established by the free communication between most of the large branches of the arteries and its corresponding artery in the opposite side and also anastomosing with the internal carotid sysytem