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Irrigation of the Neck: Understanding the Common Carotid Artery

Introduction to Neck Irrigation

• The video introduces the topic of neck irrigation, focusing on arteries that supply blood to this area.

• It is stated that the discussion will be divided into two videos, with this one concentrating on the common carotid artery.

Overview of Carotid Arteries

• The common carotid artery has two branches: internal carotid and external carotid; emphasis is placed on the external carotid as it supplies most branches to the neck.

• Six main branches and two terminal branches of the external carotid are identified: ascending pharyngeal, superior thyroid, lingual, facial, occipital, posterior auricular arteries; terminal branches are superficial temporal and internal maxillary arteries.

Aorta and Its Branches

• The aorta's anatomy is explained as originating from the left ventricle and arching before descending; focus is given to its role in supplying neck arteries.

• The first branch from the aortic arch is identified as the brachiocephalic trunk (innominate trunk), which further divides into right common carotid and right subclavian arteries.

Origins of Common Carotid Arteries

• Differences in origins between right and left common carotids are highlighted: right originates from brachiocephalic trunk while left arises directly from aortic arch.

• Anatomical reference points for locating these arteries include sternum and clavicle; specific locations for both common carotids are discussed.

Significance of "Carotid"

• The term "carotid" derives from Greek meaning "deep sleep," referencing how compressing these arteries can induce fainting or syncope.

Anatomy of Common Carotid Artery

• The left common carotid ascends without giving direct branches until it bifurcates at thyroid cartilage level (C4 vertebra).

• Relationships of common carotid artery with surrounding structures such as esophagus, recurrent laryngeal nerve, prevertebral muscles, scalenes, cervical sympathetic chain, vagus nerve are described.

Neurovascular Package

Understanding the Internal and External Carotid Arteries

Anatomy of the Internal Carotid Artery

• The internal carotid artery is largely covered by the sternocleidomastoid muscle, with its intermediate tendon crossing over the primitive carotid at C6, near the cricoid cartilage.

• The internal carotid does not branch in the neck; it solely supplies blood to the skull and brain. Its cervical portion extends from C4 to where it pierces the skull through the carotid foramen.

• Anatomical relationships include lateral coverage by muscles like sternocleidomastoid and posterior digastric, as well as proximity to cranial nerves IX (glossopharyngeal) and XII (hypoglossal).

• Medially, it is associated with pharyngeal constrictor muscles and lies within the carotid sheath alongside the internal jugular vein and vagus nerve.

• At its origin, two structures are present: the carotid sinus (a dilation acting as a pressure receptor) and carotid corpuscles (chemoreceptors monitoring CO2 and oxygen levels).

Overview of External Carotid Artery

• The external carotid artery branches supply blood to structures in the neck. It ascends laterally before bifurcating into terminal branches: internal maxillary artery and superficial temporal artery.

• Relationships of external carotid include lateral connections with digastric muscle, sternocleidomastoid, platysma muscle, hypoglossal nerve, and stylohyoideus muscle.

• Medial relationships involve pharyngeal muscles such as glossopharyngeus, styloglossus, stylopharyngeus along with their respective nerves.

• The external carotid originates at C4 level and ends at an imaginary line drawn from lower jaw angle to mastoid process.

External Carotid Artery and Its Branches

Anatomy of the External Carotid Artery

• The external carotid artery anatomically ends at the midpoint of a line corresponding to the earlobe, where it gives rise to its two terminal branches.

Branches of the External Carotid Artery

• The six main branches from the external carotid artery that supply the neck include:

• Superior thyroid artery (anterior face)

• Ascending pharyngeal artery (medial face)

• Lingual artery (anterior face)

• Facial artery (anterior face)

• Occipital artery (posterior face)

• Posterior auricular artery

• The two terminal branches are superficial temporal and internal maxillary arteries, which are not covered in this section as they pertain to skull anatomy.

Superior Thyroid Artery

• The superior thyroid artery arises from the anterior surface and has five notable branches:

• Superior laryngeal artery (perforates thyroid membrane)

• Sternocleidomastoid branch (supplies sternocleidomastoid muscle)

• Cricothyroid branch (supplies cricothyroid muscle)

• Additional branches include glandular branches for thyroid glands and an infrahyoid branch that anastomoses with its counterpart on the opposite side.

Ascending Pharyngeal and Lingual Arteries

• The ascending pharyngeal artery supplies various constrictor muscles of the pharynx and gives off meningeal branches entering the skull.

• The lingual artery emerges below the greater horn of hyoid bone, divided into three portions relative to hyoglossus muscle:

• First portion: posterior to hyoglossus

• Second portion: deep to hyoglossus

• Third portion: anterior to hyoglossus

Branches of Lingual Artery

• Key branches from the lingual artery include:

• Suprahyoid artery (above hyoid bone)

• Dorsal tongue artery (from second portion deep to hyoglossus)

• From its third portion, it gives rise to sublingual and renin arteries, also known as deep arteries of the tongue.

Facial Artery Overview

• The facial artery originates above the greater cornu of hyoid bone with cervical and facial portions.

Irrigation of the Neck: Understanding Arterial Branches

Tonsillar and Glandular Branches

• The tonsillar branch pierces the superior constrictor muscle of the pharynx, providing irrigation to the palatine tonsils visible when the mouth is opened.

• Glandular branches irrigate the submandibular or submental glands, with a notable submental branch that runs along the lower edge of the jaw to the chin.

Facial Artery and Its Anastomoses

• The facial artery ends by anastomosing in the inner corner of the eye with branches from the ophthalmic artery, marking its termination point.

Occipital Artery Anatomy

• The occipital artery emerges at a similar level as the facial artery but travels towards the posterior face; it initially lies lateral to hypoglossus before becoming medial as it ascends.

• This artery has three portions relative to sternocleidomastoid: anterior, deep, and posterior. It also gives off a sternocleidomastoid branch and meningeal branches towards occipital bone.

Collateral Circulation Contributions

• The descending occipital artery plays a crucial role in collateral circulation by anastomosing with branches from both deep cervical and superficial cervical arteries of the subclavian.

Posterior Auricular Artery Overview

• The posterior auricular artery arises from the external carotid's posterior surface, branching into occipital and auricular branches upon reaching the pinna.

• Additional branches include a posterior tympanic branch entering the auditory canal and a mastoid style branch directed towards styloid process.

Conclusion