🥇 ARTERIA CARÓTIDA Y SUS RAMAS, ¡Fácil y Sencillo!

Irrigation of the Neck: Carotid System

Key Concepts:

• Common Carotid Artery (Primitive Carotid Artery)
• External Carotid Artery
• Internal Carotid Artery
• Branches of the External Carotid Artery: Superior Thyroid, Ascending Pharyngeal, Lingual, Facial, Occipital, Posterior Auricular
• Terminal Branches of the External Carotid Artery: Superficial Temporal, Internal Maxillary
• Carotid Sinus (Baroreceptor/Pressure Receptor)
• Carotid Corpuscle (Chemoreceptor)
• Neurovascular Bundle of the Neck
• Anastomosis
• Collateral Circulation

1. Introduction to Neck Irrigation

The video focuses on the arterial irrigation of the neck, specifically addressing the carotid system. It is divided into two parts, with this video covering the common carotid artery and its branches. The subsequent video will cover the subclavian artery's contribution to neck irrigation.

2. Origin of the Common Carotid Artery

• The entire arterial system originates from the left ventricle, leading to the aorta.
• The aorta has three parts: ascending aorta, aortic arch, and descending aorta.
• The arteries irrigating the neck originate from the aortic arch.
• The aortic arch gives rise to three main branches:
  • Brachiocephalic trunk (innominate artery)
  • Left common carotid artery
  • Left subclavian artery
• The right common carotid artery originates from the brachiocephalic trunk, while the left common carotid artery originates directly from the aortic arch.
• The brachiocephalic trunk divides into the right common carotid and right subclavian arteries.
• The sternoclavicular joints serve as anatomical reference points for locating the brachiocephalic trunk (right) and the beginning of the left common carotid artery (left).

3. Common Carotid Artery (Primitive Carotid)

• "Carotid" comes from the Greek word for "deep sleep," as compression of both carotid arteries can cause fainting.
• The common carotid artery ascends in the neck without giving off any direct branches to the neck itself.
• At the level of the upper edge of the thyroid cartilage (vertebra C4), the common carotid bifurcates into the internal and external carotid arteries.
• Relationships:
  • Posterior: Posterior face of the thyroid cartilage.
  • Medial: Esophagus, recurrent laryngeal nerve, inferior constrictor muscle of the pharynx.
  • Lateral: Prevertebral muscles, scalene muscles, cervical sympathetic chain, vagus nerve.
• The common carotid is contained within the carotid sheath, along with the internal jugular vein and vagus nerve, forming the neurovascular bundle of the neck.
• The omohyoid muscle's intermediate tendon crosses the common carotid at the level of C6 (cricoid cartilage).

4. Internal Carotid Artery

• The internal carotid artery does not give off any branches in the neck. Its primary function is to irrigate the skull and brain.
• It has four portions, but only the cervical portion is relevant to neck anatomy.
• The cervical portion extends from C4 (bifurcation point) to the carotid foramen in the temporal bone.
• Relationships (Cervical Portion):
  • Lateral: Sternocleidomastoid, posterior digastric, stylohyoid, glossopharyngeal nerve (IX), hypoglossal nerve (XII), occipital artery.
  • Medial: Constrictor muscles of the pharynx (inferior, middle, superior).
  • Anterolateral: Internal jugular vein (within the carotid sheath).
  • Posterior: Prevertebral muscles, scalene muscles, cervical sympathetic chain (superior cervical ganglion), vagus nerve.

5. Carotid Sinus and Carotid Corpuscle

• Carotid Sinus: A dilation at the beginning of the internal carotid artery. It contains baroreceptors (pressure receptors) that detect blood pressure changes. High blood pressure triggers the receptors to signal the body to lower it.
• Carotid Corpuscle: Located at the bifurcation of the common carotid artery, outside the walls of the arteries. It is a chemoreceptor that detects CO2 and oxygen levels in the blood. It signals the body to increase oxygen intake or eliminate CO2 when levels are abnormal.
• The carotid corpuscle is innervated by the vagus and glossopharyngeal nerves.

6. External Carotid Artery

• The external carotid artery ascends in the lateral neck, then becomes posterior to the internal carotid.
• It pierces the parotid gland, and its two terminal branches (internal maxillary and superficial temporal) are said to originate within the gland.
• Relationships:
  • Lateral: Digastric, sternocleidomastoid, platysma, hypoglossal nerve, stylohyoid.
  • Medial: Constrictor muscles of the pharynx, styloglossus, stylopharyngeus, glossopharyngeal nerve.
• The styloglossus, stylopharyngeus, and glossopharyngeal nerve are medial relations of the external carotid but lateral relations of the internal carotid, positioning themselves between the two arteries.
• The external carotid originates at C4 and ends at the midpoint of an imaginary line from the angle of the mandible to the mastoid process (approximately at the earlobe).

7. Branches of the External Carotid Artery

The external carotid artery gives off six main branches in the neck:

• Superior Thyroid Artery:
  • Originates from the anterior surface of the external carotid.
  • Branches:
    • Infrahyoid branch: Anastomoses with the contralateral infrahyoid artery along the lower edge of the hyoid bone.
    • Superior laryngeal artery: Pierces the thyrohyoid membrane along with the internal branch of the superior laryngeal nerve and the superior laryngeal vein.
    • Sternocleidomastoid branch.
    • Cricothyroid branch: Anastomoses with the contralateral cricothyroid artery at the level of the cricothyroid muscle.
    • Glandular branches: Supply the thyroid gland and anastomose with contralateral glandular branches along the upper edge of the thyroid gland.
• Ascending Pharyngeal Artery:
  • Originates from the medial surface of the external carotid.
  • Ascends along the constrictor muscles of the pharynx (inferior, middle, superior).
  • Branches: Pharyngeal branches, meningeal branch (enters the skull).
• Lingual Artery:
  • Originates from the anterior surface of the external carotid, below the greater horn of the hyoid bone.
  • Divided into three portions based on its relationship to the hyoglossus muscle:
    • Posterior portion: Posterior to the hyoglossus. Branch: Suprahyoid artery.
    • Deep portion: Deep to the hyoglossus. Branch: Dorsal artery of the tongue.
    • Anterior portion: Anterior to the hyoglossus. Branches: Sublingual artery, deep artery of the tongue (ranine artery).
• Facial Artery:
  • Originates from the anterior surface of the external carotid, above the greater cornu of the hyoid bone.
  • Has a cervical portion (in the neck) and a facial portion (begins at the lower edge of the mandible).
  • Cervical portion branches:
    • Ascending palatine artery: Supplies the soft palate and pharynx.
    • Tonsillar branch: Pierces the superior constrictor muscle and supplies the palatine tonsils.
    • Glandular branches: Supply the submandibular gland.
    • Submental artery: Runs along the lower edge of the mandible towards the chin.
  • The facial artery terminates in the inner corner of the eye, anastomosing with branches of the ophthalmic artery.
• Occipital Artery:
  • Originates from the posterior surface of the external carotid, at the same level as the facial artery.
  • Initially lateral to the hypoglossus nerve, then becomes medial as it ascends.
  • Divided into three portions based on its relationship to the sternocleidomastoid muscle:
    • Anterior portion: Anterior to the sternocleidomastoid.
    • Deep portion: Deep to the sternocleidomastoid.
    • Posterior portion: Posterior to the sternocleidomastoid.
  • Branches:
    • Sternocleidomastoid branch.
    • Meningeal branches.
    • Occipital branches (to the scalp).
    • Descending occipital artery: Anastomoses with branches of the subclavian artery (deep cervical and superficial cervical arteries), forming a collateral circulation in the neck.
• Posterior Auricular Artery:
  • Originates from the posterior surface of the external carotid.
  • Passes over the digastric and sternocleidomastoid muscles.
  • Reaches the pinna (auricle) and divides into two branches:
    • Occipital branch.
    • Auricular branch.
  • Additional branches:
    • Posterior tympanic branch (to the auditory canal).
    • Stylomastoid branch (parotid branch).

8. Terminal Branches of the External Carotid Artery

• Superficial Temporal Artery
• Internal Maxillary Artery

These are not discussed in detail as they are studied in the context of the skull.

9. Conclusion

The video provides a detailed overview of the carotid system's contribution to neck irrigation, focusing on the common carotid artery, its bifurcation into the internal and external carotid arteries, and the specific branches of the external carotid artery that supply the neck. It emphasizes anatomical relationships, key landmarks, and the functional significance of structures like the carotid sinus and carotid corpuscle. The importance of collateral circulation through anastomoses is also highlighted. The next video will cover the subclavian artery's role in neck irrigation.