Atlas of Anatomy. Head and Neuroanatomy. Michael Schuenke

3 Blood Vessels of the Head and Neck

3.1 Arteries of the Head, Overview and External Carotid Artery

A Overview of the arteries of the head

Left lateral view. The common carotid artery divides into the internal carotid artery and external carotid artery at the carotid bifurcation, which is at the approximate level of the fourth cervical vertebra. The carotid body (not shown) is located at the carotid bifurcation. It contains chemoreceptors that respond to oxygen deficiency in the blood (hypoxia) and to changes in pH (both are important in the regulation of breathing). While the external carotid artery divides into eight branches (seeD), the internal carotid artery does not branch further before entering the skull (see p. 246, cerebral vessels), where it mainly supplies blood to the brain. It also gives off branches that supply areas of the facial skeleton (see p. 60).

C Branches of the external carotid artery: typical anatomy and variants (after Lippert and Pabst)

a In typical cases (50%) the facial artery, lingual artery, and superior thyroid artery arise from the external carotid artery above the carotid bifurcation.

b-f Variants:

b, c The superior thyroid artery arises at the level of the carotid bifurcation (20%) or from the common carotid artery (10%).

d-f Two or three branches combine to form a common trunk: linguofacial trunk (18%), thyrolingual trunk (2%), or thyrolinguofacial trunk (1 %).

В Branches of the external carotid artery

a Left lateral view, b anterior view.

The four groups of branches of the external carotid artery are shown in different colors (anterior branches: red, medial branch: blue, posterior branches: green, terminal branches: brown).

Certain branches of the external carotid artery (facial artery, red) communicate with branches of the internal carotid artery (terminal branches of the ophthalmic artery, purple) through anastomoses in the facial region b. Extracerebral branches of the internal carotid artery are described onp.60.

D Overview of the branches of the external carotid artery (more distal branches are described in the units below).

Subsequent units deal with the arteries of the head as they are grouped in the table below, followed by the branches of the internal carotid artery and the veins.

Name of the branches	Distribution
Anterior branches:
• Superior thyroid artery	• Larynx, thyroid gland
• Lingual artery	• Oral floor, tongue
• Facial artery	• Superficial facial region
Medial branch:
• Ascending pharyngeal artery	• Plexus to the skull base
Posterior branches:
• Occipital artery	• Occiput
• Posterior auricular artery	• Ear
Terminal branches:
• Maxillary artery	• Masticatory muscles, posteromedial part of the facial skeleton, meninges
• Superficial temporal artery	• Temporal region, part of the ear

3.2 External Carotid Artery:

Anterior, Medial, and Posterior Branches

A Facial artery, occipital artery, and posterior auricular artery and their branches

Left lateral view. An important anterior branch of the external carotid artery is the facial artery, which gives off branches in the neck and face. The principal cervical branch is the ascending palatine artery; the tonsillar branch is ligated during tonsillectomy. Of the facial branches, the superior and inferior labial arteries combine to form an arterial circle around the mouth. The terminal branch of the facial artery, the angular artery, anastomoses with the dorsal nasal artery. The latter vessel is the terminal branch of the ophthalmic artery, which arises from the internal carotid artery. Because there are extensive arterial anastomoses, facial injuries have a tendency to bleed profusely but also tend to heal quickly and well owing to the copious blood supply. The pulse of the facial artery is palpable at the anterior border of the masseter muscle insertion on the mandibular ramus. The principal branches of the posterior auricular artery include the posterior tympanic artery and the parotid artery (b).

В Superior thyroid artery, ascending pharyngeal artery and their branches

Left lateral view. The superior thyroid artery is typically the first branch to arise from the external carotid artery. One of the anterior branches, it supplies the larynx and thyroid gland. The ascending pharyngeal artery springs from the medial side of the external carotid artery, usually arising above the level of the superior thyroid artery. The level at which a vessel branches from the external carotid artery does not necessarily correlate with the course of the vessel.

C Origin of the ascending pharyngeal artery: typical case and variants (after Lip pert and Pabst) a In typical cases (70%) the ascending pharyngeal artery arises from the external carotid artery.

b-d Variants:

The ascending pharyngeal artery arises from b the occipital artery (20%), c the internal carotid artery (8%), or d the facial artery (2%).

Branch	Distribution
Anterior branches: • Superior thyroid artery (see B)
-Glandular branches	• Thyroid gland
- Superior laryngeal artery	• Larynx
- Sternocleidomastoid branch	• Sternocleidomastoid muscle
• Lingual artery (see D)
- Dorsal lingual branches	• Base of tongue, epiglottis
-Sublingual artery	• Sublingual gland, tongue,
- Deep lingual artery	oral floor, oral cavity • Tongue
• Facial artery (see A)
- Ascending palatine artery	• Pharyngeal wall, soft palate,
- Tonsillar branch	pharyngotympanic tube • Palatine tonsil (main branch)
- Submental artery	• Oral floor, submandibular gland
- Labial arteries	• Lips
- Angular artery	• Nasal root
Medial branch: • Ascending pharyngeal artery (see B)
- Pharyngeal branches	• Pharyngeal wall
- Inferior tympanic artery	• Mucosa of middle ear
- Posterior meningeal artery	• Dura, posterior cranial fossa
Posterior branches: • Occipital artery (see A)
- Occipital branches	• Scalp, occipital region
- Descending branch	• Posterior neck muscles
• Posterior auricular branch (see A)
- Stylomastoid artery	• Facial nerve in the facial canal
- Posterior tympanic artery	• Tympanic cavity
- Auricular branch	• Posterior side of auricle
- Occipital branch	• Occiput
- Parotid branch	• Parotid gland

3.3 External Carotid Artery: Terminal Branches

В The two terminal branches of the external carotid artery with their principal branches

Branch		Distribution
Maxillary artery Mandibular part:	• Inferior alveolar artery	• Mandible, teeth, gingiva (the mental branch is its terminal branch)
	• Middle meningeal artery (see C)	• Calvaria, dura, anterior and middle cranial fossae
	• Deep auricular artery	• Temporomandibularjoint, external auditory canal
	• Anterior tympanic artery	• Tympanic cavity
Pterygoid part:	• Masseteric artery	• Masseter muscle
	• Deep temporal branches	• Temporalis muscle
	• Pterygoid branches	• Pterygoid muscles
	• Buccal artery	• Buccal mucosa
Pterygopalatine part:	• Posterior superior alveolar artery	• Maxillary molars, maxillary sinus, gingiva
	• Infraorbital artery	• Maxillary alveoli
	• Descending palatine artery - Greater palatine artery	• Hard palate
	- Lesser palatine artery	• Soft palate, palatine tonsil, pharyngeal wall
	• Sphenopalatine artery - Lateral posterior nasal arteries	• Lateral wall of the nasal cavity, conchae
	- Posterior septal branches	• Nasal septum
Superficial temporal artery	• Transverse facial artery	• Soft tissues below the zygomatic arch
	• Frontal and parietal branches	• Scalp of the forehead and vertex
	• Zygomatico-orbital artery	• Lateral orbital wall

C Selected clinically important branches of the maxillary artery

a Right middle meningeal artery, b left infraorbital artery, c right sphenopalatine artery with its branches that supply the nasal cavity. The middle meningeal artery passes through the foramen spinosum into the middle cranial fossa. Despite its name, it supplies blood not just to the meninges but also to the overlying calvaria. Rupture of the middle meningeal artery by head trauma results in an epidural hematoma (see p.262). The infraorbital artery is a branch of the maxillary artery and thus of the external carotid artery, while the supraorbital artery (a branch of the ophthalmic artery) is a terminal branch of the internal carotid artery. These vessels provide a path for a potential anastomosis between the external and internal carotid arteries. When severe nasopharyngeal bleeding occurs from branches of the sphenopalatine artery (a branch of the maxillary artery), it may be necessary to ligate the maxillary artery in the pterygopalatine fossa (see pp. 100,110; see also C, p.61).

D Superficial temporal artery

Left lateral view. Particularly in elderly or cachectic patients, the often tortuous course of the frontal branch of this vessel can easily be traced across the temple. The superficial temporal artery may be involved in an inflammatory autoimmune disease (temporal arteritis), which can be confirmed by biopsy of the vessel. The patients, usually elderly males, complain of severe headaches.

3.4 Internal Carotid Artery:

Branches to Extracerebral Structures

A Subdivisions of the internal carotid artery and branches that supply extracerebral structures of the head

a Medial view of the right internal carotid artery in its passage through the bones of the skull, b Anatomical segments of the internal carotid artery and their branches. The internal carotid artery is distributed chiefly to the brain but also supplies extracerebral regions of the head. It consists of four parts (listed from bottom to top):

• Cervical part

• Petrous part

• Cavernous part

• Cerebral part

The petrous part of the internal carotid artery (traversing the carotid canal) and the cavernous part (traversing the cavernous sinus) have a role in supplying extracerebral structures of the head. They give off additional small branches that supply local structures and are usually named for the areas they supply. Only specialists may be expected to have a detailed knowledge of these branches. Of special importance is the ophthalmic artery, which arises from the cerebral part of the internal carotid artery (see B).

В Ophthalmic artery

a Superior view of the right orbit, b Anterior view of the facial branches of the right ophthalmic artery.

Panel a shows the origin of the ophthalmic artery at the internal carotid artery. The ophthalmic artery supplies blood to the eyeball itself and to the orbital structures. Some of its terminal branches are distributed to the eyelid and portions of the forehead (b). Other terminal branches (anterior and posterior ethmoidal arteries) contribute to the supply of the nasal septum (see C).

Note: Branches of the lateral palpebral artery and supraorbital artery (b) may form an anastomosis with the frontal branch of the superficial temporal artery (territory of the external carotid artery) (seep.55). With atherosclerosis of the internal carotid artery, this anastomosis may become an important alternative route for blood to the brain.

C Vascular supply of the nasal septum

Left lateral view. The nasal septum is another region in which the internal carotid artery (anterior and posterior ethmoidal arteries, green) meets the external carotid artery (sphenopalatine artery, yellow). A richly vascularized area on the anterior part of the nasal septum, called Kiesselbach’s area (blue), is the most common site of nosebleed. Since Kiesselbach’s area is an area of anastamosis, it may be necessary to ligate the sphenopalatine/maxillary artery and/or the ethmoidal arteries through an orbital approach, depending on the source of the bleeding.

3.5 Veins of the Head and Neck: Superficial Veins

A Superficial head and neck veins and their drainage to the brachiocephalic vein

Left lateral view. The principal vein of the neck is the internal jugular vein, which drains blood from the interior of the skull (including the brain). Enclosed in the carotid sheath, the left internal jugular vein descends from the jugular foramen to its union with the subclavian vein to form the brachiocephalic vein. The main tributaries of the internal jugular vein in the head region are the facial and thyroid veins. The external jugular vein drains blood from the occiput (occipital vein) and nuchal region to the subclavian vein, while the anteriorjugular vein drains the superficial anterior neck region. Besides these superficial veins, there are more deeply situated venous plexuses (orbit, pterygoid plexus, middle cranial fossa) that are described in the next unit. Note: The superficial veins are most closely related to the deep veins in the area of the angular vein, with an associated risk of spreading infectious organisms intracranially (see p.65).

В Overview of the principal veins in the head and neck

Left lateral view. Only the more important veins are labeled in the diagram. As at many other sites in the body, the course and caliber of the veins in the head and neck are variable to a certain degree, except for the largest venous trunk. The veins interconnect to form extensive anastomoses, some of which extend to the deep veins (see A, pterygoid plexus).

C Drainage of blood from the head and neck

Blood from the head and neck is drained chiefly by three jugular veins: the internal, external and anterior jugular veins. These veins have a variable size and course, but the anterior jugular vein is usually the smallest and most variable of the three. The external and internal jugular veins communicate by valveless anastomoses that allow blood to drain from the external jugular vein back into the internal jugular vein. This reflux is clinically significant, as it provides a route by which bacteria from the skin of the head may gain access to the meninges (see p. 65 for details). The neck is subdivided into spaces by multiple layers of cervical fascia. One fascia-enclosed space is the carotid sheath whose contents include the internal jugular vein. The other two jugular veins lie within the superficial cervical fascia.

Vein	Region drained	Relationship to deep cervical fasciae
• Internal jugularvein	* Interior of the skull (including the brain)	• Within the carotid sheath
			• External jugularvein	* Head (superficial)	• Within the superficial cervical fascia
• Anterior jugularvein	* Neck, portions of the head	• Within the superficial cervical fascia

3.6 Veins of the Head and Neck: Deep Veins

A Deep veins of the head: pterygoid plexus

Left lateral view. The pterygoid plexus is a venous network situated behind the mandibular ramus between the muscles of mastication. It has extensive connections with the adjacent veins.

В Deep veins of the head: orbit and middle cranial fossa

Left lateral view. There are two relatively large venous trunks in the orbit, the superior and inferior ophthalmic vein. They do not run parallel to the arteries. The veins of the orbit drain predominantly into the cavernous sinus. Orbital blood can also drain externally via the angular vein and facial vein. Because the veins are valveless, extracranial bacteria may migrate to the cavernous sinus and cause thrombosis in that venous channel (see E and p. 93).

C Veins of the occiput

Posterior view. The superficial veins of the occiput communicate with the dural sinuses by way of the diploic veins. These vessels, called emissary veins, provide a potential route for the spread of infectious organisms into the dural sinuses.

D Clinically important vascular relationships in the facial region

The facial artery and its branches and the terminal branch of the ophthalmic artery, the dorsal nasal artery, are clinically important vessels in the facial region because they may bleed profusely in patients who sustain midfacial fractures. The veins in this region are clinically important because they may allow infectious organisms to enter the cranial cavity. Bacteria from furuncles (boils) on the upper lip or nose may gain access to the cavernous sinus byway of the angular vein (see E).

E Venous anastomoses as portals of infection	Extracranial vein	Connecting vein	Venous sinus
	• Angularvein	• Superior ophthalmic vein	• Cavernous sinus *
• Very important clinically because the deep spread of bacterial infection from the facial region may result in cavernous sinus thrombosis (infection leading to clot formation that may occlude the sinus). Bacterial thrombosis is less common at other sites.	• Veins of palatine tonsil	• Pterygoid plexus,	• Cavernous sinus *
		inferior ophthalmic vein
	• Superficial temporal vein	• Parietal emissary vein	• Superior sagittal sinus
	• Occipital vein	• Occipital emissary vein	• Transverse sinus,
			confluence of the sinuses
	• Occipital vein, posterior auricular vein	• Mastoid emissary vein	• Sigmoid sinus
				• External vertebral venous plexus	• Condylar emissary vein	• Sigmoid sinus