Anatomy - Dolichoarteriopathy – Severe kinking with luminal narrowing type I/III of the right internal carotid artery

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Common carotid artery

Origin	Left: Aortic arch Right: Brachiocephalic trunk
Course	Ascends posterior to the sternocleidomastoid muscle Within the carotid sheath of cervical fascia
Bifurcation	Carotid bifurcation (bifurcatio carotidis): Bifurcation into external and internal carotid artery
Supplies	1. Internal carotid artery Brain Eye Forehead Anterior nasal cavity 2. External carotid artery Extracranial structures on head and neck

Internal carotid artery

Origin

Branch of the common carotid artery (bifurcatio carotidis)

Caudocephalad course

1. Cervical portion

Segment between the origin of the common carotid artery and the base of the skull
Enters the cranial cavity via the carotid canal
Does not give off any branches

2. Petrosal portion

Courses in the petrosal portion of the temporal bone
Gives off smaller branches to the tympanic cavity and pterygoid canal

3. Cerebral portion

Courses in the subarachnoid space
Perforates the dura mater
Branches into the anterior and middle cerebral arteries
The anterior cerebral artery communicates with its contralateral counterpart via the anterior communicating artery

The circle of Willis is an arterial vascular ring at the base of the brain and supplies blood to the brain. It comprises the following vessels - from anterior to posterior:

Anterior communicating artery (azygous)
Anterior cerebral artery (left and right)
Internal carotid artery (left and right) and its direct extension - the middle cerebral artery
Posterior communicating artery (left and right)
Posterior cerebral artery (left and right; both arising from the basilar artery)

However, the circle of Willis is quite variant in terms of branch caliber and anastomoses (hypoplasia of some branches and even agenesis in some segments). This is clinically important for the collateral blood supply in stenoses.

External carotid artery

The region supplied by the external carotid artery can be divided into four groups according to their localization: anterior, middle, and posterior group and terminal branches.

1. Anterior group

Branches (cranial -> caudal)	Branches/Rami	Supply
Thyroid artery	R. infrahyoideus R. cricothyreoideus R. sternocleidomastoideus Homonymous muscles Superior laryngeal artery Laryngeal interior Rr. glandulares Thyroid
Lingual artery	R. suprahyoideus Hyoid Rr. dorsales linguae Dorsum of tongue Sublingual artery Sublingual gland Deep lingual artery Tip of tongue
Facial artery	Ascending palatine artery Soft palate Tonsils Pharynx Submental artery Submandibular glands Suprahyoid muscles Inferior labial artery Lower lip Superior labial artery Upper lip Angular artery Medial angle of eye

2. Middle group

Branches (cranial -> caudal)	Branches/Rami	Supply
Ascending pharyngeal artery	Rr. pharyngeales Pharynx Inferior tympanic Tympanic cavity Posterior meningeal artery Dura mater

3. Posterior group

Branches (cranial -> caudal)	Branches/Rami	Supply
Occipital artery	R. mastoideus Mastoid cells Rr. occipitales Occipital region R. meningeus Dura mater
Posterior auricular artery	R. auricularis External ear R. occipitalis Occipital region Stylomastoid artery Facial nerve Tympanic cavity Mastoid cells Posterior tympanic artery Tympanic cavity Mastoid cells Rr. pharyngeales Pharynx R. parotideus Parotid gland

4. Terminal branches

Branches (cranial -> caudal)			Supply
Superficial temporal artery	Transverse artery of face Face Zygomatico-orbital artery Lateral corner of the eye Middle temporal artery Temporal muscle R. frontalis Scalp
Maxillary artery	Mandibular part	Deep auricular artery Temporomandibular joint External auditory canal Inferior tympanic artery Tympanic cavity Inferior alveolar artery Teeth Mandibula R. mylohyoideus: Floor of mouth R. mentalis: Chin Middle meningeal artery Meninges
	Pterygoid part	Masseteric artery Masseter muscle Rr. pterygoidei Pterygoid muscles Deep temporal arteries Temporal muscle Buccal artery Buccinator muscle
	Pterygopalatine part	Posterior superior alveolar artery Teeth Maxilla Infraorbital artery Maxilla Descending palatine artery Tonsils Soft palate Sphenopalatine artery Nasal cavity Nasal septum Artery of pterygoid canal Pharynx Tympanic cavity

Venous system

The brachiocephalic vein is formed by the confluence of the superficial and deep venous system in the venous angle ("Pirogoff angle") and drains into the superior cava.

1. Superficial veins

External jugular vein

Runs caudad in the lateral neck and is covered by the platysma
Perforates the superficial lamina of the cervical fascia
Joins the internal jugular vein at the venous angle, possibly also earlier, which then drains into the superior vena cava

Anterior jugular vein

Most often takes an inferior course on the sternocleidomastoid muscle
The anterior jugular veins from both sides unite in the suprasternal space to the jugular (transverse) venous arch
Empties into the venous angle or external jugular vein

2. Deep veins

Internal jugular vein

See below

Subclavian vein

Continuation of axillary vein
Runs caudad anterior to the major scalene muscle
Joins the internal jugular vein at the venous angle to give rise to the brachiocephalic vein -> superior vena cava

Internal jugular vein

Origin	Extracranial origin: Confluence of sigmoid and inferior petrosal sinuses Originates as superior bulb of the jugular vein Enters the base of the skull through the jugular foramen
Course	Parallels the common carotid artery within the carotid sheath Unites with the subclavian vein at the venous angle-> brachiocephalic vein
Tributaries (cranial -> caudal)	Superior ophthalmic vein Facial nerve Retromandibular vein Pterygoid plexus Pharyngeal veins Lingual vein Superior and middle thyroid vein Sternocleidomastoid vein
Drainage area	Entire brain Face Thyroid

Lymphatics
The lymphatic drainage of head and neck empties into the paired jugular trunks
Left jugular trunk
- Drainage area: Left side of the head and neck
- Draining into: Thoracic duct
Right jugular trunk
- Drainage area: Right side of the head and neck
- Draining into: Right lymphatic duct

Nervous system

1. Cervical plexus - primarily motor innervation

Nerve	Segments	Course/special aspects	Motor innervation	Sensory innervation
Ansa cervicalis	Superior root C1, C2 Inferior root C2, C3 Superior root parallels the hypoglossal nerve Geniohyoid muscle Infrahyoid muscles			Ø
Phrenic nerve	C3 - C5 Descends obliquely across the anterior scalene muscle In mediastinum between mediastinal pleura and pericardium to the diaphragm Diaphragm			R. pericardiacus: Pericardium Mediastinal pleura Diaphragmatic pleura R. phrenicoabdominalis: Peritoneum Inferior aspect of diaphragm Peritoneum Gallbladder
R. sternocleidomastoideus	C1 - C3 Forms a plexus with branches of the accessory nerve (XII) Sternocleidomastoid muscle (together with XII)			Ø
R. trapezius	C2 - C4 Trapezius muscle (together with XII)			Ø

2. Cervical plexus - solely sensory innervation

Nerve	Segments	Course, special aspects	Innervation
Minor occipital nerve	C2, C3 Courses posterior to the sternocleidomastoid muscle Lateral occiput
Great auricular nerve	C2, C3 Crosses the sternocleidomastoid muscle Skin inferior to auricle
Transverse cervical nerve	C2, C3 Crosses the sternocleidomastoid muscle R. superior: Anastomoses with R. colli of facial nerve Anterior cervical region
Supraclavicular nerves	C3, C4 Fan-shaped course toward clavicle Clavicle Anterior region of chest Shoulder

3. Sympathetic nerve

Sympathetic ganglion	Special aspects	Nerve branches, innervation
Superior cervical ganglion	Level cervical vertebra 2/3 Most branches parallel the corresponding arteries Jugular nerve -> glossopharyngeal and vagus nerves Internal carotid nerve -> deep petrosal nerve External carotid nerves -> salivary glands Rr. laryngopharyngei -> pharyngeal plexus Superior cardiac nerve -> cardiac plexus Fibers to the epiphysis
Middle cervical ganglion	Different localizations, not always present Middle cardiac nerve -> cardiac plexus
Inferior cervical ganglion	often common with first ganglion of sympathetic chain to stellate ganglion Inferior cardiac nerve -> cardiac plexus Vertebral nerve - > sympathetic fibers to cranial nerves Ansa subclavia -> linked with inferior and middle cervical ganglia when fused to stellate ganglion -> sympathetic fibers to sweat glands and skin vessels of upper extremity