What Is the Internal Carotid Artery?

Internal carotid artery: The internal carotid artery is one of the terminal branches of the common carotid artery. The upper edge of flat thyroid cartilage emanates from the common carotid artery. First at the posterolateral side of the external carotid artery, then turn to the posteromedial side and rise to the skull base, and then enter the cranial cavity through the carotid artery. The artery has no branches in the neck, and the branches in the skull are mainly distributed in the front 2/3 of the brain and the sight (see the vascular strips of the central nervous system brain for details). The line from the upper edge of the thyroid cartilage to the posterior edge of the mandible neck is the body surface projection of the internal carotid artery.

Branch of common carotid artery. It is located in the arterial stem of the brain. It is branched from the common carotid artery on the ventral side of the atlantooccipital joint and extends forward and upward through the rupture hole into the cranial cavity. It enters the cavernous sinus through the inferior petrosal sinus, forms an S-shaped bend in the cavernous sinus, and then extends forward through the cerebral dura mater. The branch is divided into the posterior communication branch, the anterior and middle arteries, and participates in the formation of the cerebral artery ring.

Chinese name: Internal carotid artery

Foreign name: internal carotid artery

Internal carotid artery anatomy

The internal carotid artery is divided by the common carotid artery at the plane of the upper edge of the thyroid cartilage. It initially resides behind the external carotid artery, then moves to its posteromedial side, rises along the lateral wall of the pharynx to the skull base, and passes outside the carotid canal of the temporal bone. The mouth enters the carotid canal and exits the carotid canal into the cranial cavity. In the carotid artery, the internal arteries are changed from vertical to horizontal and exit the tube at the rupture hole. The arteries pass through the cavernous sinus along the carotid sulcus on the outer side of the saddle. In the sinuses, the arterial flat sphenoidal saddle travels from the back to the front, and gradually deviates to the outside in the anterior direction; it reaches below the anterior bed process and then bends upward, exits the cavernous sinus surface and backwards on the inside of the anterior bed process, and enters the spider web. The submembranous cavity forms a forward convex curve, the curved upper part backs up above the posterior bed process, and then turns to the upper and outer sides to the bottom of the brain. The end is divided into the anterior cerebral artery and the middle cerebral artery. Because the internal carotid artery does not go straight in the intracranial path and has multiple bends, it can be divided into the cavernous sinus segment in the cavernous sinus, the upper segment of the bed process above the medial tip of the flat anterior process, and the end divided into terminal branches. Previous brain segments, etc. The cavernous sinus segment and the upper part of the bed process are collectively referred to as the siphon, the upper part of the bed process is the upper half of the siphon, and the cavernous sinus is the lower half of the siphon. The transition between the two is called the carotid siphon or siphon. Normally, the siphon can take the shape of "U", "C", "V", "S", etc. Elderly people can bend as arteriosclerosis becomes longer. Internal carotid angiography is commonly used clinically to diagnose intracranial space occupying lesions. The intracranial branches of the internal carotid artery include the ophthalmic artery, anterior cerebral artery, and middle cerebral artery. The line from the upper edge of the thyroid cartilage to the posterior edge of the jaw neck represents the body surface projection of the internal carotid artery.

Internal carotid artery and its surrounding structure

After the internal carotid artery was separated from the common carotid artery, it resided on the outside of the external carotid artery, and then slanted upwards and backwards on the inside of the external carotid artery. The internal carotid artery does not branch in the neck, and the line from the upper edge of the thyroid cartilage up to the posterior edge of the mandible neck, that is, the body surface projection of the internal carotid artery. After the internal carotid artery enters the carotid foramen, it advances in the carotid canal of the temporal bone rock, and then turns upward to enter the middle cranial fossa.

The internal carotid artery runs from the bottom to the top, with the hypoglossal nerve, the occipital artery, the posterior abdomen, and the external carotid artery across the superficial surface. Styloid hyoid bone ligament, styloid pharyngeal muscle, glossopharyngeal nerve and pharyngeal branch of vagus nerve pass through between internal and external carotid arteries. Inside the internal carotid artery, there are superior pharyngeal constrictors and tonsil fossa. Seen from the oropharynx, the internal carotid artery is about 3 cm behind the lower end of the pterygoid process, so removing the pterygium with a bite forceps will not damage the internal carotid artery. The internal carotid artery is located behind the junction of the posterior pharyngeal wall and the pharyngeal wall, and is about 1.5 cm away from the tonsils.

In the upper part, important adjacencies are: the upper sympathetic ganglia and the vagus nerve between the internal carotid artery and the long muscles of the head located behind it. The internal jugular vein passes from its outer or posterior direction. At this level, the accessory nerve and hypoglossal nerve usually run between the arteries and veins, and the transverse process of the first cervical spine is just behind it.

Internal carotid artery and carotid artery related diseases

Internal carotid cavernous sinus fistula

For some reason, the internal carotid artery cavernous sinus segment is damaged, and the arterial blood flows directly into the cavernous sinus through the injured breach, that is, the internal carotid cavernous sinus fistula is formed. The disease is divided into two types of traumatic and spontaneous, with the majority being traumatic.

Essential points of internal carotid artery diagnosis

(1) Most cases have a history of trauma, which is usually caused by crushing the head, causing fractures of the skull base, and directly or indirectly damaging the cavernous sinus segment of the internal carotid artery.

(2) After the traumatic brain injury, the protruded eyeballs gradually appear, accompanied by fluctuations in accordance with the pulse, ocular conjunctiva and varicose veins and edema, and even the eyelids cannot be closed, the bulbar conjunctiva is bleeding, the orbital and frontal veins are open.

(3) Palpitations of prominent eyeballs may be tremored, and vascular murmurs may be heard on the frontal, orbital, and temporal sides of the affected side to enhance systole. The common carotid artery was compressed, and the murmur disappeared or reduced, and the murmur on the contralateral side remained.

(4) The oculomotor nerve, the pulley nerve, the first and second trigeminal nerves, and the abductor nerve can all be oppressed by the high pressure in the cavernous sinus, resulting in obstruction of ophthalmic vein return, resulting in eye movement disorders, optic nerve edema or atrophy, and vision Decline and so on.

(5) The above manifestations occur simultaneously or successively in both eyes of bilateral fistula.

(6) Unilateral or bilateral carotid angiography can determine the location of fistula and blood circulation.

Internal carotid artery treatment

(I) Common carotid artery compression test: The patient lies on his back and presses the common carotid artery on the transverse process of the cervical vertebra at the plane of the upper edge of his thyroid cartilage. When the superficial temporal artery pulse disappears, the compression is effective. Each compression is 5 to 10 minutes, and gradually increases to 0.5 h, and the compression is performed 2 to 3 times a day.

(2) Depending on the specific conditions and technical conditions of the fistula, neck ligation of the carotid artery, isolated surgery and various embolizations can be selected.

(3) Advances in microneurosurgery, in order to open the cavernous sinus directly to find the fistula, suture or repair is possible. This method requires excellent equipment conditions, skilled technology and familiar anatomical knowledge.

CT CT findings of internal carotid artery

1. It can manifest as cavernous sinus enlargement, dilated supraocular veins, exophthalmos, and extraocular muscle thickening. Among them, dilated supraocular veins are the most specific imaging signs of CCF. Multislice spiral CT angiography section can show fistula.

2. Internal carotid artery aneurysms: Internal carotid artery aneurysms occur at the junction with the posterior communicating artery. Other parts include the cavernous sinus, the starting point of the ophthalmic artery, the terminal carotid artery bifurcation, and the anterior choroid Junction and so on.

3. Internal carotid artery distortion: Internal carotid artery distortion refers to deformities such as varicose veins, circular movements, and palate formation in the cervical segment. For a rare cerebrovascular disease. It can occur on one side or both sides. Generally, it is more or more severe on the right side. The disease is often congenital, but it can also be secondary to hypertensive arteriosclerosis, which causes the aortic arch to expand and lift, causing the relative lengthening and distortion of the branches of the aorta. Fibrous muscular dysplasia can also weaken and deform the arterial wall. The varicose veins of the internal carotid artery increase the blood flow resistance and affect the blood flow of the brain. In severe cases, it can cause insufficient blood supply to the brain. The chance of secondary internal carotid artery thrombosis is also more common. The clinical manifestations are similar to various other cerebral insufficiency diseases, and they often have paroxysmal consciousness and transient ischemic attacks, which are especially easy to induce when turning the neck. It is often diagnosed as a stroke. The neck physical examination can feel twisted, thickened, circular arteries, and murmurs can be heard, so it is easy to be misdiagnosed as carotid aneurysm, carotid bulboma, pharyngeal abscess, thyroid tumor and others. Blood-supplying tumors. Carotid angiography is most helpful in determining the diagnosis. Carotid angioplasty can be used to treat the arteries that have been twisted into the iliac crest freely, straighten out the excessively long part, and then perform anastomosis. The proximal end of the external carotid artery can also be transferred to the distal side of the twisted artery to replace the function of the twisted segment of the internal carotid artery. Intracranial and external artery bypass surgery, especially the superficial temporal artery and middle cerebral artery anastomosis, can also be applied to those with severe distortion.