The occipital artery is a blood vessel involved in supplying blood to the muscles of the neck and back. In addition, the artery supplies the occipital region (regio occipitalis). Pulse-synchronous tinnitus may be associated with disorders of the occipital artery, for example, arteriovenous fistulas or circulatory disturbances due to arteriosclerosis.
What is the occipital artery?
Part of the head and certain areas of the neck and back muscles receive arterial blood from the occipital artery. Because of its function, it is less commonly called the occipital artery in German. It branches off from the external carotid artery, also known as the external carotid artery, which in turn is a branch of the common carotid artery. The occipital artery divides in its course into different branches, which are known in technical language as rami. In the systemic or great circulation, arteries carry oxygen-rich blood from the lungs to more distant cells. Without an adequate supply of the respiratory gas, the cells of the human body are unable to function and eventually die. The oxygen-depleted blood flows out again via veins. However, in the pulmonary circulation, arteries carry deoxygenated blood and veins are responsible for carrying oxygenated blood.
Anatomy and structure
The occipital artery separates from the external carotid artery at the digastric muscle and continues toward the head (cranially), passing the internal carotid artery, internal jugular vein, vagus nerve, and accessorius nerve. At the temporal bone (Os temporale), the course of the occipital artery passes through the sulcus arteriae occipitalis. This is a groove in the Os temporale located in the pars mastoidea of the bone. In the occipital region (regio occipitalis), the branches of the occipital artery run under the scalp. The anatomy differentiates between five different branches: Ramus auricularis, Ramus descendens, Ramus meningeus, Rami musculares, and Ramus sternocleidomastoideus. They each supply different anatomical structures with arterial blood. Subsequently, the branches converge in the auricular artery and the superficial temporal artery. In some people, the occipital artery originates in the internal carotid artery rather than the external carotid artery. This deviation from the normal origin represents an anatomic variant. When the occipital artery branches from the external carotid artery, as in most cases, its origin is opposite the branch of the facial artery.
Function and Tasks
The function of the occipital artery is to supply blood to various regions, with its branches helping to distribute blood appropriately. The ramus auricularis conveys blood to the auricle (auricle auris), which is involved in acoustic perception and helps determine the direction of a sound by its spatial shape. Larger than the ramus auricularis and all other branches of the occipital artery is the ramus descendens, which is responsible for parts of the skin, for the periosteum (bone skin) of the regio occipitalis as well as for the trapezius muscle (Musculus trapezius). In contrast, the ramus meningeus is responsible for the blood supply to the meninges or dura mater at the posterior cranial fossa. Arterial blood flows through the rami musculares to suprahyoid muscles (digastric muscle and stylohyoid muscle) and back muscles (splenius muscle and longissimus capitis muscle). Finally, the sternocleidomastoid ramus provides supply to the sternocleidomastoid muscle, which is involved in lateral and backward head movements as a “head nodder” and serves as an auxiliary respiratory muscle when the head is immobile. In one anatomic variant, the sternocleidomastoid ramus branches not from the occipital artery but from the greater external carotid artery.
Diseases
Ringing in the ears can occur in association with the occipital artery. Also known as tinnitus aurium, they manifest as whistling, hissing, cracking, or other sounds that affected individuals perceive even though no external acoustic stimulus is present. Since numerous causes for tinnitus can be considered, an individual clarification is necessary in each case.Circulatory disorders of the occipital artery or other blood vessels are not the only possible basis of ringing in the ears: Tinnitus also frequently manifests as part of a hearing loss or as a result of high levels of psychological stress. Cervical vertebrae problems, increased intracranial pressure, tumors and Meniere’s disease are other potential causes. Impairment of hearing may accompany ringing in the ears, but does not occur in every case. In addition to possible other physiological aspects, tinnitus often places a psychological burden on those affected, which can result in further complaints such as sleep disturbances and concentration problems. Many patients experience tinnitus as demoralizing. Arteriovenous fistulas in the occipital artery can cause pulse-synchronous tinnitus. An arteriovenous fistula is a so-called short circuit between an artery and a vein: an unwanted connection forms between blood vessels. An undersupply of the area that depends on the artery is possible. In addition, the change in blood flow can result in the blood in the vein not being able to flow freely in the correct direction. Tinnitus resulting from such an arteriovenous fistula often manifests as a hissing sound. The short circuit between the artery and vein may be congenital or result from injury. Another possible cause of tinnitus is damage due to arteriosclerosis. The buildup of calcium, thrombi, fat or connective tissue constricts the interior of the blood vessel and can lead to complete occlusion. In addition, blood flow can entrain such obstructions and cause circulatory problems elsewhere.