The posterior auricular artery is a small branch of the external carotid artery that primarily supplies blood to the region behind the ear (auricular region) and portions of the scalp. It is one of the eight branches of the external carotid artery and is involved in the vascularization of the ear and surrounding tissues.
Location
The posterior auricular artery arises from the external carotid artery, just above the level of the digastric muscle, near the angle of the mandible. It ascends behind the ear, running between the external ear (auricle) and the mastoid process of the temporal bone. As it courses upward, it distributes blood to the auricular region, the scalp behind the ear, and portions of the middle ear.
Structure and Anatomy
Origin
The posterior auricular artery arises from the external carotid artery, near its terminal branches. Specifically, it originates just superior to the posterior belly of the digastric muscle and inferior to the origin of the occipital artery, making it one of the final branches of the external carotid before it bifurcates into the maxillary and superficial temporal arteries.
Course
After arising from the external carotid artery, the posterior auricular artery courses upward and posteriorly, passing behind the auricle (external ear). It travels between the auricle and the mastoid process of the temporal bone, which is the prominent bony structure located behind the ear. As it ascends, it runs superficially, making it accessible for palpation and easy to identify during surgical procedures involving the ear or mastoid region.
Branches
The posterior auricular artery gives off several important branches as it ascends, each contributing to the blood supply of specific anatomical regions:
- Stylomastoid Branch: This branch enters the stylomastoid foramen to supply the structures of the middle ear, including the facial nerve (within the facial canal) and the tympanic cavity. It plays a role in vascularizing the internal structures of the ear.
- Auricular Branch: The auricular branch provides blood supply to the posterior portion of the external ear (auricle), including the skin and cartilage. This branch is responsible for nourishing the structures of the auricle, particularly the region behind the ear.
- Occipital Branch: The posterior auricular artery also contributes to the blood supply of the posterior scalp through its occipital branch. This branch anastomoses with branches of the occipital artery, helping to form a network that provides blood to the scalp region.
Termination
The posterior auricular artery terminates by dividing into its terminal branches near the scalp behind the ear. These terminal branches help supply the posterior auricular region and the posterior scalp. The artery also forms anastomoses with other nearby arteries, including the occipital artery and superficial temporal artery, creating a vascular network in the head and neck region.
Anastomoses
The posterior auricular artery forms important anastomoses with nearby arteries, particularly the occipital artery and branches of the superficial temporal artery. These anastomotic connections contribute to a robust vascular network that ensures adequate blood flow to the scalp and auricular region. Additionally, its anastomoses with the superficial temporal artery provide collateral circulation, which is critical if one of the primary arteries is compromised.
Surrounding Structures
As it ascends, the posterior auricular artery is closely related to several important anatomical structures:
- Mastoid Process: The artery runs alongside the mastoid process of the temporal bone, providing blood to the surrounding tissues.
- Auricle: It supplies the posterior aspect of the external ear, including the skin and cartilage.
- Facial Nerve: The stylomastoid branch of the artery runs in close proximity to the facial nerve as it enters the stylomastoid foramen, which makes its blood supply important for the nerve’s function within the ear.
Function
Blood Supply to the External Ear (Auricle)
The posterior auricular artery is responsible for supplying blood to the posterior portion of the auricle, or external ear. Through its auricular branch, the artery nourishes the skin, cartilage, and soft tissues of the ear. This ensures that the auricle remains healthy, facilitating normal tissue maintenance and healing in case of injury. The artery’s role in providing blood to the posterior ear is crucial for the structural integrity and function of the external ear.
Vascularization of the Scalp Behind the Ear
Another critical function of the posterior auricular artery is its contribution to the blood supply of the scalp, particularly in the region behind the ear. Through its occipital branches, the artery supplies the skin and subcutaneous tissues of the scalp, ensuring adequate nourishment for the maintenance of healthy scalp tissues. This blood flow supports the growth and vitality of hair and helps prevent ischemic damage in this region.
Blood Supply to the Mastoid Process and Surrounding Structures
The posterior auricular artery supplies blood to the mastoid process of the temporal bone, a bony structure located just behind the ear. This blood supply is important for the health of the bone itself and the surrounding muscles, such as the sternocleidomastoid muscle, which attaches to the mastoid process. By ensuring a steady flow of oxygenated blood to this region, the artery supports bone and muscle health, which is critical for head and neck movements.
Vascularization of the Middle Ear Structures
Through its stylomastoid branch, the posterior auricular artery provides blood to the middle ear, including the facial nerve as it travels through the facial canal, as well as the tympanic cavity (part of the middle ear). The artery’s supply to these structures is essential for the proper function of the facial nerve, which controls the muscles of facial expression, and for maintaining the health of the tympanic cavity and other middle ear structures.
Collateral Circulation and Anastomoses
The posterior auricular artery plays an important role in providing collateral circulation to the scalp and auricular regions through its anastomoses with other arteries. It forms anastomoses with the occipital artery and the superficial temporal artery, creating a network of vessels that can maintain blood flow in case one artery is compromised. This redundancy in blood supply helps protect the tissues of the scalp and ear from ischemia and ensures a continuous flow of oxygenated blood.
Nutrient Delivery for Tissue Repair and Healing
As with any artery, the posterior auricular artery delivers essential nutrients, including oxygen and glucose, to the tissues it supplies. This function is vital for maintaining the health of the skin, cartilage, muscles, and bones in the regions it vascularizes. In the event of injury, such as lacerations or trauma to the scalp or ear, the artery plays a crucial role in tissue repair and healing by providing the necessary blood supply for regeneration and recovery.
Support for Facial Nerve Function
Through its stylomastoid branch, the posterior auricular artery plays a key role in the health and function of the facial nerve. The facial nerve passes through the stylomastoid foramen, and the artery supplies this region with oxygenated blood. The artery’s contribution to the facial nerve’s vascularization is important for ensuring proper nerve function, which is critical for controlling the muscles of facial expression. Without adequate blood flow, the facial nerve could suffer from ischemia, leading to facial muscle weakness or paralysis.
Clinical Significance
The posterior auricular artery holds clinical significance due to its location and its role in supplying blood to the ear, scalp, and surrounding structures.
Ear and Scalp Surgery
The posterior auricular artery is a key consideration during surgical procedures involving the ear and posterior scalp, such as otoplasty (ear surgery), mastoidectomy, or scalp reconstructions. Surgeons must be mindful of this artery to avoid excessive bleeding and ensure proper healing. The artery can also be used as a landmark during procedures in the mastoid and auricular regions.
Temporal Bone and Middle Ear Conditions
The stylomastoid branch of the posterior auricular artery is important for the vascularization of the middle ear and facial nerve. In conditions such as mastoiditis (infection of the mastoid bone) or facial nerve disorders like Bell’s palsy, the artery’s role in supplying the facial nerve may become significant. Ischemic issues involving this artery can potentially affect facial nerve function.
Trauma and Lacerations
Due to its superficial course behind the ear, the posterior auricular artery is susceptible to injury in cases of trauma to the head or ear. Lacerations or blunt trauma in this region can cause significant bleeding, and the artery may require surgical repair or ligation to control hemorrhage.
Arterial Grafting and Reconstruction
The posterior auricular artery may sometimes be used in arterial grafting or as a donor vessel in reconstructive surgeries, given its accessibility and robust blood supply. Understanding its anatomy is crucial for plastic and reconstructive surgeons during complex grafting procedures.
