Deep auricular artery

The deep auricular artery is a small branch of the first (mandibular) part of the maxillary artery, which primarily supplies blood to the external acoustic meatus (ear canal) and part of the tympanic membrane (eardrum).

Location

The deep auricular artery arises from the maxillary artery within the infratemporal fossa. It ascends laterally, traveling toward the external acoustic meatus, where it provides blood to the external ear canal and part of the tympanic membrane. The artery passes through the cartilage and bone of the ear canal, eventually reaching the outer surface of the tympanic membrane. It may also contribute to the blood supply of the temporomandibular joint (TMJ), located nearby.

Origin

The deep auricular artery originates from the first (mandibular) part of the maxillary artery, which is one of the terminal branches of the external carotid artery. The maxillary artery is divided into three parts, and the deep auricular artery arises from the first part within the infratemporal fossa. This region is located deep to the zygomatic arch and is home to multiple branches of the maxillary artery, as well as the mandibular nerve and associated muscles.

Course and Pathway

Infratemporal Fossa

After its origin from the maxillary artery, the deep auricular artery ascends laterally from the infratemporal fossa. The artery initially courses upward and outward, directed toward the lateral aspect of the skull, where it approaches the external acoustic meatus (the ear canal). This pathway brings the artery into close relation with several key structures of the infratemporal and auricular regions.

External Acoustic Meatus

As the artery ascends toward the ear, it reaches the external acoustic meatus, the opening of the ear canal. The deep auricular artery supplies blood to the cartilaginous and bony portions of the external acoustic meatus. The ear canal itself is divided into two sections: the outer third is cartilaginous, and the inner two-thirds are bony. The artery’s course through this region allows it to supply the tissues that line the external acoustic meatus.

Tympanic Membrane

The deep auricular artery continues to supply blood to the outer surface of the tympanic membrane (eardrum). The tympanic membrane is a thin, delicate structure that plays a crucial role in transmitting sound waves to the middle ear. The deep auricular artery’s branches supply the outer (lateral) surface of the tympanic membrane, ensuring that this structure receives the necessary blood flow to maintain its health and function.

Branching

The deep auricular artery gives off several small branches as it travels toward the external ear and tympanic membrane:

• Auricular branches: These branches supply the external acoustic meatus, nourishing both the cartilaginous and bony portions of the ear canal. The artery helps maintain the health of the skin and tissues lining the ear canal, which are important for sound transmission and protection against infections.
• Tympanic branches: These branches specifically supply the outer surface of the tympanic membrane, ensuring that the eardrum remains functional and capable of transmitting sound vibrations to the auditory ossicles in the middle ear.

Relations with Surrounding Structures

The deep auricular artery is closely related to several important anatomical structures, particularly as it ascends from the infratemporal fossa to the external ear:

• Temporomandibular Joint (TMJ): The artery passes near the temporomandibular joint (TMJ), the joint that connects the mandible to the temporal bone of the skull. Some small branches of the deep auricular artery may also contribute to the blood supply of the TMJ, making it an important vessel in the vascularization of this region.
• Auriculotemporal Nerve: As the artery ascends toward the ear, it runs in close proximity to the auriculotemporal nerve, a branch of the mandibular division of the trigeminal nerve (CN V3). This nerve provides sensory innervation to the external ear and the temporomandibular joint. The deep auricular artery and auriculotemporal nerve travel together as they reach the external acoustic meatus.

Anastomoses

The deep auricular artery forms important anastomoses with other arteries that supply the ear and surrounding structures, contributing to a rich vascular network that ensures proper blood flow to the external ear and tympanic membrane:

• Posterior auricular artery: The deep auricular artery may anastomose with the posterior auricular artery, a branch of the external carotid artery that supplies the posterior part of the ear. This anastomosis helps maintain a consistent blood supply to the ear, even if one artery is compromised.
• Stylomastoid artery: There may also be anastomoses between the deep auricular artery and the stylomastoid artery, a branch of the posterior auricular artery that supplies structures within the temporal bone, including parts of the middle ear.

Distribution

The deep auricular artery primarily supplies the following structures:

• External Acoustic Meatus: The artery provides blood to the cartilaginous and bony portions of the external acoustic meatus, ensuring that the ear canal remains healthy and capable of supporting the transmission of sound waves.
• Tympanic Membrane: The outer surface of the tympanic membrane is supplied by branches of the deep auricular artery, which help maintain the membrane’s structural integrity and function in hearing.
• Temporomandibular Joint (TMJ): The artery may also provide small branches to the temporomandibular joint, contributing to its blood supply and supporting the joint’s movement and function during chewing and speaking.

Variations

Anatomical variations in the deep auricular artery are rare but can occur. In some individuals, the artery may arise from a different location on the maxillary artery or exhibit variations in its branching pattern. These variations can be clinically significant, particularly during surgical procedures involving the external ear, TMJ, or infratemporal fossa.

Function

The deep auricular artery plays a crucial role in supplying blood to several important structures in and around the external ear. Its function ensures the health and nourishment of the external acoustic meatus, the outer surface of the tympanic membrane, and possibly the temporomandibular joint (TMJ). Below is a detailed explanation of the specific functions it performs.

Blood Supply to the External Acoustic Meatus

One of the primary functions of the deep auricular artery is to supply blood to the external acoustic meatus, the canal that conducts sound waves from the outer ear to the tympanic membrane.

• Cartilaginous Part: The artery supplies the cartilaginous portion of the external ear canal, which is the outer third of the meatus. This part of the canal is flexible and lined with skin that contains hair follicles and glands that produce cerumen (earwax). The artery ensures that these tissues receive the necessary oxygen and nutrients to maintain their health and function.
• Bony Part: The artery also supplies the bony portion of the external acoustic meatus, which makes up the inner two-thirds of the canal. This part of the ear canal is more rigid and closely associated with the temporal bone. Adequate blood flow to this area ensures the integrity of the skin lining the canal and helps maintain a healthy barrier against infections.

Blood Supply to the Tympanic Membrane

The deep auricular artery is responsible for supplying the outer surface of the tympanic membrane (eardrum), a critical structure in the hearing process.

• Nourishment of the Tympanic Membrane: The artery delivers oxygenated blood to the outer layer of the tympanic membrane, ensuring that the membrane remains healthy and intact. The tympanic membrane plays a key role in transmitting sound waves from the external ear to the middle ear by converting sound energy into mechanical vibrations. The deep auricular artery supports the membrane’s ability to function by providing it with the necessary nutrients.
• Structural Support: By maintaining the blood supply to the tympanic membrane, the deep auricular artery helps preserve the structural integrity of the membrane. A healthy blood flow ensures that the membrane remains flexible and resilient, preventing perforations or thinning that could impair its function.

Blood Supply to the Temporomandibular Joint (TMJ)

Although the primary function of the deep auricular artery is related to the ear, it also plays a role in supplying blood to the temporomandibular joint (TMJ), the joint that connects the lower jaw (mandible) to the temporal bone of the skull.

• Nourishment of the TMJ: Some small branches of the deep auricular artery provide blood flow to the capsule and surrounding tissues of the TMJ. Adequate blood supply to the joint ensures its proper function and helps support the complex movements required for chewing, speaking, and other jaw functions.
• Support for Joint Movement: The TMJ is highly mobile and is involved in a variety of movements, including hinge and gliding motions. The deep auricular artery supports these movements by delivering blood to the joint, keeping the tissues well-nourished and preventing degeneration or stiffness.

Role in Healing and Tissue Repair

The deep auricular artery plays an essential role in healing and tissue repair following injuries or infections affecting the ear or temporomandibular joint.

• Tissue Repair in the Ear: In the event of trauma to the external acoustic meatus or damage to the tympanic membrane, the artery ensures that the affected tissues receive the necessary blood supply to support healing and tissue regeneration. This is particularly important after injuries such as tympanic membrane perforation or ear canal lacerations.
• Joint Repair and Recovery: If the TMJ is affected by trauma, inflammation, or surgical interventions, the artery provides blood to the joint and surrounding tissues to support healing and recovery. Proper blood flow ensures that the joint recovers its full range of motion and function after injury or surgery.

Contribution to Collateral Circulation

The deep auricular artery forms anastomoses with other arteries that supply the ear and surrounding areas, contributing to a collateral blood supply that ensures continuous blood flow even if one arterial pathway is compromised.

• Anastomosis with Posterior Auricular Artery: The artery anastomoses with the posterior auricular artery, providing additional blood supply to the external ear and surrounding tissues. This collateral circulation ensures that the external acoustic meatus and tympanic membrane continue to receive blood flow even in cases of arterial blockage or injury.
• Anastomosis with Stylomastoid Artery: The deep auricular artery may also anastomose with the stylomastoid artery, contributing to the vascular supply of the middle ear and the TMJ. This anastomosis helps maintain the health of these structures, ensuring proper function even under conditions of increased demand or vascular compromise.

Role in Ear Protection and Function

By maintaining the blood supply to the external acoustic meatus and tympanic membrane, the deep auricular artery indirectly supports the overall health and function of the ear, particularly in sound transmission and protection against infections.

• Support for Hearing: The artery’s role in supplying blood to the outer ear structures is essential for maintaining the health of the ear canal and tympanic membrane, which are critical for conducting sound waves into the middle and inner ear. A healthy blood supply ensures that the ear remains functional and capable of transmitting sound effectively.
• Barrier against Infections: The blood flow from the deep auricular artery helps maintain the health of the skin lining the external acoustic meatus, which serves as a protective barrier against infections like otitis externa (outer ear infections). By nourishing the skin and underlying tissues, the artery helps prevent infections from taking hold or spreading deeper into the ear.

Support for Facial Movements and Mastication

Through its contribution to the blood supply of the temporomandibular joint (TMJ), the deep auricular artery indirectly supports facial movements and chewing.

• Jaw Mobility: The artery’s supply to the TMJ helps maintain the mobility of the jaw, allowing for smooth movements during speaking, chewing, and facial expressions. Proper blood flow is essential for ensuring the joint’s cartilage and soft tissues remain healthy and functional.
• Support for Jaw Muscles: By nourishing the joint and surrounding tissues, the artery also supports the muscles involved in mastication (chewing) and jaw control, ensuring that these muscles can generate the necessary force for effective chewing.

Clinical Significance

The deep auricular artery is clinically significant due to its role in supplying blood to the external acoustic meatus (ear canal), the tympanic membrane, and potentially the temporomandibular joint (TMJ). It is important during otologic surgeries or procedures involving the ear canal and tympanic membrane, as injury to the artery can result in bleeding or complications in wound healing.

In cases of ear infections, such as otitis externa, the deep auricular artery provides the necessary blood flow to aid in tissue repair and recovery. Additionally, its involvement in supplying the TMJ can make it relevant in conditions like TMJ disorders, where vascular compromise could affect joint function. The artery also plays a role in maintaining the integrity of the ear structures necessary for proper hearing and sound conduction.