The ascending pharyngeal artery is one of the smaller branches of the external carotid artery. Despite its size, it plays a crucial role in supplying blood to several structures in the neck and head, including the pharynx, cranial meninges, and prevertebral muscles.
Location
The ascending pharyngeal artery arises from the medial side of the external carotid artery, near its origin, just above the bifurcation of the common carotid artery. It travels upward along the pharyngeal wall, between the internal and external carotid arteries. As it ascends, it runs deep in the neck, following a path close to the base of the skull. The artery gives off several small branches that supply the pharynx, prevertebral muscles, middle ear, and meninges, forming important connections with other arteries in the region.
Structure and Anatomy
Origin
The ascending pharyngeal artery is a small but significant branch of the external carotid artery. It typically arises from the medial side of the external carotid artery near its origin, just above the bifurcation of the common carotid artery. In some cases, it may arise directly from the bifurcation of the common carotid artery itself. The ascending pharyngeal artery is usually the smallest branch of the external carotid artery but is essential for supplying blood to several key structures in the neck and head.
Course
After originating from the external carotid artery, the ascending pharyngeal artery ascends vertically along the pharyngeal wall. It runs between the internal and external carotid arteries, following a deep course near the base of the skull. The artery stays close to the pharynx as it travels upward, making its way to the base of the cranium. It is one of the few arteries that run medially from the external carotid artery, giving it a distinctive course compared to the other branches.
The artery’s course brings it into proximity with several important anatomical structures, including the internal carotid artery, cranial nerves, and vertebral column.
Branches
The ascending pharyngeal artery gives off several small branches that supply a variety of structures in the pharynx, head, and neck. These branches include:
- Pharyngeal Branches: These small branches supply the walls of the pharynx, including the muscles and mucous membranes of the nasopharynx, oropharynx, and hypopharynx. The pharyngeal branches are responsible for the blood supply to much of the pharyngeal musculature and surrounding soft tissues.
- Prevertebral Branches: These branches supply the prevertebral muscles in the neck, including muscles such as the longus capitis and longus colli, which are involved in stabilizing and moving the neck. The prevertebral branches also supply nearby connective tissues and ligaments.
- Inferior Tympanic Artery: One of the more distal branches, this small artery enters the tympanic cavity through the inferior tympanic canaliculus. It provides blood to portions of the middle ear and contributes to the vascular supply of the tympanic membrane and middle ear structures.
- Meningeal Branches: The ascending pharyngeal artery also sends small branches through the jugular foramen and hypoglossal canal to supply the cranial meninges (protective layers around the brain) in the posterior cranial fossa. These meningeal branches are important for supplying the dura mater in this region.
- Neurovascular Branches: Some smaller branches of the ascending pharyngeal artery supply nearby cranial nerves and contribute to the vascular supply of the surrounding neural structures. The artery provides blood to parts of the vagus nerve (cranial nerve X) and hypoglossal nerve (cranial nerve XII) through these neurovascular branches.
Termination
The ascending pharyngeal artery continues its ascent toward the base of the skull, where it terminates by distributing its blood supply to the pharyngeal, meningeal, and prevertebral structures. It often ends near the base of the skull, contributing to the vascular supply of the cranial meninges, particularly in the posterior cranial fossa.
The artery forms anastomoses with other arteries in the head and neck region, including branches of the internal carotid artery, vertebral artery, and other external carotid artery branches, ensuring an extensive vascular network in the area.
Relationship with Surrounding Structures
The ascending pharyngeal artery runs deeply along the neck and is associated with several important anatomical structures, including:
- Pharynx: The artery runs along the pharyngeal wall, providing blood to the mucous membranes and muscles of the pharynx.
- Internal Carotid Artery: The ascending pharyngeal artery is located medial to the internal carotid artery as it ascends toward the base of the skull.
- Cranial Nerves: Several cranial nerves are in close proximity to the ascending pharyngeal artery, particularly the vagus nerve and hypoglossal nerve, both of which receive vascular supply from small branches of the artery.
- Jugular Foramen and Hypoglossal Canal: As the artery nears the base of the skull, some of its meningeal branches enter the cranial cavity through the jugular foramen and hypoglossal canal, supplying blood to the meninges in the posterior cranial fossa.
Anastomoses
The ascending pharyngeal artery forms several important anastomotic connections with nearby arteries. These include:
- Vertebral Artery: The ascending pharyngeal artery forms anastomoses with branches of the vertebral artery, contributing to the collateral blood supply to the upper cervical spine and base of the skull.
- Internal Carotid Artery: The artery anastomoses with small branches of the internal carotid artery, particularly in the region near the base of the skull.
- Other External Carotid Artery Branches: The ascending pharyngeal artery forms anastomoses with other branches of the external carotid artery, such as the occipital and lingual arteries, creating a robust vascular network in the neck and pharynx.
Variations
While the ascending pharyngeal artery typically arises from the external carotid artery, anatomical variations can occur. In some individuals, the artery may arise directly from the common carotid artery or share a common trunk with nearby branches such as the occipital artery. The course and branching pattern of the artery can also vary, particularly in its distribution to the pharynx and base of the skull. These variations are important to consider during surgical procedures in the neck and head region.
Surrounding Vascular Structures
The ascending pharyngeal artery is located near several other key vascular structures in the neck:
- Internal Carotid Artery: The ascending pharyngeal artery runs medial to the internal carotid artery, contributing to the vascular supply of the deep neck and pharyngeal region.
- Vertebral Artery: As the artery ascends, it anastomoses with branches of the vertebral artery, particularly near the base of the skull.
- Occipital Artery: The ascending pharyngeal artery forms connections with the occipital artery, another branch of the external carotid artery, which supplies the posterior scalp and neck.
Relationship with the Skull Base and Cranial Cavity
As the ascending pharyngeal artery ascends toward the skull base, its branches pass through various foramina to enter the cranial cavity. These include the jugular foramen, hypoglossal canal, and foramen lacerum, through which the artery’s meningeal branches supply the dura mater and surrounding structures.
Function
Blood Supply to the Pharynx
The primary function of the ascending pharyngeal artery is to supply blood to the pharynx, a key structure involved in swallowing and the passage of air to the lungs. Through its pharyngeal branches, the artery provides oxygenated blood to the mucous membranes and muscles of the nasopharynx, oropharynx, and hypopharynx. These branches ensure that the pharyngeal muscles, which are responsible for the coordination of swallowing and speech, receive adequate blood flow to function properly.
Blood Supply to the Prevertebral Muscles
The prevertebral branches of the ascending pharyngeal artery supply blood to the prevertebral muscles of the neck, including the longus capitis and longus colli muscles. These muscles are involved in the flexion, rotation, and stabilization of the cervical spine and head. By delivering oxygen and nutrients to these muscles, the ascending pharyngeal artery supports the movement and stability of the neck and upper spine.
Blood Supply to the Cranial Meninges
Another important function of the ascending pharyngeal artery is to supply blood to the cranial meninges through its meningeal branches. These small branches pass through foramina at the base of the skull, such as the jugular foramen and hypoglossal canal, to reach the dura mater in the posterior cranial fossa. The dura mater is the outermost protective layer surrounding the brain, and its proper function relies on a steady blood supply. The meningeal branches of the ascending pharyngeal artery contribute to maintaining the health and integrity of these protective membranes.
Blood Supply to the Middle Ear
The inferior tympanic branch of the ascending pharyngeal artery supplies blood to parts of the middle ear. It enters the middle ear through the inferior tympanic canaliculus and helps vascularize the tympanic membrane and other structures within the middle ear. This blood supply is essential for maintaining the health of the middle ear and supporting its role in sound transmission.
Blood Supply to the Base of the Skull
The ascending pharyngeal artery also plays a key role in supplying blood to the base of the skull, particularly near the jugular foramen, hypoglossal canal, and other foramina. As it ascends along the pharyngeal wall, the artery delivers oxygenated blood to the bony and neural structures at the base of the skull. These structures include the cranial nerves that pass through these foramina, such as the vagus nerve (CN X) and hypoglossal nerve (CN XII), which are critical for motor and sensory functions in the neck and head.
Contribution to Cranial Nerve Function
The ascending pharyngeal artery provides small branches that contribute to the blood supply of several cranial nerves, including the vagus nerve and hypoglossal nerve. By ensuring a healthy blood flow to these nerves, the artery helps maintain their proper function. The vagus nerve is involved in autonomic control of the heart, lungs, and digestive tract, while the hypoglossal nerve controls the muscles of the tongue. A reliable blood supply from the ascending pharyngeal artery is essential for the functionality of these nerves.
Blood Supply to the Soft Palate and Tonsillar Region
Through its pharyngeal branches, the ascending pharyngeal artery also provides blood to parts of the soft palate and the tonsillar region. These areas are involved in speech and immune defense, particularly through the function of the tonsils, which help to protect the body from infection. Adequate blood supply is important for the proper function of the tonsils and the soft palate, especially during swallowing and speech.
Nutrient Delivery and Waste Removal
As with all arteries, the ascending pharyngeal artery plays a key role in delivering essential nutrients, such as oxygen and glucose, to the tissues it supplies. In turn, it facilitates the removal of waste products like carbon dioxide and metabolic byproducts from these tissues. This function is critical for maintaining the health of the pharynx, prevertebral muscles, and cranial meninges, allowing them to perform their respective functions efficiently.
Contribution to Collateral Circulation
The ascending pharyngeal artery contributes to collateral circulation in the neck and head region. Through its anastomoses with other arteries, such as the vertebral artery, internal carotid artery, and occipital artery, the ascending pharyngeal artery ensures that blood can still reach key areas if other arteries are compromised or obstructed. This network of vessels provides redundancy in the blood supply, which is critical for maintaining proper blood flow to the brain, pharynx, and skull base.
Role in Speech and Swallowing
The blood supplied by the ascending pharyngeal artery supports the muscles of the pharynx, soft palate, and nearby structures involved in speech and swallowing. By ensuring that the pharyngeal muscles and related structures are adequately nourished, the artery contributes to the smooth coordination of these vital functions. Swallowing involves the precise movement of muscles in the throat, while speech requires the coordination of muscles in the pharynx and soft palate. A healthy blood supply is essential for the proper functioning of these processes.
Blood Supply to the Lymphoid Tissues
The ascending pharyngeal artery also provides blood to the lymphoid tissues located in the pharyngeal region, including parts of the Waldeyer’s ring, a collection of lymphoid tissue that includes the tonsils and adenoids. These structures play a role in the body’s immune defense by trapping and destroying pathogens entering the upper respiratory and digestive tracts. The artery’s blood supply supports the immune functions of these lymphoid tissues.
Thermoregulation
The ascending pharyngeal artery helps in thermoregulation by supplying blood to deep structures in the neck and head. The flow of blood through the artery can help dissipate heat or conserve warmth in response to changes in environmental temperature. This regulation is important for maintaining the temperature of the muscles and tissues in the neck and pharynx, especially during physical exertion or temperature fluctuations.
Support for Tissue Repair and Healing
As with all arteries, the ascending pharyngeal artery contributes to tissue repair and healing by delivering blood rich in oxygen and nutrients to the areas it supplies. In the event of injury, infection, or surgery involving the pharynx, cranial meninges, or neck muscles, the artery plays a vital role in supporting the recovery process by providing the necessary resources for cellular repair and regeneration.
Clinical Significance
The ascending pharyngeal artery, despite being a small vessel, holds considerable clinical significance due to its deep location and the critical structures it supplies.
Pharyngeal and Skull Base Surgeries
During surgeries involving the pharynx and skull base, such as tumor excisions or procedures to address vascular malformations, the ascending pharyngeal artery can pose a risk of significant bleeding due to its deep location and proximity to critical structures. It must be carefully managed to avoid complications during these delicate surgeries.
Vascular Malformations and Tumors
The ascending pharyngeal artery is often involved in supplying blood to tumors or arteriovenous malformations (AVMs) in the head and neck. In cases of nasopharyngeal tumors, for instance, the artery may be embolized to reduce blood flow to the tumor before surgical resection.
Stroke Risk and Collateral Circulation
The ascending pharyngeal artery contributes to collateral circulation in the head and neck. Its anastomoses with the vertebral and internal carotid arteries help maintain blood supply to key areas in cases of arterial blockage, reducing the risk of ischemic events such as strokes.
Infections and Inflammation
Infections or inflammation involving the pharynx, tonsils, or middle ear may affect the blood flow through the ascending pharyngeal artery, influencing the progression of these conditions and the body’s ability to heal.
