The supratrochlear veins are superficial veins located in the forehead, responsible for draining blood from the upper part of the forehead and scalp.[6] They arise from the venous plexus in the forehead and travel downwards, eventually joining the supra-orbital veins near the root of the nose.
Location
The supratrochlear veins are located in the medial aspect of the forehead, running vertically downward from the scalp. They course toward the medial canthus (inner corner) of the eye, where they merge with the supra-orbital veins to form the angular vein. These veins are situated close to the skin surface, making them easily identifiable in some individuals.
Anatomy
Origin
The supratrochlear veins originate from a venous plexus in the forehead, just above the eyebrows. They begin as small veins that collect blood from the superficial tissues of the forehead, including the skin and underlying connective tissues.
Course and Pathway
The supratrochlear veins follow a downward course, traveling from the upper forehead toward the nose:
- Forehead Region: The veins run vertically downward from the forehead, near the midline of the face.[7] They are situated medially, close to the glabella (the smooth part of the forehead between the eyebrows).
- Medial Canthus: As the supratrochlear veins descend, they approach the medial canthus of the eye (the inner corner of the eye near the nose), where they eventually join the supra-orbital veins.
Relations to Neighboring Structures
- Frontalis Muscle: The supratrochlear veins run superficially over the frontalis muscle, a muscle involved in elevating the eyebrows and wrinkling the forehead. The veins lie between the skin and this muscle.
- Supra-orbital Veins: As the supratrochlear veins descend, they eventually join the supra-orbital veins near the medial canthus.[5] This union forms the angular vein, a major vein that contributes to the drainage of the face.
- Trochlea of the Eye: The supratrochlear veins are named after their proximity to the trochlea, a cartilaginous loop through which the superior oblique muscle of the eye passes. However, the veins do not interact directly with the trochlea; they are simply located above this structure.
Tributaries
Throughout their course, the supratrochlear veins receive blood from smaller veins in the surrounding tissues:
- Forehead Veins: These smaller veins drain the skin and connective tissues of the medial forehead and scalp, contributing to the volume of the supratrochlear veins as they travel downward.[4]
Drainage and Termination
The supratrochlear veins drain into larger venous structures as they descend:
- Supra-orbital Veins: At the medial canthus, the supratrochlear veins join the supra-orbital veins, forming the angular vein. This junction occurs near the root of the nose and contributes to the overall venous drainage of the forehead and upper face.
- Angular Vein: The angular vein, formed by the junction of the supratrochlear and supra-orbital veins, continues downward along the side of the nose, eventually draining into the facial vein. The facial vein is a major superficial vein of the face that ultimately drains into the internal jugular vein.
Connections with Other Venous Systems
The supratrochlear veins are part of a network of superficial veins in the forehead and face. They form important connections with other venous systems, including:
- Facial Vein: Through their contribution to the angular vein, the supratrochlear veins connect to the facial vein, which drains venous blood from the superficial tissues of the face into the internal jugular vein.
- Superior Ophthalmic Vein: The supratrochlear veins indirectly communicate with the superior ophthalmic vein via the angular vein and supra-orbital vein. This connection links the superficial venous system of the face with the deep venous system of the orbit, allowing venous blood to be drained from the face into the cavernous sinus within the cranial cavity.
Anatomical Variations
The anatomy of the supratrochlear veins can vary slightly between individuals:
- Size and Prominence: In some individuals, the supratrochlear veins may be more prominent or visible, particularly near the forehead and medial canthus.[3] In others, they may be smaller or less noticeable.
- Course: The exact course of the veins can vary, with some individuals having more extensive venous networks in the forehead, leading to variations in the pattern of venous drainage.[8]
Surface Anatomy and Identification
The supratrochlear veins are located superficially in the forehead and are often visible or palpable in some individuals, particularly in those with thin skin or low body fat.[2] They can be easily identified near the glabella and the medial canthus of the eye, making them important anatomical landmarks during surgeries or cosmetic procedures involving the forehead or upper face. These veins are also visible during expressions that engage the frontalis muscle, such as raising the eyebrows.
Function
Venous Drainage of the Forehead and Scalp
The primary function of the supratrochlear veins is to drain deoxygenated blood from the forehead and anterior scalp. These veins collect blood from the superficial layers of the forehead, including the skin, subcutaneous tissues, and underlying muscles, particularly the frontalis muscle. By removing blood from these areas, the supratrochlear veins help maintain proper circulation in the upper face, ensuring that blood is efficiently returned to the central venous system for reoxygenation.[1]
Connection with the Supra-orbital and Angular Veins
The supratrochlear veins play an essential role in connecting the venous drainage of the forehead to the supra-orbital vein and angular vein. The supratrochlear veins join the supra-orbital veins near the medial canthus of the eye, forming the angular vein. The angular vein eventually drains into the facial vein, which channels venous blood from the superficial tissues of the face toward the internal jugular vein. This connection allows for the integration of venous return from the upper face into the larger venous system of the head and neck.
Support in Venous Drainage from the Midline Forehead
The supratrochlear veins provide crucial venous drainage for the medial aspect of the forehead, particularly around the glabella (the smooth area between the eyebrows). This region has a dense network of small veins that drain into the supratrochlear veins. By draining the midline area of the forehead, these veins help prevent venous congestion or the accumulation of blood in this central part of the face, maintaining smooth venous return from this critical region.
Communication with the Orbital Venous System
The supratrochlear veins have an indirect connection with the superior ophthalmic vein, which is part of the orbital venous system. This communication occurs through the angular vein and the supra-orbital vein, allowing venous blood from the superficial forehead and face to flow toward the orbit. This connection between the superficial venous system and the deep orbital venous system helps integrate venous return from both regions, ensuring that blood can be drained efficiently from the face and the orbit.
Regulation of Venous Pressure in the Forehead and Face
The supratrochlear veins contribute to the regulation of venous pressure in the forehead and upper face. Movements of the frontalis muscle, such as raising the eyebrows or frowning, can affect venous blood flow in the forehead.[1] The supratrochlear veins help accommodate these pressure changes, ensuring that venous return is not interrupted during facial expressions or other activities involving the forehead muscles. By maintaining stable venous pressure, these veins prevent the buildup of blood in the forehead, reducing the risk of venous congestion or swelling.
Contribution to Collateral Circulation
The supratrochlear veins form part of a larger network of superficial veins in the face, contributing to collateral circulation. This network provides alternate pathways for venous blood to flow if one of the primary veins becomes blocked or obstructed. If venous return from the supra-orbital or facial veins is compromised, the supratrochlear veins can assist in rerouting blood through alternative venous channels, ensuring that venous return from the forehead and face is maintained. This redundancy helps prevent complications such as venous stasis or edema.
Prevention of Venous Stasis and Swelling in the Forehead
The supratrochlear veins help prevent venous stasis, a condition where blood pools in the veins due to insufficient flow. By continuously draining blood from the forehead and directing it toward the angular vein and facial vein, the supratrochlear veins ensure that blood does not accumulate in the superficial tissues of the forehead. This function is particularly important in preventing swelling or the appearance of dilated veins in the forehead, which can result from poor venous return.
Role in Heat Dissipation and Thermoregulation
Like other superficial veins, the supratrochlear veins play a minor role in thermoregulation. As they carry blood close to the surface of the skin, they facilitate heat exchange between the blood and the environment. This process helps dissipate excess heat from the forehead and scalp, particularly during periods of physical exertion or exposure to warm environments. By allowing heat to be released from the blood, the supratrochlear veins contribute to maintaining normal body temperature.
Clinical Significance
The supratrochlear veins play a crucial role in draining venous blood from the forehead and contributing to the overall venous return of the face. They are clinically significant due to their superficial location and proximity to the angular vein and facial vein, which makes them susceptible to facial trauma or injury during surgical procedures, such as forehead lifts, brow surgeries, or cosmetic injections.
Infections or clots in the supratrochlear veins can spread to the superior ophthalmic vein and potentially lead to severe complications, such as cavernous sinus thrombosis, given their indirect connection to the deep orbital venous system. Additionally, their superficial location can make them prominent in some individuals, affecting the aesthetic appearance of the forehead due to visible or dilated veins, particularly in cases of venous hypertension or poor venous drainage. Understanding their anatomy is important in both clinical and cosmetic procedures involving the upper face.