Section 6.3: Vessel Selection & Anatomical Guides

Vessel selection is a critical pre-embalming decision that directly impacts the distribution and diffusion of arterial fluid. An embalmer must possess a comprehensive understanding of human anatomy, surgical dissection, and the specific landmarks used to locate, raise, and prepare blood vessels for injection and drainage.

Principles of Vessel Selection

When selecting injection and drainage sites, the embalmer evaluates several case-specific factors:

• Age of the deceased: In infants, smaller vessels (such as the ascending aorta or common carotid) are preferred, whereas in adults, the common carotid or femoral artery are standard.
• Weight and body fat: Obese individuals have deeper vessels, requiring longer incisions and deeper dissection.
• Vascular pathology: Arteriosclerosis (hardening of the arteries) may block flow in the femoral artery, necessitating the use of the common carotid.
• Trauma or autopsy: Autopsied bodies require sectional injection (using the subclavian, common carotid, and external iliac arteries).
• Injection methods:
  • One-Point Injection: Injection and drainage occur at the same location (e.g., injecting the right common carotid and draining from the right internal jugular).
  • Split Injection: Injection occurs at one site, and drainage occurs at another (e.g., injecting the right femoral artery and draining from the right internal jugular vein).
  • Multipoint Injection: Used when fluid distribution is poor, requiring injection into multiple arteries (e.g., carotid, femoral, and axillary).

The Common Carotid Artery & Internal Jugular Vein

The right common carotid artery is the most frequently used injection site due to its large size, elasticity, and proximity to the center of circulation (the arch of the aorta). The accompanying internal jugular vein provides excellent drainage.

• Linear Guide: A line drawn on the surface of the skin from the sternoclavicular articulation to the anterior lobe of the earlobe.
• Anatomical Guide: Along the posterior border of the inferior third of the sternocleidomastoid (SCM) muscle.
• Anatomical Limits:
  • Right Common Carotid: Begins at the level of the sternoclavicular articulation and terminates at the superior border of the thyroid cartilage.
  • Left Common Carotid: Begins at the level of the second costal cartilage (arch of the aorta) and terminates at the superior border of the thyroid cartilage.
• Relative Surgical Position: The common carotid artery lies medial and deep to the internal jugular vein. Both vessels are enclosed within the carotid sheath, along with the vagus nerve. The vein is superficial and lateral to the artery.

The Femoral Artery & Femoral Vein

The femoral artery is the second most common injection site. It is located in the groin and is ideal for achieving uniform distribution to the lower extremities while keeping the head and neck free of incisions.

• Linear Guide: A line on the surface of the skin from the center of the inguinal ligament to the medial condyle of the femur.
• Anatomical Guide: Through the center of the femoral triangle, bounded laterally by the sartorius muscle and medially by the adductor longus muscle.
• Anatomical Limit: Begins posterior to the inguinal ligament and terminates at the opening in the adductor magnus muscle (entering the popliteal space).
• Relative Surgical Position: The femoral vein lies medial and deep to the femoral artery. The femoral nerve lies lateral to the artery.

The Axillary Artery & Axillary Vein

The axillary artery is primarily used as a secondary injection site when fluid fails to reach the arm during primary injection, or as a primary site in infant cases.

• Linear Guide: A line through the center of the axillary space parallel to the long axis of the upper extremity.
• Anatomical Guide: Along the medial border of the coracobrachialis muscle.
• Anatomical Limit: Begins at the lateral border of the first rib and terminates at the inferior border of the tendon of the teres major muscle (where it becomes the brachial artery).
• Relative Surgical Position: The axillary vein lies medial and superficial to the axillary artery. The brachial plexus of nerves surrounds the artery and can be mistaken for the vessel during dissection.

Protocol for Raising and Preparing Vessels

To raise a vessel for embalming, a precise surgical protocol must be followed:

1. Locate the Incision Site: Choose the appropriate landmark based on the linear guide.
2. Make the Skin Incision: Incisions can be parallel (along the muscle border), transverse (across the muscle border), diagonal, or a strap incision (for cosmetic concealment).
3. Blunt Dissection: Use an aneurysm needle or dissecting scissors to separate fat and fascia. Avoid cutting tissues blindly to prevent tearing veins or nerves.
4. Isolate the Vessel: The artery is identified by its thick, elastic, creamy-white wall and distinct lumen that remains open when cut. The vein is thinner, bluish-red, and collapses when empty. Nerves are solid, white, and do not have a lumen.
5. Place Ligatures: Pass two pieces of cotton ligature around the vessel. One ligature is used to secure the arterial tube (cannula) during injection, and the other is used to tie off the vessel after embalming is complete.
6. Incise the Vessel: Use a scalpel or scissors to make a transverse or wedge-shaped incision in the artery wall. Insert the arterial tube toward the body (or toward the extremity) and tie it securely in place using the ligature.