The sternal notch, also called the suprasternal notch or jugular notch, is the shallow, U-shaped dip you can feel at the top of your breastbone, right between the two collarbones. Press a finger into the soft hollow at the base of your throat and you are touching it. Despite being easy to locate and small enough to cover with a fingertip, this little divot punches well above its weight in medicine: surgeons, anesthesiologists, cardiologists, and emergency physicians all rely on it as a fixed reference point for procedures, measurements, and diagnostic imaging.
Exactly Where It Sits and What Surrounds It
The sternal notch marks the upper border of the manubrium, the broad, roughly trapezoidal bone that forms the top portion of the sternum. On either side, the inner ends of your collarbones (the clavicles) articulate with the manubrium at the sternoclavicular joints, creating the bony frame around the notch. Below and behind it lies the trachea, along with several major blood vessels, nerves, and the upper lobes of the lungs.
Relative to the spine, a CT-based study of over 1,000 patients found that the sternal notch lines up most often with the T2 or T3 vertebral body, following a bimodal distribution clustered at those two levels.1Journal of Clinical Neuroscience. Surface anatomical landmarks for spine surgery: A CT-based study of the sternal notch and sternal angle in 1,035 patients An earlier radiographic study confirmed the same pattern, noting that because the notch typically falls below T2–T3, spine surgeons can often reach upper thoracic vertebrae through a low cervical approach rather than opening the chest.2PubMed. Radiographic assessment of sternal notch level and its significance in approaching the upper thoracic spine Knowing this relationship helps surgeons decide before they even pick up a scalpel whether a given patient’s anatomy allows a simpler, less invasive route to the spine.
A Crowded Intersection of Blood Vessels
Just behind the sternal notch, the airway and the arterial system are uncomfortably close neighbors. A study of 500 CT scans found that in over half of cases, a major blood vessel sat directly in front of the trachea at the level of the suprasternal notch, most often the brachiocephalic (innominate) artery.3British Journal of Anaesthesia. Prevalence of major vessels anterior to the trachea at sites of potential front-of-neck emergency airway access in adults That is a sobering number for anyone performing emergency airway procedures: more than one in two patients has a large artery sitting right where a needle or scalpel might go if the anatomy is misjudged.
The same region is the gateway used in a novel cardiac procedure. In suprasternal direct aortic approach valve replacement, a surgeon inserts a finger through a small incision above the notch and follows the tissue plane downward between the strap muscles of the neck until the aorta and innominate artery can be felt. The device is then guided along the same path into the thoracic inlet.4European Journal of Cardio-Thoracic Surgery. Suprasternal direct aortic approach transcatheter aortic valve replacement avoids sternotomy and thoracotomy: first-in-man experience The procedure avoids cracking the chest altogether, but it works only because the notch provides reliable access to that vascular corridor.
Why Anesthesiologists Measure From the Notch Before Intubation
Before placing a breathing tube, anesthesiologists need a quick way to predict whether the procedure will be difficult. One of their tools is the sternomental distance: you tilt your head back as far as it will go, and the clinician measures from the sternal notch to the tip of your chin. A short distance suggests limited neck extension, a receding jaw, or both, all of which make it harder to see the vocal cords during intubation.
There is some debate about the best cutoff. One study found that a sternomental distance below about 12.5 cm predicted a difficult intubation with roughly 91% sensitivity and 93% specificity.5PubMed Central. Validation of modified Mallampati test with addition of thyromental distance and sternomental distance to predict difficult endotracheal intubation in adults Another study used a slightly higher cutoff of about 14.75 cm and reported lower accuracy, with sensitivity around 66% and specificity around 60%.6PubMed Central. Sternomental distance and sternomental displacement as predictors of difficult laryngoscopy and intubation in adult patients The discrepancy likely reflects differences in patient populations and how “difficult” was defined, but the underlying logic is consistent: the sternal notch serves as the fixed lower anchor for a measurement that tells the anesthesiologist whether to prepare extra tools and extra help before the airway procedure begins.
Tracheostomy and the Trachea Between Notch and Larynx
When someone needs a surgical airway, the sternal notch frames the lower boundary of the working zone. Anatomical dissections have measured the trachea between the cricoid cartilage (the ring you can feel just below the Adam’s apple) and the suprasternal notch at roughly 7 to 8 cm, with about 11 tracheal cartilage rings and 10 soft-tissue gaps (annular ligaments) in between.7PubMed Central. Clinically correlated anatomical basis of cricothyrotomy and tracheostomy Tracheostomy tubes are typically placed through one of the middle rings in that stretch, well above the notch to avoid the tangle of vessels lurking behind it.
When tracheostomy is done percutaneously, meaning through the skin with a needle and guidewire rather than a full surgical incision, the distance from the cricoid cartilage to the manubrium becomes a practical predictor of how smoothly the procedure goes. A recent study found that a greater cricoid-to-manubrium distance independently predicted longer procedure times, likely because it alters the angle and depth the operator must navigate.8PubMed. Landmark-Guided Percutaneous Tracheostomy Without Visualization in Resource-Limited Settings In resource-limited settings where bronchoscopy or ultrasound may not be available, palpating the sternal notch and measuring from it is sometimes all a clinician has to guide tube placement safely.
Placing Central Venous Catheters at the Right Depth
Central venous catheters are long, thin tubes threaded through a neck or chest vein into the large veins near the heart. Push the catheter too far and its tip can irritate the heart wall or trigger an abnormal rhythm; leave it too short and medications may not mix into the bloodstream properly. The sternal notch is the external landmark clinicians use to estimate the correct insertion depth before they thread the line.
For a catheter placed through the right internal jugular vein, a common formula adds the straight-line distance from the needle insertion site to the suprasternal notch plus half the length of the sternum.9PubMed Central. The mid-sternal length, a practical anatomical landmark for optimal positioning of long-term central venous catheters For a left-sided catheter, the calculation is a bit longer because the vein takes a more winding path across the chest: the distance from the insertion point to the sternal notch, plus the span between the left and right sternoclavicular joints, plus half the sternal length.10PubMed Central. Practical anatomical landmark for optimal positioning of left-sided long-term central venous catheter (a pilot study) In both cases, the notch is the pivot point. A chest X-ray afterward confirms the tip is in the right spot, but the notch-based estimate gets the clinician close enough on the first pass to avoid most complications.
Measuring Arterial Stiffness
Cardiologists assess how stiff your arteries have become by measuring pulse wave velocity: how fast the pressure wave from each heartbeat travels from the carotid artery in your neck to the femoral artery in your groin. Faster travel means stiffer arteries, which is a strong predictor of cardiovascular problems. The catch is that the “travel distance” between those two arteries has to be estimated on the body surface, and the method you choose changes the result dramatically.
One approach uses a tape measure to trace the straight line from the carotid to the femoral pulse. Another breaks the path at the sternal notch, measuring from the carotid down to the notch and from the notch down to the femoral artery, then subtracting the upper segment from the lower. These two methods can produce pulse wave velocity values that differ by up to 30%.11Journal of Hypertension. Distance measurements for the assessment of carotid to femoral pulse wave velocity When researchers compared non-invasive surface estimates against invasive catheter measurements, the subtracted method using the sternal notch as an intermediary turned out to be closer to the true arterial path length.12Journal of Hypertension. Noninvasive determination of carotid–femoral pulse wave velocity depends critically on assessment of travel distance: a comparison with invasive measurement Even the type of measuring device matters: a rigid sliding caliper gives more reproducible results than a flexible tape, because the tape tends to follow body contours and overestimate the distance.13Journal of Hypertension. Crucial importance of using a sliding calliper to measure distance for carotid-femoral pulse wave velocity assessment In all of these measurement schemes, the sternal notch is the shared reference point, and getting its location wrong ripples through the entire calculation.
The Suprasternal Notch View in Ultrasound
Emergency physicians and cardiologists sometimes press an ultrasound probe directly into the sternal notch to visualize the aortic arch. The notch provides a natural acoustic window, a gap in the bone where sound waves can pass through soft tissue and reach the vessel. In a study of 79 patients, emergency physicians were able to obtain this “suprasternal notch view” in 97% of attempts, and in about two-thirds of cases they rated it as easy to obtain.14PubMed Central. Evaluation of the aortic arch from the suprasternal notch view using focused cardiac ultrasound When the ultrasound measurements of the aorta were compared against CT angiography, the average differences at the aortic arch were less than a millimeter, suggesting the bedside ultrasound view through the notch is surprisingly accurate for assessing conditions like aortic aneurysm or dissection in real time.
Thyroid Examination and Substernal Goiter
The sternal notch also defines where a normal thyroid ends and a worrisome one begins. A goiter is an enlarged thyroid gland, and when it grows large enough to extend below the sternal notch or clavicle, it is classified as a substernal goiter. The American Thyroid Association guideline defines substernal goiter as clinical or radiological protrusion of the thyroid gland over the sternal notch or clavicle with the patient lying supine and the neck slightly extended.15PubMed Central. Substernal Goiter: From Definitions to Treatment Once a goiter dips below the notch, it can compress the trachea, the esophagus, or the large veins in the chest, and surgical removal becomes more complex because the surgeon may need to work in the narrow space behind the breastbone rather than operating entirely in the neck.
Sternoclavicular Joint Injuries
The sternoclavicular joints flanking the notch are among the strongest in the body, reinforced by thick ligaments. It takes serious force to dislocate them. When the inner end of the collarbone gets knocked backward (a posterior dislocation), it can press against the trachea, esophagus, or the major blood vessels sitting just behind the notch. These injuries carry a risk of life-threatening complications including airway compression, vascular injury, and esophageal damage, and they require rapid recognition and treatment.16PubMed Central. Sternoclavicular joint dislocation and its management: A review of the literature Because the notch sits right between the two joints, swelling or asymmetry around it is one of the first clinical signs that something has gone wrong.
ECG Lead Placement
Correct placement of electrocardiogram (ECG) leads depends on finding the fourth intercostal space, the gap between the fourth and fifth ribs, which is where leads V1 and V2 go. Counting ribs from the top can be tricky, especially on larger patients. One study found that the distance from the sternal notch to the right fourth intercostal space is consistently about 67% of the total sternal notch-to-xiphoid length (the xiphoid being the small bony point at the very bottom of the breastbone).17PubMed. Identification of 4th intercostal space using sternal notch to xiphoid length for accurate electrocardiogram lead placement That two-thirds rule gives technicians a quick sanity check: measure your breastbone, take two-thirds of that distance, and you should be close to the right spot.
Breast and Reconstructive Surgery
Plastic surgeons use the sternal notch as a fixed reference point when planning breast surgery. The distance from the suprasternal notch to the nipple is a standard measurement for assessing breast symmetry, designing reduction patterns, and evaluating results. In vertical mammaplasty (breast reduction), a longer suprasternal-notch-to-nipple distance is geometrically associated with a longer superior pedicle, the tissue bridge that keeps the nipple alive during the procedure, and has been investigated as a predictor of blood-supply complications.18Journal of Plastic, Reconstructive & Aesthetic Surgery. Importance of the suprasternal notch to nipple distance (SSN:N) for vascular complications of the nipple areola complex (NAC) in the superior pedicle vertical mammaplasty One geometric method for nipple positioning after reconstruction places the nipples at the lower angles of an equilateral or short isosceles triangle whose apex sits at the sternal angle, the bony ridge just below the notch.19PubMed Central. A geometric method for nipple localization Because the notch does not shift with weight changes, aging, or tissue loss the way the breast itself does, it gives surgeons a stable anchor for achieving symmetry.
How the Manubrium Develops Before Birth
The manubrium, the bone whose top edge forms the sternal notch, has an unexpectedly complicated origin story. Embryological studies show that it does not grow from a single block of tissue. Instead, it assembles from at least two sources: an interclavicular mesenchyme that is continuous with the developing clavicles and appears to originate from neural crest cells, and paired sternal bands at the front of the rib cage that derive from a different tissue layer. The interclavicular tissue expands downward and sideways until it meets the upper ends of the sternal bands, and the two fuse to form the primitive manubrium, with the sternoclavicular joint and its ligaments developing from the same interclavicular tissue.20PubMed. Morphogenesis of the manubrium of sternum in human embryos: a new concept This dual origin means the manubrium sits at a junction of embryonic tissues that elsewhere in the body give rise to very different structures: the neural crest contributes to parts of the skull and face, while the lateral plate forms the limb bones and body wall. It is a reminder that even a simple-seeming bone has a developmental history as layered as the anatomy it supports.
Variation Across Species
The sternal notch is not unique to humans, but the shape of the manubrium beneath it varies strikingly across primates. A comparative study of anthropoid primates found that apes, including humans, tend to have broader manubria and sterna than monkeys, a pattern that tracks with thoracic shape and how an animal moves through its environment.21PubMed. Manubriosternal Morphology of Anthropoid Primates Apes have barrel-shaped chests oriented front-to-back, an arrangement that supports upright posture and overhead arm movement. Monkeys, with their narrower, deeper chests, have correspondingly narrower manubria. The shape of the bone at the sternal notch, in other words, is a signature of an animal’s postural and locomotor strategy written into its skeleton.