Where Is Your Flank in Your Body? An Anatomical Overview

September 30, 2025 •

5 min read

The term “flank” refers to the area on your side, and it's a common point of medical reference, but where is your flank in your body? Anatomically, it’s the region on the side of your torso, located between the bottom of your rib cage and the top of your hip bone (iliac crest). This area is home to several important muscles and vital organs, most notably the kidneys.

Quick Summary

The flank is the side of the human torso between the lower ribs and the hip. It houses several key organs, including the kidneys, and contains important abdominal and back muscles. Understanding its location is crucial for identifying the potential sources of pain or discomfort.

Key Points

Flank Definition: The flank is the area on the side of your body, spanning from your lower ribs down to your hip bone (iliac crest).
Location of Flank Pain: Flank pain can occur on one or both sides, either deeper inside the torso or closer to the surface.
Contents of the Flank: Key internal organs in or near this region include the kidneys, pancreas, and parts of the liver and intestines.
Flank Pain vs. Back Pain: Unlike most back pain, which worsens with movement, kidney-related flank pain often feels constant and isn't affected by changing positions.
Muscular vs. Organ Pain: Pain from a muscle strain typically feels like a dull ache exacerbated by movement, while organ-related pain may come with additional symptoms like fever or nausea.
When to Seek Medical Help: Severe flank pain accompanied by fever, chills, blood in the urine, or nausea requires immediate medical attention.

Defining the Flank: An Anatomical Landmark

For many, the word 'flank' is not part of their everyday vocabulary, but it's a critical term in medicine and anatomy. It refers to the soft, fleshy area on the sides of your body, encompassing both the lateral (side) and posterolateral (side and back) aspects of the torso. It is not a single, defined muscle or organ, but rather a descriptive region of the body. To find your flank, place your hands on your hips and trace a line upwards to your lower ribs. The area you are touching is your flank.

This region is not only important for its anatomical position but also for what it contains. A range of conditions, from benign muscle strains to more serious issues with internal organs like the kidneys, can manifest as pain in the flank. A clear understanding of its boundaries and contents is essential for anyone experiencing discomfort in this area.

The Structures and Borders of the Flank

The flank is defined by several key anatomical landmarks that help healthcare professionals precisely locate the area. Its superior border is the lower margin of the ribcage, while its inferior border is the iliac crest, the curved ridge of the hip bone. The posterior border is the spine, and the anterior border is the abdominal wall. These boundaries delineate a space that is dense with crucial body components.

Several layers of muscles form the structural support of the flank. These include:

External and Internal Obliques: These are two of the three main flat abdominal muscles located on the lateral sides of the abdomen. They allow for trunk rotation and lateral flexion.
Transversus Abdominis: The deepest layer of abdominal muscle, it wraps around the torso and provides stability for the spine.
Quadratus Lumborum: This is a key muscle of the posterior abdominal wall, situated deep in the lower back. It aids in lateral flexion of the vertebral column.

Beyond the muscular structure, the flank also contains a variety of internal organs. The kidneys are the most well-known organs in this region, nestled on either side of the spine, partially protected by the lower ribs. Other organs that can cause pain in the flank area include the pancreas, gallbladder, and parts of the liver and intestines.

The Medical Significance of Flank Pain

Pain in the flank can be a critical indicator of an underlying health problem, and pinpointing the exact location and nature of the pain can help narrow down the cause. It can range from a dull, persistent ache to sharp, intense spasms, depending on the root issue.

For instance, kidney stones are infamous for causing severe, radiating flank pain that often comes in waves as the stone moves. Conversely, a musculoskeletal issue like a strained back muscle might cause a dull, aching pain that worsens with specific movements or exertion.

Comparing Kidney Pain vs. Musculoskeletal Flank Pain

Distinguishing between pain caused by internal organs and muscle or spinal issues can be challenging. Below is a comparison to help differentiate the two common types of flank pain.


Feature	Kidney Pain	Musculoskeletal Pain
Location	Often deeper, under the ribs on one or both sides of the spine.	Can be anywhere in the lower back or sides, but often feels more superficial.
Sensation	Dull ache that is often constant, or sharp, severe spasms that come in waves.	Often a dull, aching sensation, sometimes a sharp pain during specific movements.
Movement Effect	Typically does not change with movement or position.	Usually worsens with certain motions, such as bending, twisting, or lifting.
Accompanying Symptoms	May include fever, nausea, vomiting, blood in urine, and painful urination.	May involve stiffness, muscle spasms, and tenderness to the touch in the affected area.
Other Indicators	Pain may radiate toward the groin or lower abdomen.	Pain may start after exercise, lifting heavy objects, or sudden, awkward movements.

Potential Causes of Flank Pain

Flank pain can have a variety of causes, ranging from the easily manageable to serious conditions that require immediate medical attention. Some common causes include:

Kidney Stones: Hard mineral deposits that form in the kidneys and can cause excruciating pain as they move through the urinary tract.
Kidney Infections (Pyelonephritis): A type of urinary tract infection that travels up to the kidneys, causing fever, chills, and flank pain.
Muscle Strains: Overexertion or injury to the muscles in the abdominal wall or lower back can cause localized flank pain.
Urinary Tract Infections (UTIs): Infections in the bladder or ureters can sometimes cause referred pain in the flank.
Spinal Issues: Problems like herniated discs or spinal arthritis can cause nerve compression that refers pain to the flank.
Gallbladder Disease: Conditions affecting the gallbladder, particularly gallstones, can cause pain on the right side that radiates to the flank.
Diverticulitis: Inflammation of pouches in the digestive tract can cause abdominal pain that may extend to the flank area.

When to Seek Medical Attention

While some minor flank pain can be resolved with rest and at-home care, certain symptoms necessitate a visit to a healthcare provider. It's crucial to seek prompt medical attention if you experience flank pain accompanied by any of the following:

Fever or Chills: A high fever and chills often indicate an infection, which could be a kidney infection requiring antibiotics.
Blood in the Urine: The presence of blood in the urine, even if a small amount, is a major indicator of a urinary tract or kidney issue.
Severe Nausea or Vomiting: These symptoms often accompany kidney stones or severe infections.
Painful or Difficult Urination: Pain, burning, or increased urgency during urination can point to a UTI or kidney problem.
Persistent or Worsening Pain: If the pain does not subside after a few days or becomes more intense, a medical evaluation is necessary.

Conclusion

Understanding where is your flank in your body is more than just a matter of anatomical trivia; it's a vital piece of knowledge for monitoring your own health. The flank, defined as the region between your lower ribs and hips, is a crossroads for several important bodily systems. Its muscles provide structure and mobility, while the organs nestled within, especially the kidneys, play essential roles. Recognizing the location of the flank and the nature of any pain or discomfort can help you and your healthcare provider differentiate between minor issues and serious medical conditions. Paying attention to any persistent, severe, or accompanied pain is key to ensuring proper and timely treatment.

For more information on the anatomy of the abdominal wall and back, you can refer to resources from reputable medical institutions.

Frequently Asked Questions

Flank pain can present as a variety of sensations, from a dull, throbbing ache to a sharp, stabbing, or cramping pain. The specific feeling can often depend on the underlying cause, whether it's a kidney issue, a muscle strain, or another condition.

No, while flank pain is a classic symptom of kidney issues, it is not the only cause. Other potential culprits include muscle strains, spinal problems like herniated discs, gallstones, and certain gastrointestinal conditions.

A key difference lies in how the pain responds to movement. Pain from a muscle strain often worsens with specific movements (like bending or twisting) and improves with rest. Kidney pain, conversely, tends to be more constant and is not typically affected by movement.

Back pain can be felt anywhere along the back, while flank pain is specifically located higher up on the side, just below the ribs. Kidney pain, a common cause of flank pain, often feels deeper and is constant, whereas musculoskeletal back pain may vary with movement.

Yes, dehydration can be linked to flank pain. It can contribute to the formation of kidney stones and can put stress on the kidneys, which may lead to discomfort or pain in the flank area.

The organs in or near the right flank include the right kidney, the liver, the gallbladder, and parts of the intestines. Pain in the right flank could be associated with any of these organs.

If you experience flank pain accompanied by a fever, chills, or other severe symptoms like nausea or painful urination, you should seek medical attention right away. This can be a sign of a kidney infection, which needs prompt treatment with antibiotics.