Buzz
While organs like the heart, brain, and liver often dominate the conversation, and features such as smiles or athletic physiques capture admiration, there exists a fascinating array of lesser-known body parts that are equally deserving of recognition.
These hidden anatomical marvels may not be the most visually striking, but they play crucial roles in ensuring you don’t bump into obstacles, swallow without choking, or collapse unexpectedly while engrossed in this article. Below, we explore ten of the most overlooked yet vital components of the human body.
10. Vestibular System
Have you ever pondered how your brain senses your head’s position in space? Or why you remain steady when nodding or tilting your head? And what causes that disorienting feeling after spinning around repeatedly?
The solution lies in the vestibular system (VS), a tiny yet intricate structure made up of three semicircular canals and two chambers located in each inner ear. Positioned behind the eardrum and adjacent to the cochlea, the VS features fluid-filled canals oriented in different planes, allowing it to detect motion in all directions. At the ends of these canals are specialized areas known as maculae (distinct from those in the retinas), covered with sensory hairs. These hairs are topped with a gel-like substance containing small weights called otoliths. When you move your head, the canals and maculae shift, but the fluid and gel lag, bending the sensory hairs and sending signals to your brain about the head’s movement. When stationary, gravity’s effect on the weighted gel helps your brain determine your spatial orientation.
Why do we feel dizzy after spinning in circles? Have a friend spin rapidly for 30 seconds, then stop abruptly and try to focus on a fixed point. They’ll likely feel disoriented, struggle to walk straight, and exhibit rapid eye movements called nystagmus. This occurs because the VS stops moving, but the fluid inside continues due to momentum, confusing your brain. While your VS signals spinning, your eyes and cerebellum disagree, leading to imbalance and distorted vision. You can observe this effect in the medical student’s demonstration above.
9. Kneecaps
If you’ve ever taken a fall onto your knees or winced after hitting a table leg while sliding a chair, you’ve likely appreciated their protective role. However, kneecaps are far more than simple, natural kneepads.
It all comes down to leverage. The kneecap, or patella, primarily aids in knee extension (straightening the leg). Connected to the shinbone (tibia) by a robust tendon and linked to a key quadriceps muscle at the top, the patella enhances the knee’s extension force by 33 to 50 percent. This boost is due to the improved leverage around the joint. The quadriceps, a group of four muscles, derive their name from their number.
8. Cerebrospinal Fluid
Among the flesh, blood, and organs of the human body lies a stunning, crystal-clear liquid known as cerebrospinal fluid (CSF). This fluid is generated in the brain’s ventricles and flows around both the brain and spinal cord.
CSF serves multiple purposes, including safeguarding the brain by acting as a shock absorber during impacts or sudden movements of the skull. Additionally, it delivers nutrients and removes waste from the brain and spinal cord, functioning similarly to blood in other body regions. The production and absorption of CSF are finely balanced to maintain optimal pressure, ensuring proper support for the central nervous system (brain and spinal cord).
Medical professionals collect CSF through a procedure known as a lumbar puncture, where a needle is inserted into the spinal canal to extract the fluid. This method helps diagnose conditions like infections (e.g., meningitis), brain hemorrhages (hemorrhagic stroke), and other disorders.
7. Uterus
While many women may not hold their uterus in high regard due to the pain or issues it can cause, it undoubtedly earns a spot of honor on this list.
One of the uterus’s most astonishing traits is its capacity to grow from roughly the size of a clenched fist to occupying much of the abdominal and thoracic space during pregnancy, accommodating a fully developed fetus, placenta, and amniotic fluid. Its ability to expand is unmatched by any other organ in the human body.
The uterus also boasts unique muscular capabilities. While many are aware of the intense pain and strength of contractions during labor—a physiological marvel in itself—fewer know about its critical role immediately after birth. Once the placenta separates from the uterine wall, there’s a significant risk of bleeding (postpartum hemorrhage) as numerous large blood vessels are left exposed.
Imagine this happening on your arm or leg—what would you do? Apply pressure, right? The uterus does exactly that! Right after delivering the baby and placenta, a hormone surge triggers powerful uterine contractions, compressing the blood vessels and aiding their healing and closure.
6. Valves
While many of us appreciate our sphincters (and rightly so), let’s not overlook the importance of our valves. The cardiovascular system operates like a sophisticated plumbing network, with one-way valves ensuring blood flows in the correct direction. Our four powerful pumps (the heart) work in harmony to circulate blood in a figure-eight pattern—first to the lungs for gas exchange, then to the rest of the body to deliver nutrients, remove waste, and maintain equilibrium.
Blood is propelled from the heart into arteries, which expand and contract with each heartbeat, creating the pressure wave known as your “pulse.” As blood travels away from the heart, arteries divide into progressively smaller vessels until they reach capillaries, which are just a single cell wide. This is where the exchange of nutrients and waste occurs between blood and tissues. Blood flow slows significantly here, losing its pulse due to the vast surface area of these microscopic capillaries.
On its return journey to the heart, blood flows through veins, which merge into larger vessels. However, the pressure driving blood back is minimal, and it must often work against gravity. To address this, veins are equipped with one-way valves that ensure blood moves in the correct direction. These valves are sometimes visible in the arms, especially when a tourniquet is applied during a blood test, appearing as small bumps along an otherwise smooth vein.
The heart itself contains four crucial one-way valves. Each of the heart’s four chambers has a valve that snaps shut during contraction to prevent backflow. These chambers function in pairs, and the sound of the valves closing creates the familiar “lub-dub” heartbeat. Any malfunction in these valves can produce additional heart sounds and reduce the heart’s efficiency.
5. Lens
Anyone who has gone through the process of getting glasses knows how challenging it can be to find the perfect lens for vision correction. Similarly, your eyes contain natural lenses. These transparent, concave structures refract light to project images onto the retina at the back of your eyeball, which then sends visual information to your brain for interpretation.
Unlike artificial lenses made of glass or polycarbonate, the lenses in your eyes are flexible and can adjust their shape to focus on objects at varying distances. However, as we age, the lens loses its elasticity. This is why many people need reading glasses later in life—the lens struggles to return to its thickest form, which is essential for near vision. Glasses compensate by bending light more before it enters the eye.
4. Ciliary Muscle
How do our lenses change shape? This is accomplished by the ciliary muscle, a ring of muscle surrounding the lens that contracts and relaxes to alter the lens’s thickness. By doing so, it adjusts the degree to which incoming light is bent, ensuring images remain in focus.
This process, called accommodation, is one of the body’s most intricate motor functions. In fact, our eyes rank among the most complex organs in the human body.
3. Skin
As the body’s largest organ, the skin is widely recognized, yet its critical importance is often overlooked. It performs six essential functions, and if any of these were to fail, it could lead to severe illness or even death.
First, the skin acts as a protective shield against physical, thermal, chemical, and radiation-related injuries encountered in everyday life. Additionally, it plays a vital role in regulating your body temperature. While sweating may seem inconvenient, it is crucial for maintaining normal physiological functions and contributes to balancing the body’s fluids and electrolytes.
The skin also serves multiple immune roles, functioning as both a physical and immunological barrier against infections and allergens. Its metabolic functions include producing vitamin D and other proteins necessary for cellular activity. Lastly, the skin is the body’s most versatile sensory organ, capable of detecting heat, cold, light touch, firm pressure, pain, and vibrations.
2. Diaphragm
The diaphragm is a broad sheet of fibrous and muscular tissue that divides the abdominal and thoracic cavities. Its involuntary twitching causes hiccups. While the rib cage aids in expansion and contraction, the diaphragm is the primary muscle driving respiration. In its relaxed state, it forms a dome shape, curving upward into the thoracic cavity. When it contracts, it flattens, enlarging the thoracic space and creating a vacuum that pulls air into the expanding lungs.
Beyond breathing, the diaphragm assists in regulating pressure during activities like vomiting, coughing, urinating, and defecating.
On a chest X-ray, the diaphragm appears higher on the right side due to the liver’s position. With each breath, the abdominal contents beneath the diaphragm shift slightly as you inhale and exhale.
1. Epiglottis
Anatomically, the trachea lies in front of the esophagus, meaning every time we swallow, food or liquid must pass over the windpipe to enter the food pipe. If this process isn’t perfectly coordinated, choking occurs.
The epiglottis is a flexible flap of cartilage located at the top of the larynx (the upper section of the windpipe). During swallowing, the larynx moves upward, which is why you can observe the throat’s movement. In males, the “Adam’s apple,” a prominent cartilage structure, makes this motion more noticeable. As the larynx rises, the epiglottis folds over the windpipe’s opening, directing food and liquids into the esophagus.
This mechanism underscores the importance of placing someone in the recovery position during first aid when necessary. Lying them on their side helps keep the airway clear, allowing fluids or secretions to drain from the mouth rather than entering the airway.
