BASIC BODY

BASIC BODY Real science for a curious mind.

BASIC BODY turns complex human-body science into simple, fascinating stories. 🧠 From anatomy and the brain to health, vision, cells, and everyday biology discover what’s really happening inside you.

Tarsal bones are the seven strong bones of the rear and middle foot that connect the lower leg to the metatarsals and he...
10/08/2026

Tarsal bones are the seven strong bones of the rear and middle foot that connect the lower leg to the metatarsals and help support body weight, balance, and movement. They include the talus, calcaneus, navicular, cuboid, and three cuneiform bones. The talus sits directly beneath the tibia and forms a major part of the ankle joint, transferring weight from the leg into the foot. The calcaneus, or heel bone, is the largest tarsal bone and provides a strong base for standing, walking, and pushing off the ground. In front of the talus lies the navicular, which helps support the medial arch of the foot. The cuboid is located on the outer side of the foot and helps stabilize the lateral arch. The medial, intermediate, and lateral cuneiform bones sit between the navicular and the first three metatarsals, helping maintain the shape and flexibility of the foot’s arches.
Together, the tarsal bones form multiple small joints that allow the foot to adapt to uneven surfaces while remaining stable during movement. Strong ligaments hold these bones together, while nearby tendons and muscles help control foot position and movement. Because the tarsal region carries significant body weight, injuries such as fractures, sprains, arthritis, or joint irritation can cause pain, swelling, stiffness, and difficulty walking. Maintaining good footwear, healthy body mechanics, and appropriate activity levels can help protect these important bones.

Yellow bone marrow is a soft, fat-rich tissue found mainly inside the hollow medullary cavities of long bones, especiall...
10/08/2026

Yellow bone marrow is a soft, fat-rich tissue found mainly inside the hollow medullary cavities of long bones, especially in adults. It contains large numbers of adipocytes, or fat cells, which store energy primarily as triglycerides. Unlike red bone marrow, which actively produces red blood cells, white blood cells, and platelets, yellow marrow normally has much lower blood-cell-producing activity.
As a person grows, some of the red marrow present during childhood is gradually replaced by yellow marrow. This is why adults usually have more yellow marrow in the shafts of long bones such as the femur, tibia, and humerus, while active red marrow remains concentrated mainly in areas such as the pelvis, vertebrae, ribs, sternum, and certain parts of long bones.
Yellow bone marrow is not simply inactive fat. Its stored lipids provide an important energy reserve, while marrow fat cells and surrounding supportive cells contribute to the internal bone-marrow environment. In situations of severe physiological stress, such as major blood loss or greatly increased demand for blood-cell production, some yellow marrow can shift toward a more blood-forming state and support hematopoiesis.
The infographic also highlights the major difference between red and yellow marrow. Red marrow is rich in hematopoietic cells and is responsible for producing blood cells, whereas yellow marrow contains a much larger proportion of adipose tissue and mainly serves as an energy-storage tissue.
Changes in the amount or appearance of bone marrow can also be important medically. Doctors may evaluate marrow using imaging studies and, when necessary, laboratory testing or bone-marrow examination to investigate conditions affecting blood formation, bone marrow, or overall skeletal health.

This infographic explains the ulnar artery, one of the two major arteries of the forearm. It usually begins as a branch ...
10/08/2026

This infographic explains the ulnar artery, one of the two major arteries of the forearm. It usually begins as a branch of the brachial artery near the elbow and travels down the medial, or little-finger side, of the forearm toward the wrist and hand. Along its course, it gives off several important branches that help supply blood to the forearm muscles, wrist structures, and hand.
The central anatomical illustration shows the ulnar artery in red, running through the forearm alongside muscles, tendons, nerves, and other blood vessels. Near the elbow, the artery gives rise to the common interosseous artery, which then divides into anterior and posterior interosseous branches that supply deeper structures of the forearm. As the ulnar artery continues toward the wrist, it also produces smaller muscular, palmar carpal, and dorsal carpal branches.
At the wrist, the ulnar artery passes into the hand and contributes significantly to the superficial palmar arch. This arterial arch distributes blood through branches that supply much of the palm and fingers, particularly the little-finger side of the hand. The infographic includes close-up views of the artery at the wrist and within the palm so viewers can clearly understand how the vessel continues into the hand.
The poster also highlights why the ulnar artery is clinically important. Damage from a deep cut, trauma, compression, arterial disease, or repetitive injury can reduce blood flow to the hand. Possible warning signs include hand pain, unusual coolness, pale or bluish fingers, reduced circulation, delayed wound healing, or numbness and tingling when nearby nerves are also affected.
The ulnar artery is also important during clinical circulation testing. Healthcare professionals may assess blood flow through the radial and ulnar arteries before certain procedures involving the wrist or hand. Because the artery helps maintain circulation to the palm and fingers, significant injury or blockage may require urgent medical attention.
Key takeaway: The ulnar artery is a major blood vessel that travels along the inner forearm and plays an essential role in supplying oxygen-rich blood to the forearm, wrist, palm, and fingers through its branches and the superficial palmar arch.

This infographic explains the jugular veins, the major veins of the neck that return deoxygenated blood from the brain, ...
10/08/2026

This infographic explains the jugular veins, the major veins of the neck that return deoxygenated blood from the brain, face, scalp, and neck back toward the heart. The jugular venous system is especially important because it provides one of the main drainage pathways for blood leaving the head and plays a major role in maintaining normal circulation between the brain and the chest.
The central anatomical illustration shows the jugular veins running vertically through the neck. The two most important vessels are the internal jugular vein and the external jugular vein. The internal jugular vein is the larger and deeper vessel. It begins near the base of the skull and travels downward within the neck beside the carotid artery and vagus nerve. It drains blood mainly from the brain, deep structures of the face, and deeper tissues of the neck.
The external jugular vein lies more superficially, closer to the skin. It usually runs over the sternocleidomastoid muscle and carries blood from the scalp, superficial face, and outer parts of the neck. Because it is closer to the surface, the external jugular vein may sometimes become more visible when venous pressure increases.
Another smaller vessel, the anterior jugular vein, runs near the front of the neck and helps drain superficial tissues in this region. These veins communicate with one another and eventually direct blood toward the larger central veins of the chest.
Near the lower neck, the internal jugular vein joins the subclavian vein to form the brachiocephalic vein. The right and left brachiocephalic veins then join to form the superior vena cava, which carries deoxygenated blood into the right atrium of the heart.
The infographic also highlights the close relationship between the internal jugular vein, carotid artery, and vagus nerve. These structures travel together within the carotid sheath, which is why procedures in this area require careful anatomical knowledge.
The jugular veins are clinically important as well. The internal jugular vein is commonly used for central venous access, allowing healthcare professionals to deliver medications, fluids, nutrition, or monitor certain pressures in critically ill patients. The jugular veins are also examined when estimating jugular venous pressure, or JVP, which can provide information about pressure on the right side of the heart and overall fluid status.
Abnormally prominent or swollen neck veins may sometimes be associated with conditions such as right-sided heart failure, fluid overload, obstruction of major veins, or increased pressure within the chest. Sudden neck swelling, severe shortness of breath, chest pain, or unusual enlargement of the neck veins should therefore be medically assessed.
Although the jugular veins mainly carry deoxygenated blood, they are essential for maintaining efficient blood flow away from the brain and head. Any significant blockage, clot, compression, or injury affecting these vessels may interfere with normal venous drainage.
Key takeaway: The jugular veins are major neck vessels that drain blood from the brain, face, scalp, and neck and return it toward the heart. The internal jugular vein handles most deep venous drainage, while the external jugular vein mainly drains superficial structures of the head and neck.

10/08/2026

Can bone grow beneath your toenail? Yes!

Taste buds are tiny sensory structures that allow you to detect the five basic tastes: sweet, salty, sour, bitter, and u...
10/07/2026

Taste buds are tiny sensory structures that allow you to detect the five basic tastes: sweet, salty, sour, bitter, and umami. Most taste buds are located within specialized structures on the tongue called papillae, although taste receptors are also found in areas such as the soft palate and upper throat. Each taste bud contains clusters of specialized taste receptor cells arranged around a small opening called the taste pore. When food enters the mouth, chemicals from the food dissolve in saliva and reach the taste pore, where they interact with tiny projections called microvilli on the receptor cells.
Different chemicals activate different taste pathways. Sweet compounds usually signal sources of carbohydrates and energy, salty taste detects dissolved salts such as sodium, sour taste responds mainly to acids, bitter receptors can help detect potentially harmful or toxic compounds, and umami responds strongly to amino acids such as glutamate that are commonly associated with protein-rich foods. Once a taste receptor cell is activated, it converts the chemical signal into an electrical message. These signals travel through sensory nerves, including branches of the facial, glossopharyngeal, and vagus nerves, toward the brain, where they are processed and recognized as taste.
Taste is also closely connected with the sense of smell. Much of what people experience as “flavor” comes from the combination of taste, aroma, food temperature, texture, and other sensations inside the mouth. This is why food may seem unusually bland when your nose is blocked during a cold.
Taste receptor cells do not last forever. They are continually replaced by new cells, allowing the taste system to maintain its function over time. Taste perception can still change because of aging, smoking, certain medications, infections, nutritional deficiencies, dry mouth, nerve problems, or damage to structures involved in taste.
Healthy taste sensation is important not only for enjoying food but also for nutrition and protection. It helps the body recognize appealing nutrients, detect spoiled or potentially harmful substances, and regulate eating behavior. If someone develops a persistent unexplained loss or major change in taste, especially when accompanied by other neurological or oral symptoms, medical evaluation may be appropriate.

Sesamoid bones are small, rounded bones that develop inside tendons, usually in places where a tendon passes over a join...
10/07/2026

Sesamoid bones are small, rounded bones that develop inside tendons, usually in places where a tendon passes over a joint and experiences repeated pressure or friction. Unlike most bones, which connect directly with other bones, sesamoid bones are embedded within tendons and help those tendons work more efficiently. The patella, or kneecap, is the largest sesamoid bone in the human body.
In the foot, two important sesamoid bones are located beneath the head of the first metatarsal, near the base of the big toe. They sit inside the tendons of the flexor hallucis brevis muscle. One is positioned on the medial, or inner, side of the foot and the other on the lateral, or outer, side. These bones help support the big-toe joint during standing, walking, running, and pushing off the ground.
Sesamoid bones perform several important jobs. They reduce friction between tendons and surrounding tissues, protect tendons from excessive pressure, absorb and distribute forces, and improve the mechanical leverage of muscles. By acting almost like small pulleys, they change the direction of tendon pull and make certain movements stronger and more efficient.
Problems can develop when these bones are exposed to repeated stress. Sesamoiditis is irritation or inflammation around the sesamoid area and is often associated with repetitive loading, running, jumping, or activities that place heavy pressure on the forefoot. A stress fracture can form gradually from repeated loading, while an acute fracture may happen after a sudden injury. In some cases, reduced blood supply can lead to osteonecrosis, which may cause persistent pain.
Common symptoms include pain beneath the big toe, tenderness when the area is pressed, swelling or bruising, discomfort during walking or running, pain while pushing off the foot, and difficulty bending the big toe. Severe pain, inability to bear weight, major swelling, or pain that does not improve should be assessed by a healthcare professional.
Treatment depends on the cause and severity. Initial care may include rest, reducing high-impact activity, applying ice, using supportive footwear, cushioned insoles or sesamoid pads, and temporarily reducing pressure on the affected area. Persistent or severe symptoms may require an examination and imaging such as an X-ray or MRI to check for a fracture or other underlying problem.

Extraocular muscles are six small skeletal muscles located inside the eye socket that control nearly every movement of t...
10/07/2026

Extraocular muscles are six small skeletal muscles located inside the eye socket that control nearly every movement of the eyeball. They work together continuously so both eyes can point toward the same target, follow moving objects, scan the environment, and maintain clear single vision. These muscles are the superior re**us, inferior re**us, medial re**us, lateral re**us, superior oblique, and inferior oblique.
The superior re**us mainly moves the eye upward, while also helping turn it slightly inward and rotate it inward. The inferior re**us moves the eye downward and also assists with inward movement and outward rotation. The medial re**us pulls the eye toward the nose, a movement called adduction, while the lateral re**us pulls the eye away from the nose, called abduction. The superior oblique helps move the eye downward when the eye is turned inward and produces inward rotation, known as intorsion. The inferior oblique helps move the eye upward when the eye is turned inward and produces outward rotation, called extorsion.
These muscles are controlled by three cranial nerves. The oculomotor nerve, cranial nerve III, controls the superior re**us, inferior re**us, medial re**us, and inferior oblique. The trochlear nerve, cranial nerve IV, controls the superior oblique, while the abducens nerve, cranial nerve VI, controls the lateral re**us. Precise coordination between these nerves, the brain, and the muscles allows both eyes to move smoothly together.
Problems affecting the extraocular muscles or their nerves can cause double vision, abnormal eye alignment, restricted eye movement, eye strain, or strabismus. Conditions such as cranial nerve palsy, thyroid eye disease, orbital inflammation, trauma, or certain neurological disorders may interfere with normal eye movement. Sudden double vision, a new change in eye position, severe pain with eye movement, bulging of the eye, or sudden loss of vision should be evaluated promptly by an eye-care professional.

10/07/2026

How does your body remove a blood clot?

Metacarpals are the five long bones of the hand located between the wrist bones, called the carpals, and the finger bone...
10/06/2026

Metacarpals are the five long bones of the hand located between the wrist bones, called the carpals, and the finger bones, called the phalanges. They form the main bony framework of the palm and are numbered Metacarpal I to V, beginning with the thumb and ending with the little finger. Each metacarpal has three main regions: the base, which connects with the wrist; the shaft, which forms the long middle portion; and the head, which forms the prominent knuckle where the bone meets the finger.
These bones are essential for normal hand movement. They help transfer force from the wrist toward the fingers, provide stability during gripping and pinching, and work together with muscles, tendons, ligaments, and joints to produce precise movements. The first metacarpal of the thumb is especially mobile, allowing the thumb to move across the palm for actions such as holding, writing, and picking up small objects.
The metacarpals contain a hard outer layer of compact bone and an inner network of spongy bone with bone marrow. Their bases participate in the carpometacarpal joints, while their heads form the metacarpophalangeal joints, commonly known as the knuckles. Strong ligaments between neighboring metacarpals help keep the bones aligned and stabilize the palm.
Common metacarpal injuries include fractures, dislocations, and impact-related trauma. A well-known example is a boxer’s fracture, which usually affects the neck of the fifth metacarpal near the little finger and can occur after striking a hard object. Warning signs such as severe swelling, visible deformity, difficulty moving the fingers, numbness, an open wound, or persistent pain after an injury should be medically assessed.
Protecting the metacarpals is important because damage to these bones can reduce grip strength, finger alignment, hand coordination, and everyday hand function. Wearing appropriate protective equipment during high-risk activities, avoiding repeated direct impacts, and allowing injuries enough time to heal can help maintain healthy hand movement.

Address

1460 Golf Road
Rolling Meadows, IL
60008

Website

Alerts

Be the first to know and let us send you an email when BASIC BODY posts news and promotions. Your email address will not be used for any other purpose, and you can unsubscribe at any time.

Shortcuts

Share

Category