Skeletal and Muscular System

Bone plays a part in homeostasis because it helps to maintain a constant level of calcium in the blood.

By virtue of the smooth surface of hyaline cartilage, it provides a sliding area which reduces friction, thus facilitating bone movement.

The lacrimal bone, the smallest and most fragile bone of the face, is situated at the front part of the medial wall of the orbit. It has two surfaces and four borders.

Sharks have skeletons made entirely of cartilage rather than bone, which makes them lighter and more flexible than bony fish. This type of skeleton is characteristic of cartilaginous fish (Chondrichthyes), a group that also includes rays and skates. Cartilage is a firm but flexible connective tissue that allows sharks to swim efficiently and maneuver quickly through water. Their cartilage skeleton also heals more slowly than bone when injured.

The hyoid bone is unique in the human body because it's the only bone that doesn't articulate (form a joint) with any other bone. It floats in the neck, suspended by ligaments and muscles, and supports the tongue and other structures. All other bones listed (femur, tibia, ulna) form joints with other bones.

The ossicles (malleus, incus, and stapes) are the three smallest bones in the human body, located in the middle ear. The stapes is the smallest of all, measuring approximately 3mm × 2.5mm. These tiny bones transmit sound vibrations from the eardrum to the inner ear. The tibia, skull bones, and kneecap (patella) are all significantly larger.

The 'funny bone' is actually the ulnar nerve where it passes around the elbow. When you hit your elbow in a certain spot, you're compressing this nerve against the bone, causing the characteristic tingling sensation. It's not a bone, muscle, or blood vessel despite the name.

Caries is a progressive destruction of any kind of bone structure, including the skull, ribs and other bones, or the teeth. Caries can be caused by osteomyelitis, which is a microorganism disease. A disease that involves caries is mastoiditis, an inflammation of the mastoid process, in which the bone gets eroded.

Osteomyelitis simply means an infection of the bone or bone marrow. It can be usefully subclassified on the basis of the causative organism (pyogenic bacteria or mycobacteria), the route, duration and anatomic location of the infection.

The maxilla forms the upper jaw and holds the upper teeth. The mandible (B) is the lower jawbone (the only movable skull bone), vault (C) refers to the cranial vault (skull cap), and sagittarius (D) is a zodiac sign, not an anatomical term.

Sesamoid bones are usually short bones, imbedded in a tendon. The most obvious example of this is the patella (knee cap) which sits within the patella or quadriceps tendon.

Ligament most commonly refers to a band of rona, fibrous dense regular connective tissue bundles, made of attenuated collagenous fibers; with said bundles protected by dense irregular connective tissue sheaths.

In a saddle joint, the opposing surfaces are reciprocally concave-convex. Saddle joints are said to be biaxial, allowing movement in the sagittal and frontal planes. The best example of saddle joints are first carpo metacarpal joints, joints between femur and patella, calcaneocuboid joints.

The femur (thigh bone) is the longest and heaviest bone in the human body, typically about 50 cm long in adults. The 'born' in option A is a typo for 'bone'. The spine (back bone) consists of many small vertebrae, ribs form the ribcage, and ulna is a forearm bone.