Bones and Skeletal system (Bones (Carpals, Tibia, Femur, Finula, Pelvis,…
Bones and Skeletal system
Compct bone tissue
Every bone has a dense outer layer that looks smooth and solid to the naked eye. This external layer is compact bone . Internal to this is spongy bone, a honeycomb of small needle-like or flat pieces called trabeculae. In living bones the open spaces between trabeculae are filled with red or yellow bone marrow.
The functional classification is based on the amount of movement allowed at the joint. On this basis, there are synarthroses, which are immovable joints; amphiarthroses , slightly movable joints; and diarthroses, or freely movable joints.
A tubular diaphysis, or shaft, forms the long axis of the bone.The epiphyses are the bone ends. Between the diaphysis and each epiphysis of an adult long bone is an epiphyseal line, a remnant of the epiphyseal plate. The epiphyseal plate, commonly called the growth plate, is a disc of hyaline cartilage that grows during childhood to lengthen the bone.
Type of bones
Short bones are roughly cube shaped. The bones of the wrist and ankle are examples. Sesamoid bones are shaped like a sesame seeds and are a special type of short bone that form in a tendon
Flat bones are thin, flattened, and usually a bit curved. The sternum (breastbone), scapulae (shoulder blades), ribs, and most cranial bones of the skull are flat bones
Long bones, as their name suggests, are considerably longer than they are wide. A long bone has a shaft plus two ends, which are often expanded. All limb bones except the patella (kneecap) and the wrist and ankle bones are long bones. Notice that these bones are named for their elongated shape, not their overall size.
Irregular bones have complicated shapes that fit none of the preceding classes. Examples include the vertebrae and the hip bones
Bone remodeling and fracture repair
The presence of bone cells is what makes bone a dynamic living tisue because these cells continuously resorb and deposit bone in a process called remodeling.Osteocytes communicate this information to the cells responsible for bone remodeling (osteoblasts and osteoclasts) so that bone matrix can be made or degraded as mechanical stresses dictate. Osteocytes can also trigger bone remodeling to maintain calcium homeostasis as we will see shortly.
Bone’s resilience is thought to come from sacrificial bonds in or between collagen molecules. These bonds stretch and break easily on impact, dissipating energy to prevent the force from rising to a fracture value. In the absence of continued or additional trauma, most of the sacrificial bonds re-form.
The female pelvis is modified for childbearing: It tends to be wider, shallower, lighter, and rounder than that of a male. The female pelvis not only accommodates a growing fetus, but it must be large enough to allow the infant’s relatively large head to exit at birth.
Chondromalacia patellae-Damage and softening of the articular cartilages on the posterior patellar surface and the anterior surface of the distal femur; most often seen in adolescent athletes. Produces a sharp pain in the knee when the leg is extended
Rheumatism-A lay term referring to disease involving muscle or joint pain; may be used to apply to arthritis, bursitis, etc.
Synovitis- Inflammation of the synovial membrane of a joint. Caused by injury, infection, or arthritis. Excess synovial fluid accumulates in the joint cavity, a condition called effusion that causes the joint to swell, limiting joint movement.
Ankylosing spondylitis-) A variant of rheumatoid arthritis that chiefly affects males; it usually begins in the sacroiliac joints and progresses superiorly along the spine. The vertebrae become interconnected by fibrous tissue, causing the spine to become rigid.
Flexio is a bending movement, usually along the sagittal plane, that decreases the angle of the joint and brings the articulating bones closer together.
Extension is the reverse of flexion and occurs at the same joints. It involves movement along the sagittal plane that increases the angle between the articulating bones and typically straightens a flexed limb or body part.
Angular movements increase or decrease the angle between two bones.
Abduction is movement of a limb away from the midline or median plane of the body, along the frontal plane.
Gliding occurs when one flat, or nearly flat, bone surface glides or slips over another (back-and-forth and side-to-side) without appreciable angulation or rotation.
Adduction is the opposite of abduction, so it is the movement of a limb toward the body midline or, in the case of the digits, toward the midline of the hand or foot
Circumduction is moving a limb so that it describes a cone in space (circum = around; duco = to draw). The distal end of the limb moves in a circle, while the point of the cone (the shoulder or hip joint) is more or less stationary.
Rotation is the turning of a bone around its own long axis. It is the only movement allowed between the first two cervical vertebrae and is common at the hip and shoulder joints. Rotation may be directed toward the midline or away from it.
The terms supination and pronation refer to the movements of the radius around the ulna .
Nonangular anterior and posterior movements in a transverse plane are called protraction and retraction, respectively .
Inversion and eversion are special movements of the foot ). In inversion, the sole of the foot turns medially. In eversion, the sole faces laterally.
Lifting the foot so that its superior surface approaches the shin is dorsiflexion (corresponds to wrist extension), whereas depressing the foot (pointing the toes) is plantar flexion (corresponds to wrist flexion).
Elevation means lifting a body part superiorly.
Opposition of the thumb is the movement taken when you touch your thumb to the tips of the other fingers on the same hand.