Dr. Martin's notes

Thursday September 1, 2016

The Abdomen and the Abdominal Cavities

Because of the organs of the body, the abdomen is divided in a few different ways to determine where things are located. The simplest division is into four QUADRANTS. One line is at the midline and the other line is at the umbilicus. Using these two divisions, the abdomen is divided into the upper left, upper right, lower left and lower right quadrants.

Please note the organs that are located in each quadrant.

To further detail the abdomen, a more complex system divides it into 9 areas called abdominal REGIONS. The center region is called the umbilical. To the left and right are the lumbar regions, and above the umbilical is the epigastric region. To the left and right of the epigastric is the hypochondriac region. Below the umbilical region is the hypogastric region, with the illiac regions to the left and right.

Bones have openings into them. A hole or opening in a bone is called a foramen

The Cranium has the largest foramen (opening) in the body, the Foramen Magnum, located in the occipital bone in the back of the head.

A bump on a bone is called a process (usually but not always, part of a joint)
A large rough protrusion is called a trochanter
A smaller rough protrusion is called a tuberosity
A depression into a bone (a socket) is called a fossa.

Osteology - Study of b.

Every adult skeleton contains 206 major bones. We can divide these bones into six broad categories according to their individual shapes

1. Long bones are relatively long and slender. Long bones are found in the arm and forearm, thigh and leg, palms, soles, fingers, and toes. The femur, the long bone of the thigh, is the largest and heaviest bone in the body.
2. Short bones are boxlike in appearance. Examples of short bones include the carpal bones (wrists) and tarsal bones (ankles).
3. Flat bones have thin, roughly parallel surfaces. Flat bones form the roof of the skull, the sternum, the ribs, and the scapula. They provide protection for underlying soft tissues and offer an extensive surface area for the attachment of skeletal muscles.
4. Irregular bones have complex shapes with short, flat, notched, or ridged surfaces. The spinal vertebrae and several skull bones are irregular bones.
5. Sesamoid bones are generally small, flat, and shaped somewhat like a sesame seed. They develop inside tendons and are most commonly located near joints at the knees, the hands, and the feet. Everyone has sesamoid patellae, or kneecaps, but individuals vary in terms of the location and abundance of other sesamoid bones. (Sesamoid bones may form in at least 26 locations.)
6. Sutural bones, or Wormian bones, are small, flat, irregularly shaped bones between the flat bones of the skull . There are individual variations in the number, shape, and position of the sutural bones. Their borders are like puzzle pieces, and they range in size from a grain of sand to the size of a quarter.

Each bone in the skeleton contains two different forms of osseous tissue, or bone tissue: (1) compact bone and (2) spongy bone. Compact bone, or dense bone, is relatively solid, whereas spongy bone forms an open network of struts and plates. Compact bone is always located on the surface of a bone, where it forms a sturdy protective layer. Spongy bone is in the interior of a bone. The relationship between compact and spongy bone and their relative proportions vary with the shape of the bone. (See Graphic on Pg. 177)

There is compact b. (hard) and cancellous bone (softer, more porus)
Diagram cross section of bone from outside to inside Periosteum-Compact (hard) bone-Cancellous (porus) bone - Bone Marrow

Four basic features of a representative sample of bone:
1. The matrix of bone is very dense and contains deposits of calcium salts.
2. The matrix contains bone cells, or osteocytes, within pockets, or lacunae. The lacunae are typically organized around blood vessels that branch through the bony matrix.
3. Narrow passageways through the matrix, called canaliculi, extend between the lacunae and nearby blood vessels, forming a branching network for the exchange of nutrients, waste products, and gases.
4. Except at joints, the outer surfaces of bones are covered by a periosteum that has outer fibrous and inner cellular layers.

Bone is composed mostly of mineral contents around a matrix - Mostly consists of CA, Mg and other minerals.Calcium phosphate, Ca3(PO4)2, accounts for almost two-thirds of the weight of bone. The calcium phosphate interacts with calcium hydroxide [Ca(OH)2] to form crystals of hydroxyapatite, Ca10(PO4)6(OH)2. As they form, these crystals also incorporate other calcium salts, such as calcium carbonate (CaCO3), and ions such as sodium, magnesium, and fluoride. Roughly one-third of the weight of bone is contributed by collagen fibers. Osteocytes and other cell types account for only 2 percent of the mass of a typical bone.

Marrow is where blood cells are formed. It is a fluid. Describe how a marrow transplant is done