Skeletal System 3

Skeletal System 3

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Skeletal System 3...

Skeletal System 3:

The spine or the vertebral column is a long and sturdy protective gridwork for our spinal cord. It is made up of a series of separate bones that are connected in such a way to allow flexibility and protection.

Although they are made up of several parts there are very distinct characteristics to these sets of irregular bones. The vertebral column supports the head and provides for the attachment of the ribs.

The sets of irregular bones are separated from each other by pads of cartilage tissue called intervertebral disks. Page 140 in your text book shoes a graphic of the vertebral body. The parts include the spinous process, two transverse processes and the whole in the center of the vertebrae called the vertebral foramen.

Again, it is to your advantage to remember the sets of the vertebral column and the number of bones in each location.

Cervical- 7, Thoracic- 12, Lumbar- 5, Sacrum- 1, Coccyx- 1

In the child, the sacrum and the coccyx in children have intervertebral separations but become fused together as they mature.

When looking at the normal curves within your spinal column. The cervical and lumbar curves of the spine are called concave issues. The thoracic and sacral curves are called the convex curves. You will notice the difference between the baby and the adult relative to their ability to stand erect, hold their head up and offer support for their muscular structure especially in relation to walking.

Our normal curves of the spine have important functions. They give it strength to support the rest of the body. They provide balance for us to stand erect and be able to walk on two feet.

THORAX- 12 pairs of ribs, the sternum and the thoracic vertebrae for the bony cage known as the thorax or chest. Each of the 12 pairs of ribs are attached posteriorly to the thoracic vertebrae. The sternum is divided into three parts; the upper area or the manubrium, the body, and the lower cartilaginous part called the xiphoid process. Attached to each side of the upper sternum by ligaments are the two clavicles. Seven pairs of costal cartilages join 7 pairs of ribs directly to the sternum. These 7 pairs are known as the true ribs. The next 3 pairs are known as false ribs because they are attached to the 7 rib instead of directly to the sternum. Finally, the last two ribs are known as floating ribs as they are attached only to the spinal column and are not connected to the costal cartilage or the sternum.

APPENDICULAR SKELETON

The appendicular skeleton consists of the bones in the upper and lower extremities. There are 126 bones in this skeletal division.

SHOULDER GIRDLE

The shoulder girdle consists of 4 bones.

2- curved clavicle bones

2- triangular scapulae bones

The only direct point of attachment between bones occurs at the sternoclavicular notch or joint. This joint is very small. Due to the wide range of motion of the upper extremities with the small joint there is great pressure at or near the joint and therefore the chance for fracture is quite common for the clavicle. They permit the attachment of muscles which assist in arm movement. They also serve as an attachment for the arms. The structure of the shoulder girdle also assist in helping to brace the joints and prevent excessive forward motion.

ARM

The humerus is the long bone of the arm and it is attached to the scapula. It articulates with the 2 bones of the forearm. The 2 bones of the forearm are the radius and the ulna. The ulna being the larger of the two bones. The large bony process of the proximal ulna is called the olecranon process. There is a groove or depression in the distal end of the humerus which accepts this process for a fit that allows good ROM. This is referred to as the olecranon fossa.

HAND

The human hand is a remarkable piece of engineering and dexterity. It contains more bones for it’s size than any other part of the body. (27)

The hand itself is composed of 2 parts; the palmar surface which is composed of 5 metacarpal bones and the 5 fingers which are comprised of 14 phalanges. Each finger (not the thumb) have 3 phalanges except for the thumb which has two. The thumb is the most flexible due to the round metacarpal joint and the muscles that attach to the hand. Only man and other primates are known to have the digit known as the opposable thumb. This gives us great dexterity.

WRIST

8 small bones arranged in two rows are held together by ligaments which permit a great deal of mobility and flexion. However there is little lateral movement in these carpal bones.

PELVIC GIRDLE

The hip bone or the pelvic girdle connect the legs to the trunk. The hip girdle as a whole has 2 large os coxae or bones, one located on each side of the pelvis. These two bones with the sacrum and the coccyx behind them provide a strong base of support for the torso and connect the lower extremities.

In an infant the 3 bones called the ilium, ischium and the pubis are separate and as we grow older they fuse together to become one. The femur the long bone in the upper leg articulate with the os coxa. The femur is the strongest bone in the body. In fact it is amazingly strong being able to withstand a direct force to the top of the femur of 15,000- 19,000 psi. There is a deep cup shaped socket called the acetabulum or the acetabular socket which the head of the greater trochanter articulates.

Distally, the femur articulates with the patella and the tibia. A slender, non weight bearing and rather fragile bone is the fibula of the lower leg. Toe bones have the same name as finger bones- phalanges. There are the same number of toe bones as there are finger bones it is just that the toe bones are shorter than the finger bones. The names are the metatarsals and tarsals instead of carpals. The foot however has only 7 tarsal bones versus the hands eight. The largest bone in the foot is the calcaneus or the heel bone.