Contents
Basic Anatomy
Bones
Our bones have bony landmarks on them. These bumps, divots and indentations help identify specific areas and some also act as connective areas for tissues. Our bones are affected as we age by a decrease in collagen. This makes the bones more brittle. It is typical that a man will experience less bone loss than a woman, because of hormone and weight differences. Bone density usually starts to decrease in both men and women after age thirty-five. Ethnicity also plays a role in the amount and rate of bone loss we incur as we age. After menopause some women experience ten times the amount of bone loss vs when they were in their thirties.
Skeletal Systems
There are two types of skeletons: The Axial and The Appendicular.
The Axial skeleton consists of 80 bones and includes the skull and facial bones, the spinal column and the ribcage.
The Appendicular skeleton consists of 126 bones and includes the pectoral girdle, pelvic girdle and upper and lower extremities.
Combined this totals 206 bones in the entire human body.
All bones fall into one of four shape categories: Long, flat, short or irregular. Most limb bones are categorized as long bones and are longer than they are wide. The scapulae (shoulder blades), ribs and sternum (breastbone) are some examples of flat bones. Typically, flat bones have some curvature. Carpal (wrist) and tarsal (ankle) bones are good examples of short bones, these bones are typically somewhat cube shaped. Irregular bones are bones that do not fit into one of the other categories. Vertebrae and facial bones are examples of irregular bones.
Vertebral Column
The bones make up the framework of the body. Without them we would not be able to stand tall. The four natural curves of the spine help us maintain good posture. We have 5 Lumbar vertebrae located in the lower back, 12 Thoracic vertebrae located above the lumbar and connecting above to the 7 Cervical vertebrae of the neck. The sacrum and coccyx are typically fused in adults and lie below the lumbar vertebrae where they come together with more bones to form the pelvis. The most flexible part of the spine is the neck. The cervical vertebrae are the smallest of all the vertebrae in the human body. The next largest is the thoracic vertebrae which have an area on them for the ribs to attach. The lumbar vertebrae are the largest and restricted with certain types of movement. The spinal cord runs the length of the spine and comes out the sacrum at the base of the spine.
Ribcage
Total we have 12 pairs (24 individual) ribs. All the ribs attach to the spine in the back of the body. Ribs 1-7 are called true ribs because they are attached to the sternum (breastbone) by cartilage. Ribs 8-10 are called false ribs and are not attached to the sternum but instead to the 7th rib. Ribs 11-12 are also false ribs but are called floating ribs because they only attach to the spine.
There are different sizes and shapes of bones which serve different purposes in the body. Often the femur is used for leverage. The femur is the thigh bone, it is the strongest and longest bone in the body. The tibia and fibula are the lower leg bones which connect above to the femur to form the knee, and below at the foot to form the ankle joint. There are lots of connective tissue and small bones that connect to form the foot and ankle joint. The knee has four major ligaments which help strengthen and support the joint.
Leg and Foot Bones
Pelvic Girdle
The pelvis supports our body and completes the spinal column. Pelvic bones are unique to each person. They are not the same shape in all women or all men. The pelvis is held together by almost completely immobile joints. The sacrum does allow movement at the pubic symphysis through connective tissue which allows the birth canal to open.
Shoulder Girdle
The shoulder is a mobile joint like the hip. The shoulder girdle is made of the shoulder blade (scapula) and the collar bone (clavicle). The humerus is the upper arm bone which connects to the scapula in the glenoid fossa. The glenoid fossa of the scapula is the socket part of the ball and socket joint. The head of the humerus makes up the ball part of the ball and socket joint. The humerus attaches at the other end with the radius and the ulna to make up the elbow joint. The forearm bones connect to the carpals of the hand to form the wrist. Like the foot and ankle, here are a lot of small bones and connective tissue that make up the wrist and hand.
Arm and Hand Bones
Cranium
The cranium, or head, is made up of immobile joints called sutures. There are many bones in the face. The mandible, which is the lower jawbone is the only movable bone in the face.