Your Remarkable Anatomy
An Overview for Health Professionals, Students, and the General Public
Author: Dr. Don Lowell Fisher
Table of Contents
Chapter 1--Unusual You
Chapter 2--Multiple Births
Chapter 3--The Newborn Child
Chapter 4--General Body and Skin
Chapter 5--Anatomical Differences between the Sexes
Chapter 6--Upper Extremity
Chapter 7--Vertebral Column
Chapter 9--Thorax (The Chest Region)
Chapter 11-Larynx (The Voice Box)
Chapter 16-Scalp and Skull
Chapter 17-Brain and Spinal Cord
Chapter 18-Abdominal Wall and Digestive System
Chapter 19-Lower Extremities
Chapter 20-Reproductive System and Anus
Chapter 21-When Things Go Wrong
List of Some of Illustrations Contained
Fig. 1 The Placental Barrier
Fig. 5 Elbow of a 12 year-old
Fig. 6 Elbow of an Adult
Fig. 7 Creases of the Hand
Fig. 11 The Human Heart
Fig. 12 Muscles of the Larynx
Fig. 13 The Larynx
Fig. 18 The Brain
Fig. 23 Inguinal Hernia
Fig. 27 The Knee Joint
Fig. 28 Bones of the Foot
The thigh contains the longest muscle in the body (the sartorius). The large muscles in the back of the thigh (hamstring muscles) are slightly shorter than is necessary for full motion. When you straighten your legs to touch your toes, the knees naturally bend because of the shortness of these muscles. The only way you can touch your toes without bending your knees is by practice. This, then, stretches and lengthens the tendons of the hamstrings. The muscles in the back of the thighs are a third as powerful as the muscles in front.
The knee joint (Fig. 27) is the largest joint in the body, but it is also the least stable. The knee cap (patella) moves only on the lower (distal) end of the thigh bone (femur). It begins to form at about age 3 or 4 and finishes forming by puberty. Now, you know why little children crawl so easily and it hurts so much when you try to follow them. They dont have a bone in the front of the knee. It is supported mainly by muscles and ligament attachments. It is, therefore, subject to many types of injury including muscular strains or sprains of associated ligaments. On the inside (medial side) of the knee is a thick stabilizing ligament (the medial collateral ligament) which attaches to an internal cartilaginous disk (the medial meniscus). Forward movement of the shin bone (tibia) on the bone of the thigh (femur) is prevented by a thick internal ligament (the anterior cruciate ligament). This ligament is tight when the leg is straightened. The terrible triad of football involves a clipping incident in which the player is hit from slightly in back on the outside of the leg. If the leg is straight and the foot planted, the following structures are sometimes torn: the medial collateral ligament, the medial meniscus, and the anterior cruciate ligament. Approaching a football coach about this once, I asked what could the sports world possibly do to prevent knee injury.
|Figure 27. The Knee Joint|
He answered me with, If a football player wants to avoid knee injury, he could do so by never allowing his feet to touch the ground....
Shinsplints involve the front of the shin and are created by excessive muscular development in the lower leg. As the muscles begin to swell, this creates internal pressure involving vessels and nerves. Excessive expansion of these muscles is known as anterior compartment syndrome.
The calf muscles in the back of the leg attach to the heel bone by a very thick tendon (the Achilles tendon). This is named after the Greek hero whose mother dipped him in the river Styx to give him immortality. She held him by the heel, making this his only weak spot. Hence, the expression for the weak spot: the Achilles heel.
The ankle is much more stable going upstairs than downstairs. Most twisted ankles occur when the toes are pointed slightly in and the body is moving forward. The muscles of the calf region may become shortened by various means such as the wearing of high heels. If this happens, it becomes very painful to walk without shoes. With the toes pointed and the heel raised, the ankle becomes very unstable
The inside arch of the foot is supported mainly by ligaments. Muscles support ligaments in dynamic loading such as running and jumping. Standing for a long period of time causes muscle fatigue, allowing underlying ligaments to lengthen slowly, thus creating flat feet. When the major foot bone (talus) which moves on the lower leg (Fig. 28) drops between the heel bone (calcaneus) and the bone in front of the talus (navicular), you end up walking on the head of your talus, which becomes very painful for flat-footed people.
Running requires the use of the big toe. Sometimes, the second toe is longer than the first. This is called a Grecian foot. It is more often seen in women than in men. It was often used as a sign of beauty. It is found on many of the Greek statues. It was once thought that the statue of Venus de Milo had a Grecian foot; however, most people dont look at the feet. If they did, they would see that the left foot is missing and the right second toe is not straight enough to tell if it is longer than the big toe.
|Figure 28. Bones of the Foot|