The calcaneus and tarsus are two of the seven tarsal bones that are posterior to the first long bones of the foot, the metatarsal bones. The bones of the toes are phalanges , the same name used for finger bones.
Skip to main content. Module 7: The Appendicular Skeleton. Search for:. The lower limbs Information For anatomists, the lower limb consists of the thigh the upper leg , the leg the lower leg , and the foot. The bones of the left lower limb. The Right patella. The interosseous membrane of the left leg. The bones of the left foot. Lab 7 exercises 7. They are united behind to the vertebral column at the sacroiliac joints and in front to each other at the symphysis pubis.
Access to the complete content on Very Short Introductions online requires a subscription or purchase. Public users are able to search the site and view the abstracts and keywords for each book and chapter without a subscription. Please subscribe or login to access full text content.
If you have purchased a print title that contains an access token, please see the token for information about how to register your code.
For questions on access or troubleshooting, please check our FAQs , and if you can't find the answer there, please contact us. Very Short Introductions online. Publications Pages Publications Pages. Recently viewed 0 Save Search. Google Preview.
Read More. Go to page:. Your current browser may not support copying via this button. The main function of all muscles is to provide movement for the body. The muscular system consists of three different types of muscle tissues: skeletal, cardiac and smooth. Each of these different tissues has the ability to contract, which then allows body movements and functions. There are two types of muscles in the system and they are the involuntary muscles, and the voluntary muscles.
The muscles working under our conscious control are called the voluntary muscles and the ones the function of which can not be consciously controlled are the involuntary muscles. The heart, or the cardiac muscle, is an example of an involuntary muscle. It has stripe-like markings, or striations. The skeletal muscles are composed of long muscle fibers. The nervous system controls the contraction of the muscle.
Many of the skeletal muscle contractions are automatic. However we still can control the action of the skeletal muscle. And it is because of this reason that the skeletal muscle is also called voluntary muscle. They are found in the urinary bladder, gallbladder, arteries, and veins. Also the digestive tract is made up of smooth muscle as well. The smooth muscles are controlled by the autonomic nervous system and hormones.
We cannot consciously control the smooth muscles and that is why they are often called involuntary muscles. Its function is to "pump" blood through the circulatory system by contracting.
Muscles generally work in pairs to produce movement: when one muscle flexes or contracts the other relaxes, a process known as antagonism. An extensor muscle is any skeletal muscle that opens a joint increasing the angle between components of a limb, such as straightening the knee or elbow and bending the wrist or spine. With the exception of the knee joint the movement is directed backward. This action is known as extension. A flexor muscle is a skeletal muscle whose contraction bends a joint, decreasing the angle between components of a limb, such as bending the knee or elbow.
This action is known as flexion. An abductor muscle is any of the muscles that cause movement of an extremity limb away from the midline of the body or away from a neighbouring part or limb.
An adductor muscle is any of the muscles that draw a part of the body toward its median line or toward the axis of an extremity. In all skeletal muscles, contraction is stimulated by electrical impulses transmitted by the nerves, and motor neurons efferent neurons, motoneurons in particular. Neurons are basic nerve cells consisting of three parts: cell body, dendrite and axon.
Dendrites are extensions from the cell body which conduct impulses to the cell body, axons are extensions carrying the impulses away from the cell body. Neurons communicate with one another via synapses. A synapse is a microscopic space between an axon and a dendrite. Chemicals which help an impulse cross the synapse such as acetylcholine and catecholamine are called neurotransmitters. Motor neurons innervate or activate muscles groups to perform.
A single motoneuron may synapse with one or more muscle fibers. One motoneuron and all of the muscle fibers to which it connects is a motor unit. Groups of motor units often work together to coordinate contractions of a single muscle; the number of muscle fibers within each unit can vary. Thigh muscles can have a thousand fibers in each unit, eye muscles might have only ten.
In general, the number of muscle fibers innervated by a motor unit is a function of a muscle's need for refined motion. Muscles requiring more refined motion are innervated by motor units that synapse with fewer muscle fibers.
The term sports injury, in the broadest sense, refers to the kinds of injuries that most commonly occur during sports or exercise. Some sports injuries result from accidents, others are due to poor training practices, improper equipment, lack of conditioning, or insufficient warm-up and stretching. Although any part of your body can be injured during sports or exercise, the term is usually reserved for injuries that involve the musculoskeletal system, which includes the muscles, bones, and associated tissues like cartilage.
A strain is an injury which occurs to a muscle in which the muscle fibers tear as a result of overstretching. Strains are also colloquially known as pulled muscles. The equivalent injury to a ligament is a sprain.
Typical symptoms of a strain include localized pain, stiffness, swelling, inflammation, and bruising around the strained muscle. Strains can happen to anyone and are certainly not restricted to athletes; nevertheless, people who are involved in sports are more at risk of developing a strain. A sprain is an injury which occurs to ligaments caused by a sudden overstretching.
0コメント