Medical Terminology for Cancer

© Copyright 1996-2013

7: The Muscular System

Found this page useful?


Functions of muscles
Characteristics of muscle tissue
Types of muscles
Examples of muscles
Muscle movements
Roots, suffixes, and prefixes
Cancer Focus
Related Abbreviations and Acronyms
Further Resources

Functions of muscles

The main function of muscles is for motion, for example in conjunction with bones for walking. Many muscles work in groups but some may work alone e.g. the diaphragm for breathing, and the heart for circulating blood.

Characteristics of muscle tissue

(excitability) muscles receive and respond to stimulation.
allows muscles to change shape to become shorter and thicker.
living muscle cells can be stretched and extended; longer and thinner.
once the stretching force is removed a living muscle cell retains it's original shape.

Types of muscles

Different types of muscle respond, contract, and relax at different rates.

Skeletal muscles
are striated (have distinct bands) made up of fibres (long cells). The cells are multinucleated (many cell nuclei) and contract and relax quickly. These are voluntary muscles attached to the skeleton that help to move the bones. There are nearly 700 skeletal muscles spread all over the body.
Visceral muscles
are smooth and without banding. They have short fibres and single cell nuclei. These are involuntary muscles e.g. found in walls of blood vessels and viscera (organs in the abdominal cavity).
Cardiac muscles
are striated (but less distinct than skeletal muscles), and are involuntary .

Examples of muscles

The diaphram
is the major muscle for breathing (respiration). The diaphragm is located in the rib cage below the lungs. It is a dome shaped muscle that pulls / pushes air in and out of the lungs. 'Hiccups' are a spasm of the diaphragm.
also aid respiration Inter- (between) Costals (ribs). Internal intercostals lift the ribs during respiration, whilst external intercostals draw the ribs together during expiration to lessen the volume of the rib cage and thoracic cavity to push air out of the lungs.
Biceps and triceps
are antagonist(have the opposite functions). Triceps (with three 'heads') extend the forearm so it can be held straight, while biceps (two 'heads') flex the forearm and draw it up.
connect muscles to the bone, these are formed from the connective tissue that cover the muscle. They are dense white cords of tissue which are strong and flexible, they serve to anchor muscles to the bone.
Muscles anterior labeled Muscle posterior labeled
Selected major muscles: anterior (left) and posterior (right). Images c/o Wikimedia.

Muscle movements

Most movements involve several skeletal muscles working together. Most skeletal muscles are arranged in opposing pairs at joints, for example one muscle tightens up while the other extends.

tighten to decrease the angle of a joint
relax to increase the angle of a joint
move a bone away from the midline
move a bone toward the midline
make an upward movement
make a downward movement
turn the palm upwards or inwards
turn the palm downwards or outwards
decrease the size of an opening
makes part of the body more rigid
moves a bone around

Roots, suffixes, and prefixes

Most medical terms are comprised of a root word plus a suffix (word ending) and/or a prefix (beginning of the word). Here are some examples related to the Muscles. For more details see Chapter 4: Understanding the Components of Medical Terminology

SARC-tissue sarcoma = tumour of supportive tissues (muscle, bone etc.)
INTRA-into intramuscular injection = injection into a muscle
MYO-muscle myocardium = heart muscle
BI- two biceps = muscles with two heads
TRI-three triceps = muscles with three heads

Cancer Focus

Rhabdomyosarcoma is a malignant tumour of striated muscle found in children and young adults. Rhabdomyosarcoma accounts for about two thirds of childhood soft tissue sarcomas. There are 3 broad histological sub-types:
  1. Embryonal rhabdomyosarcoma occurs maily in infants and young children, usually arising in the head, neck or genitourinary system (especially the testis, prostate, vagina, and bladder).
  2. Alveolar rhabdomyosarcoma is most common in adolescents and young adults, mostly found in peripheral muscles.
  3. Pleomorphic rhabdomyosarcoma is most common in adults, usually found in the muscles of the extremities in adults.

Internet Resources for Rhabdomyosarcoma
Other types of Soft Tissue Sarcoma
Other types of cancer affecting muscles and soft tissues include:
fibrosarcoma (begins in fibrous tissue in the arms and legs)
neurofibrosarcoma (begins in nerves near the surface of arms, legs, and trunk)
leiomyosarcoma (muscles in the trunk)
liposarcoma (begins in fat in the arms and legs)
synovial sarcoma (begins in linings of joint cavities and tendon sheaths)
hemangiopericytoma (begins in blood vessels in the arms, legs, trunk, head,and neck).
alveolar soft part sarcoma (begins in nerves of the muscles in the arms and legs)
malignant fibrous histiocytoma (begins in fibrous tissue).

Internet Resources for Soft Tissue Sarcoma
Potential Side Effects of Radiotherapy on Muscles
Muscles can be damaged by radiotherapy which can cause fibrosis, muscle shortening and atrophy. Any potential side effects will depend on the site of the tumour, the patients age, and the dose of radiotherapy. For example high dose radiotherapy in may result in footdrop which is a condition where the anterior muscles of the leg are paralysed. Second malignancies particularly fibrosarcomas can also develop in previously irradiated sites.

Related Abbreviations and Acronyms

ARMSAlveolar rhabdomyosarcoma
IMIntramuscular - into a muscle
MPNSTMalignant Peripheral Nerve Sheath Tumour
NRSTSNon-Rhabdomyosarcoma Soft Tissue Sarcoma

Further Resources (4 links)

Main Contents of this Guide Alphabetical Index Next Chapter: Cardiovascular System

This guide by Simon Cotterill

First created 4th March 1996
Last modified: 1st February 2014

Medical Terminology for Cancer

What is Cancer?
Basic Terms
Components of Terminology

Body Systems

© 1996-2013