Muscular System

Muscle Function

-Movement -Posture -Stabilization of joints -Body temp. maintenance.

leiomyoma

A benign tumor of smooth muscle tissue (e.g., the uterus).

charley horse

A bruised or torn muscle accompanied by cramps and severe pain. This particular injury most commonly affects the quadriceps muscle. (Incidentally, quadriceps is like biceps or triceps, which always ends in -s, whether singular or plural.) Lay people refer to any muscle spasm of the legs or feet as a charley horse.

myasthenia gravis

A chronic progressive neuromuscular weakness, usually starting with the muscles of the face and throat.

tetanus

A disease caused by the bacterium Clostridium tetani, which produces a toxin that causes muscles to go into tetany (hyperexcitability of nerves and muscles, specifically characterized by muscular cramps and twitching). Jaw muscles are affected first. Lockjaw is the more common name.

myositis ossificans

A disease characterized by bony deposits or the ossification of muscle tissue.

aponeurosis

A flat tissue sheet that connects muscle to bone.

muscular dystrophy

A genetic abnormality of muscle tissue characterized by dysfunction and ultimately deterioration.

transverse

A horizontal plane situated at right angles to the long axis, or sagittal and coronal planes; placed crosswise.

Muscular System

A muscle is an organ that contracts to produce movement. Muscle contraction in conjunction with skeletal flexibility makes movement possible in human beings.

Location

A muscle may be named for its actual location within the body relative to other body structures. Examples Pectoralis: Chest muscle located within the pectoral girdle. Intercostal: Muscle located between ribs (intercostal literally means between ribs). Abdominis: Located in the abdominal area.

quadriplegia

A paralysis of all four limbs.

paraplegia

A paralysis of the legs (lower extremities).

fibromyalgia

A rheumatic disorder characterized by achy pain, tenderness, and stiffness.

tendon

A rope-like structure that binds muscles to bone.

bursa

A sac-like cavity filled with synovial fluid and located in places where tendons or muscles pass over bony prominences.

cramp

A sustained spasm or contraction of a muscle accompanied by severe, localized pain.

ganglion

A thin-walled band cyst formed on a joint capsule or tendon sheath.

tennis elbow

Also called lateral and medial epicondylitis. A strain of the lateral forearm muscles or the tendinous attachments near their origin on the epicondyle of the humerus. (Again note that when "tendon" is changed to another form, the "o" changes to "i"—tendinous.)

polymyositis

An autoimmune disorder which causes atrophy and weakness of the muscles.

myopathy

Any disease of the muscles.

Cardiac muscle

Cardiac muscle forms the majority of the walls of the heart. It is similar in appearance to skeletal muscle with respect to its striated appearance, but it has a single-cell nucleus. This is an involuntary muscle and direct stimuli from the central nervous system (CNS) is not required for contraction. However, the CNS does modify (not initiate) contraction of cardiac muscle.

sagittal

Division of body into left and right sides in a vertical lengthwise fashion.

coronal

Division of the body into anterior and posterior sections. Also called frontal plane. Can mean pertaining to the head or the crown.

plantar fasciitis

Excessive pulling or stretching of the calcaneal periosteum by the plantar fascia, resulting in pain along the inner border of the plantar fascia. This definition applies specifically to the process that affects the plantar surface of the foot. Fasciitis is inflammation of the fascia. There are other types of fasciitis, which can be seen in a medical dictionary under fasciitis.

myofascial pain syndrome

Fibromyalgia is also called myofascial pain syndrome and fibromyositis. A group of rheumatic disorders caused by achy pain, tenderness, and stiffness of muscles and tendon insertions.

bursitis

Inflammation of a bursa.

tendinitis

Inflammation of tendons and of tendon-muscle attachments due to trauma or repetitive wear. (Note the spelling: tendonitis is an acceptable alternative spelling, but tendinitis is preferred.)

atony

Lack of normal tone or strength. This happens in muscles that are deprived of innervation (which is the supply of nerve fibers functionally connected with a part). Try not to confuse this term with atrophy (below) or atopy (which is a genetic predisposition towards hypersensitivity to common environmental antigens).

indirect attachments

Long strands of connective tissue extending beyond the muscle.

Attachment

Many muscles are named for the bones to which they are attached. The muscle name may combine more than one name when more than one bone is involved. Examples Zygomaticus: Attached to the zygoma (bone of the face). Sternocleidomastoid: Attached to the sternum, clavicle, and mastoid process of the skull.

Anatomical Position

Medical personnel refer to the human body in a fixed or standard position when referring to specific body areas. The anatomical position refers to the human body as erect (standing), facing forward with eyes straight ahead, arms at the sides with palms open and facing forward, and feet parallel and flat on the floor. In anatomical terms, any veins, muscles, ligaments, bones, tendons, or other structures that utilize one of these descriptive terms will be specifically related to this anatomical position.

Muscular Diseases

Minor muscle injuries are usually diagnosed and treated by family practice doctors. They are also routinely treated in emergency rooms and clinics. However, more serious injuries or disease processes affecting the muscles will be managed by orthopedists and orthopedic surgeons. Several brain functions or neurological problems manifest themselves through the muscles, taking the form of abnormal muscular movements. Clonic - the adjectival form of clonus, which means alternate muscular contraction and relaxation in rapid succession. Tonic - normal tone.

Shape

Muscle names are often derived from the actual physical shape of the muscle itself or a defining physical characteristic, such as the number of heads that it has. Examples Rhomboideus: A muscle of the back that is shaped like a rhomboid. Triangularis: A muscle of the face that is triangular in shape. Triceps: A muscle with three (tri-) heads. Biceps: A muscle with two (bi-) heads.

myalgia

Muscle pain.

Function

Muscles are responsible for movement. However, there are several different types of movements, and muscles are often classified according to the actual movement that they produce. Examples Adductor: Movement to draw toward a medial plane. Extensor: General term for a muscle that extends a joint. Flexor: General term for a muscle that flexes a joint. Levator: A muscle that elevates or lifts an organ or structure.

proximal

Nearest; closer to any point of reference; opposite of distal. (The shoulder is distal to the wrist but proximal to the elbow.)

Dupuytren contracture

Painless thickening and contracture of the palmar fascia due to fibrous proliferation, resulting in loss of function of the fingers.

torticollis

Persistent contraction of a sternocleidomastoid muscle, drawing the head to one side and distorting the face. Causes rotation of the head.

ventral

Pertaining to the abdomen; used to denote a position that is more toward the belly/abdominal surface than some other object of reference.

dorsal

Pertaining to the back of the body; also used to denote a position that is more toward the back than another object of reference. Sometimes called posterior.

medial

Pertaining to the middle; closer to the midline of a body; pertaining to the middle layer.

lateral

Pertaining to the side; denoting a position farther from the midline (median plane) of a structure.

distal

Remote; farther from any point of reference; opposite of proximal. (The shoulder is distal to the wrist but proximal to the elbow.)

rigor mortis

Rigor means chilled, stiffness, rigidity. Rigor mortis is the muscular hardness occurring 4-7 hours after death.

direct (fleshy) attachments

Short strands of connective tissue that make muscles appear as if they are directly connected to the bone.

fasciculations

Similar to fibrillations or tremors. A repetitive, involuntary contraction of muscle. The main cause is nerve damage.

superior

Situated above, or directed upward; in official anatomic nomenclature, used in reference to the upper surface of an organ or other structure, or to a structure occupying a higher position.

inferior

Situated below a structure or directed downward; also used to denote the lower portion of an organ or the lower of two structures. Sometimes called caudal.

anterior

Situated in front of or toward the front of a body part or organ. This term is also used in reference to a ventral or belly surface of the body. Frontal is a common synonym for anterior.

posterior

Situated in the back; also used in reference to the back or dorsal surface of the body.

Muscle Types

Skeletal muscle - The primary muscle used to allow voluntary movement of the body; they are usually attached to the skeleton by tendons. Smooth muscle - The muscle that lines the walls of internal organs. This muscle is usually short in its strands and allows for the movement of body fluids and waste through the internal systems. Cardiac muscle - This type of muscle is found only in the heart.

dystonia

Sustained abnormal postures or disruptions of normal movement resulting from alterations of muscle tone.

Size

The actual size of the muscle or its relative size to a similar muscle may be used in naming a muscle. Examples Maximus or Major: Both of these terms mean larger or largest. Minimus or Minor: Meaning smaller or smallest. Longus: Meaning long. Brevis: Meaning short.

origin

The less movable attachment of a muscle.

paralysis

The loss of nervous control of a muscle. Paralysis is commonly thought of as related to paraplegia, a paralysis of the legs (lower extremities) or quadriplegia, a paralysis of all four limbs. However, there are many different types of paralysis affecting many different muscles and organs of the body. These can be seen in a medical dictionary under paralysis.

insertion

The more movable attachment of a muscle.

Smooth Muscle

The muscle that lines the walls of internal organs. This muscle is usually short in its strands and allows for the movement of body fluids and waste through the internal systems. They are involuntary: they contract with stimuli from the nervous system, but without conscious thought. Spindle-like (i.e., length greater than width) and fragile in appearance, smooth muscle cells have a single nucleus. Smooth muscle tissue has no striations. Smooth muscle occupies six major location sites: •walls of the circulatory vessels •digestive tubes •urinary organs •reproductive organs •respiratory tubes •inside the eye Smooth muscle is not easily fatigued and keeps a steady, slow contraction rate.

Naming muscles

The names of muscles are descriptive. Therefore, it will help you to learn and remember them if you have an understanding of how they are named. There are seven (7) primary ways the names assigned to muscles are derived.

Skeletal Muscle

The primary muscle used to allow voluntary movement of the body; they are usually attached to the skeleton by tendons. Voluntary b/c they move when we direct them to. Cells are usually large and have more than one nucleas. We refer to the cells as fibers b/c of their long and thin appearance. We call skeletal muscles "striated" b/c of their striped (or band-like) appearance. At least one nerve, artery, and veign supplies each muscle. Most skeletal muscles extend from one bone to another crossing over a joint. When crossing a joint, one bone moves while the other remains stationary. The less moveable attachment of a muscle is called the origin. The more moveable attachment of a muscle is called the insertion. The insertion is always pulled towards the origin.Direct attachments have such short strands of connective tissue that muscles appear to be directly connected to the bone. Indirect attachments are the opposite, with long strands of connective tissue extending far beyond the muscle. These long strands form either a rope-like structure called a tendon, or a flat tissue sheet called an aponeurosis, which connects to the bone. There are over 600 skeletal muscles in the human body (most of these are voluntary or striated muscles). Skeletal Muscle is easily fatigued.

peristalsis

The process of propelling substances through hollow visceral organs.

atrophy

The wasting away or weakening of muscle fibers due to a lack of usage. There are many different kinds of atrophy. Look up "atrophy" in a medical dictionary and read or scan the terms that appear under this category.

Relative position

These delineations contain basic directional planes and are used on similar muscles to designate a slightly different orientation. Often a "medial" will have a corresponding "lateral"; likewise, an "internal" will have a corresponding "external." Examples Lateral: Something that is further from the midpoint or to the side. Medial: Something closer to the middle or the midline. Internal: Situated or occurring within or on the inside. External: Situated or occurring on the outside.

Orientation of fibers

This is the direction that the individual fibers of a muscle extend. Examples Oblique: In a slanting or inclined direction. Rectus: Meaning straight. Transverse: Meaning across or placed crosswise.

Masticate

To chew food. Muscles of mastication: lateral pterygoid - This is a muscle of mastication. It originates on the pterygoid process of the sphenoid bone. It moves the mandible and limits sideways jaw movement. medial pterygoid - Also a muscle of mastication. Both pterygoid muscles are on the inside of the mandible. The medial pterygoid elevates the jaw and provides sideways jaw movement. risorius - The risorius originates on the side of the face and inserts on the orbicularis oris muscle. It draws the angle of the mouth laterally (to the side) and enables the human being to smile. mentalis - The mentalis muscle originates on the chin and goes into the orbicularis oris muscle. It elevates and protrudes the lower lip. Basically it allows for pouting. depressor labii inferioris - This muscle also originates on the mandible and inserts on to the orbicularis muscle. It depresses the bottom lip. (Names: depressor=depress, labii=lips, inferioris=below or bottom) depressor anguli oris - This muscle originates on the lower part of the mandible. It pulls down the angle of the mouth. (Names: depressor=depress, anguli=angle, oris=mouth)

Actions of Arm Muscles

anconeus - Located on the back of the humerus, it extends the forearm. extensor digiti minimi - A long narrow muscle located on the ulnar side of the extensor digitorum communis muscle. It assists in extension of the wrist and little finger. extensor digitorum communis - Positioned in the center of the forearm along the posterior surface. Its tendon divides into four tendons beneath the extensor retinaculum, which attach to the distal tips of fingers one through four. flexor digitorum profundus - Lies just underneath the flexor digitorum superficialis muscle. This muscle flexes the distal ends of the fingers (but not the thumb). flexor pollicis longus - Positioned deep on the front of the radius. It attaches at the base of the thumb and flexes the thumb and makes grasping possible. pronator teres - Positioned in upper middle part of the forearm. It arises from the epicondyle (a prominence or projection on a bone). It turns the hand downwards (called pronation) and flexes the elbow. epicondyle - A prominence or projection on a bone. pronator quadratus - Positioned deep and extends between the ulna and radius. It works with the other pronator muscle to rotate the palm of the hand down, as well as position the thumb medially. supinator - Positioned around the upper portion of the radius. It works with the biceps to turn the palm upwards (called supination).