Muscles system/Muscle Tissue

About the muscular system

– consist only of skeletal muscles

– Muscle organization/attachment affects power, range, & speed of movement

(appearance dictates function)

What are fascicles?

Bundles of skeletal muscle fibers

What are the 4 major fascicle arrangements?

• Parallel

• convergent

• pennate

• circular

What is a parallel muscle?

• Fascicles run parallel to long axis of the muscle

• some are flat

• Cylindrical muscles have a central body (belly)

  • ex: biceps brachii

What are the types of Parallel muscles?

• Parallel muscle; Biceps brachii

• Parallel muscle with tendinous bands (tendons inscription); Rectus abdominis

• Wrapping Muscle; supinator (posterior & wraps anteriorly)

What is a convergent muscle?

• Fascicles spread like a fan & converge on an attachment site (wide→narrow)

• ex.pectoralis muscle

• fibers pull in different directions depending on activity

What can a convergent muscle pull on?

(where muscle attaches to bone)

• tendon

• aponeurosis (sheet of tendon; areas in head & lower back)

• raphe (slender band of collagen fibers)

What is a pennate muscle?

Muscle fibers attach to tendon at an angle, like shape of a feather

How do pennate muscles compare with parallel muscles?

• contain more myofibrils (muscle fibers; more contraction power)

• move their tendons less far

• develop more tension

What is a unipennate muscle?

pennate muscle type

All fascicles are on same side of tendon

ex. Extensor digitorum.

What is a bipennate muscle?

pennate muscle type

Fascicles are on both sides of a central tendon

ex. Rectus femoris

What is a multipennate muscle?

pennate muscle type

The tendon branches inside the muscle

(large and in charge; muscle surrounds)

ex. Deltoid

What are circular muscles?

• Sphincters, to close & open areas

• Act as valves in digestive & urinary tracts

• Surround body openings & hollow organs

• Contraction makes diameter of opening smaller (O→o)

Ex. orbicularis oris of mouth

What is a lever in the body?

• A bone acting as a rigid, moving structure

• all muscle attach to bone

What is the fulcrum?

• fixed point around which a lever moves; in the body, each joint is a fulcrum

(like seesaw)

bones move on fulcrum when muscles give AF to overcome load

Levers can change

levers=bones

– Direction of applied force (AF)

– Distance & speed made by AF

– Effective strength of AF

What is the load?

The resistance the applied force must overcome

(like weight at other end of seesaw)

What is applied force (AF)?

The force provided to move the load

(like kid on left side of seesaw trying to lift kid on right side)

How are the 3 classes of levers determined?

By the relative positions of the applied force, fulcrum, & load

What is a first-class lever?

The fulcrum lies between the applied force & the load

ex. Extension of the neck to lift head

(like using crow bar)(overworks muscle)

What is a second-class lever?

• The load lies between applied force & fulcrum

• advantage: small force moves large weight

ex. Ankle extension (plantar flexion) by the calf muscles

(wheelbarrow)

What is a third-class lever?

• The applied force lies between the load & the fulcrum

• most common lever in the body

• Increases/maximizes speed & distance, but decreases force

ex. A pair of tongs (ONLY TILL HERE

What is the origin of a muscle?

The fixed point of attachment of a muscle to a bone

-Origin usually proximal to insertion

What is the insertion of a muscle?

The movable point of attachment of a muscle to a bone

distal

What is a muscle action?

Movements caused by muscle contraction

• Described by effect on bone/joint

• Ex. flexion, adduction, elevation, pronation

• Ex. flexion of the forearm at the elbow

Muscle interactions

Muscles work together for efficient movement.

• Smaller muscles activate first (tension 1st), then larger primary muscles

4 types of muscle interactions

– Agonist

– Antagonist

– Synergist

– Fixator

What is an agonist?

The prime mover; the muscle mostly responsible for a particular movement

What is an antagonist?

A muscle that opposes the movement of an agonist

What is a synergist?

A smaller muscle that assists a larger agonist

What is a fixator?

A synergist that helps an agonist by preventing movement at another joint;stabalizer

-holds bone/body/joint part so other muscles can move efficiently

How do agonists & antagonists work together?

When one contracts, the other stretches

ex. of opposing muscle pairs: Flexors–extensors & abductors–adductors

(shorten & lengthen)

What 4 types of information can muscle names describe?

• Body region

• position/direction/fascicle arrangement

• structural characteristics

• action

What does abdominal indicate?

Abdomen

What does ancon indicate?

Elbow

What does auricular indicate?

Ear

What does brachial indicate?

Arm

What does capitis indicate?

Head

What does carpi indicate?

Wrist

What does cervicis indicate?

neck

What does costal indicate?

Rib

What does coccygeal indicate?

coccyx

What does cutaneous indicate?

skin

What does femoris indicate?

Thigh

What does glossal indicate?

Tongue

What does hallux indicate?

Great toe.

What does ilium/inguinal indicate?

groin

What does lumbar indicate?

Lumbar region.

What does nasalis indicate?

Nose

What does ocular indicate?

Eye

What does oris indicate?

Mouth

What does palpebra indicate?

Eyelid

What does pollex indicate?

thumb

What does popliteal indicate?

Posterior to the knee.

what does Psoas indicate?

Loin

What does radial indicate?

Forearm

What does scapular indicate?

Scapula

What does temporal indicate?

Temple

What does thoracic indicate?

Thorax

What does tibial indicate?

Tibia/shin.

What does ulnar indicate?

Ulna

What does externus (superficialis) mean?

Muscles visible at the body surface.

What does internus (profundus) mean?

Deeper muscles.

What is an extrinsic muscle?

A muscle outside a structure that positions/stabilizes an organ.

What is an intrinsic muscle?

A muscle located entirely within an organ.

What does transversus mean?

Runs perpendicular to body’s long axis.

What does oblique mean?

Runs at a slant to the long axis.

What does rectus mean?

Straight; runs along the long axis

ex.rectus abdominis

What does anterior mean?

Front

What does external mean?

on the outside

What does extrinsic mean?

outside the structure

What does inferior mean?

Below

What does internal mean?

away from the surface

What does intrinsic mean?

within the structure

What does lateral mean?

on the side

what does medial mean?

middle

oblique

slanting

posterior

back

profundus

deep

rectus

straight

superficial

towards the surface

superior

towards the head

transverse

crosswise

Structural characteristics of muscles

• Origin & insertion: First name = origin; second = insertion

• # of tendons: Biceps = 2 tendons

• Shape: Names can describe shape → trapezius, deltoid, rhomboid

• Size: Names can indicate muscle size

What does biceps mean?

Two heads.

What does triceps mean?

Three heads.

What does quadriceps mean?

Four heads.

What does deltoid indicate about shape?

Triangle

What does orbicularis indicate about shape?

Circle.

What does rhomboid indicate about shape?

Parallelogram

What does serratus indicate about shape?

Serrated;notched (like saw)

What does pectinate indicate about shape?

comblike

What does piriformis indicate about shape?

pear shaped

What does platysma indicate about shape?

flat plate

What does pyramidal indicate about shape?

pyramid

What does splenius indicate about shape?

bandage

What does teres indicate about shape?

round & long

What does trapezius indicate about shape?

Trapezoid

What does alba mean?

white

What does brevis mean?

short