Muscle Rules

Classification by Size: • Gluteus maximus is the largest muscle in the group • Gluteus minimus is the smallest in the group

Gluteus maximus and Gluteus minimus

cross-striations occur in the fibers as a result of regular overlapping of thick and thin myofilaments

Striated Muscle

Actin and Myosin Muscle contraction occurs when these filaments slide over one another in a series of repetitive events.

Striated Muscle has two major protein filaments

two, joint

There are at least ___ attachments and the muscle will cross a __ at the elbow

thick filament

myosin

180 degrees angle gets smaller

straight arm starts at ___ degrees, but as you flex the angle gets ___

Classification by number of origins: • Biceps brachii has two origins on the scapula • Triceps brachii has three origins on the humerus

Biceps Brachii and Tricps Brachii

flexes elbow

Brachial Muscle action

proximal ulna

Brachial Muscle insertion

• halfway down the humerus • not medial and lateral of radial grove

Brachialis Muscle origin

A muscles structure consists of connective tissue and muscle fibers, which work like a rope or rubber band to stretch and contract. The connective tissues' elasticity helps to ensure that the tension developed by the muscle is smoothly transmitted and that a muscle will return to its original shape after being stretched.

Describe how the structural makeup of a muscle contributes to the muscle's ability to do its job

Skeletal muscle - striated and looks like long fibers. Cardiac muscle- striated and has visible nuclei. Smooth muscle non-striated and has a wave type structure with visible nuclei

Describe the differences you see in the three types of muscle tissues.

yes

Does skeletal muscle has striations?

The insertion of the muscle is the end of the muscle attaching to the freely moving bone. The origin of the muscle is the end of the muscle attaching to the fixed, non-moving bone.

Explain how you know which attachment of a muscle is the origin and which attachment is the insertion.

Classification by action: • Flexor carpi ulnaris flexes the hand at the wrist • Extensor digitorium longus extends the foot and toes upward

Flexor Carpi Ulnaris and Extensor digitorum longus

decrease the angle between ventral surfaces

Flexors

No because when the flexors are pulling, the extensors are relaxing.

For smooth movements to occur, can both extensors and flexors be contracting at the same time?

Classification by location in the body: • Frontalis is located on the frontal bone of the skull • Temporalis is located on the temporal bone of the skull

Frontalis and Temporalis

As you flex your arm, the brachialis muscle pulls you lower arm up as the muscle contracts and gets shorter.

Rule #2 example

Brachialis Muscle • Origin = halfway down the humerus (both medial and lateral of the radial groove) [Stationary] • Insertion = proximal ulna [Movable]

Rule #3 example

flex your arm - brachialis muscle - flexor. extend your arm - brachii muscle - extensor.

Rule #4 example

Brachialis is a flexor and brachii is an extensor. They are opposing pairs since they cause the arm to move in opposite directions.

Rule #5 example

Long stringy lines that extend from one point of attachment to the other, but become narrower near the point of origin since the bone will be pulled towards the point of origin.

Rule #6 example

Brachialis Muscle • Origin = halfway down the humerus (both medial and lateral of the radial groove) • Insertion = proximal ulna • Crosses the elbow joint

Rule 1 example

helps move the scapula forward and is often used at the end of big movements such as a bench press, a baseball pitch, or a swimming stroke.

Serrates Anterior action

medial border of the scapula

Serrates Anterior insertion

lateral surface of ribs 1-8 (bone only)

Serrates Anterior origin

striated muscle tissue voluntary control somatic nervous system tendons

Skeletal Muscle

blood vessels and hollow internal organs, such as the stomach, intestine, and bladder involuntary not striated

Smooth Muscle

Classification by origin and insertion: • Sternocleidomastoid has origins on the breastbone (sternum) and the collage bone (clavicle or "cleido") and insertions of the mastoid process of the skull's temporal bone • Brachioradialus has an origin on the brachium or arm and an insertion on the radius

SternoCleidomastoid and Brachioradialis

yes

are there striations in Cardiac Muscle

point to the attachments and show the direction of pull

striations

attachment that moves

insertion

no

is cardiac muscle voluntary

No

is sooth muscle voluntary

smooth muscle connective tissue because its function is to surrounds muscle fibers and fascicles, connecting them and helping them retain shape

what type of tissue do you think makes up the three layers of membrane you encountered in your muscle?

involuntary striated

Cardiac Muscle

no

does smooth muscle have striations?

extends elbow

triceps brachii action

Rule #1: Muscles must have at least two attachments and must cross at least one joint. Rule #2: Muscles always "pull" and get shorter. Rule #3: The attachment that moves is known as the insertion and the attachment that remains stationary is known as the origin. Rule #4: Muscles that decrease the angle between ventral surfaces of the body are known as flexors. Muscles that increase the angle between ventral surfaces of the body are known as extensors. Rule #5: Muscles work in opposing pairs. Rule #6: Muscle striations point to the attachments and show the direction of pull.

6 Muscle Rules

Rule 1: two attachments one joint Rule 2: only pull Rule 3: insertion and origin Rule 4: flexor and extensor Rule 5: opposing pairs Rule 6: striations

6 muscle rules, my version

Thin filament

Actin

Another muscle must pull to get the arm back to 180°.

If muscles can only be pulled, then how does a flexed arm go back to being straight?

Attachment that moves

Insertion

Yes

Is skeletal muscle a voluntary muscle?

attached to bones

Location of skeletal muscle

PULL

MUSCLES ONLY ___

Classification by direction of fibers: • Fibers in orbicularis oculi form a circle • Fibers in transverse abdominis "traverse" or go across the abdomen

Orbicularis Oculi and Transverse abdominis

Stationary

Origin

to rotate the shoulder forward.

Pectoralis minor action

coracoid process of the scapula (piece of the scapula visible on the front

Pectoralis minor insertion

anterior surface of ribs 3 - 5 (just past the origins of the serratus anterior)

Pectoralis minor origin

tennis serve or a volleyball spike Downward motion

Pectorals Major action

lateral edge of the most proximal part of the humerus

Pectorals Major insertion

ribs 5-7 (actually attaches to fascia of abdominal muscles)

Pectorals Major origin

Classification by Shape: • Trapezius is shaped like a trapezoid • A rhomboid is shaped like a rhombus

Trapezius and Rhomboid minor

Involuntary muscle contraction is when muscles contract without a conscious effort, like the heart beating or digestion of food

What does it mean when we say a muscle contracts involuntarily? Describe one body function that is linked to an involuntary muscle contraction.

Shivering causes you to involuntary contract and relaxes your muscles which will increase heat production, keeping the body at a stable 98.6 degrees F

When you are cold, your muscles begin to contract involuntarily and cause you to shiver. Why do you think this occurs? How does the contraction of muscles help the body maintain homeostasis?

ulnar pulled humeral stationary

When you bend your forearm, the __ attachment is being pulled, and the ___ attachment stays stationary

She has injured the muscle on the backside of her tibia. This muscle acts to dorsiflex and invert the foot

Your mom comes back from the doctor and says she has pulled her tibialis anterior. She knows you are taking Human Body Systems and asks you to tell her about her injury. Based on the classroom discussion, what can you deduce about this muscle?

controls motion at a joint that increases the angle between articulating bones

extensor muscle

Muscles that increase the angle between ventral surfaces

extensors

muscle at a joint that decreases the angle between articulating bones

flexor muscle

flexors - ventral extensors - dorsally

flexors are on the ___ side of the body, and extensors are on the __ side

heart contractions

function of cardiac muscle

movement, heat, posture

function of skeletal muscle

Movement of Blood Through Vessels, Food through Digestive system

function of smooth muscle

heart

location of cardiac muscle

Lines blood vessels and hollow internal organs, such as the stomach, intestine, and bladder

location of smooth muscle

• attachment that does not move • pulls the other attachment toward it • usually the proximal attachment

origin

extensor

triceps brachii flexor or extensor

distal of elbow on the ulna

triceps brachii insertion

proximal half of dorsal humerus

triceps brachii origin