ANAT 100- Module 3 muscles 낱말 카드

Functions of Muscles

- movement (moving the skeleton)

- beating heart

- digestion

- constriction of blood vessels

Types of Muscle

- skeletal

- cardiac

- smooth

Skeletal Muscles

- helps the human body move

- most skeletal muscle is attached to the bones via tending

- striated

- multi nucleated

- Voluntary Movement

- makes up about 1/2 of a persons weight

- each muscle is composed of skeletal muscles, epithelial, connective, and nervous tissue

Cardiac Muscles

- found in the heart

- contracts rhythmically from signals from neurons and hormones

- striated

- uni/bi nucleated

- involuntary movement

Smooth Muscle

- controlled by the nervous system or hormones

- may be generally inactive and then response to stimulation, or it may be rhythmic

- NOt striated

- uni nucleated

- involuntary movement

Characterization of Muscle

Morphological characterization

Functional Characterization

Morphological characterization

Striated Muscle

Smooth Muscle

Morphological characterization: Striated Muscle

- cardiac and skeletal muscle

- marked by light and dark band and long muscle fibres

- nuclei are located PERIPHERALLY for skeletal muscles

- nuclei are located centrally for cardiac

Morphological characterization: Smooth Muscle

- found in blood vessels, the digestive system, and other viscera

- each smooth muscle fibre contains a single centrally located nucleus

- fusiform-shape (spindle like) cells without striations

Functional Characterization

Voluntary muscles

- muscles that are consciously controlled

- skeletal muscles

Involuntary Muscles

- muscles that are no consciously controlled

- cardiac and smooth muscle

How to Muscles Function

Excitability:

- the muscle can respond to electrical signals from nerves or stimulation from hormones

Contractility

- this then causes the muscle to shorten, causing a contraction

Skeletal Muscle: Functions

- contracts to move parts of the body

- most muscles are attached to 2 bones across a joint, so the contracted muscles bring those 2 bones closer together

- maintain posture and stabilize joints

- control excretion (pee and poo)

- produce heat

- support and protect internal organs

Organization of Skeletal Muscle

- connective tissue surrounds the muscle tissue and attaches the end of the muscles to the bone

Connective Tissue in Muscles

1. Epimysium

2. perimysium

3. Endomysium

1. Epimysium

- layer of connective tissue on the outside of the entire muscle that becomes a tendon

2. Perimysium

- layer of connective tissue that surround bindles of muscle fibres (fascicles) inside the muscle

3. Endomysium

- layer of connective tissue that surround an individual muscle cell (muscle fibre/myofibre) in each bundle (fascicle)

Muscle cell is called

- myofibre

Microscopic anatomy of muscle tissue

- inside a muscle cell (myofibres), there are MYOFIBRILS which contain MYOFILAMENTS (the units of contraction from the muscle cell)

Microscopic anatomy of muscle tissue: Sarcolemma

- cell membrane surrounding the muscle cell (myofibre)

- different than the endomysium

- under the sarcolemma are nuclei, myofibrils, and sarcoplasm (cellular fluid)

Microscopic anatomy of muscle tissue: Nuclei

- skeletal cells are multinucleated

- nuclei are located towards the outside if the myofibre (muscle cell)

Microscopic anatomy of muscle tissue: Myofibril

- structure unit of muscle cells (myofibres)

- contain contractile myofilaments

Microscopic anatomy of muscle tissue: Myofilaments

- contractile unit of the muscle cell

Microscopic anatomy of muscle tissue: Sarcoplasmic reticulum

- surround each myofibril and is where the muscle cell stores calcium (important for muscle function)

Microscopic anatomy of muscle tissue: T-tubules

- extensions of the sarcoplasmic that surround the myofibrils and transmit nerve stimulation to the sarcoplasmic reticulum within the cell

Myofilaments: Sarcomeres

- myofilaments are organized into repeating structure called sacromeres

- when shortened, sarcomeres cause contraction of the muscle (each unit consists of actin or myosin)

- 1 sacromere spans from 1 Z line to the next

Sarcomere

- on diagram in book, myosin is the thick brown centre lines, actin is the little red ones attaching to it

Sarcomere Banding

A band

- made up of thick and thin filaments

- appears darker

Z-line

- protein that makes a zig zag line marking the beginning and end of each sarcomere

- in the muddle of the I-band and its where the thick filaments attach

M-line

- Protein down the centre of the sacromere

- thick filaments attach

I-Band

- made up of thin filaments

- appears lighter

Muscle Contraction

- actin and myosin filaments on sarcomeres slide over each other, which shortens the sarcomere

- increases muscle tension

The lighter and darker parts of sarcomeres

I-Band

- light because it is all light filaments

Z-line

- dark because it has lots of protein

A-Band

- dark because it is all thick filaments, even darker where is overlaps with actin (on the side)

M-line

- dark because it has lots of protein

Axial Muscles: Facial Expression Muscles

- muscles of facial expression insert into the skin

- contracting muscles move the skin

zygomaticus

orbicularis oris

orbicularis oculi

frontalis

Facial Expression Muscles: Zygomaticus

- extends from the zygomatic arch to the corners of the mouth

- draws the angle of the mouth superiorly and posteriorly, creating a smile

Facial Expression Muscles: Orbicularus oris

- surrounds the mouth and puckers the lips

- originates on the maxillary bone

- kissing muscle

Facial Expression Muscles: Orbicularis oculi

- muscle surrounding the eye that forcefully closes it

- originates in the frontal and maxillary bones

Facial Expression Muscles: Frontalis

- muscle that covers the frontal bones and lifts the eyebrows, causing the forehead to wrinkle

muscles of mastification (chewing)

Temporalis

massester

Temporalis

- muscle that extends from the temporal fossa of the parietal bone to the cornalid process of the mandible

- pulls the mandible back

Masseter

- powerful muscle that extends from the zygomatic arch to the angle of the mandible (lower jaw)

- elevates and protracts (move jaw forward) the jaw

3 muscles that move the head

- sternocleidomastoid muscle (anterior)

- semispinalais capitis (posterior)

- splenius capitis (posterior)

Sternoclediomastoid

- flexes the neck, and rotates the head to the opposite side

Semispinalis capitis

- turns the face slightly to the opposite side

Splenious Capitis

- extends the neck, causing flexion and lateral rotation of the neck

Muscles of the Thorax (muscles that help with the process of breathing)

External Intercostal

Internal Intercostal

external intercostals

- most superficial

- help in breathing in

- fibres run: imagine putting hands in to pockEt

internal intercostals

- deeper than external intercostals

- help in breathing out

- fibres run: imagine putting hands on tIts

Muscles of the Back

Erector Spinae muscles

- run down both sides of the spinal column

Muscles of the abdomen wall (help with breathing)

External Oblique

Internal Oblique

Transversus Abdominus

Rectus Abdominus

External Oblique

- most superficial

- functions:

bilateral- flexes the vertebral column and compresses the abdominal wall, used in forced expiration

unilateral- lateral flexion and rotation of the spine

FIBRES: ANTERIORLY AND INFERIORLY

Internal Oblique

- deeper than the external oblique

functions:

- bilateral- flexes the vertebral column and compresses abdominal wall

- unilateral- lateral flexion of the vertebral column

FIBRES: ANTERIORLY AND SUPERIORLY

Transversus Abondminus

- runs horizontally, deep to the internal oblique

functions:

- bilateral: flexes the vertebral column and compresses the abdominal wall. Used in forced expiration

- unilateral: lateral flexion of the vertebral column

Rectus Abdominus

- lies on either side of the line alba (line of connective tissue down the middle of the abdomen)

- separated why tendinous intersections

function:

- flexion of the trunk

- forced expiration