Muscle Tissue Types

Muscle Tissue Types

• There exist three primary types of muscular tissue
• Skeletal muscles exhibits a striated appearance and is responsible for voluntary movements
• Skeletal muscle consists of long, cylindrical, multinucleated fibers
• Muscles of the skeletal system contract with varying degrees of strength and attaches to bone to facilitate movement
• Cardiac muscle is striated and responsible for involuntary movement
• Intercalated discs in cardiac muscle establish specialized junctions that connect cardiomyocytes (cardiac muscle cells)
• Cardiac muscle cells are uni- or binucleate, containing one or two nuclei
• Cardiac muscle exists exclusively in the heart
• Smooth muscle lacks striations and mediates involuntary movements
• Fusiform fibers are muscle fibers arranged in parallel, found in the biceps brachii, and taper at the ends
• Smooth muscle cells are uninucleate with a single nucleus facilitating continuous, slow sustained contractions within the walls of hollow organs like the stomach

Characteristics of Muscle Tissue

• Excitability is responsiveness to stimuli
• Contractibility facilitates muscle shortening
• Extensibility permits muscle lengthening
• Elasticity empowers muscular return to original form

Muscle Tissue Functions

• Muscles facilitate locomotion, manipulation, and rhythmic heartbeats which all contribute to movement
• Posture maintenance requires continuous adjustments to counteract gravity
• Joint stabilization aids movement
• Heat generation through muscle contraction helps to maintain body temperature

Skeletal Muscle Structure

• Skeletal muscle system composition includes skeletal muscle fibers, blood vessels, nerves, and connective tissue
• Connective tissue sheaths support and reinforce the muscle
• Epimysium (Epi = Outside) surrounds the entire muscle
• Perimysium (Peri = Around) bundles muscle fibers into fascicles
• Endomysium (Endo = Within) surrounds each individual muscle fiber

Muscle to Bone Attachments

• The insertion of a muscle is located on the most movable bone and it moves towards the origin
• The origin of a muscle is located on the least movable bone
• The origin usually lies proximal to the insertion in limb muscles
• Muscle attachments can be either direct, via epimysium fused to the periosteum, or indirect
• The connective tissue extends, connecting to the tendon which connects to the muscle

Muscle Terminology

• Location can be indicated in some muscle names by the bone or body region it connects with, such as the brachium
• Shape of a muscle can also be denoted, such as deltoid
• Muscles can be named by their size; for example, Maximus implies largest and Minimus implies Smallest
• Fiber direction can dictate a name
• For example, Rectus implies Straight arrangement
• The number of origins can dictate a name
• For example, Biceps implies two origins and Triceps implies three origins
• Muscle action can result in terms like Flexor or Extensor can dictate muscle names based on movement produced
• Location of Attachment: Muscle are named per their origin and insertion points
• The sternocleidomastoid originates from the manubrium of the sternum and clavicle, inserting at the mastoid process of the temporal bone

Functional Muscle Groups

• Muscles classify into three functional groups
• Agonists (Prime Movers) are responsible for the movement
• The agonists perform the "agony" of the movement
• Biceps Brachii is a prime mover
• Antagonists oppose or reverse agonist actions;
• For example, the Triceps Brachii
• Agonists and antagonists perform opposite actions and often lie in opposing compartments
• Synergists are muscles that work together to perform the same task
• For example, the Brachioradialis
• Fixators are synergists that stabilize joints.

Head Muscles

• Facial expression and chewing are the primary function of head muscles
• Orbicularis Oculi is responsible for blinking and squinting by encompassing the eye
• The Zygomaticus (Minor and Major) facilitates smiling and connects to the temporal bone
• The Risorius assists smiling and connects to the buccinator and masseter
• The Buccinator cheek muscle acts around the zygomaticus and masseter
• The Orbicularis Oris is critical to kissing and encircles the lips
• The Temporalis muscle allows jaw closure via elevation and retraction above the ears
• The Masseter is the prime mover of the the jaw, and closes on the temporalis, risorius, buccinator, and zygomaticus

Neck Muscles

• The Sternocleidomastoid is anterior and lateral to the spinal cord
• This muscle is the prime mover for head flexion at the atlantooccipital joint
• The Splenius Capitis is viewable posteriorly and is next to the spinous process of vertebrae
• Splenius Capitus acts as the antagonist to stemocleidomastoid in head flexion

Muscle Movement Rules

• Muscles crossing anterior sides of joints will typically produce flexion
• Muscles crossing posterior sides of joints will typically produce extension
• Muscles crossing lateral sides of joints typically produce abduction
• Muscles crossing medial sides of joints will typically produce adduction
• The upper limbs, thorax, abdomen, and hip apply these rules
• The knee and ankle, due to developmental rotation, exhibit opposite movement patterns.

Regions and Compartments

• Anterior compartments, of the upper limbs are responsible for flexing
• The opposite is true for the lower limbs which exhibit functional role reversals due to embryonic development
• Anterior components of lower limbs, such as the legs, facilitate extension
• The quadriceps extends the knee whereas the hamstrings flex the knee

Muscle Compartment Rules

• Muscles superior from the hips are flexors, while inferior muscles are extensors in the anterior
• The opposite applies to posterior
• This rule applies to all limbs, the abdomen, and the erector spinae
• Thoracic muscles stabilize and extend the vertebral column, stabilize and move the scapula, assist respiration, and move the arm at the shoulder joint
• Abdominal muscles stabilize and flex the vertebral column and help to move the lower limbs at the hip.

Posterior Trunk Muscles

• The Erector Spinae, located in the posterior compartment, enables trunk extension
• Erector Spinae is a collective term for multiple main muscles

Erector Spinae Muscles

• The Spinalis resides along the spinous process within the middle of spine
• The Longissimus resides laterally to the spinalis and is the middle group muscle
• The Iliocostalis connects the ilium to the ribs and lies most laterally
• Iliocostalis is located on the equivalent point as the mastoid process of the temporal bone, positioned somewhat laterally
• The Quadratus Lumborum serves as the main muscle for trunk extension that laterally flexes the vertebral column
• It is situated oppositely to the erector spinae towards its medial side, and articulates between hip bone and iliac crest
• Quadratus Lumborum forms the opposite section and acts antagonistically to abdominal muscles
• Deep stabilizers like Rotatores are located in Posterior Trunk
• Rotatores are located superiorly on the posterior
• The Multifidus facilitates and articulates with the longer rotatores muscle

Superficial Posterior Muscles

• Superficial muscles are agonists for shoulder and arm movement
• Main muscles include Trapezius and Latissimus dorsi
• The Trapezius extends from the side of the heck towards the midpoint of the spine
• The Latissimus dorsi is lateral compared to the Trapezius with a tapering near the shoulder

Anterior Abdominal Muscles

• The Rectus abdominis is located posteriorly in relation to external obliques
• The External Oblique resides on the side of the abdominal wall and represents the outermost (most superficial muscle
• The Internal Oblique lies opposite to the external obliques
• It is located more posteriorly as it is located in relation to the rectus abdominus
• The Transversus Abdominis represents the innermost part of the wall
• It acts as a deep corset
• Connective tissue for these muscles forms Linea Alba
• The anterior wall is the muscle responsible for the flexion of the vertebral column through forwarding bending
• As such, the the erector spinae is that wall antagonistic group, facilitating trunk extension and erect posture

Muscle of the Shoulder

• Muscles perform movement and stabilize this joint
• Anterior Compartment muscles include Subclavius, Pectoralis Minor, and Serratus Anterior
• The Subclavius lies behind, and deep to, the clavicle
• The Pectoralis Minor extends outward roughly toward the fifth thoratic rib
• The Serratus Anterior lies along the coracobrachialis, along what appears as a sawtooth
• Posterior Thoratic Wall is the second compartment of the shoulder
  • The Trapezius presents as a trapeziod from the side of the neck across to spine
• The Rhomboids Major/Minor help stabilize the scapula and are on the side of the spine
  • The minor is the more superior located muscle
• The Levator Scapular enables the raising of the scapula near the spine
• Originating on the upper spine and expands along what remains of the cervical vertebrae

Scapula Movement and Stabilization

• Refer to table for actions, examples and muscles*

Rotator Cuff

• Contains the four basic muscles that reinforce articulation
• Also prevents damage to the shoulder and maintain humeral and gelnoid articulation
• The Subscapularis is located viewable from the Anterior
• It is all over the scapula. and underneath this structure
• Supraspinatus on spine
• The Infraspinatus is located underneath
• -- This contains smaller heads
• The Major Head is more longer and lateral with tapered ends than minor Head

Shoulder Joint

• These muscles are viewed with action along shoulder
• These actions are flexion, and their counterparts and synergists include: Anterior Muscle
• Major Petoralis, major for action and lateral to it
• It contains flexibility to it for the prime mover is action
• Coracobrachialis surrounds subclavius and humerus and gives it flexibility for it is the synergist
• Extension, this action has its counterpart and muscles of the posterior that include
• The action, latissimus will be prime with flex and connect like teres and humerus as synergist

Shoulder Movement

• Abductions
• This is with side joints like the Deltoid and supraspinatus to the effect with side action The serratus anterior is involved and is what completes at 90 degrees and
• Addition, located joint by adducts.

Forearm Muscle

• With Flexion come the Brachilias, and the Biceps brachi involved
  • The prime muscle articulates to the head shoulder
• The other muscle comes from the Brachioradialis, along the Brachii

Elbow Contraction

• A contraction is what is opposite and what will come that is from overuse that will be cause
  • A Tennis elbow from forearm on posterior The lateral side in the medical terms
• And other times a Golfers that causes contraction

Wrist Features

• The Flexion, are by bone radius largest in what takes in the flexor carpi and is relative to the brachioradialis
• At ulna come muscles that go past palmaris longus
• Finger flexor, flex the first digitorum and its parts

Posterior Forearm

• In a posterior muscle the Radialis Longus and the Raditalis Brevis are what allow the muscles of wrist
• At ulnaris there is Extensor Carpi

Joints and Long Muscles

• Digtrorum is a muscle with lateral
• A more long version would be at digitiminimi

Back Area

• In the upper arm you would find the pollicus longus that connects what remains with others that are located with digitorum
• With these muscles are what moves and interacts with the digitorum

Main Pelvic

• Area with most area with the Hip Flexion
• These are often at anterior with many actions
• That in both includes the pelvic floor for many attachments
• To prevent damage what covers is Iliac

Gluts Actions

• They do many motions like extension and adduction
• It is covered through what they form the gluteus maximus
  • Then you have the Gluteus Medius with abduction and such rotation
  • It runs down the illiac
• There exist some minor muscle, one for adduction and another for rotation

Thighs

• Flexation can be seen like short or long thighs all help out or have rotation
• This comes with many different muscle depending on area or function

Shin Functions

• Shin runs the leg
• For what the thigh and foot do
• At knee joints you have these functions by what area
• Muscles located here
• Can be flexor or extensor muscle with these articulations
• Some articulations happen by muscles that are at opposite sides

Posterior Tibula Functions

• These muscles do knee and fibula
• They control leg
• And in the anterior it is much of feet actions

Ankle

• What action there causes is a dorsflexion, in both anterior and posterior
• There exist Digitorum that helps many muscle flex
• More specifically long
• You are able to help it with extensor
• This is with foot inversion
• Extensor helps for big toe

Ankle Motions

• Ankle Motion Plant can get movement by the Gastrochemius action to flex with calf as it does
• With the area the soleus helps directly
• Plantaris a small lateral tendon
• With this insert calcaenue

Later Joints

• With stabilized lateral you can get more functions
• And it is all with fibularis

Fibularis Parts

• Higher, with higher Fibula action
• And can function in multiple part of small toe
• It is often a brevis muscle and is deep and near tendon

Floor Foot

• With movement come with a need for heel functions is what helps
• Which you will find
• From back, A action with toe that can action

Muscle Properties

Popliteus: Muscle is important so deep and can give with muscles

• Leg is the prime function of the muscle here to flex
• Muscles and areas of function in here comes the properties that is important for respiration
• This functions comes external intercostals

Muscle Function for Respiratory

• The main goal there is to create functions to help diaphragm and breathing
• The primary system is for abdominals, in deep areas of respiration

What Is in there and what can do?

• In Urogenital
• Will be seen from the female and males
• Often to be deep, so that it can
• Have function
• The perineal can Be made from it all

Muscle Form/Size

• There exists sizes what can be there with 100's to 1000's is connected
• The Fascicle is in charge with to make muscles bundles
• Muscle Fiber and fibers makes a way to muscle can contract
• Mryofibrils is there to make bundles
• In the bundle
• What you will need and find is actins and the thin that makes those structures

Muscle Structure

• All the features are just
• Some examples include muscle fiber that include actin and the thin structure to it
• In structure it acts, Or how it contracts, With some of the key words
• These are the main proteins to help muscle contract with structures

Muscle Type

• What there does in the mix includes the important properties that needs
• Each filament then can come into play to have a contraction Muscle Movement
• And then after you know the filament and what those are is important to understand the function
• How a contraction is at best explained By having a start action to end it with relaxation

Phases in Motion

• To be able to create that
• Can get to get started
• Or to come down or up from these processes
• What comes there With potential energy
• Will be an energy process that are needed

Neuronal Response

In that you have key things that makes things move when the sodium changes in location that what triggers the cell to contract in which calcium is needed for

Types of Neuronal Movement

• Once that happens is what helps those channels for the ability for movement to happen
• To make contraction happens with and creates a formation
• A power stroke is what will take place for the phosphate energy

Types Of Strokes

• With that you will need to have a detachment from those bonds after the phosphate has energy created
• With all of there this all needs energy that are going to help the movement

Action of What to Start For Motion

• This is what creates all that to do it, all which is from actions
• All the 1 part
• Fiber what makes and allows all from the muscles

Structure of Fiber

• Axon muscle then needs innervation
• Can vary on strength and stimulus

In Relation to Muscles

• Key concepts that are involved is to show strength and build up
• Most importantly there needs to be fiber what are called in science to what happens to make up the energy

Muscle Types Based Function

• What each of these functions serve come down the two types
• There exist the fast fibers that are fatigued And the opposite the ones what takes from this that don't