Lack striation.

cells elongated/spindle shaped.

joined into sheets (which wrap around organs).

Monomucleated.

Associated with Viscera.

Slow, sustained contractions.

Involuntary:

Mygoenic (stim initiated in muscle and stretched) vs. Neurogenic (stim by Nerve Cells and spread throughout)

Appear striated.

Cells elongated, branch frequently.

Cells joined at intercalated disks.

Mononucleate.

Involuntary mygenic contractions.

Pace maker (SA Node) initiates contraction that is spread as a unit beat.

Striated.

Cells are long, thing and attach together to form fibers.

Multinucleated.

Voluntary - (neurogenic contraction)

rapid contraction from one nerve cell.

Stimulation initiated in the muscle and stretches.

Slow and sustained.

Outter layer of connective tissue on muscle.

Fascia.

Formed from all the layers of connective tissue within the muscle and extends beyond the ends of the muscle to connect muscle to bone.

Permits delicacy of control (ex: fingers).

Each muscle surrounded by fascia.

Muscle are composed of muscle fibers found in fasicles.

Each fiber is surrounded by endomysium and composed of myofibrils.

In each myofibril there are sarcomeres stacked end to end.

Third layer of connective tissue.

Cylindrical.

Parallel subunits.

Composed of sacromeres.

Thick and thin filaments of the sarcomere slide past one another that causes the sarcomere to shrink, shortening the muscle and causing contraction.

Occurs simultaneously though all sarcomeres in the muscle cell.

Chains of sarcomere shorten together.

Amount of force that a muscle generates.

Not constant, but depends on length of muscle where contracts.

Length reflects spacing of thick and thin filaments within the sarcomere.

Highly vascularized (blood supply) and higher myoglobin.

Aerobic production of ATP.

Resist fatigue.

Endurance.

Contract slowly.

Low vascularization and less myoglobin.

Anaerobic.

Quick bursts.

Fatigue Rapidly.

Contract Rapidly.

Relatively slow contraction.

Produce low force.

Can sustain the contraction for a long time.

Postural muscles in amphibians (rare in mammals beside the extrinsic eye slits).

Produce Fast contractions for rapid movement.

In the somatic muscles of all vertebrates.

Two types: slow twich and fast twitch.

White fibers.

Reach max. contraction faster.

Multiple types:

Fast Twitch fatiguable.

Fast Twitch Fatigue Resistant.

Red Fibers.

Longer to reach max. contraction force (38ms vs. 13ms fast)

Fatigue Resistant.

1. Slow Twitch
2. Fast Twitch, Fatiguable
3. Fast Twitch, Fatigue Resistant

1. Sliding Filaments: active comp (uses ATP)
2. Elastic Components: connective tissue within the muscle and tendons.

Motor neuron and all the fibers it contacts.

Delicate movements require small # of muscle fibers.

Large motor units are used to lift large weights (many)

Max force produced is proportional to the total CSA.

Increased CSA => Increased # fibers => greater tension produced.

1. Parallel 2. Pinnate

Effects the tension generated.

All fibers lie along the line of tension generated.

Muscle moves light loads long distances.

Fibers lie oblique to the line of force generated.

Move heavy loads short distances.

Distal: Strength

Proximal: Speed 

1. Mesenchyme: Loose group of cells that are dispersed throughout the embyo. Smooth muscle within the walls of blood vessels and some viscera.
2. Hypomere: Paired around the gut. Smooth muscle around the digestive tract and cardiac muscle.
3. Paraxial Mesoderm(epimere):Forms next to the neural tube along the body axis. Somites(trunk) and somitomeres (head) and most skeletal muscle.

Clumps of mesdoerms attached by tight junctions.

Segmentally arranged.

Form ant->post.

Contribute to 3 structures:

1. Dermatome: skin=>dermis
2. Myotome: Muscles (expaxial and hypaxial musculature)
3. Sclerotome: VC

Clusters of mesoderm that remain conected to each other.

In series with somites.

7 Pairs (amniotes)

Form head and pharyngeal musculature.

Ventral tups of myotomeres grow downward into fin bud.

Fin muscles are from vent tips of somites and grow down to develop fin.

Myotomes that diff from somite from muscle assoc with the ribs, VC, and lat body wall.

Dorsal: Epaxial

Ventral: Hypaxial

Hypobranchial Musculature: run between the ventral elements of gills arches and between gill ares and pect. girdle.

Ventral tips of somites grow down and forward into the throat along the vent. side of the gills (tongue)

Nerve inputs from spinal nerves.

Branchiomeric Musculature: From somitomeres in the head.

Branchio muscles get input from cranial nerves.

Associated with sides of the branchial arches.

n=6.

On outside of eyeball.

rotates eye within orbit.

From 3-4 somites.

Input from cranial nerves.

Axial>Appendicular

Axial is maj force for locomotion, append is just for fins.

Appendicular>Axial

App. muscles are used in locomotion.

Muscle complex (epaxial reduced and hypaxial specialized)

Girdles transmit force to VC differently:

pectoral: muscular sling

pelvic: attached to column, fewer muscles assoc with holding in place.