The Long Haul

This final installment of my 16 hours of capacity building that would go towards my symposium presentation was an interesting case (this portion of research I completed before finalizing my proposal). I worked from 10 PM to 1 AM on my online coursework, completing the muscular and integumentary systems, and stayed up the rest of the night filming the video I would need for Saturday, as I was leaving for the Outer Banks the next morning with my soccer team and would have no further opportunity to do so.

Therefore, this post is sponsored by 5 Hour Energy (and sorry I fell asleep in calculus, Ms. Cohen)!

Skeletal Muscle Movement

Apaneuroses- Connect muscles

Tendons- Attach muscles to bones and help stabilize joints

Bursae- Fluid-filled sacs which join to tendons to reduce friction as they move

Levers

First Class

- Few occur in the body

- One is involved in head flexion/extension (fulcrum located on the first cervical vertebrae, applied force comes from the neck muscles, and the load is the weight of the head)

Second Class

- The load is located between the applied force and fulcrum

- Standing on the toes (fulcrum is the ball of the foot, the load is the body weight, and effort comes from the calf muscles)

Third Class

- Force is applied between the load and fulcrum

- Most common levers in the body

- Ex. bicep (load located in the hand, the bicep muscle applies force, and the fulcrum is located at the elbow)

• Skeletal muscles are typically arranged in pairs

• Agonists are the prime movers

• Antagonists are muscles which oppose the actions of the agonist (i.e. when the agonist contracts, the antagonist stretches while maintaining tension to prevent injury)

• Synergists are a special kind of muscle which improve the efficiency of an agonist muscle

Some agonist-antagonist combinations include...

Agonist: Biceps brachii, located on the anterior surface of the upper arm

Antagonist: Triceps brachii, located on the posterior surface of the upper arm

Movement: The bicep flexes the forearm, while the tricep extends it

Agonist: Hamstrings, a group of three muscles located on the posterior of the thigh

Antagonist: Quadriceps femoris, four muscles located on the anterior of the thigh

Movement: The hamstring flexes the lower leg, while the quadriceps extends it. An imbalance in the recruitment of these muscles can contribute to ACL injury.

Agonist: Flexor digitorum superficialis and profundus, located in the hand

Antagonist: Extensor digitorum, also located in and around the hand

Movement: The flexor digitorum superficialis and flexor digitorum profundus flex the fingers and hand at the wrist; the extensor digitorum extends it (as context clues suggest)

Gross Anatomy of Muscles/Nomenclature

Muscle names are based on numerous criteria including the location of the muscle, its shape, its orientation, the number of muscles in a group, the action it generates, and the location of its origin(s) and insertion(s).

Origin- The unmoving, stable connection of muscle to a structure (i.e. bone); it is typically found on the proximal end

Insertion- The moveable end of the muscle, typically found on the distal end

*Important Muscle Terminology*

NAME DEFINITION EXAMPLE

• Direction relative to the midline of the body

Rectus Straight Rectus abdominis

Transverse At a right angle Transverse abdominis

Oblique Diagonal External oblique

• Relative size

Maximus Largest Gluteus maximus

Medius Medium Gluteus medius

Minimus Smallest Gluteus minimus

Longus Long Longus capitis

Brevis Short Extensor carpi radialis brevis

Latissimus Widest Latissimus dorsi

Longissimus Longest Longissimus thoracis

Magnus Large Adductor magnus

Major Larger Rhomboid major

Minor Smaller Rhomboid minor

Vastus Huge Vastus medialis

• Relative shape

Deltoid Triangular Deltoid

Trapezius Trapezoidal Trapezius

Serratus Serrated Serratus anterior

Rhomboid Diamond-shaped Rhomboid minor

Orbicularis Circular Orbicularis oris

Pectinate Comb-like Pectineus

Piriformis Pear-shaped Piriformis

Platys Flat Platysma

Quadratus Four-sided and square Quadratus lumbarum

Gracilis Slender Gracilis

• Action

Flexor Decreases the angle at a joint Flexor digitorum superficialis

Extensor Increases the angle at a joint Extensor digitorum

Abductor Moves the bone away from the midline Abductor pollicis longus

Adductor Moves the bone towards the midline Adductor magnus

Levator Elevates a body part Levator scapulae

Depressor Lowers a body part Depressor labii inferioris

Supinator Turns the palm anteriorly Supinator

Pronator Turns the palm posteriorly Pronator teres

Sphincter Decreases the size of an opening External anal sphincter

Tensor Tenses a body part Tensor fasciae latae

Rotator Rotates a bone around its longitudinal axis Rotator

• Number of origins

Biceps Two Biceps brachii

Triceps Three Triceps brachii

Quadriceps Four Quadriceps femoris

MUSCULAR LEVELS OF ORGANIZATION

- Molecular level: actin and myosin

- Microscopic level: sarcomere and myofibrils

- Cell level: myoblasts and myofibers

- Tissue level: neuromuscular junctions and fascicles

- Organ level: major skeletal muscles of the body

For space purposes I'll have to continue my record of this chunk of research in the next blog post.

Hasta pronto!

#muscularsystem #anatomy #seniorproject #capacitybuilding #physiology