anatomy - muscular system (pt.2) 💪

What are the muscle fiber types?

1. Slow-Twitch Oxidative (Type l)

2. Fast-Twitch Oxidative (Type lla)

3. Fast-Twitch Glycolytic (Type llx)

1. Slow-Twitch Oxidative

→ Contract slowly and rely on aerobic respiration (due to lots of mitochondria to produce ATP).

→ Prolonged contraction, low power, best for endurance, abundant in postural muscles (e.g back)

*”red (due to myoglobin), fatigue-resistance (due to endurance)

2. Fast-Twitch Oxidative

aka glycolytic fibers

→ Store a lot of glycogen, can generate strong, rapid contractions for short bursts of activity (ex/ jumping or sprinting)

→ Can fatigue quickly, appearing with a white color (due to fewer mitochondria = less myoglobin)

→ Mix of aerobic and anaerobic metabolism and common in leg muscles

3. Fast-twitch Glycolytic

→ Fewer mitochondria, lots of glycogen

→ Strong, rapid contractions, fatigue quickly

→ Best for short, powerful bursts

• found in upper limb muscles

*white, anaerobic

What’s best for the following activity and why?

• Maintain posture

Fiber type: Type l

Why?: Resistant to fatigue; aerobic

What’s best for the following activity and why?

• Long-distance running

Fiber type: Type l

Why?: sustained ATP production using oxygen

What’s best for the following activity and why?

• 400m sprint

Fiber type: Type lla

Why?: Combines power with moderate endurance

What’s best for the following activity and why?

• Jumping

Fiber type: Type llx

Why?: Produces rapid, powerful contractions

What’s best for the following activity and why?

• Transferring a client once

Fiber: Type llx

Why?: Maximum force generation

How are skeletal muscles divided?

1. Axial muscles

2. Appendicular muscles

Axial muscles

• Arise from the axial skeleton

• About 60% of skeletal muscles

• Position head, spinal cord and move rib cage

Appendicular muscles

• Stabilize or move the appendicular skeleton

origin

→ the end of the muscle that stays stationary

• located on the more proximal (closer to the body’s midline) or stable bone

• acts as an ‘anchor’

insertion

→ the end of the muscle that moves when the muscle contracts

• located on the more distal (further from the body’s midline) or mobile bone

• moves toward the orgigin when the muscle contracts

action

→ what happens when the muscle contracts

ex. flexion, extension, adduction, abduction

What are the Primary Actions of Muscles

1. Primer mover (agonist)

2. Antagonist

3. Synergist

Muscles cannot push. They can only _____ by _______

pull, contracting

Primer mover (agonist)

→ the muscle that is chiefly responsible for producing a movement (aka. main character)

ex. when you bend your elbow, the biceps brachii is the prime mover

Antagonist

→ muscle that opposes a movement by another muscle

→ a functional opposite to the agonist

Synergist

→ muscle that helps the prime mover works efficiently

• Fixators are synergists that stabilize the origin of the prime mover

Flexion of the elbow: Biceps brachii would be what?

prime mover

Flexion of the elbow: Triceps brachii would be what?

antagonist to the biceps brachii

Flexion of the elbow: Brachialis would be what?

synergist

How are muscles named?

• Shape

• Location

• Function

• Fibre Direction

• Number of Heads or Divisions

• Points of Attachment

• Size of Muscle

Shape (state an ex.)

→ deltoid muscle is delta shaped

Location (state an ex.)

→ Brachialis (arm), gluteus (buttock), frontalis (muscle over the frontal one), lateralis (to the side), medialis (toward the midline)

Function

→ adductor muscles in the thigh adduct the leg (move it toward the midline)

Fibre Direction

→ fibres of the rectus abdominus are straight up and down and parallel (rectus means straight)

Number of Heads or Divisions

→ Biceps and triceps refer to multiple points of origin

• Biceps brachii has two heads

Points of Attachment

→ points of origin and insertion may be identified in the name

• sternocleidomastoid originates on the sternum and clavicle inserts on the mastoid process

Size of Muscle

→ relative to other muscles in a region

• gluteus minimus, gluteus medius and gluteus maximus

Muscle-Related Terminology

• Abductor

• Adductor

• Bi

• Brevis

• Extensor

• Flexor

• Lateralis

abductor

→ moves the bone away from the midline

adductor

→ moves the bone toward the midline

bi

two

brevis

short

extensor

→ muscle that increases the angle at the joint

flexor

→ muscle that decreases the angle at the joint

lateralis

to the outside

Muscle-Related terminology (contid.)

• Longus

• Maximus

• Medialis

• Medius

• Minimus

• Obqliue

• Rectus

• Tri

longus

long

maximus

largest

medialis

to the inside

medius

medium

oblique

at an angle

rectus

straight

tri

three

Specific Muscle Groups (header)

→ facial expressions

describe muscles of facial expression

• subcutaneous tissue of the face and scalp

• most insert into the skin or fascia (not bone)

→ movement of skin (NOT JOINTS!)

describe the functions of muscles of facial expression

→ Functions: control facial expressions, speech articulation, eating, blinking

Innervated by __________________

Cranial Nerve VII (Facial Nerve) (allowing us to smile, frown, raise our eyebrows or purse our lips)

Muscles of Facial Expression

• frontalis

• orbicularis oculi

• orbicularis oris

• platysma

• occipitalis

• zygomaticus major

• depressor anguli oris

Joined by a tendon called

aponeurosis

frontalis

• forehead

• raises the eyebrows and wrinkles the forehead

The two muscles, frontalis and occipitalis make up….

the epicranius

occipitalis

• back of the head

• joined to frontalis by a flat tendon called an aponeurosis

orbicularis oculi

• around the eye

• circular muscle to close eyes tightly or blink

orbicularis oris

• around the mouth

• pucker or close the lips

zygomaticus major and minor

• pulls the corners of the mouth upward

• muscle most responsible for smiling

depressor anglui oris

• opposes zygomaticus major

• pulls the corners of the mouth downward

• frowning

platysma

• runs along the neck and lower jaw

• tenses the skin of the neck

• pulls corners of the mouth down slightly

Specific Muscle Groups (header)

→ neck muscles (responsible for actions such as chewing, swallowing and supporting the airway)

Muscles of Masticati

• move the mandible for chewing, grinding and speaking

• muscles action at the temporomandibular (TMJ)

• Masseter and temporalis are primary elevators of the mandible (close mouth)

• Pterygoids act together for side-to-side motion

What are the superficial muscles of muscles mastication?

• masseter

• temporalis

masseter

• powerful elevator of the mandible

• main chewing muscle that helps close the jaw

temporalis

• fans out across the side of the skull

• elevates the mandible and helps retract it

What are the deep muscles of muscles mastication?

• lateral pterygoid

• medial pterygoid

lateral pterygoid

• protrudes the mandible

• helps with side-to-side grinding movements

medial pterygoid

• works with the masseter to elevate the mandible

• contribute to grinding

What are the muscles of the tongue?

• Intrinsic muscles

• Extrinsic muscles

• Innervation: cranial nerve Xll (hypoglossal)

What’s another word for tongue?

glossus

Functions of muscles that move tongue?

→ swallowing, moving food, speaking

Extrinsic muscles

• orginate outside, insert into tongur

• control position of tongue

What are the three parts of extrinsic muscles?

• Genioglossus: sticks the tongue out and helps depress it

• Hypoglossus: pulls the tongue down and back

• Styloglossus: pulls the tongue up and back

pharynx

→ muscular tube that connects the nasal and oral cavities to the larynx and esophagus

• protects airway, assits swallowing and maintains ear pressure

What are muscle functions?

• close nasopharynx

• open eustachian tubes

• constrict pharynx during swallowing

Innervation for muscles of the pharynx?

→ Cranial nerves IX (glossopharynngeal) and X (vagus)

• involved with the gag reflex (CN IX)

What are constrictor muscles in the pharynx?

• Superior constrictor

• Middle constrictor

• Inferior constrictor

superior constrictor

• constricts upper pharynx

• closes nasopharynx during swallowing

middle constrictor

• constricts middle pharynx

inferior constrictor

• constricts lower pharynx

• helps guide food into esophagus

_________ wave-like conttractions to push bolus down

peristaltic

________ muscles to elevate pharynx

longitudinal

What are the broad groups of anterior neck muscles?

• superficial

• suprahyoid

• infrahyoid

• scalene

• deep

superficial

→ sternocleidomastoid, platysma)

suprahyoid

→ above hyoid, elevate hyoid

Which muscles are in the suprahyoid group?

• mylohyoid

• stylohyoid

• digastric

• geniohyoid

functions of muscles in suprahyoid?

• swallowing and mouth movements

→ lift the larynx superiorly/anteriorly to widen pharynx

→ open the mouth

→ elevate hyoid and floor of the mouth (chewing)

→ allows backward pressure from the tonggue (push food toward pharynx)

→ form floor of oral cavity

infrahyoid

→ below hyooid, depress hyoid

What are the types of infrahyoid muscles?

• superficial

• deep

Describe what infrahyoid muscles are

aka strap muscles

• thin, falt muscles connecting hyoid to sternum, clavicle and thyroid cartilage

what are functions of infrahyoid muscles?

• swallowing

• stabilizing the hyoid and larynx

• depress the hyoid

superficial

• sternohyoid (depress the hyoid)

• omohyoid (depress and retracts the hyoid)

deep

• sternothyroid (depresses the thyroid cartilage)

• thyrohyoid (depresses the hyoid or elevates the thyroid)

scalene

→ lateral neck, aid respiration & neck flexion

deep

→ prevertebrak, postural support

What are functions of the anterior neck muscles?

• support head, hyoid bone, larynx and assist in swallowing, breathing and movement

Most muscles attached to _______ bone

hyoid

Describe the sternocleidomastoid muscle

• prominent muscle on the anterolateral neck

• two inferior origins; sternum & clavicle

• one suprior insertion: mastoid process

functions of the sternocleidomastoid muscle?

• flexes neck

• rotates head to opposite side