axial muscles.

what is this and what is its action(s)?

temporalis

actions: elevation of mandible

what is this and what is its action(s)?

masseter

action: elevation of the mandible

what is this and what is its action(s)?

obicularis oculi

actions: sphincter of eyelids, closed eye in blinking, squinting and sleep, aids in flows of tears across the eye

what is this and what is its action(s)?

obicularis oris

actions: encircles mouth, closes lips, protrudes lips as in kissing, uniquely developed in humans for speech

what is this and what is its action(s)?

levator palpabrae superioris

actions: elevates upper eyelid, opens the eye

what is this and what is its action(s)?

platysma

actions: draws lower lip and angle of the mouth downwards when in surprise or horror, may aid in opening the mouth widely

what is this and what is its action(s)?

zygomaticus major

action: elevates the corner of the mouth when smiling or laughing

what is this and what is its action(s)?

zygomaticus minor

action: elevation of the top lip

what is this and what is its action(s), and its origin and insertion?

sternocleidomastoid

action: unilateral: contralateral rotation of the head. bilateral: flexion of the neck

origin: manubrium of the sternum, medial 1/3 of the clavicle

insertion: mastoid process of the temporal bone

what is this and what is its action(s)?

scalenes (anterior, posterior and middle)

action: bilateral: neck flexion, if spines fixed elevation of ribs 1-2 (helps with breathing). unilateral: lateral flexion of the neck

what is this and what is its action(s), insertion and origin?

digastric

• Origin: 

  • Anterior belly: Digastric fossa of mandible.

  • Posterior belly: mastoid process of temporal bone.

• Insertion: hyoid bone via fascial sling.

• Action: 

  • Depresses mandible when hyoid is fixed

  • Elevates hyoid when mandible is fixed.

what is this? what’s its origin, action, insertion?

stylohoid

• Origin: Styloid process of temporal bone.

• Insertion: Hyoid bone.

• Action: 

  • elevates hyoid

  • Retracts hyoid.

what is this? what’s is its action?

• Action: 

  • Spans mandible from side to side and forms floor of mouth

  • elevates floor of mouth in initial stage of swallowing.

what is this? what’s its origin, action and insertion?

sternohyoid

• Origin: Manubrium of sternum; medial end of clavicle.

• Insertion: hyoid bone.

• Action: 

  • depresses hyoid after it has been elevated.

what is this? what’s its origin, action and insertion?

sternothyroid

• Origin: Manubrium of sternum; costal cartilage

• Insertion: thyroid cartilage of larynx

• Action: 

  • Depresses larynx after it has been elevated in swallowing and vocalization

what is this? what is its action?

omohyoid

Action: depressed hyroid after it has been elevated

what is this? what’s its action?

thyrohyoid

action: depresses the hyoid

what is this? what’s its action?

external intercostals

• Action: 

  • When scalenes fix rib 1, elevation and protraction of ribs 2-12, expanding the thoracic cavity (aiding in inspiration).

what is this? what’s its action?

internal intercostals

• Action: 

  • In forced expiration, the interosseous part depresses and retracts the ribs, compressing the thoracic cavity and expelling air.

what is this? what’s its action?

diaphragm

• Action: 

  • prime mover of inspiration; contraction compresses abdominal viscera and aids in childbirth and expulsion of urine and feces.

what is this? what is its origin, action and insertion?

rectus abdominis

• Origin: Pubic symphysis and superior margin of pubis.

• Insertion: Xiphoid process; costal cartilages 5-7.

• Action: 

  • Flexion of the trunk

  • Stabilizes pelvic region during walking

  • Compresses abdominal viscera.

what is this? what’s its action?

external abdominal oblique

• Action: 

  • Support viscera

  • Stabilizes vertebral column

  • Maintains posture.

  • Unilateral: contralateral rotation of waist

what is this? what is its action?

internal abdominal obliques

• Action: 

  • Support viscera 

  • Stabilizes vertebral column

  • Maintains posture

  • Unilateral action: ipsilateral rotation of waist.

what is this? what’s its action?

transverse abdominis

• Action: 

  • Compresses abdominal contents

  • Does NOT contribute to vertebral column movements.

what is this?

linea alba, Non-muscular, fibrous structure running between the xiphoid process and pubic symphysis.

what is this? what’s its origin, insertion, and action?

serratus anterior

• Origin: All or nearby all ribs.

• Insertion: medial border of scapula.

• Action: 

  • With pectoralis minor, protracts scapula 

  • Is the prime mover in all forward-reaching and pushing actions 

  • Fixes scapula during abduction of arm.

• Also known as the Boxer’s muscle

what is this? what’s its origin, action and insertion?

pectoralis major

• Origin: Medial half of clavicle; lateral margin of sternum; costal cartilages 1-7; aponeurosis of external oblique.

• Insertion: Intertubercular sulcus of humerus

• Action: 

  • Flexion of the shoulder

  • Adduction of the shoulder

  • Medial rotation of the shoulder

what is this? what is its origin, insertion and action?

pectoralis minor

• Origin: Ribs 3-5 and overlying fascia.

• Insertion: Coracoid process of scapula.

• Action: 

  • With serratus anterior, protracts the scapula

what is this? and what makes it up?

erector spinae group

• Iliocostalis

• Longissimus

• spinalis 

what is this? what’s its action and what group is it apart of?

iliocostalis

• Part of Erector Spinae group.

• Action: 

  • Unilateral action: lateral flexion of vertebral column

  • Extension action: extension of vertebral column.

  • depression of ribs

• “Antigravity” muscle.

what is this? what’s its action and what group is it apart of?

longissimus

• Part of Erector Spinae group.

• Action:

  • Unilateral: 

    • lateral flexion of vertebral column

    • ipsilateral rotation of the head

  • Bilateral: 

    • extension of vertebral column 

    • Extension of the head

  • Depresses ribs.

what is this? what’s its action and what group is it apart of?

spinalis

• Part of Erector Spinae group

• Action: 

  • Unilateral: lateral flexion of vertebral column

  • Bilateral: extension of vertebral column

• “Antigravity” muscle

what is this? what it’s action?

semispinalis

• Action:

  • Unilateral action: contralateral rotation of the neck

  • Bilateral action: extension of the head and neck.

what is this? what’s its origin, insertion and action?

serratus posterior (superior)

• Origin: nuchal ligament and spinous processes of vertebrae C7-T3

• Insertion: Ribs 2-5 (superior border) 

• Action: elevation of ribs 2-5

what is this? what is its origin, insertion and action?

serratus posterior (inferior)

• Origin: Spinous processes of T11-L2 vertebrae

• Insertion: Ribs 9-12 (inferior border) 

• Action: depression of ribs 9-12

what is this? what’s its action?

rhomboid minor

• Action: 

  • Retracts scapula (braces shoulder, fixes scapula during arm movements)m movements

what is this? what’s its action?

rhomboid major

• Action: 

  • Retracts scapula (braces shoulder, fixes scapula during arm movements)

what is this? what’s its action?

levator scapulae

• Action: 

  • Elevates scapula if cervical vertebrae are fixed

  • Lateral flexion of the neck if scapula is fixed

what is this? what is its origin, insertion and action?

trapezius

• Origin: External occipital protuberance; medial one-third of superior nuchal line; nuchal ligament; spinous processes of vertebrae t1-t12.

• Insertion: Acromion and spine of scapula; lateral one-third of clavicle.

• Action: 

  • Stabilizes scapula and shoulder during arm movements; 

  • elevates and depresses shoulder

  • rotates and retracts scapula.

what is this? what’s its action?

latissimus dorsi

• Action: 

  • adduction of the shoulder

  • Extension of the shoulder

  • Medial rotation of the shoulder

what are the four rotator cuff muscles?

SITS

Supraspinatus

Infraspinatus

Teres Minor

Subscapularis

what is this? what’s its action, origin and insertion?

teres major (not part of rotator cuff)

Origin: Inferior angle of scapula

•Insertion: Intertubercular sulcus of humerus.

•Action:

Extends the arm

Medially rotates humerus

what is this? what’s its action, origin and insertion?

supraspinatus

Origin: Supraspinous fossa of scapula.

•Insertion: Greater tubercle of humerus.

•Action:

•Aids deltoid in abduction of arm

•Supports humeral head when carrying weight.

what is this? what’s its action, origin and insertion?

infraspinatus

Origin: Infraspinous fossa of scapula.

•Insertion: Greater tubercle of humerus.

•Action:

•Modulates action of deltoid

•Prevents humeral head from sliding upward

•Rotates humerus laterally.

what is this? what’s its action, origin and insertion?

teres minor

Origin: Lateral border and adjacent posterior surface of scapula.

•Insertion: Greater tubercle of humerus; posterior surface of joint capsule.

•Action:

•Modulates action of deltoid

•Prevents humeral head from sliding upward as arm is abducted

•Rotates humerus laterally.

what is this? what’s its action, origin and insertion?

subscapularis

Origin: Subscapular fossa of scapula.

•Insertion: Lesser tubercle of humerus; anterior surface of joint capsule.

•Action:

• Modulates action of deltoid

• Prevents humeral head from sliding upward was arm is abducted

• Rotates humerus medially

what is this? what’s its action, origin and insertion?

deltoid

•Origin: acromion and spine of scapula; lateral portion of clavicle.

•Insertion: Deltoid tuberosity of humerus.

•Action:

•Anterior fibers flex and medially rotate arm

•Lateral fibers abduct arm

•Posterior fibers extend and laterally rotate arm.

•*Shaped like Greek letter delta (Δ).