A&P: chapter 10

sternocleidomastoid

origin: manubrium and medial clavicle

insertion: mastoid process and superior nuchal line

action:

one contracting alone: laterally flexes head and neck to same side and rottaes head and neck to opposite side

both contracting together: flex neck

scalene muscles

origin: C2-C6

insertion: first and second ribs

action: flex, laterally flex, and rotate neck

Splenius capitis

origin: C4-T6

insertion: superior nuchal line and mastoid process

action: extends, rotates, and laterally flexes neck

trapezius

origin: occipital protuberance, nuchal ligament, spinous processes of C7-T12

insertion: clavicle, acromion process, and scapular spine

Action: extends and laterally flexes neck

scalp (epicranium) - occipitofrontalis

origin: occipital bone

insertion: skin of eyebrow and nose

action: moves scalp; raises eyebrows; wrinkles forehead; “surprise”

eye - corrugator supercilli

origin: nasal bridge and orbicularis oculi

insertion: skin of eyebrow

action: depresses medial portion of eyebrow; draws eyebrows together, as in frowning

eye - orbicularis oculi

origin: maxilla and frontal bones

insertion: circles orbit and inserts near origin

action: closes eyes; blinking, winking, squinting

mouth: buccinator

origin: mandible and maxilla

insertion: orbicularis oris at corner of mouth

action: draws corners of mouth posteriorly; compresses cheek to hold food between teeth

mouth - depressor labii inferioris

origin: lower border of mandible

insertion: skin of lower lip and orbicularis oris

action: depresses lower lip

mouth - levator labii superioris

origin: maxilla

insertion: skin and orbicularis oris of upper lip

action: raises upper lip, “sneer”

mouth - orbicularis oris

origin: nasal septum, maxilla, and mandible

insertion: fascia and other muscles of lips

action: closes and purses lips; “kissing”

mouth - risorius

origin: platysma and masseter fascia

insertion: orbicularis oris and skin at corner of mouth

action: draws corner of mouth laterally; risor— laughter

Mouth - zygomaticus major

origin: zygomatic bone

insertion: angle of mouth

action: elevates and abducts upper lip and corner of mouth; “smile”

mouth - zygomaticus minor

origin: zygomatic bone

insertion: orbicularis oris of upper lip

action: elevates and abducts upper lip; “smile”

neck - platysma

origin: fascia of deltoid and pectoralis major

insertion: skin over inferior border of mandible

action: depresses lower lip; wrinkles skin of neck and upper chest; to express fear

temporalis

origin: temporal fossa

insertion: anterior portion of mandibular ramus and coronoid process

action: elevates and retracts (moves posteriorly) mandible; involved in excursion (chapter 8)

masseter

origin: zygomatic arch

insertion: lateral side of mandibular ramus

action: elevates and protracts (moves anteriorly) mandible; involved in excursion

lateral pterygoids

origin: lateral side of lateral pterygoid plate and greater wing of sphenoid

insertion: condylar process of mandible and articular disk

action: depresses and protacts mandible; involved in excursion; side-to-side movements

medial pterygoids

origin: medial side of lateral pterygoid plate and tuberosity of maxilla

insertion: medial surface of mandible

action: elevates and protracts mandible; involved in excursion; side-to-side movements

mylohyoid

origin: body of mandible

insertion: hyoid

action: elevates floor of mouth and tongue; depresses mandible when hyoid is fixed

extrinsic muscles: genioglossus (aka myloglossus)

origin: mental protuberance of mandible

insertion: tongue

action: depresses and protrudes tongue

hyoglossus

origin: hyoid

insertion: side of tongue

action: retracts and depresses side of tongue

styloglossus

origin: styloid process of temporal bone

insertion: tongue (lateral and inferior)

action: retracts tongue

erector spinae: iliocostalis

origin: Sacrum, ilium, and lumbar vertebrae

insertion: ribs and cervical vertebrae

action: extends and laterally flexes vertebral colum

erector spinae: longissmis

origin: sacrum, ilium, and lumbar vertebrae

insertion: ribs, vertebrae, and skull

action: extends and laterally flexes vertebral column

erector spinae: spinalis

origin: spinous processes of lower vertebrae

insertion: spinous processes of upper vertebrae

action: extends vertebral column

deep: quadratus lumborum

origin: illiac crest and lower lumbar vertebrae

insertion: twelfth rib and upper lumbar vertebrae

action: laterally flexes vertebral column and depresses twelfth rib

diaphragm

o: interior of ribs, sternum, and lumbar vertebrae

i: central tendon of diaphragm

a: inspiration depresses floor of thorax

scalene muscles: anterior

o: transverse processes of C3-C6

I: first rib

A: elevates first rib

scalene muscles: medial

O: transverse processes of C2-C6

I: first rib

A: elevates first rib

Scalene Muscles: posterior

O: transverse C4-C6

I: second rib

A: elevates second rib

rectus abdominis

O: pubic crest and symphysis pubis

I: xiphoid process and inferior ribs

A: flexes vertebral column; compresses abdominal wall

External abdominal oblique

O: fifth to twelfth ribs

I: illiac crest, inguinal ligament, and rectus sheath

A: flexes and rotates vertebral column; compresses abdominal wall; depresses thorax

internal abdominal oblique

O: illiac crest, inguinal ligament, and lumbar fascia

I: tenth to twelfth ribs and rectus sheath

A: flexes and rotates vertebral column; compresses abdominal wall; depresses thorax

transversus abdominis

O: seventh to twelfth costal cartilages, lumbar fascia, illiac crest, and inguinal ligament

I: xiphoid process, linea alba, and pubic tubercle

A: compresses abdominal wall

levator scapulae

O: transverse processes of C1-C4

I: superior angle of scapula

A: elevates, retracts, and rotates scapula; laterally flexes neck

Pectoralis minor

O: third to fifth ribs

I: coracoid process of scapula

A: depresses scapula or elevates ribs

Rhomboideus: Major

O: spinous processes of T1-T4

I: medial border of scapula

A: retracts, rotates, and fixes scapula

Rhomboideus: minor

O: spinous processes of C6-C7

I: medial border of scapula

A: retracts, slightly elevates, rotates, and fixes scapula

serratus anterior

O: first to eigth or ninth ribs

I: medial border of scapula

A: rotates and protracts scapula; elevates ribs

Coracobrachilias

O: coracoid process of scapula

I: midshaft of humerus

A: adducts arms and flexes shoulder

deltoid

O: clavicle, acromion process, and scapular spine

I: deltoid tuberosity

A: flexes and extends shoulder; abducts and medially and laterally rotates arm

Latissimus dorsi

O: spinous processes of T7-L5; sacrum and iliac crest; inferior angle of scapula in some people

I: medial crest of intertubercular groove

A: adducts and medially rotates arm; extends shoulder

Pectoralis major

O: clavicle, sternum, superior six costal cartilages, and abdominal aponeurosis

I: lateral crest of intertubercular groove

A: flexes shoulder; adducts and medially rotates arm; extends shoulder from flexed position

Teres Major

O: lateral border of scapula

I: medial crest of intertubercular groove

A: extends shoulder; adducts and medially rotates arm

Infraspinatus

O: infraspinous fossa of scapula

I: greater tubercle of humerus

A: laterally rotates arm; holds head of humerus in place

Subscapularis

O: subscapular fossa

I: lesser tubercle of humerus

A: medially rotates arm; holds head of humerus in place

Supraspinatus

O: supraspinous fossa

I: greater tubercle of humerus

A: abducts arm; holds head of humerus in place

Teres Minor

O: lateral border of scapula

I: greater tubercle of humerus

A: laterally rotates and adducts arm; holds head of humerus in place

Biceps brachii

O:

short head: coracoid process of scapula

long head: supraglenoid tubercle of scapula

I: radial tuberosity and bicipital aponeurosis

A: flexes elbow and supinates forearm; assists shoulder flexion

brachialis

O: distal half of anterior humerus

I: coronoid process and tuberosity of ulna

A: primary flexor of elbow

brachioradialis

O: lateral superacondylar ridge of humerus

I: styloid process of radius

A: flexes elbow

Flexor carpi radialis

O: medial epicondyle of humerus

I: second and third metacarpal bones

A: flexes and abducts wrist

Flexor carpi ulnaris

O: medial epicondyle of humerus and ulna

I: pisiform, hamate, and fifth metacarpal bones

A: flexes and adducts wrist

Flexor digitorum profundus

O: ulna

I: distal phalanges of digits 2-5

A: flexes fingers at metacarpophalangeal joints and interphalangeal joints and wrist

flexor digitorum superficialis

O: medial epicondyle of humerus, coronoid process, and radius

I: middle phalanges of digits 2-5

A: flexes fingers at interphalangeal joints and wrist

flexor pollicis longus

O: radius

I: distal phalanx of thumb

A: flexes thumb

palmaris longus

O: medial epicondyle of humerus

I: palmar fascia

A: tenses palmar fascia; flexes wrists

pronator teres

O: medial epicondyle of humerus and coronoid process of ulna

I: radius

A: pronates forearm (and hand)

Supinator

O: lateral epicondyle of humerus and ulna

I: radius

A: supinates forearm (and hand)