Skeletal Muscles (Complete Lec)

Class 1 Lever

Flucrum between force & weight, seesaw, ex. Head movement @ the atlantoccipital joint

Class 2 Lever

Weight is between pulcrum & pull, wheelbarrow, ex. standing on toes

class 3 lever

pull located between flucrum & weight, person using a shovel, ex. biceps brachii with elbow as fulcrum

scalene muscles origin

c2-c6

scalene muscles insertion

First and second ribs

Scalene muscles action

Flex, laterally flex, & rotate neck

Longissimus capitis origin

Upper thoracic and lower cervical vertebrae

Longissimus capitis insertion

Mastoid process

Longissimus capitis action

Extends, rotates & laterally flexes neck

Oblique capitis superior origin

atlas

Oblique capitis superior insertion

Occipital bone - inferior nuchal line

Oblique capitis superior action

extends and laterally flexes neck; turns head

Rectus capitis posterior origin

axis, atlas

Rectus capitis posterior insertion

Occipital bone

Rectus capitis posterior action

Extends and rotates neck; turns head

Semispinalis capitis origin

c4-t6

Semispinalis capitis insertion

occipital bone

Semispinalis capitis action

extends and rotates neck

Splenius capitis origin

c4-t6

Splenius capitis insertion

Superior nuchal line and mastoid process

Splenius capitis action

Extends, rotates and laterally flexes neck

Levator palpebrae superioris origin

Lesser wing of sphenoid

Levator palpebrae superioris insertion

Skin of eyelid

Levator palpebrae superioris action

elevates upper eyelid; opens eye

Occipitofrontalis origin

Occipital bone

Occipitofrontalis insertion

skin of eyebrow and nose

Occipitofrontalis action

Moves scalp; raises eyebrow; wrinkles forehead; “surprise”

Nasalis origin

Maxilla

Nasalis insertion

Bridge and side of nose

Nasalis action

Dilates nostril

Procerus origin

Bridge of nose

Procerus insertion

Frontalis

Procerus action

Creates horizontal wrinkles between eyes, as in frowning

Platysma origin

Fascia of deltoid and pectoralis major

Platysma insertion

Skin over inferior border of mandible

Platysma action

Depresses lower lip; wrinkles of skin and neck & upper chest; to express fear

Buccinator origin

Lower border of mandbile

Buccinator insertion

Skin of lip near corner of mouth

Buccinator action

Lowers corner of mouth - frown

Lateral Pterygoid origin

Lateral side of lateral pterygoid plate and greater wing of sphenoid

Lateral Pterygoid insertion

Condylar process of mandible and articular disk

Lateral Pterygoid action

Depresses and protracts mandible; involved in excursion; side to side movements

Medial Pterygoid origin

Medial side of lateral pterygoid plate and tuerosity of maxilla

Medial Pterygoid insertion

medial surface of mandible

Medial Pterygoid action

elevates and protracts mandible; involved in excursion; side to side movements

Infrahyoid

When the hyoid is fixed by the ____ muscles so that the bone is stabilized from below, the suprahyoid muscles can help depress the mandible.

Suprahyoid

If the ____ muscles fix the hyoid and thus stabilize it from above, the thyrohyoid muscle can elevate the larynx

Intrinsic muscles of tongue

Longitudinal transverse and vertical

Longitudinal, transverse and vertical muscles origin

within tongue

Longitudinal, transverse and vertical muscles insertion

Within tongue

Longitudinal, transverse and vertical action

Change tongue shape

Extrinsic tongue muscles

Genioglossus, hypoglossus, styloglossus & palatoglossus

Genioglossus origin

Mental protuberance of mandible

Genioglossus insertion

Tongue insertion

Genioglossus action

Depresses and protrudes tongue

Hypoglossus origin

Hypoid

Hypoglossus insertion

Side of tongue

Hypoglossus action

retracts and depresses side of tongue

Styloglossus origin

Styloid process of temporal bone

Styloglossus insertion

tongue (lateral & inferior)

Styloglossus action

Retracts tongue

Platoglossus origin

Soft palate

Platoglossus Insertion

Tongue

Platoglossus action

Elevates posterior tongue

Oblique Arytenoid origin

Arytenoid cartilage

Oblique Arytenoid insertion

opposite arytenoid cartilage

Oblique Arytenoid action

narrows opening to larynx

Transverse Arytenoid

has same origin, insertion, & action as oblique Arytenoids

Iliocostalis origin

The iliac crest, sacrum, thoracolumbar fascia & spinous processes of the vertebrae from T11 to L5

Iliocostalis insertion

Iliocostalis cervicus: transverse processes of vertebrae c4-c6

Iliocsotalis thoracis: Angles of ribs 1-6, transverse process of vertebrae c7

Iliocostalis lumborum: Angle of ribs 5-12, transverse processes of vertebrae l1-l4 (+adjacent thoracolumbar fascia)

Iliocostalis action

Bilateral contraction: extension of spine

Unilateral contraction: lateral flexion of spine (ipsilateral)

Longissimus origin

transverse & spinous process of l1-l5, medial sacral crest, posterior sacrum, posterior iliac crest, & lumbrosacral aponeurosis

Longissimus insertion

the transverse processes of t1-l5 and the tubercles and angles of the lowest 9 or 10 ribs

Longissimus action

Neck extension: bending the neck backwards.

Lateral neck flexion: bending the neck to each side

Back extension: bending the back backwards

Spinalis origin

Spinous processes of c7-t1 vertebrae, spinous processes of c7-t1 vertebrae; nuchal ligament and spinous process of t11-l2

Spinalis insertion

occipital bone (midline), spinous process of c2-c4 vertebrae and spinous process of t2-t8 vertebrae

Spinalis action

Bilateral contraction: extension of head, cervical and thoracic spines

Unilateral contraction: ipsilateral lateral flexion of cervical and thoracic spine

Anterior Scalene origin

transverse process of c3-c6

Anterior Scalene insertion

1st rib

Anterior Scalene action

elevates 1st rib

Medial Scalene origin

Transverse processes of c2-c6

Medial Scalene insertion

First rib

Medial Scalene action

elevates first rib

Posterior Scalene origin

transverse process of c4-c6

Posterior Scalene action

elevates 2nd rib

Levator Scapulae origin

Transverse process of c1-c4

Levator scapulae insertion

superior angle of scapula

Levator scapulae action

elevates, retracts and rotates scapula; laterally flexes neck

Pectoralis minor origin

3rd-5th ribs

Pectoralis minor insertion

superior angle of scapula

Pectoralis minor action

depresses scapula or elevates the ribs

Rhomboideus Major origin

Spinous processes of T1-T4

Rhomboideus Major insertion

medial border of scapula

Rhomboideus Major action

retracts, rotates and fixes scapula

Rhomboideus Minor origin

Spinous processes of c6-c7

Rhomboideus Minor insertion

medial border of scapula

Rhomboideus Minor action

retracts, slightly elevates, rotates and fixes scapula

Serratus anterior origin

1st to 8th/9th ribs

Serratus anterior insertion

medial border of scapula

Serratus anterior action

rotates and protracts scapula; elevates ribs