B7: Back Muscles

Bones involved in back muscle attachment

occipital bone of skull

vertebrae

sacrum

hip bone

clavicle

scapula

humerus

origin

attachment of a muscle that remains relatively fixed during muscular contraction

Insertion

moveable point of attachment

bones involved in back muscle attachments: occipital bone

Bone that protrudes at the base of the skull

occiput = back of skull

*do not need to know this latin term*

external occipital protuberance

Bump in the back of the head on occipital bone

origin for trapezius

superior nuchal line

runs horizontally from external occipital protuberance

splenius capitis muscle, the trapezius muscle, and the occipitalis attaches here (not too sure if we need to know this)

inferior nuchal line

occipital bone

obliquus capitis superior muscle, rectus capitis posterior major muscle, and rectus capitis posterior minor muscle. attaches here (not too sure if we need to know this)

bones involved in back muscle attachments: vertebrae

cervical, thoracic, lumbar

the spine or spinous process is a single posterior projection from the junction of the two laminae

the transverse process is a lateral projection from the junction of a pedicle and a lamina. It is paired.

bones involved in back muscle attachments: sacrum

os = bone

sacer = sacred (part of animals that were offered in sacrifices)

*do not need to know this latin term*

bones involved in back muscle attachments: hip bone

iliac crest

iliacus = flank, side, entrails

crest= creste, to come over the top of

*do not need to know this latin term*

bones involved in back muscle attachments: clavicle

clavicula = small key, bolt

*do not need to know this latin term*

medially articulates with sternum

laterally articulates with scapula

bones involved in back muscle attachments: scapula

acromion ledge that overlies the shoulder joint

scapular spine is prominent ridge continuous laterally with acromion. Posterior surface is its crest, the edges of which are the upper lip and lower lip

medial border parallels the vertebral column

scapula= shoulder, shoulder blade

*do not need to know this latin term*

acromion

Outward extension of the shoulder blade forming the point of the shoulder.

akro = highest topmost

omos=shoulder

*do not need to know this latin term*

scapular spine

ridge that crosses the posterior surface of the scapular body before ending at the medial border

spina= thorn, prickle

*do not need to know this latin term*

medial border of scapula

parallels the vertebral column

coracoid process of scapula

not needed for insertion of back muscles

coracoid means crows feet and this appears to look like a crows feet

inferior angle of scapula

bottom point of scapula

bones involved in back muscle attachments: humerus

an intertubercular groove is found between the greater tubercle and lesser tubercule

umerus = bone of upper arm

intertubercular (inter=between, tuberculum = small swelling lump)

*do not need to know this latin term*

tubercle

small rounded projection

intertubercular groove/sulcus

bicipital groove; narrow groove located between the greater and lesser tubercles of the humerus

superficial muscles of the back

1.trapezius,

2.latissimus dorsi,

3.rhomboid major,

4.rhomboid minor,

5.levator scapulae

trapezius: origin

posterior skull (occipital bone)

spinous processes of all cervical vertebrae via ligament (ligamentum nuchae)

spinous process of all thoracic vertebrae

ligamentum nuchae

where trapezius origin is

ligamentum = band, tie

nuchae- nucha= pertaining to spinal cord

*do not need to know this latin term*

trapezius: insertion

Spine of scapula

Acromion

Clavicle (lateral third)

SAC

embraces the origin of the deltoid

trapezius: action

upward rotation of the scapula in which the inferior angle moves laterally

elevation of the scapula and lateral clavicle (upper fibers)

depression of the scapula and lateral clavicle

upward rotation of scapula

trapezius action

elevation AND depression of the scapula and later clavicle

trapezius action

trapezius: innervation

CN XI (cranial nerve 11) accessory nerve

ventral rami of c3 and c4

*one of the 12 cranial nerves

trapezius: SUMMARY

trapezion= irregular quadrilateral

*do not need to know this latin term*

latissimus dorsi: origin

lower 3 or 4 ribs

spinous processes of lower 6 thoracic vertebrae

spinous process of lumbar and sacral vertebrae via aponeurosis

iliac crest

aponeurosis

A broad, flat tendon

latissimus dorsi: insertion

intertubercular groove/sulcus of humerus

latissimus dorsi: action

ADduction of the arm at shoulder joint

extension of the arm at shoulder joint

medial rotation of arm at shoulder joint

adduction of arm at shoulder

latissimus dorsi action

extension of arm at shoulder

latissimus dorsi action

medial rotation at shoulder joint

latissimus dosri action

latissimus dorsi: innervation

thoracodorsal nerve

latissimus dorsi: summary

latus = wide

dorsi = back

*do not need to know this latin term*

under the trapezius is 3 more superficial back muscles

levator scapulae

rhomboid minor

rhomboid major

levator scapulae: origin

transverse processes of CV1-CV4

levator scapulae: insertion

medial border of scapula superior to the scapular spine

levator scapulae: action

elevates scapula

elevation of scapula

trapezius, levator scapulae

levator scapulae: innervation

ventral rami of C3 and C4

levator scapulae: summary

levatus = to raise

scapulae = shoulders, shoulder blades

*do not need to know this latin term*

rhomboid minor: origin

spinous processes of CV7-TV1

rhomboid minor: insertion

medial border of scapula at the scapular spine

rhomboid minor: action

ADducts scapula

adduction of scapula

trapezius, rhomboid major, rhomboid minor

rhomboid minor: innervation

dorsal scapular nerve

rhomboid minor: summary

rhombos = rhombus

oeides = form

rhomboid major: origin

spinous processes of TV2-TV5

rhomboid major: insertion

medial border of scapula inferior to the scapular spine

rhomboid major: action

ADduction of scapula

rhomboid major: innervation

dorsal scapular nerve

rhomboid major: summary

Summary of superficial back muscles

levator scapulae, rhomboid minor and rhomboid major relative to the spine of scapula

levator scapulae inserts into medial border ABOVE spine (purple)

rhomboid major inserts into medial border AT spine (blue)

rhomboid major inserts at medial border BELOW spine (green)

muscles of the deep back `

1. erector spinae (sacrospinalis)

a. spinalis

b. longissimus

c. iliocostalis

2. splenius

a. splenius capitis

b. splenius cervicis

3. Transversospinal group

a. semispinalis (semispinalis capitis, semispinalis cervicis, semispinalis thoracis)

b. Multifidus

c. Rotatores (rotatores longus and rotatores brevis)

4. Suboccipital muscles

a. Rectus capitis posterior major

b. Rectus capitis posterior minor

c. obliquus capitis inferior

d. obliquus capitis superior

erector spinae (sacrospinalis)

1. three longitudinally coursing muscles, largest muscular mass of the back

2. above the 12th rib it separates into 3 muscles from lateral to medial

-iliocostalis

-longissimus

-spinalis

3. important postural muscle that holds spine erect by extending vertebral column

4. innervation is segmental form of dorsal rami

erectus = upright

*do not need to know this latin term*

3 columns of erector spinae

from lateral to medial

iliocostalis

Longissimus

Spinalis

how to remember

i

Love

Spaghetti

spinalis

most medial of erector spinae

centimeter wide along the spinous processes, 1cm from the spine

spinalis = pertaining to a thorn or spine

*do not need to know this latin term*

longissimus [long-jis-e-miss]

intermediate erector spinae

extends all the way to skull (inserts into skull)

longest column

lang= that extends considerably from end to end

*do not need to know this latin term*

Iliocostalis

most lateral of erector spinae

ilio= origin at iliac crest

costal = insertion at ribs

extending from ilium to ribs

splenius

1. deep back muscle located in the neck

2. two parts

-splenius capitis

-spenius cervicis

-the two parts are continous at their origin, separable only at their insertion

3. when one side acts, the head and cervical column rotate toward that same side; when both act together the head and cervical column extend (looking up)

4. Innervation is segmental form of dosal rami

5. Action: extension of the neck (don't need to know this)

splenius means bandage

*do not need to know this latin term*

ligamentum nuchae

an elastic ligament that connects the vertebrae of the neck to the skull

splenius inserts into this

splenius capitis

upper, attaches to the skull

origin at ligamentum nuchae and CV7-TV4 and inserts into the skull

capitis = of the head

*do not need to know this latin term*

splenius cervicis

lower

origin at TV3 to TV6 and inserts at CV1-CV3

cervix = neck

*do not need to know this latin term*

dorsal rami and intercostal level

each intercostal level a dorsal ramus will come out and head on out to supply the muscles

transversospinal group

semispinalis, multifidus, rotatores

all muscles origin from transverse process and insert into a spinous process of a certain vertebrae above it

transversus = lying across

spinalis = pertaining to the spine

*do not need to know this latin term*

semispinalis

course 4-6 vertebrae

deep back muscle that occupies upper half of vertebral column

3 parts: semispinalis capitis, semispinalis cervicis, semispinalis thoracis

innervation is segmental from the dorsal rami

semispinalis capitis

aka biventer cervicis (tendinous band near neck creates two bellies of muscle)

extends the head and rotates toward the same side

insert into skull

capitis means head

semispinalis cervicis

deep to semispinalis capitis (cant see it)

works with semispinalis thoracis to rotate vertebrae toward the oppsite side

cervicis = neck

*do not need to know this latin term*

semispinalis thoracis

inferior to semispinalis capitis in thoracic region

works with semispinalis cervicis to rotate vertebrae toward the opposite side

semi = half

spinalis = pertaining to spine

*do not need to know this latin term*

Multifidus (plural: multifidi)

courses 2-4 vertebral segments

deep back muscles that are most developed in the lumbar region deep to erector spinae

rotate vertebral column toward the opposite side (opposite side rotation)

innervation is segmental from the dorsal rami

does not have attachment to the head

multi = many

-fidus = split

*do not need to know this latin term*

Opposite side rotation

rotation away from the contracting muscle

Rotatores

courses 1-2 vertebral segments

deep back muscles best developed in the thoracic region deep to semispinalis thoracis

lie directly on the laminae in the groove between the spines and the transverse processes

deepest back muscle

two types:

1.rotatores longus

2. rotatores brevis

they rotate the vertebral colum toward the opposite side

innervation is segmental from the dorsi rami

rotare= turn

*do not need to know this latin term*

rotatores longus

crosses 2 vertebrae

longi= long

*do not need to know this latin term*

rotatores brevis

This muscle spans 1 spinal segment

brevis = short, little, low

*do not need to know this latin term*

transversospinal muscles summary chart

suboccipital muscles

deep in the neck

Rectus capitis posterior major (not in the triangle)

Rectus capitis posterior minor (triangle)

Obliquus capitis inferior (triangle)

Obliquus capitis superior (triangle)

sub = below

occiput = back of skull

*do not need to know this latin term*

dont worry about origin or insertion, just names and region

Rectus Capitis Posterior Major

part of triangle

A

rectus= straight

*do not need to know this latin term*

Rectus Capitis Posterior Minor

NOT part of triangle

B

Obliquus capitis inferior

part of triangle

C

Obliquus capitis superior

part of triangle

D