Lect 5: Axial Skeleton Myology

(and thoracic vert) pair with lab manual info + a brain map

How many vertebrae in the thoracic spine?

12

What curvature is rounded in the saggital plane toward the posterior?

kyphotic

What features distinguish typical thoracic vertebrae?

small circular vertebral foramen

equal thoracic bodies

2 pairs (inferior and superior) of costal (demi) facets

that articulate with ribs

Which vertebrae have bodies that are approximately equal anterior-posterior and transversly?

thoracic

Which thoracic vertebrae are considered typical?

T2-8

How many costal facets are found on a typical thoracic vertebrae?

2 pairs (4 total)

2 superior + 2 inferior

What is another term for demifacets?

costal facels

Where are the superior demifacets located?

root of the pedical

Where are the inferior demifacets located?

just anterior to the vertebral notch

what 3 parts of the thoracic vertebrae articular with the ribs?

superior + inferior (demi/(costal) facets

transverse process

Which demifacet articulates with the numerically responding rib?

superior demifacet (costal facet)

rib 5 articulate with superior facet of T-5

'superior bc coorelate to same #'

Rib 6 articulates with the inferior facet of what vertebrae?

T5

'inferior bc don't line up'

How does does the structure/function of the spinous processes of T-vertebrae effect movement?

slants posteriorly / inferiorly (in groups of 3- rule of threes)

usually overlap with vertebrae below

limit extenion

How do the inferior vs superior articular facets of T-vertebrae slant?

superior facets: face posterior, slight lateral/superior

inferior facets: face anterior, slight medial/inferior

What are the features of the transverse processes of T vertebrae?

thick

lat / slight post

oval facets anterior tip - articulate with tubercles of #cooresponding rib

What does the Rule of Threes (Thorax) describe?

spinous processes in relation to transverse processes

Which thoracic vertebrae have spinous processes projecting post in same plane as transverse processes?

T1-3

T12

(rule of threes)

Which Thoracic spinous processes slant slightly down, midway between transverse of own and vertebra below?

T4-6

T11

(rule of threes)

Which Thoracic spinous processes are in the same plane as the transverse processes of the vertebra below?

T7-9

T10

(rule of threes)

Rule of Threes (ALL)

T1-3: post same plase as own transverse

T4-6: slightly down, between own transverse and one below

T7-9: in same as plane transverse below

(then in inverse order)

T10- same as 7-9

T11- same as 4-6

T12 -same as 1-3

Which plane is the spinous process of T10 in?

plane as transverse of below

same as 7-9

Which plane is the spinous process of T11 in?

midway between own transverse process and below

same as 4-6

Which plane is the spinous process of T-12 in?

same plane as own transverse processes

same as T1-3

What are the features of a thoracic intervertebral discs?

relatively thin (esp in upper Ts)

uniform thickness (no binder)

nucleus pulposis not developed as well

Typical thoracic vertebra include vertebra:

A. T1

B. T5

C. T9

D. T11

T5

(T2-8)

Facet Joints: what plane are they oriented in? what movement do they favor?

frontal plane (primarily)

flexion / extension

*limited in upper thoracic- rib cage

Anterior Longitudinal Ligament

(Hour glass- thin/broad - narrow thick)

relatively thick

narrow in thoracic region

attatchments into thoracic intervertebral discs

Posterior Longitudinal Ligament

(“Opp of hour glass” doesn’t attach to C discs, potential herniating L)

upper thoracic region: broad / uniform width

lower T: narrow over bodies broader over disks

attachments into thoracic intervertebral discs

Which ligaments have attachments into thoracic intervertebral discs?

Anterior longitudinal + Posterior longitudinal ligaments

How do facet joint capsules differ between the cervical and thoracic regions?

more taught in thoracic (restrict excessive flexing- forward bending)

Ligaments in the thoracic region

Facet joint capsules- more taught than cervical

Ligamentum flavum- relatively thick

Supraspinous- blended with fascia

Interspinous ligament- thin

Intertransverse ligament- rounded cords

To what extent does each movement occur in the thoracic spine?

more flexion than extension

flexion: checked by ligament, discs, ant height of vertebral body, joint capsules, postvertebral muscle tension

extension: limited by spinous process contact

rotation: relatively free, alway coupled with some lateral flexion, more in upper less caudal bc facet orientation

lateral flexion: facet orientation doesn’t limit, movement limited esp upper bc ribs/sternum

Describe rotation ability of the thoracic region

relatively free

alway coupled with some lateral flexion

more in upper less caudal bc facet orientation

How many vertebrae make up the Lumbar spine?

5

What are the destinguishing features of lumbar vertebrae?

• large bodies (greater load)

• body/disc *deeper anteriorly- binder effect- sacrovertebral angle

• sturdy laminae

• short pedicle- vertebral canal triangular

• transverse process L1-4 1” and thing, L5 short/thick

• spinous process- short/sturdy hatchet (‘Lumbarjack’)

• facets (synovial) stabilize from excessive moevement/shear

• pars interarticularis- L5 common for spondylolisthesis

• accessory* + mamillary* processes

(moose- in the woods)

What processes (besides spinal/transverse) are found on lumbar vertebrae?

accessory processes: roots of TPs, medial intertransverse muscle attachment

*mamillary: tip of superior facet, multifundus attachment

What are the components of an intervertebral disc?

anulus fibrosus

nucleus pulposis

What animal could help you remember each section of the spine?

Pars interarticularis of L5 is a common site for what issue?

spondylolisthesis

issues that can occur at the par interarticularis

help understanding difference

Iliolumbar ligament

O: L5/4 transv proc > 2 bands (to ilium)

counteract ant shear forces at L5/S1

reinforcing lig of lumbosacral

How does movement vary by combined use of spinal segments?

most movement when used in conjunction

Intervertebral discs are uniform in thickness is

this region:

A. Cervical

B. Thoracic

C. Lumbar

• thoracic

(cervicle and lumbar (more so- binders)

What main movements do neck/back muscles contribute to?

flexion / extension

side bending

rotation (ipsi/contralateral)

What divides anterior and lateral prevertebral muscles?

sternocleidomastoid

Cervical spine: Prevertebral Muscle Overview

anterior

• longus capitis

• longus colli

• rectus capitis anterior

• anterior scalene*

sternocleidomastoid divide ant/lateral muscles

lateral

• rectus capitis lateralis*

• splenius capitis*

• levator scapula

• middle + post scalenes*

Cervical spine: Postvertebral muscle overview

suboccipital

• rectus capitis post major + rectus capitis post minor

• obliquus capitis inf + obl cap superior

Postvertebral muscles

• splenius capitis

• splenius cervicis

What do the scalenes do?

scalenes (3): anterior, middle, lateral

all: lat neck flex

ant / mid : elevate 1st rib

lat: elevate 2nd rib

What do all the suboccipital muscles do?

• rectus capitus posterior (major + minor, not lat)

• obliquus capitus (superior + inferior)

rotate C1 on C2 (minor j assists)

extend head on C1

What are all the suboccipital muscles innervated by?

Dorsal rami C1

What are the suboccipital muscles?

rectus capitus posterior minor

rectus capitus posterior Major

obliquus capitus superior

obliquus capitus inferior

What are the postvertebral muscles of the cervical spine?

splenius capitis

splenius cervicis

Where do both the splenius (capitis + cervicis) insert?

nuchal ligament + spinous process C7-T6

Anterior Scalene

(OIAN) - think abt how muscle pulls

O: trans proc C3-6

I: 1st rib

A: (elevate 1st rib) (lat neck flex)

N: ventral rami C4-6

‘scale/raise- scaling something 1st = a flex’

Sternocleidomastoid

(OIAN) - picture pull

O: mastoid process + lat ½ sup nuchal line

I: (sternal head- ant surface manubrium) (clavicular head- sup medial 1/3 clavicle)

• unilaterally: ipsilateral aide bend, contralateral rot

• bilaterally: neck extension at OA joint, cervical flexion, approximation chin to chest

N: spinal accessory nerve (CN XI)

Middle Scalene

(OIAN) - picture pull

O: post TP C4-7

I: sup surface 1st rib (post to groove for subclavian artery)

• elevate 1st rib + lat neck flex

N: ventral rami C spinal Nerves

Post Scalene

(OIAN) - picture pull

O: post TP C4-6

I: external boarder *2nd rib

• elevate 2nd rib

• lat neck flex

N: ventral rami CN C7 and C8

Rectus Capitis Lateralis

(OIAN) - picture pull

O: occipital bone jugular process

I: ant surface lateral mass of C1

N: ventral rami CN C1-2

• flex head

Suboccipital muscles overview

Rectus Capitis Posterior Minor

(OIAN) - picture pull

O: occiput along the medial 1/3 of inferior nuchal line

I: post tubercle of posterior arch C1

N: dorsal ami C1

• extend head on C1

• assist major with rotation C1-2

Rectus Capitis Posterior Major

(OIAN) - picture pull

O: occiput along the lat inferior nuchal line

I: spinous process of C2

N: dorsal rami C1

• extend head C1

• rotate head C1 on C2

Obliquus Capitis Superior

(OIAN) - picture pull

O: Occipital bone between inferior and superior nuchal line

I: transverse process C1

N: dorsal rami C1

• extend head C1

• Rotate head C1 on 2

Obliquus Capitis Inferior

(OIAN) - picture pull

O: transverse process of C1

I: posterior tubercle of post arch C2

N: dors ram C1

• extend head C1

• rotate head C1 on 2

Which of the following is a postvertebral muscle:

A. Obliquus Capitis Superior

B. Sternocleidomastoid

C. Posterior Scalene

D. Longus Capitis

Obliquus Capitis Superior

The middle scalene helps:

A. Extend the head on C1

B. Laterally flex the head

C. Elevate the 1st rib

D. Elevate the 2nd rib

lat flex

Back muscle general overview

Cervical Region muscles layers (lab inspired- just for this class)

*find spine superior = nucal ligament

Deepest: Suboccipitals

• RCPm/M: rectus capitus posterior minor + major (inner/outer V)

  • extend head, do-M or assist with-m rotation C1/2

• Obliquus capitis superior (straight) + inferior (angled)

  • extend (C1) and rotate (C1/2) head

Next layer: Semispinalis

• capitis + cervicis blend

superficial: Splenius

• capitis and cervisis unique (capitic closer to spine medially)

  • unilat: ipsilat side bend / rotation

  • bilat: extension

Splenius Capitis

OIAN- picture layer

O: mastoid process and lateral third of superior nuchal line

I: nuchal ligament & C7-T6 spinous processes

N: dorsal rami middle cervical spinal nerves

• unilarerally: ipsilat side bend / neck rotation

• Bilat: extension of head/neck

visually blend with cervicis

Splenius Cervicis

OIAN- picture layer

O: transverse process of C1-C4

I: nuchal ligament and spinous processes of C7-T6

N: dorsal rami SNs

• unilat: ipsilat side bend / rotation

• bilat: extension (head/neck)

visually blend with capitis

The Back Includes

1) The Skin and Subcutaneous Tissue

2.) Muscles:

a.) Superficial layer- Extrinsic Back Muscles

b.) Deep Layer- Intrinsic Back Muscles

3.) Vertebral Column

a.) Vertebrae

b.) Intervertebral Discs

c.) Joints and Ligaments

4.) Vertebral Canal

a.) Spinal cord

b.) Meninges and related spaces

Thoracic Lumbar Myology Overview

Minor Deep Intrinsics

• unisegmental

  • interspinal

  • intertransverse

  • levators costarum

Deep intrinsics

• transversospinal

  • rotatores

  • multifundus

  • semispinalis

Intrinsic back

• Erector Spinae (ILS)

  • Iliocostalis- L, T, C, no cap

  • Longissimus- T, C, cap

  • Spinalis- T, C, cap

What is the structure/function of interspinal muscles in the lumbar region?

• unisegmental

• connect consecutive spinous processes

• best developed in cervic + lumbar

• aid in extension ^

What is the structure/function of intertransver muscles in the lumbar region?

• unisegment

• connect consecutive TPs

• best developed in cervical + lumbar

• side bending ^

• bilaterally stabilize spine

• %Rectus capitis anterior

  and lateralis are

  homologues of

  intertransversarii

What are to transversospinal muscles occupy?

area between transverse and spinous processes

• 3 layers

What are the layers of the transversospinal muscles?

• Deep outer layer: semispinalis

  • not in lumbar

• Deep mid layer: multifidus

• Deep inner layer: rotators

Semispinalis

OIAN

O: SP of lower thoracic vert 4-6 segments + sup medial occipital bone

I: TP of C4-T10

N: dorsal rami spinal nerves

• extension (occipital, neck, trunk)

• contralat rotation ^

*capitis, cervicis, and toracis

Semispinalis Capitis

(location/action)

occipital ext + contralat rotation

• larest + strongest post neck muscle*

Multifundus

OAIN

O: SP of vertebra 2-4 segments above, oblique fibers

I: 1) aponeurosis of erector spinae in lumbar spine 20 TP of vertebrae 2-4 levels inferior 3) mamillary processes in L, T,a nd C4-5

N: dorsal rami

• trunk ext

• contralat rotation

• stabilization during bilateral action

*best developed in Lumbar spine

Rotatores (brevis + longus)

OIAN

O: SP vertebrae 1 level (brevis) or 2 layer (longus) superior

I: junction of TP and lamina ½ levels inferior

N: dorsal rami

• trunk extension

• contralat rotation

deep back visual review

The actions of the transversospinal muscles (deep intrinsics) are:

A. Extension and ipsilateral rotation

B. Extension and contralateral rotation

C. Ipsilateral side bending

D. Contralateral side bending

*your deep back A shapes

• bilateral: extension

• unilateral: contralateral rotation

What muscles make up the intrinsic back? (erector spinae)

*I Love Spaghetti

• iliocostalis

• longissimus

• spinalis

*all run along straight up/down one side of the spine:

• bilat- trunk extension

• unilat- ipsilat side bending

Iliocostalis

(OIAN) + what sections of the spine

O: angle of lower ribs + cervical TP

I: erector spinae aponeurosis > post ilium/sacrum

N: dorsal rami

• trunk ext (bilat)

• ipsilat side bend (unilat)

*L, T, C, no cap —-ech does A at associated level

*bc ilio-cost

(lumbar no cap)

Longissimus

(OIAN) + what sections of the spine

O: ribs, T + cervical TPs, mastoid process

I: erector spinae aponeurosis

N: dorsal rami

• trunk extension (bilat)

• ipsilat side bending (unilat)

*thoracis, cervicis, capitis (3 seperate muscle names)

Spinalis

(OIAN) + what sections of the spine

O: thoracis SP, occiput

I: erector spinae aponeurosis

N: dorsal primary rami

• trunk ext (bilat)

• ipsilat side bending (unilat)

*thoracis, cervicis, capitis

What innervates the skin of the back?

each spinal sement innervated by dorsal ramus of te correspindin spinal nerve

(j like true/intrinsic back muscles)

The actions of the erector spinae are what?

extension + ipsilateral side bending