1.5 (2) Back Muscles

8/6/2019 1.5 (2) Back Muscles

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1 7Gener, Anne, Tinelle, Ryzee, Em, Jan

THE MUSCLES OF THE BACK

y Serratus Posterior Superiory Serratus Posterior Inferiory Erector Spinae / Sacrospinalisy Segmental muscles of the back

EXTRINSIC MUSCLES

SUPERFICIAL MUSCLES

- Connected with the shoulder girdle.- immediately deep to the skin and superficial fascia- attach superior part of appendicular skeleton (clavicle, scapula,

humerus) to axial skeleton (skull, ribs, vertebral column)

- Primarily involved w/ movements of upper appendicularskeleton; referred to as the appendicular group

INTERMEDIATE MUSCLES

- involved with movements of thoracic cage- consist of 2 thin muscular sheets in superior & inferior regions of

back, immediately deep to the muscles in the superficial group

- Fibers from these two serratus posterior muscles (serratusposterior superior & serratus posterior inferior) pass obliquely

outward from vertebral column to attach to the ribs

- referred to as the respiratory group

Extrinsic Intermediate Muscles of the Back

The Serratus Posterior Muscles (Superior and Inferior)

y Serratus posterior superior is deep to rhomboid musclesy Serratus posterior inferior is deep to latissimus dorsiy Both serratus posterior muscles are attached to vertebral

column and associated structures medially, and either descend

(the fibers ofserratus posteriorsuperior) or ascend (the fibers

ofserratus posteriorinferior) to attach to the ribs.

INTRINSIC MUSCLES

DEEP MUSCLES

- Postvertebral muscles belonging to vertebral column- The postural tone of deep muscles is major factor responsible

for maintenance of the normal curves of the vertebral column

- extend from the sacrum to the skull

GROSS ANATOMY

MUSCLESOF THE BACK

1.5 2JULY 20, 2011

DR. MALIJAN

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Intermediate Muscles

(Intrinsic Deep Muscles)

Erector spinae (Sacrospinalis)

- large musculotendinous mass which differs in size andcomposition at different vertebral levels

- consists of fascicles that assume systematic attachments tohomologous parts of the skull, the cervical, thoracic, and lumbar

vertebrae, the sacrum, and the ilium

- individual muscles are defined by the attachments of theirfascicles and the regions that they span.

Three erector spinae muscles: (with three regional parts each):

Iliocostalis

Iliocostalis cervicis

Iliocostalis thoracis

Iliocostalis lumborum

Longissimus

Longissimus capitis

Longissimus cervicis

Longissimus thoracis

Spinalis

Spinalis thoracis

Spinalis cervicis

Spinalis capitis

Erector Spinae Muscle groups

Origin, Insertion, Actions:

Superficial

Erector spinae

1. iliocostalis

2. longissimus

3. spinalis

ORIGIN:From iliac crest, sacrum, sacroiliac

ligaments, inferior lumbar spinous

processes

INSERTION:

Iliocostalis:

angles of the ribs

Longissimus:

transverse process of thoracic

& cervical vertebrae, mastoid

process of temporal bone

Spinalis:

spinous process of the thoracic

vertebrae

ACTIONS:

- Extends the head and thevertebral column

- Rotates the head to same side(longissimus)

- Releases to allow flexion tobe slow and controlled

LongestNERVE SUPPLY:

Dorsal ramus of

the spinal nerves

Deep Muscles

(Intrinsic Deep Muscles)

Segmentals (Spinotransverse group)

- consists of muscles where the fascicles span between a spinousprocess & transverse elements of vertebrae at various levels below

- grouped according to length of fascicles & region that they coverRegions of the segmental muscles:

Rotatores

Rotatores thoracis

Rotatores cervicis

Rotatores capitis

Multifidus Multifidus

Semispinalis

Semispinalis cervicis

Semispinalis thoracis

Semispinalis capitis

Interspinalis

Intertransversarius

Levatores costarum

Rotatores (Thoracic region)

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Multifundus. A. cervicothoracic B. Lumbosacral

Origin, Insertion, Actions:

Muscular Triangles of the BackThe Triangle of Auscultation

a.k.a Auscultatory Triangle The site where breath sounds may be most easily heard with a

stethoscope

Boundaries:oTrapeziusoMedial Border of the ScapulaoLatissimus Dorsi

The Triangle of Petit

- a.k.a. Lumbar Triangle- where pus may emerge from the abdominal wall

[*sabi ni Maam did pa raw siya nakakaencounter ng case na may

pus sa triangle na ito, baka daw super effective ng antibiotics]

y Boundaries:oLatissimus dorsioPosterior border of external oblique muscle of abdomeno Iliac crest

Content of the Vertebral Canal

I. Meninges and SpacesII. External Features of the Spinal Cord and Its Blood VesselsIII. Cerebrospinal Fluid

MENINGES AND SPACES

Meninges

y Dura matery Arachnoid matery Pia mater

Dura Mater

- Most external- Dense, strong and fibrous- Encloses spinal cord up to the cauda equina- Continuous with dura of brain through foramen magnum- Ends on filum terminale (lower border of S2)- Continuous with connective tissue surrounding each spinal nerve

(epineurium) at the intervertebral foramen

- Lies loosely in vertebral canal and is separated from walls of canalby the Extradural Space

- Inner surface is separated from Arachnoid mater by potentialSubdural Space

Segmental

MusclesAction Nerve Supply

Semispinalis

- Extends cervical & thoracic regionsof vertebral region

- Rotates these regions towards theopposite side

- Extends the headDorsal rami of

cervical spinal nervesMultifidus

- Unilaterally- flexes trunk laterally;rotates it to opposite side

- Bilaterally extends trunk &stabilizes vertebral col.

RotatoresRotate superior vertebrae to the

opposite side

Interspinalis Helps extend vertebral column

Inter-

transversariusLateral flexion of superior vertebra

ventral rami of

cervical nerves

-some dorsal rami of

cervical nerves

Levatores

costarum Raises ribs during inspiration

Dorsal rami of

cervical region(lateral division)

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Arachnoid Mater

- Delicate, impermeable avascular membrane- Continuous with arachnoid membrane of brain (through foramen

magnum)

- Ends at filum terminale (lower border of S2)- Continued along the spinal nerve roots, forming extensions- Separated from the Pia mater by the Subarachnoid Space (filled

with CSF)

Pia Mater

Vascular membrane Continuous with the pia mater of the brain (through the

foramen magnum)

Fuses with the filum terminale Thickened on either side of the nerve roots to form the

ligamentum denticulatum

Extends along each nerve root and becomes continuous withthe connective tissue surrounding each spinal nerve

THE SPINAL CORD

- cylindrical, grayish white structure- From foramen magnumcontinuous with the medulla

oblongata of the brain

- terminates at the level of: L1 adults L2 children

Fusiform enlargements

ocervical gives origin to the brachial plexusC4 to T1

o lumbar in the lower thoracic and lumbar regions;gives origin to the lumbosacral plexus

T11 TO L1

y Inferiorly:

o the spinal cord tapers off into the conus medullaris, from the apexof which a prolongation of the pia mater, filum terminale descends

to be attached to the back of the coccyx

y in the midline:anterior median fissure deep longitudinal fissure

anterior

posterior median sulcusshallow furrow

posterior

Roots of the Spinal Nerves

Spinal nerves

- 31 pairs by anterior (motor) roots & posterior (sensory) roots- mixture of motor and sensory fibers.- formed by spinal nerve roots which pass laterally from each

spinal cord segment to the level of their respective

intervertebral foramina

- Each root is attached to the cord by series of rootlets, whichextend whole length of corresponding segment of cord

- Each posterior nerve root possesses a posterior root ganglion,the cells of which give rise to peripheral and central nerve fibers

Because of the disproportionate growth in length of the vertebralcolumn during development compared to that of the spinal cord,the length of the roots increases progressively from above

downward In the upper cervical region the spinal nerve roots are

short and run almost horizontally, but the roots of the lumbar and

sacral nerves below the level of the termination of the cord (lower

border of the first lumbar vertebra in the adult) form a vertical

leash of nerves around the filum terminale. The lower nerve roots

together are called the cauda equina

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After emergence from the intervertebral foramen, each spinal nerveimmediately divides into a large anterior ramus and a smaller posterior

ramus, which contain both motor and sensory fibers.

Blood Supply of the Spinal Cord

2 Posterior Spinal arteries- arise either directly or indirectlyfrom vertebral arteries- run down the side of spinal cord, close to attachments of

posterior spinal nerve roots Anterior Spinal artery- arise from the vertebral arteries, unite to form a single artery,

which runs down within the anterior median fissure.

Derived from:

o Vertebral arterieso Deep cervical arterieso Intercostal arterieso Lumbar arteries

- Reinforced by the Radicular Arteries enter the vertebralcanal through intervertebral foramina

Segmental branches of the intercostal and lumbar arteries

yVenous Drainage 3 anterior spinal sinuses or veins 3 posterior spinal sinuses or veins

*The vein

s of spinal cord drain into internal vertebral venous plexus.

Meninges of the Spinal Cord

Dura Mater

- most external membrane- dense, strong, fibrous sheet- encloses the spinal cord and cauda equine- continuous above through foramen magnum with meningeal

layer of dura covering brain- Inferiorly: ends on the filum terminale at the level of the lower

border of the second sacral vertebra

- dural sheath lies loosely in the vertebral canal separated from walls of canal by extradural space (epidural

space)

Extradural space (epidural space)

- contains loose areolar tissue & internal vertebral venous plexus- extends along each nerve root and becomes continuous with

connective tissue surrounding each spinal nerve (epineurium) at

the intervertebral foramen.

- inner surface : separated from arachnoid mater by potentialsubdural space

Subdural space

- Separates dura and arachnoid- contains a thin film of tissue fluid

Arachnoid Mater

- delicate impermeable membrane covering the spinal cord andlying between the pia mater internally and the dura mater

externally

- continuous above through foramen magnum with arachnoidcovering brain

- Inferiorly: ends on the filum terminale at the level of the lowerborder of second sacral vertebra (S2)

- Between the levels of conus medullaris and lower end of thesubarachnoid space lie the nerve roots of the cauda equina

bathed in cerebrospinal fluid

- continued along spinal nerve roots, forming small lateralextensions of the subarachnoid space.

Subarachnoid space

- wide space separating arachnoid and pia mater- filled with CSF

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Pia Mater

- vascular membrane that closely covers the spinal cord- continuous above through the foramen magnum with pia

covering brain

- below it fuses with the filum terminale.- thickened on either side between the nerve roots to form the

ligamentum denticulatum

Passes laterally to be attached to dura It is by this means that the spinal cord is suspended in the

middle of the dural sheath.- extends along each nerve root and becomes continuous with

the connective tissue surrounding each spinal nerve

CEREBROSPINAL FLUID

Clear, colorless fluid Formed by the choroid plexus (lateral, 3rd and 4th ventricles of

the brain)

CSF enters the blood via the arachnoid villi into the dural sinus(superior sagittal sinuses).

Lumbar Tap

Definition

A procedure to withdraw cerebrospinal fluid for examination

For clinical diagnosis Introduce drugs Remove excess spinal fluid (headache)Specific Spaces Where it is Done

The patient lies on his side with his vertebrae well flexed.- This widens the space between the adjoining laminae.

The level of the fourth lumbar spine is determined by drawingan imaginary line joining the highest points of the iliac crest.

Structures Pierced By the Spinal Needle

The lumbar puncture needle is passed into the vertebral canal,above or below the fourth lumbar spine.

STRUCTURES:

1. Skin2. Superficial fascia3. Supraspinous ligament4. Interspinous ligament5. Ligamentum flavum6. Areolar tissue (containing the internal vertebral venous plexus in

the epidural space)

7. Dura matter8. Arachnoid matter9. Subarachnoid space

- needle introduced into the subarachnoid space in thisregion usually pushes the nerve roots to one side without

causing damage

Depth to which the needle will have to pass varies from 1 in.(2.5 cm) or less in a child to as much as 4 in. (10 cm) in obese

adults

As stylet is withdrawn, a few drops of blood commonly escape.- indicates that the point of the needle is situated in one of

the veins of the internal vertebral plexus and has not yet

reached the subarachnoid space.

If the entering needle should stimulate one of the nerve roots ofthe cauda equina, the patient will experience a fleeting

discomfort in one of the dermatomes, or a muscle will twitch,depending on whether a sensory or a motor root was impaled.

If the needle is pushed too far anteriorly, it may hit the body ofthe third or fourth lumbar vertebra.

In the recumbent position, the normal CSF pressure is about 60to 150 mm H2O.

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Tables to memorize: (Copy paste from Dr. Malijans powerpoint)

Muscle Origin Insertion Nerve Supply Action

Serratus Posterior

Superior

Lower cervical and

thoracic spines

Upper ribs Intercostal nerves Raises the ribs and therefore

inspiratory muscles

Serratus Posterior

Inferior

Upper Lumbar and

Lower Thoracic Spines

Lower ribs Intercostal nerves Depresses ribs and therefore

expiratory muscles

Superficial

ERECTOR SPINAE

1. iliocostalis

2. longissimus

3. spinalis

Longest

NERVE SUPPLY:

Dorsal ramus of the

spinal nerves

ORIGIN:

From the iliac crest, sacrum, sacroiliac ligaments, inferior lumbar spinous

processes

INSERTION:

Iliocostalis: angles of the ribs

Longissimus: transverse process of the thoracic and cervical vertebrae, mastoid

process of the temporal bone

Spinalis: spinous process of the thoracic vertebrae

ACTIONS:

Extends the head and the vertebral column

Rotates the head to same side (longissimus)

Releases to allow flexion to be slow and controlled

MUSCLE NERVE SUPPLY ACTION

Semispinalis

Dorsal rami of the cervical spinal

nerves

Extends the cervical and the thoracic regions of the vertebralregion

Rotates these regions towards the opposite side

Extends the head

Multifidus

Unilaterally- flexes the trunk laterally and rotates it to the

opposite side

Bilaterally extends the trunk and stabilizes the vertebral column

Rotatores Rotate the superior vertebrae to the opposite side

Interspinalis Helps extend the vertebral column

IntertransversariusVentral rami of the cervical nerves

Some dorsal rami of the cervical nervesLateral flexion of the superior vertebra

Levatores costarumDorsal rami of the cervical region

(lateral division)Raises the ribs during inspiration

1.5 (2) Back Muscles

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