1.5 (2) back muscles
TRANSCRIPT
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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