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6
L A B O R A T O R Y
Back
BACK
Define the terms extrinsic muscles, intrinsic muscles.
List the extrinsic muscles of the back and describe the attachment points for the extrinsic muscles
of the back.
Describe the primary action(s) for these muscles and describe the primary innervation source for
each muscle.
Describe the primary blood supply for each muscle.
Identify each muscle on the prosected cadavers, models, and drawings.
Superficial Back Muscles (extrinsic)
Muscle
Trapezius
Upper (U)
Middle (M)
Lower (L)
Latissimus dorsi
Origin
Superior
Nuchal line,
Nuchal
Ligament,
Spines C7-T12
Spines T6-T12,
Ribs 8-12, Iliac
Crest
Insertion
Innervation
Blood Supply
Action
Suprascapular A U - elevate, rotate
Transverse
(glenoid) up
Cervical A
Bend/flex Neck
(ipsi)
M - retract
L - depress, rotate
Spine of Scapula
(glenoid) down
Medial lip of
Thoracodorsal N Thoracodorsal A Adduct,
Intertubercular (C6-C8)
M-rotate, extend
groove, Humerus
Humerus
Lateral Clavicle
Acromion
Spinal
Accessory N
(CNXI)
C2-C3 ventral
rami
Levator scapulae Transverse
processes of
C1-C4
Superior angle of Dorsal
Scapula
Scapular N
(C3-C5)
Transverse
Cervical A
Rhomboid
minor
Nuchal
Ligament
Dorsal
Scapular A
Rhomboid
major
Spines C7-T5
Superior medial
border of
Scapula
Inferior medial
border of
Scapula
Dorsal
Scapular N
(C4-C5)
Dorsal
Scapular N
(C4-C5)
Dorsal
Scapular A
Elevate scapula
depress glenoid
(rotate down)
Bend/flex Neck
(ipsi)
Retract, rotate
glenoid down
and fix Scapula
Retract, rotate
glenoid down
and fix Scapula
All of these muscles receive a partial blood supply from the dorsal branches of the
posterior intercostal arteries.
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Laboratory 6 • Back
Intermediate Back Muscles (extrinsic)
Muscle
Origin
Serratus
Posterior
Superior
Nuchal
Ligament,
Spines C7-T3
Serratus
Posterior
Inferior
Levator
Costarum
Insertion
Ribs 2-5
Innervation
Blood Supply
Action
Intercostal N
(T2-T5)
Posterior
Intercostal A
Elevate ribs 2-5
Resist respire
motion
Spines T11- L3 Ribs 8-12
Intercostal N
(T9-T11)
Posterior
Intercostal A
Depress
ribs 8-12
Resist respire
motion
C7-T11
transverse
processes
Dorsal rami of
Spinal N
(C8-T11)
Posterior
Intercostal A
Elevate ribs
Resist respire
motion
Angle of
Inferior Rib
Axial Skeleton
Hyoid
Ribs
Sternum
Body
Head
Manubrium
Greater Horn
Neck
Body
Lesser Horn
Angle
Xiphoid Process
Tubercle
Body
Vertebral Column
Cervical/Thoracic/Lumbar Vertebrae
body
pedicle
intervertebral notch/foramen
transverse processes
lamina
vertebral foramen
sup/inf articular processes
spinous processes
Atlas (C1) ant/post tubercles
dens facet
Axis (C2)
sup/inf/trans costal facets
Sacrum
sacral foramina
sacral crest
sacral canal
sacral hiatus
coccyx
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Laboratory 6 • Back
DEEP BACK
Identify the intrinsic back muscles.
Describe the attachment points and actions of the intrinsic back muscles.
Identify the intrinsic muscles of the back that comprise the erector spinae.
Identify the intrinsic muscles of the back that comprise the transversospinalis group.
Identify the primary source(s) of innervation and vascularization for these muscles.
Identify each muscle on the prosected cadavers, models, and drawings.
Deep Back Muscles (intrinsic)
Muscle
Origin
Insertion
Innervation
Blood Supply
Action
Erector Spinae Iliac crest, sacral
crest, lumbar
spines
Iliocostalis
(lateral)
Inferior Ribs/
Dorsal rami of
Cervical
Spinal N
transverse process
Posterior
Intercostal A
Lumbar A
Ipsilateral bend
& extend spine
Longissimus
(intermediate)
Thoracic/
Dorsal rami of
Cervical
Spinal N
transverse
process,
mastoid process
Posterior
Intercostal A
Lumbar A
Ipsilateral bend
& extend spine,
extend head
Spinalis
(medial)
Thoracic/
Cervical spines
Posterior
Intercostal A
Lumbar A
Extend spine &
ipsilateral bend
Muscle
Origin
Insertion
Dorsal rami of
Spinal N
Innervation
Blood Supply
Action
Transversospinalis
**upside-down
Semispinalis
Cervicis/
Capitus
(4-6”)
C3-T5
transverse
processes
(distal attach)
C2-T4
Dorsal rami of
Vertebral Spines Spinal N
(proximal attach)
nuchal lines
Posterior
Intercostal A
Vertebral A
Extend
head/neck
ipsilateral bend
Multifidus
Lumborum
(2-4”)
L1-S1
transverse
processes
(distal attach)
T1-T12
transverse
processes
(distal attach)
T12-L5
Dorsal rami of
Vertebral Spines Spinal N
(proximal attach)
Posterior
Intercostal A
Lumbar A
Stabilize
vertebrae
C7-T11
Dorsal rami of
Vertebral Spines Spinal N
(proximal attach)
Posterior
Intercostal A
Assist rotation
Rotatores
Thoracis
(1-2”)
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Laboratory 6 • Back
SUB-OCCIPITAL TRIANGLE
Identify the muscles of the suboccipital triangle. Discuss their attachments, innervation, and
actions.
Muscle
Splenius
(Cervicis/
Capitus)
Muscle
Origin
Nuchal
Ligament
Spines C7-T4
Origin
Insertion
Innervation
C1-C4
Dorsal rami of
transverse
Spinal N
Mastoid process (C3-C7)
Nuchal lines
Insertion
Innervation
Blood Supply
Vertebral A
Deep
Cervical A
Blood Supply
Action
Ipsilateral bend,
extend
head/neck,
rotate head
Action
Rectus Capitus Spine of
Posterior Major Axis (C2)
Inferior Nuchal Suboccipital N
line (lateral)
(C1)
Vertebral A
Occipital A
Head extension
ipsilateral
rotation
Rectus Capitus Posterior
Posterior Minor tubercle of
Atlas (C1)
Inferior Nuchal Suboccipital N
line (lateral)
(C1)
Vertebral A
Occipital A
Head extension
Suboccipital N
(C1)
Vertebral A
Occipital A
Ipsilateral bend
neck, extend
head,
contralateral
rotate
Suboccipital N
(C1)
Vertebral A
Occipital A
Ipsilateral
rotation
Obliquus
Capitus
Superior
**upside down
Inferior Nuchal Transverse
line (distal
process of
attach)
Atlas (C1)
(proximal
attach)
Obliquus
Spine of
Capitus Inferior Axis (C2)
(proximal
attach)
Transverse
process of
Atlas (C1)
(distal attach)
Note: Splenius fulfills the same role in the neck as Erector Spinae does for the back.
Rectus capitus posterior major/minor fulfill the same role in the neck as multifidus does for the back.
Obliquus capitus superior/inferior fulfill the same role in the neck as rotatores does for the back.
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Laboratory 6 • Back
VERTEBRAL COLUMN
Identify the following regions on any vertebrae of the vertebral column:
body
spinous process
transverse processes
lamina
pedicle
vertebral arch
vertebral foramen
articular processes
costal facets
vertebral notches
Identify the unique characteristics of cervical vertebrae.
bifid spines
small (no) bodies
transverse foramina
C1 (Atlas) - no spine, no body, anterior articular cavity for dens, superior articulations for skull
C2 (Axis) - dens/odontoid process, superior articular facets for C1
C7 (vertebra prominens) - elongated spinous process
Identify the unique characteristics of the thoracic vertebrae.
superior/inferior costal facets
transverse costal facets
inferior directed spines
Identify the unique characteristics of the lumbar vertebrae.
flat, hatchet-like spines
no costal facets
large body
Identify the unique characteristics of the sacrum.
sacral canal
sacral foramina (4)
apex
median crest
hiatus
Describe the intervertebral joints as:
One fibrous/cartilaginous, amphiarthrotic joint (intervertebral disc)
Two modified plane, diarthrotic synovial joints (zygapophyseal joints at articular facets)
Describe the ligaments that hold the intervertebral joints together.
Ant/Post Longitudinal
Interspinous
Supraspinous
Ligamentum Flavum
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Laboratory 6 • Back
SPINAL CORD
Locate the following structures of the spinal cord:
dorsal horn
ventral horn
central canal
intermediate/lateral horn
dorsal root/rami
dorsal root ganglia
ventral root/rami
medullary cone
cauda equina
terminal filament
lumbar enlargement cervical enlargement
lumbar cistern
denticulate ligaments
Compare the spinal cord meninges with the cerebral meninges.
Discuss the blood supply to the spinal cord – 1 anterior and 2 posterior arteries.
Discuss the spinal nerves, including numbers and dermatomes.
8 cervical
12 thoracic
5 lumbar
5 sacral
1 coccygeal
Important representative dermatomes
C2 back of head
T10 umbilicus
C5 top of shoulder
L1 inguinal
C6 thumb
L4 knee
C8 pinkie
S1 sole of foot
T4 nipple
S5 anal canal
Laboratory 6 • Back
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Laboratory 6 • Back