1. Extrinsic Back Muscles

2. Back Objectives
Describe the gross anatomy for each system (circulatory, muscular, nervous, and skeletal) in the region of the back.
Integrate the systems to discuss the vertebral column functions.
Analyze common dysfunctions in the vertebral column.
For each muscle, describe how the attachment sites result in an action around a joint.
For each muscle, identify the innervation (peripheral nerve and nerve roots).
Objectives pulled from syllabus

3. Intermediate layer of intrinsic back muscles
Erector Spinae
Spinalis
Longissimus
Iliocostalis
Erector spinae – extensors of the spine (slow twitch aka Type I, postural)
Tendons – long, stringy, length of contractibility is low (they don’t contract very far but can contract for long periods of time, it’s more energy efficient to be mostly tendon)
Spinalis – SP L2 -> SP T1
spinalis cervicis highly variable
spinalis thoracis
Longissimus – erector spinae tendon (posterior iliac crest and sacrum) -> ribs (medial to angle), TP, mastoid process
longissimus thoracis
longissimus cervicis
longissimus capitis
Iliocostalis – erector spinae tendon -> angles of ribs & TP of cervicals
iliocostalis lumborum
iliocostalis thoracis
iliocostalis cervicis

4. Superficial layer of intrinsic back muscles
Splenius
Latin for bandaid – in its own layer of fascia wrapping the erectors and deep muscles
Explained earlier in relation to the neck

5. Cross section Thoracolumbar fascia Quadratus Lumborum
Tight, thick fascia that holds muscles in place
3 layers: anterior, middle, posterior
Iliac crest to lower ribs
Between anterior and middle is quadratus lumborum
Between middle and posterior are intrinsic muscles of the back (review intrinsic muscles)

6. The semispinalis capitis:
is part of the erector spinae group of muscles.
when acting unilaterally, rotates the head so that the face points to the ipsilateral side.
when acting bilaterally, flexes the neck.
is innervated by cervical and upper thoracic posterior rami.
is superficial to the splenius capitis. D

7. The rotatores:
have a relatively large mechanical advantage for producing trunk rotation.
possibly function primarily as "kinesiological monitors" or organs of proprioception.
are part of the erector spinae group of muscles.
are attached to the transverse processes of a pair of consecutive vertebrae.
when acting bilaterally, can produce trunk flexion. B

8. The following lateral radiograph of the thoracic part of the vertebral column is from a patient with severe osteoporosis. Which of the following conditions does it demonstrate?
kyphosis
scoliosis
lordosis
IV disc herniation
vertebral body hypertrophy A

9. Intermediate extrinsic back muscles
Serratus Posterior Superior
Serratus Posterior Inferior
Serratus comes from root serrated (like a knife) – describes the appearance of the attachments to ribs
SPS – superficial to erectors, thin, courses inferolaterally
SP C7-T3 -> ribs 2-4
elevates ribs, proprioceptive
intercostal nerves 2-4
SPI – superficial to erectors, thin, courses superiolaterally
SP T11-L2 -> ribs 8-12
depresses ribs, proprioceptive
intercostal nerves 8-12

10. Superficial extrinsic back muscles
NOT TRUE BACK MUSCLES
Axio-appendicular muscles
Trapezius
Latissimus Dorsi
Rhomboids
Levator Scapulae
Not all true back muscles – attach to scapula or humerus!
UE muscles
Reason to discuss now = functionally not back muscles, but anatomically they are. We will learn them on the cadavers with the back, so we will learn them in lecture with the back.
Protective features
spinal accessory nerve deep to trapezius
dorsal scapular nerve & dorsal scapular artery deep to rhomboids
thoracodorsal nerve & lateral thoracic artery deep to latissimus

11. Trapezius
Superior (descending)
superior nuchal line & cervical SP -> lateral 3rd of clavicle
fibers twist from origin to insertion
elevates scapula along with levator scap
doesn’t truly contract alone
upward rotation (discuss later with inferior part)
Middle
upper thoracic SP -> acromion process & part of spine of scap
horizontal fibers, thickest part of muscle
retraction (horizontal abduction)
Inferior (ascending)
lower thoracic SP -> spine of scap (wraps around to inferior surface)
angle of muscle fibers produces superior rotation of scap

12. Scapular motions Elevation / depression Protraction / retraction
Upward rotation / downward rotation

13. Upward rotation of scapula
Descending Trapezius
Ascending Trapezius
Serratus Anterior (TBD)
Draw in muscle fibers
Discuss how axis of rotation can shift since there is no bony articulation
Pic on left: all upper trap and serratus anterior (lower trap not contracting)
Pic on right: all lower trap and serratus (upper trap not contracting)

14. Latissimus Dorsi
thoracolumbar fascia & lower thoracic SP -> intertubercular groove of humerus
no attachment to scapula
crosses 2 “joints” – scapulothoracic and glenohumeral
extends, internally rotates, and adducts humerus (whole muscle)
indirectly depresses and downwardly rotates scapula (lower, vertical fibers)
fibers twist – upper fibers are posterior in axilla, inferior at insertion; lower fibers are anterior in axilla, superior at insertion
*show with theraband
Rhomboid Major
SP T2-T5 -> medial border of scap below spine
retraction and downward rotation of scap
Rhomboid Minor
SP C7-T1 -> medial border of scap at spine
Levator Scapulae
posterior tubercles of C1-C4 TP -> medial border of scap above spine
why is origin not on scap?
while running how to breathe easier story
elevation and downward rotation

15. Downward rotation of scapula
Rhomboids
Levator Scap
Latissimus
When could downward rotation be useful for daily life?
example: crutches

16. Triangles and spaces Reference points Neurovasculature
Like landmarks to help find structures and identify muscles
Many have neurovasculature that passes through them
Suboccipital triangle – suboccipital nerve
Triangle of auscultation and lumbar triangle do not – just connective tissue
Lumbar triangle – different sources say different things (thanks AJ and Sarah!) not important – we will use it as a simple reference point in surface anatomy

17. Back musculature
General muscle functions: movement, sensation, protection, metabolism
General tendon functions: transfer muscle forces efficiently, sensation
Actions
Interactions
Protective features
Sensory features

18. What muscle attaches immediately superior to the Rhomboid minor on the scapula?
Rhomboid major
Inferior trapezius
Middle trapezius
Levator Scapulae
Serratus Posterior Superior D

19. Your patient has difficulty flexing his shoulder past 90 degrees and no other difficulties. Which muscle is least likely to be weak?
Superior Trapezius
Rhomboid Major
Inferior Trapezius
Middle Trapezius
Serratus Anterior B

20. Your patient has a weak latissimus dorsi
Your patient has a weak latissimus dorsi. Which activity would she likely have the most difficulty with?
Juggling
Jumping jacks
Push ups
Supermans
Rowing E

21. Sensorimotor peripheral nervous system
Peripheral nerves as highways
Nerve roots as one-ways
Gray vs White Matter
Basics of neuroanatomy
Peripheral nerves have sensory and motor (two directions) within each nerve
neurons are all one way but the nerve has mixed neurons
Rami – are peripheral nerves (split after nerve root)
Define and differentiate nerve root, dorsal root, and ventral root
Dorsal root ganglion is bodies of sensory neurons
Gray matter is cell bodies, dendrites, and synapses
White matter is myelinated axons (we are all fat heads!)

22. sensations Skin: touch, pressure, temperature, pain
Muscles and tendons: pressure, pain, proprioception
Specialized receptors in dermis and subcutaneous tissue respond to touch, pressure, temperature and pain
Muscles, tendons and joint capsules contain proprioceptors
“In the limbs, the proprioceptors are sensors that provide information about joint angle, muscle length, and muscle tension, which is integrated to give information about the position of the limb in space. The muscle spindle is one type of proprioceptor that provides information about changes in muscle length.”

23. Spina bifida “Bifid spine” Three types: Occulta Meningocoele
Myelomeningocoele
Occulta – least problematic, may be some surface indicator but few symptoms
Meningocoele – sac of fluid present
Myelomeningocoele – (shown in pic above) sac of fluid with displaced spinal cord
co-morbidities include tethered cord syndrome & hydrocephalus & latex allergy
reduced walking ability, reduced bowel and bladder control
Failure of neural tube to close during first month of development
Known risks include:
medications, diabetes, obesity, increased core body temp from fever or hot tubs

24. The neural tube forms from which layer of tissue?
Ectoderm
Endoderm
Mesoderm A

25. Tethered cord syndrome
Various dorms that all result in a spinal cord tethered to sacrum
May go undiagnosed until adulthood
As vertebrae grow, spinal cord becomes stretched
Symptoms may not arise until late because amount of stretching will be gradual with growth
Symptoms:
pain, muscle weakness, loss of sensation, issues with bowel and bladder control, scoliosis, gait abnormalities

26. Lumbar puncture
Into CSF of Lumbar cistern
For spinal anesthesia

27. Epidural Into epidural space of Lumbar cistern
Blocks nerves where they exit the dura mater – results in anesthesia at the level of application and below

28. Deep -> superficial
rotatores, multifidus, interspinales, semispinalis cervicis, semispinalis cap, splenius (both), rhomboid minor, levator
Notes: thickness of muscles (levator is strong!), start with bony landmarks to determine vertical location, side picture will not be given

29. Lat -> med
QL, intertransversarii
ilicostalis, longissimus, spinalis, rotatores
Purple = disc
Yellow = spinal nerves
Orange = ligamentum flavum
Peach = epidural space
Mint green = thoracolumbar fascia

30. What is this muscle?
Rotatores
Multifidus
Semispinalis
Longissimus B

31. Back essay Discuss marked up exemplars
Meet with groups to discuss ideas
5 minutes per person (?)
Explain ideas and thoughts so far
Group members ask questions to clarify – try to understand their thought process
Group members give feedback or ask challenge questions
How does this idea relate to PT?
Why is this topic worth writing about?
How will you incorporate descriptive anatomy with a functional limitation?
Etc. -> really challenge each other (respectfully) to improve
Summarize new ideas
Discussions:
premise – ideas and plans should be adaptable
knowledge is gained in a messy way – updating is required constantly
Discussion framework

32. Next class 2 presentations!
Bring your essay draft to class! (printed copies for your group members)
Study for some unit wrap up questions in class (like a group quiz!)