SM MSK Anatomy - Back and Spine Flashcards
SM 221a, Lab 1
What are the functions of the intrinsic back muscles?
Move the vertebral column
Extension, lateral bend, rotation
Which structure is labeled by #3?
Vertebral foramen
(Spinal cord runs through here)
The intrinsic muscles of the back attach to the ______
The intrinsic muscles of the back attach to the vertebral column
Identify the follwing on both the MRI and the bone
- Vertebral body
- Vertebral foramen
- Spinous process
https://www.researchgate.net/publication/224950784_Unexpected_neuroimaging_abnormalities_in_patients_with_apparent_C8_radiculopathy_Broadening_the_clinical_spectrum/figures?lo=1
How many sacral vertebrae are there?
4-5
Which structure is indicated by #2?
Vertebral disc
(specifically the soft inside, Nucleus Pulposus)
True or false?
Back muscles attaching to the scapula will receive innervation from dorsal rami of the appropriate thoracic level
False
- Back muscles attaching to the scapula are extrinsic muscles
- They are innervated by ventral rami
- Except trapezius, which is innervated by CN XI (the spinal accessory)
Where could this portion of spinal cord be taken from?
T1 through L1
Spinal nerves do not originate from cervical vertebrae
(cranial nerves exit cervical vertebrae)
The spinal cord ends at L1. The cauda equina takes spinal roots down to the lumbar and sacral vertebrae, where they exit as spinal nerves
What are the 3 groups of intrinsic muscles of the back?
(From superficial to deep)
- Splenius
- Erector spinae
- Transversospinalis
What structure is labeled by #5?
Spinal nerve
Emerges from the vertebral column through the intervertebral foramen
True or False?
The erector spinae and the splenius are both extensors of the spine
True
- Both are instrinsic back muscles
- Extensors, lateral bend, rotators
- Erector spinae extends the lumbar and thoracic regions
- Splenius extends the head and neck
Which structure is labeled by #2?
Vertebral arch
(specifically the lamina)
Which structure attaches the pia mater to the coccyx?
Filum terminale
What is inside of the dural sac at the level of L3?
Cauda equina + arachnoid mater
The spinal cord ends at L1, giving rise to spinal roots that bundle together to form the cauda equina
Which structure is labeled by #4?
Spinous process
Which structure is labeled by #6?
Vertebral foramen
(This is where the spinal cord would be)
What are the most common sites for herniated discs?
Between L4-L5 in the lumbar region -> lower back/leg pain
May also occur in the cervical region -> neck/arm pain
Which structures hold the vertebrae together?
Ligaments and vertebral disks
What structure is labeled by #1?
Scapular spine
Which structure is labeled by #1?
The vertebral arch
(specifically the pedicle)
Which structures make up the vertebral arch?
Lamina + pedicle
While stopped at a light, a man’s car is rear-ended at high speed. He is brought to the emergency room with difficulty breathing and a severe hyperextension neck injury. His MRI shows a rupture of the anterior annulus of C4-5 intervertebral disc, inflammation of the disc, and a preverterbal hematoma (the cause of his breathing difficulty). Which of the following ligaments was likely disrupted?
- Anterior longitudinal
- Ligamentum flavum
- Interspinous
- Supraspinous
- Posterior longitudinal
a. Anterior longitudinal
Often injured in whiplash injuries
This is an axial T2 MRI of the lumbar spine
How is the muscle group outlined in red innervated?
Dorsal rami of the spinal nerves
These are intrinsic back muscles
Which structure is labeled by #4?
Vertebral foramen
(Spinal cord runs through here)
When does lordosis of the cervical and lumbar regions develop?
When a child starts to walk
Development continues for 1-2 years
Which group of the intrinsic back muscles is shown in this image (outlined in blue)?
What is its function?
Attachments?
Innervation?
- Muscle: Transversospinalis
- Found in the notch between the transverse process and spinous process
- Function: Extension, rotation, and lateral bending
- Attachments: Spinous process, transverse process
- Innervation: Dorsal rami of spinal nerves
Which muscles are active when you shrug your shoulders?
Levator scapulae (main)
Trapezius helps a bit
Which vertebrae are the smallest?
- Cervical
- Thoracic
- Lumbar
- Sacral
a. Cervical
What structure is labeled by #9?
Arachnoid mater
Middle layer of the meninges covering the spinal cord
What structure is labeled by #2?
Inferior articular facet
Identify the following in the image
- Spinal cord
- CSF
- Cauda equina
- L1
The spinal cord ends at L1
Which structure is labeled by #6?
Vertebral arch
(specifically, the pedicle)
Which muscles elevate the scapula?
Levator scapulae
Rhomboids
Trapezius
Which ligament is labeled by #3?
Ligamentum flavum
Which ligament is labeled by #4?
Supra-spinous ligament
Which section of the spine is shown in this image?
How do you know?
Lumbar
Look for the “scotty dog” feature
- Ear (D) = superior articular facet
- Front leg (C) = inferior articular facet
- Eye (B) = pedicle
- (A) is the intervertebral disk
Which nerves innervate the extrinsic muscles of the back?
Ventral rami of the spinal nerve
(Anterior rami)
A hyperextension injury is most likely to injure which spinal ligament?
Anterior longitudinal ligament
(a whiplash injury)
What structure is labeled by #3?
Acromion of the scapula
Which lines correspond with the following structures?
- Line of the spinous process
- Articular line
- Anterior veterbral body line
- Posterior vertebral body line
(In order from left to right)
- Blue = Anterior vertebral body line
- Red = Posterior vertebral body line
- Orange = Articular line
- Green = Line of the spinous process
Where is an epidural administered?
Outside of the dural sack - anesthetizes the nerve roots
Usually accessed through lumbar vertebrae (L4-L5), sacral hiatus, or posterior sacral foramina (but can theoretically be done anywhere along the column - there is less risk of spinal cord injury because you are not puncturing the dural sac)
Which intrinsic back muscle has fibers that extend superio-laterally?
\ //
Splenius
An 81 yo woman complains of weakness and loss of sensation in her legs. Radiological studies show bony spurs (osteophytes) narrowing the intervertebral foramina at levels T12-L3. Which of the following structures is most likely to be impinged by the osteophytes?
A. Spinal cord
B. Spinal nerve
C. Sympathetic trunk ganglion
D. Anterior rootlets of spinal nerve
E. Ventral ramus of spinal nerve
B. Spinal nerve
Dorsal root ganglion may also be affected
These structures must pass through the intervertebral foramina - if the opening is smaller, they may be impinged
What structure is labeled by #2?
Dura mater
Outermost layer of meninges covering the spinal cord
Which muscle is outlined in yellow (labeled 2)?
What is its function?
Attachments?
Innervation?
- Muscle: Rhomboids
- Function: Retract the scapula
- Attachments: Scapula, spinous process
- Innervation: Ventral rami of spinal nerves
What structure is labeled by #1?
Superior articular facet
How many lumbar vertebrae are there?
Usually 5
May be 4-6
How many cervical vertebrae are there?
7
Which structure is labeled by #4?
Articular process
What is the deepest layer of the intrinsic back muscles?
Transversospinalis
Which muscles are found underneath the trapezius?
Levator scapulae
Rhomboids
Describe the distinguishing features of the cervical vertebrae
- Smallest kind of vertebra
- Small body relative to vertebral foramen
- Has transverse foramen
Which muscle is indicated by #2?
What is its function?
Attachments?
Innervation?
- Muscle: Erector spinae
- Function: Lateral bending, rotation, extension of the back
- Attachments: Spinous process, transverse process, ribs
- Innervation: Dorsal rami of spinal nerves
Which muscle group is shown?
Erector Spinae (intrinsic back muscle)
Innervated by dorsal rami
Functions in extension, lateral flexion, rotation
Which intrinsic back muscle has fibers that are straight up and down?
|| ||
Erector spinae
Which intrinsic back muscle has fibers that extend superio-medially?
// \
Transversospinalis
Deepest layer of the intrinsic back muscles
Which layer of the meninges is labled by #1?
Arachnoid mater
(Middle layer)
Which muscles retract the scapula?
Rhomboid
Trapezius
Which structure is labeled by #3?
Ligamentum flavum
Which structure is labeled by #2?
Posterior longitudinal ligament
What structure is labeled by #5?
Filum terminale
Extension of the pia mater that attaches to the coccyx
What muscle is outlined in red (labeled #2)?
What is its function?
Attachments?
Innervation?
- Muscle: Latissimus Dorsi
- Function: Extends and adducts the arm
- Attachments: Humerus + Spinous processes + Illiac crest + Sacrum
- Innervation: Ventral rami of the spinal cord
- Via brachial plexus
What kind of vertebra is this?
Thoracic
- Long spinous process (points down)
- Kidney bean-shaped body
Which movements are controlled by the intrinsic muscles of the back?
Extension
Lateral bending
Rotation
Which structures of the vertebrae, strung together, create a space for the passage of the spinal cord?
Vertebral foramen
Together they form the spinal foramen
(Note: the intervertebral foramen is the exit pathway for the spinal nerves associated with each vertebra)
Which structure is indicated by #1?
Intervertebral disc
What structure is labeled by #6?
Pia matter
What structure is labeled by #4?
Ventral (anterior) ramus of the spinal nerve
Which structure is labeled by #3?
Transverse process
Which ligaments limit flexion of the spine?
- Supraspinous ligament
- Ligamentum flavum
- Posterior longitudinal ligament
Which parts of the spine exhibit natural lordosis?
Cervical and Lumbar regions
Which structure is labeled by #5?
Transverse process
Which layer of the meninges is labled by #3?
Pia mater
(Innermost layer)
The arrow is pointing specifically to the denticulate ligaments, which are made of pia mater
Most herniations occur posteriorly, to one side or the other of the midline, due to ligamentous reinforcement in the midline of the vertebral bodies. The ligament reinforcing in this manner is the…
Posterior longitudinal ligament
A woman reports difficulty extending her back.
Which of these muscles would you examine first?
a. latissimus dorsi
b. rhomboid major
c. pectoralis major
d. erector spinae
e. external oblique
d. erector spinae
This is the only choice that is an intrinsic muscle. Intrinsic muscles of the back participate in extension, lateral bending, and rotation
Which back muscles depress the scapula?
Lattisimus dorsi
A whiplash injury is most commonly associated with injury to which spinal ligament?
Anterior longitudinal ligament
What structure is labeled by #1?
Spinal ganglion
What structure is labeled by #1?
Spinal cord
Which ligament is labeled by #1?
Anterior longitudinal ligament
Which parts of the spine have a natural kyphosis?
Cervical and lumbar
What structure is labeled by #4?
Cauda equina
Spinal roots (dorsal and ventral) travel to their exits in the lumbar and sacral vertebrae, where they will join and become spinal nerves
Which layer of the meninges is labled by #2?
Dura mater
(outermost layer)
How many coccygeal vertebrae are there?
4
Which structure is labeled by #1?
Anterior longitudinal ligament
Through which structure do spinal nerves exit the spinal cord?
Intervertebral foramen
(#3)
The extrinsic muscles of the back attach to the ______
The extrinsic muscles of the back attach to the spinous process and limbs
What structure is labeled by #3?
What is its purpose?
Intervertebral foramen
The spinal nerves pass through here on their way to their final destinations
Which intrinsic back muscle is largest?
Erector spinae
What kind of vertebra is this?
How do you know?
Lumbar vertebra
- Broad spinous process
- Spinous process points almost straight back
- Articular processes
- Superior faces inward
- Inferior faces outward
Which ligaments limit the extension of the spine?
Anterior longitudinal ligament
What structure is labeled by #7?
Dura mater
Most superficial layer of meninges covering the spinal cord
What structure is labeled by #3?
Dorsal (posterior) ramus of the spinal nerve
Describe the distinguishing features of the thoracic vertebrae
- Larger than cervical vertebrae, smaller than lumbar
- Body is kidney-bean shaped
- Articular facets for ribs
- Large spnious process (lots of muscles attach to these vertebrae)
Which structure is labeled by #3?
Spinous process
What are the functions of the spinous and transverse processes?
Attachment sites for muscles
Which structure is labeled by #5?
Body of the vertebra
True or false?
In a typical spinal nerve the dorsal root contains motor fibers which will innervate the deep (intrinsic back musculature)
False
- The dorsal root contains sensory fibers.
- The ventral root contains motor fibers.
- When the roots merge to form the spinal nerve…
- Dorsal ramus innervates the intrinsic muscles of the back
- Ventral ramus innervates the extrinsic muscles of the back
When you hunch over your computer, you are introducing unnatural [kyphosis/lordosis] into your spine
Kyphosis
(In the cervical spine)
What are the functions of the extrinsic back muscles?
Move the limbs (arms) by moving the scapula and the humerus
This is an axial T2 MRI of the lumbar spine
What structure is outlined in blue?
What traverses it?
Structure = intervertebral foramen
The spinal nerves traverse the intervertebral foramen
What muscle is outlined in green (labeled #1)?
What is its function?
Attachments?
Innervation?
- Muscle: Trapezius
- Function: Scapular motion
- Rotates the scapula
- Moves it vertically
- Pulls it back
- Attachments: Scapula + Spinous processes + Head
- Innervation: Cranial Nerve XI
- One of the few extrinsic back muscles not supplied by the ventral ramus
How many thoracic vertebrae are there?
12
Which muscle is responsible for extending and adducting the arm?
Latissimus dorsi
Which muscle is indicated by #1?
What is its function?
Attachments?
Innervation?
- Muscle: Splenius
- Only seen in the neck and head region
- Most superficial intrinsic back muscle
- Function: Head extension, head rotation, and lateral bend of the neck
- Attachments: Spinous process, head
- Innervation: Dorsal rami of spinal nerves
Where is spinal anethesia administered?
In the subarachnoid space (in between the arachnoid and the pia mater)
Administer between L3-L4 (the spinal cord ends at L1) - this decreases the chance of a spinal cord injury.
What structure is labeled by #2?
Coracoid process of the scapula
Which part of the vertebral arch articulates with the superior and inferior vertebrae?
Articular processes
What kind of vertebra is this?
How do you know?
Cervical
- Vertebral foramen is large comapared to the body
- Spinous process is short
- Contains transverse foramen
What bone is this?
Right scapula
Which structure is labeled by #7?
Body of the vertebra
What structure is labeled by #10?
Pia mater
Deepest layer of the meninges covering the spinal cord
Firmly attached to the spinal cord
Describe the distinguishing features of the lumbar vertebrae
- Larger than thoracic or cervical vertebrae
- Body is large compared to vertebral foramen
Which ligament is labeled by #2?
Posterior longitudinal ligament
Which muscle is responsible for rotating and retracting the scapula?
Trapezius
Which muscle is outlined in red (labeled 1)?
What is its function?
Attachments?
Innervation?
- Muscle: Levator scapulae
- Function: Elevates the scapula
- Attachments: Scapula, transverse processes C1-C4
- Innervation: Ventral rami of spinal nerves
Which nerves innervate the intrinsic muscles of the back?
Dorsal rami of the spinal nerve
(Posterior rami)
This vertebra comes from which region?
Thoracic
Articulates with the ribs
What structure is labeled by #2?
(between the two layers)
Subarachnoid space
Usually filled with cerebrospinal fluid
Which extrinsic back muscle is NOT innervated by ventral rami of the spinal cord?
Trapezius
Innervated by cranial nerve XI (spinal accessory)
Identify labeled parts in this Xray of a section of thoracic vertebrae
- Rib
- Vertebral arch
- Spinous process
- Transverse process
What structure is labeled by #3?
Arachnoid mater
Middle layer of meninges covering the spinal cord
(The pia mater ends with the spinal cord at L1)
Which structure is labeled by #5?
Vertebral Arch
(Lamina + Pedicle)
Which structure is labeled by #6?
Transverse foramen
Sympathetic nerve plexus + vertebral artery + vertebral vein pass through this
Which muscle lies on top of the levator scapulae and rhomboid muscles?
Trapezius
What are the major extrinsic muscles of the back?
- Most superficial layer
- Trapezius
- Latissimus dorsi
- Middle layer
- Levator scapula
- Rhomboids
