09-11-21 - The Back - Bones, Ligaments, Muscles Flashcards
Learning outcomes
- List the functions of the vertebral column
- Describe the general morphology of the vertebral column
- Describe the features of typical vertebrae, from each region, as well as the features of atypical vertebrae e.g. axis and atlas
- Describe the intervertebral and facet (zygapophyseal) joints
- Describe briefly the vascular supply of the vertebral column
- Describe the movements available in each region of the vertebral column
- Describe the ligaments that support the vertebral column
- Describe the muscles that attach to and act upon the vertebral column
- State the boundaries of an intervertebral foramen
- Discuss clinical conditions that affect the components of the vertebral column and the contents of the vertebral canal e.g. prolapsed intervertebral disc
What does the vertebral column consist of?
What are these separated by?
What are the 5 different regions of the vertebral column from top to bottom?
How many vertebrae does each section consist of?
• The vertebral column consists of a series of irregular bones (vertebrae)
• These vertebrae are separated from each other by secondary fibrocartilaginous (symphysis) intervertebral discs
1) 7 x Cervical vertebrae
2) 12 x Thoracic vertebrae
3) 5 x Lumbar vertebrae
4) 5 x Sacral vertebrae (fused to 1 sacrum)
5) 1-4 x Coccygeal vertebra (fused)
What are the 6 roles of the vertebral column?
1) Enables upright posture
2) Supports body weight
3) Protects and transmit spinal cord and spinal nerves (all found in vertebral column)
4) Supports the skull and allows for is movement
5) Contributes to the rib cage (where ribs attach)
6) Locomotion (movement) – provides attachment for trunk muscles
What are the primary curvatures of the vertebral column?
When are they present?
How do they curve?
Where do they remain?
What are the secondary curvatures of the vertebral column?
When are they present?
How do they curve?
Where are they found?
When do they develop?
- Primary curvatures
- The primary curvatures of the vertebral column are known as Kyphosis
- They are present in utero
- They are concave anteriorly
- Primary curvatures remain in the thoracic and sacral regions after birth (thoracic kyphosis and sacrococcygeal kyphosis)
- Secondary Curvatures
- The secondary curvatures of the vertebral column are lordosis
- They are not present in utero
- They are convex anteriorly
- Secondary curvatures are found in the cervical and lumbar regions (cervical lordosis and lumbar lordosis)
- Secondary curvatures don’t develop until the infant lifts their head and stands to walk
When do the 2 areas of secondary curvature develop?
What can this development be used for?
What does each area allow?
Why does one area develop before the other?
- Cervical lordosis usually develops at around 6 months old
- Lumbar lordosis usually develops at around 18-24 months old
- This development can be used as milestones for spotting developmental delay
- Cervical lordosis allows the child to lift and support head weight
- Lumbar lordosis is associated with standing upright
- The cervical lordosis develops first as the neurons coming down from the brain are not myelinated in utero
- This occurs after birth and occurs in the cranio-caudal direction, so the cervical neurons are myelinated first
- This means muscles here have better control, and develop before lumbar regions
- This is why we can lift our head before we can walk
What are the 9 components of a typical vertebrae?
What is their purpose?
What areas are susceptible to disease?
- Vertebral body – weight bearing area
- Intervertebral surface (endplate) – articulates with intervertebral disc
- Vertebral arch:
- Pedicles – attaches vertebral arch to vertebral body
- Lamina – muscle and ligament attachment
- Vertebral foramen – vertebral canal formed by the stacking of vertebral columns
- Transverse process – attachment for muscles and ligaments
- Spinous process (spine) – serve as levers for muscles of posture and muscles of active movement
- Inferior vertebral notch – when vertebrae articulate, the superior and inferior notches form the intervertebral foramen, which is where spinal nerves emerge from
- Superior and inferior articular facets (process) – articulates with the facets from other vertebrae
* Articular facets and the symphysis joints with intervertebral discs and susceptible to arthritis, which causes back pain
What is the body of cervical vertebrae like?
What are the 3 areas of the cervical vertebrae?
What movement is allowed in cervical vertebrae?
- The body of cervical vertebrae is small
- Areas of cervical vertebrae:
- Uncinate processes
- At lateral edges
- Allows for synovial articulation with the vertebra above
- Helps stabilise the joint
- Susceptible to arthritis
- Transverse foramen
- Bifid spinous process (except C7)
- The vertebral artery and venous system pass through the transverse foramen
- Superior Articular facets
* Flat, and face posteriorly and superiorly
* Cervical vertebrae allow flexion, extension, with some lateral flexion and rotation
How does the body of the C1 Atlas vertebrae differ from the rest of the vertebral vertebrae?
What do the superior and inferior facets of C1 articulate with?
How is the vertebral artery allowed to move through this structure?
What does the vertebral artery supply?
What is unique about the C7 vertebrae?
What can this be used for?
- The Atlas C1 vertebrae has no vertebral body – the anterior and posterior arches connect the 2 lateral masses
- The Superior Articular Facets of C1 are concave and articulate with the occipital condyles of the skull
- The inferior articular facets articulate with the axis (C2)
- Behind the superior articular facets, there is a small groove, which allows for the vertebral artery to move through
- The vertebral artery supplies the brain, brain stem and spinal cord
- C7 has a sticky out spinous process called the vertebrae prominence, which can be used as a good reference point
What does the body of the C2 axis vertebrae have?
What does this articulate with?
What are the Superior Articular Facets like on C2?
What do they articulate with?
What joint does this form?
What movement does this joint allow?
- The C2 vertebrae has a body with an Odontoid Process/Dens
- This articulates with the anterior arch of the at the Atlas C1 vertebrae
- The superior articular facets of C2 are flat to articulate with the inferior facets of the Atlas C1 vertebrae
- This forms the atlanto-axial joint, which is a pivot joint, with another small synovial joint
- This joint allows for some rotation
What is the shape of the body and vertebral canal of thoracic vertebrae?
What are the Superior Articular Facets of the thoracic vertebrae like?
What type of movement do thoracic vertebrae allow?
What is the transverse process of thoracic vertebrae like?
What does it have on it? What is the role of costal demi-facets?
What is the spinous process like in thoracic vertebrae?
Why might thoracic vertebrae by asymmetric?
- Thoracic vertebrae have a heart shaped body, and a circular vertebral canal
- The superior articular facets of thoracic vertebrae are flat, and face postero-laterally, and are on the arc of a circle
- Thoracic vertebrae allow for rotation
- The transverse process of vertebrae is long and sticks out like a pair of wings
- The transverse process has a transverse costal facet for articulation with the tubercle of its own rib
- Superior and inferior costal demi-facets allow for articulation with the head of the rib at this level and the rib below (ribs attach to their own vertebral body and the one above)
- The spinous process in thoracic vertebrae is long, points inferiorly, and overlaps 2 vertebrae
- Thoracic vertebrae may be asymmetric due to the descending thoracic aorta, which can cause a dent in them (runs down the left side)
What 2 reasons is T1 considered an atypical thoracic vertebra?
Why is this?
How can T11 and T12 (and sometimes T10) be considered atypical?
- The spinous process of T1 sticks outwards instead of downwards (inferiorly)
- Instead of having super and inferior demi-facets, T1 has a full articular facet (for rib 1) and a demi facet (for rib 2)
- This is because rib 1 only articulates with T1
- T11 and T12 (and sometimes T10) only have 1 full articular facet instead of a pair of demi-facets
- This means T11 and T12 (and sometimes T10) only articulate with their own rib
How does the body of lumbar vertebrae compare with other vertebrae?
What are the superior articular facets of lumbar vertebrae like?
What do they interlock with?
What is the spinous process of the lumbar vertebrae like?
What movement do Lumbar vertebra allow?
- The body of lumbar vertebrae is the largest of all the vertebra
- The superior articular facets of lumbar vertebrae are concave and face postero-medially, and interlock with inferior facets
- The spinous process of the lumbar vertebrae is sturdy, stumpy, and quadrangular (like a square)
- Lumbar vertebrae allow extension (greatest movement), flexion, and some lateral flexion
What is the sacrum formed from?
What is the Sacral promontory?
What are the 3 different crests?
How are they formed?
What comes out of the anterior and posterior foramen of the sacrum?
What is the ventral hiatus continuous with?
What is it a route of access to?
What are the sacral cornua?
What is the last part of the vertebral column?
- The sacrum is formed by the fusion of 5 vertebrae
- The sacral promontory is the anterior projection of S1, and helps to define the boundary of the pelvis
- 3 Different types of crests:
- Median crest – union of spinous processes
- Intermediate crests – union of articular facets
- Lateral crests – union of spinous processes
- Ventral (anterior) rami of spinal nerves come out of the anterior foramen
- Doral (posterior) rami of spinal nerves come out of the posterior foramen
- The sacral hiatus is continuous with the vertebral canal, which contains the spinal cord
- The sacral hiatus is potential route of access to the epidural space around the spinal cord (area between dura mater and vertebral wall)
- The sacral cornea are the horns at the bottom of the sacral hiatus
- The last part of the vertebral column is the coccyx, which consists of 1-4 vertebrae
What are joints between articular facets?
What are the joints between vertebral bodies and intervertebral discs?
What comes out of the intervertebral foramen?
How is this formed?
- Zygapophyseal (facet) joints are synovial joints between superior and inferior articular facets of vertebrae next to each other
- There are symphysis/secondary fibrocartilaginous joints between the hyaline cartilage-lined vertebral bodies’ endplates and the intervertebral disc
- Spinal nerves emerge from the intervertebral foramen
- The intervertebral foramen is formed by the superior and inferior vertebral notches of vertebrae, with help from the intervertebral disc
What do intervertebral discs consist of?
What does the anulus fibrosus consist of?
How is it kept in place?
What does the nucleus pulposus consist of?
What is it for?
How does it change with age?
What does it contribute to?
What are the 2 contributions of intervertebral discs?
- Intervertebral discs consist of an outer anulus fibrosus, which surrounds a central nucleus pulposus
- Anulus fibrosus
- Consist of very strong, concentric lamellae of fibrocartilage (lamellae – thin layer, membrane or plate of tissue, especially in bone)
- Attached and kept in place by anterior and posterior longitudinal ligaments
- Nucleus Pulposus
- Gelatious structure consisting of 70-90% water
- Absorbs compressive forces between vertebrae
- Relative collagen content increases with age
- It is a big contributor to length of vertebral column – dehydration causes decrease in height
- Intervertebral discs contribute to the shape of the spinal curvatures
- The form 20-25% of the length of the vertebral column
How is the inner and outer layer of the intervertebral disc nourished?
- The periphery of the disc (anulus fibrosis) is supplies by neighbouring capillaries
- The centre of the disc (nucleus pulposus) is nourished by diffusion from the body of the vertebra
Why might intervertebral discs deform?
What can this put pressure on?
What weakness over time?
What causes a herniated/prolapsed disc?
In what direction does the disc normally herniate?
Why is this?
Where in the vertebral column does herniation most commonly occur?
What maybe compressed by herniation?
Why might nerves escape injury from herniation?
What does this mean for the level of vertebrae affected by herniation?
- Intervertebral discs may deform in order to allow movement between vertebrae
- This also deforms and puts pressure on the nucleus pulposus
- The annulus fibrosis may degenerate and weaken over time
- A herniated/prolapsed disc is caused when excess pressure forces the nucleus pulposus to be forced through the annulus fibrosus
- The nucleus pulposus generally herniates postero-laterally towards intervertebral foramen (towards one side instead of he middle)
- This is due to the central position of the posterior longitudinal ligament
- Herniation is most common in the lumbar region?
- Herniation by the nucleus pulposus may compress:
- The spinal cord (which stops at L1/L2)
- The caude equina
- An emerging spinal nerve
- The intervertebral disc forms the anterior and inferior aspect of the intervertebral foramen
- The spinal nerve typically emerges above the herniating disc, so it will escape injury
- This means that if the highest area affected is L5, then the herniated disc will most likely be in the level above
What are the 2 anterior membranes at the top of the vertebral column?
How do these membranes continue down the vertebral column?
What is the anterior longitudinal ligament?
What does it pass over?
Where does it lie between?
What does it limit?
- At the top anterior area of the vertebral column there are the:
- Anterior Atlanto-Axial membrane
- Anterior Atlanto-Occipital membrane
- These membranes continue down the vertebral column as the anterior-longitudinal ligament
- The anterior longitudinal ligament is a broad band on the anterior surfaces if the bodies of the vertebrae
- It lies between the atlas (C1) and the sacrum
- It limits excessive extension (hyper-extension)
Where does the tectorial membrane lie?
What does it continue down the vertebral column as?
What is the posterior longitudinal ligament?
What structures does it pass along?
Where does it lie between?
What does it form?
What does it resist?
How is the posterior-longitudinal ligament linked to herniated discs?
- The tectorial membrane extends between the foramen magnum (largest foramen of the skull) and C2 (connected occipital bone to C2)
- The tectorial membrane continues down the vertebral column as the posterior longitudinal ligament
- The posterior longitudinal ligament is a narrow band on the posterior surfaces of the bodies of vertebrae
- It lies between the axis (C2) and the sacrum
- It forms the anterior boundary of the vertebral canal
- The posterior longitudinal ligament resists hyperflexion
- The posterior longitudinal ligament is the structure that generally forces a herniated disc to one side most of the time
Where are the ligamenta flava found?
What is the structure of the ligament flava like?
Are ligamenta flava continuous?
How does it continue superiorly?
What does the ligamenta flava limit and support?
Where are intertransverse ligaments found?
- The ligamenta flava are found between the adjacent vertebral laminae (arched part of vertebral arch)
- The ligament flava have a bilateral structure that often meet in the midline to form a continuous ligament in the back
- The ligamenta flava are not continuous – formed between one lamina to the next
- The ligamenta flava continues superiorly as the posterior atlanto-axial and atlanto-occipital membranes
- The ligamenta flava limits sudden flexion and supports curvatures
- Intertransverse ligaments are found between all transverse processes
What are the 3 ligaments found in the cervical area of the vertebral column?
Where are they each found?
Where do they run to?
What is unique about the C7 vertebrae?
What can this be used for?
- Ligaments found in the cervical area of the vertebral column
1. Supraspinous ligaments - Between tips of spinous processes
- Runs form C7 to the sacrum
- Continuous with ligamentum nuchae
- Ligamentum Nuchae (Nuchal Ligament)
- Extends between external occipital protuberance and posterior edge of foramen magnum and down to C7
- Limits flexion
- Provides muscles attachment
- Interspinous ligaments
* Between all spinous processes
* C7 has a sticky out spinous process called the vertebrae prominence, which can be used as a good reference point
What are the 2 ligaments found attached to the dens/odontoid process?
What do they attach to?
What does it prevent?
What are the 2 ligaments posterior to these 2 ligaments?
What is the cruciate ligament formed from?
What does it prevent?
- The Alar ligament
- Attaches from the sides of the dens to the sides of the foramen magnum
- It prevents excessive rotation
- The Apical Ligament
- Runs from the tip of the dens to the occipital bone
- Posterior to these 2 ligaments there are:
- The Transverse Ligament
- Passes from one side of the atlas to another
- Keeps the dens close to the anterior arch
- Allows pivoting action at the atlanto-axial joint
- Longitudinal ligament
- Runs from the Occipital bone to the body of C2
- The cruciate ligament tis formed by the Transverse ligament + superior and inferior fascicles
- The cruciate ligament prevents excessive movement between the axis, atlas and occipital bone
In what way are each of the vertebrae supplied?
Where do arteries arise from?
How do they enter the vertebral canal?
What is equivalent to these arteries?
How do vertebral veins differ from other veins?
Why is this bad?
- Vertebrae are supplied segmentally
- Arteries from anastomotic rings which arise from the vertebral arteries and posterior intercostal and lumbar branches of the aorta
- The arteries rap their way round the vertebrae and enter the vertebral canal (where the spinal cord is)
- The venous plexus (interwoven network of veins - internal and external coalesce (fusion) and drain to the veins) is equivalent to the name of the above arteries
- Vertebral veins don’t have valves, meaning blood can flow in and out
- This may be detrimental, as it means metastases can get into these vertebral bodies e.g metastases from prostate cancer can infiltrate the vertebral bodies
How are muscles classified?
What is this classification based on?
- Muscles can be classified is extrinsic or intrinsic
- This is based on embryological origin and type of innervation
Where are extrinsic muscles found?
What are extrinsic muscles of the back involved in?
What are they innervated by?
- Extrinsic muscles are superficial muscles
- They are involved in movements of the upper limbs and the thoracic wall
- Extrinsic muscles are innervated by the anterior rami of spinal nerves
Where are intrinsic muscles located?
What are they adapted for?
What 2 movements are intrinsic muscles of the back also involved in?
What are intrinsic muscles of the back innervated by?
What are intrinsic back muscles generally?
What does this make them stronger than?
- Intrinsic muscles are located deep, between the spinous processes and the angle of the ribs
- Intrinsic muscles are adapted to provide support and movement in resistance to the effect of gravity
- Intrinsic muscles of the back move the vertebral column, and participate in moving the head?
- Intrinsic muscles of the back are innervated by the posterior rami of spinal nerves
- Intrinsic back muscles are generally extensors
- This make them stronger than flexors, because extension (such as lifting an object) is in opposition to gravity
What are the superficial (extrinsic) Layers of the back that are mainly for upper limb movement?
What 3 places does the trapezius attach?
What ligament provides attachment for the trapezius?
What 3 places does the upper, middle, and inferior fibres of the scapula attach?
How do each of the fibres move the scapula?
What 2 other movements is the trapezium also responsible for?
What innervates the Trapezius? Why is this unique?
- The trapezius and the latissimus dorsi are the superficial layers mainly for upper limb movement
- The trapezius attaches to:
- The skull
- The spinous processes form C7 to T12
- The scapula to the clavicle laterally
- The ligamentum nuchae (nuchal ligament) provides attachment for the trapezius
- the upper fibres of the trapezius elevate the scapula (shrug shoulders), and can elevate (rotate) the shoulders during abduction
- The middle fibres retract the scapula
- The inferior fibres depress the scapula
- The trapezium is also able to extend the neck
- The trapezius is innervated by the accessory nerve (cranial nerve 11)
- This is unique as the trapezius is the only upper limb muscle supplied by a cranial nerve
What 4 places does the latissimus dorsi attach?
What 2 movements is it responsible for?
What nerve innervates the latissimus dorsi?
Where does it come from?
- The latissimus dorsi attaches to:
- The iliac crest
- Fascial sheath (thoracolumbar fascia)
- Spinous processes of T6 to T12
- Lower ribs to the humerus (upper arm bone)
- The latissimus dorsi is responsible for shoulder extension and adduction
- The thoracodorsal nerve innervates the latissimus dorsi, which is a branch of the brachial plexus (bundle of intersecting nerves)
What are 3 extrinsic muscles of the back?
Where are they attached?
What are they involved in?
What are 2 extrinsic muscles deeper to these muscles?
Where are they attached?
What are they accessory muscles to?
- Levator scapula
- Found attached in the medial angle of the scapula up to the neck
- Scapula elevation
- Rhomboid major and minor
- Minor above major
- Attaches to medial borders of scapula
- Involved in scapular retraction and elevation
- 2 extrinsic muscles deeper to these:
1. Serratus posterior superior - Attached in jagged fashion to the ribs
- Accessory muscles of inspiration
- Serratus posterior inferior
- Attached in jagged fashion to the ribs
- Accessory muscles of expiration
Where do intrinsic back muscles run?
What are intrinsic muscles responsible for?
What are the 3 layers of intrinsic muscles?
- Intrinsic back muscles fun from the skull, through the cervical, thoracic and lumbar regions to the pelvis
- Intrinsic back muscles are responsible for keeping the vertebral column upright and in extension against gravity
- Intrinsic muscles are arranged in 3 layers:
- Superficial
- Intermediate
- Deep
What are the 2 muscles in the superficial layer of intrinsic muscles?
Where are they found?
How are they linked?
What do they act together to do?
What do they do individually?
- Muscles in intrinsic layer of superficial muscles:
- Splenius Capitis
- Splenius Cervicis
- These 2 muscles sit on the back of the neck
- These 2 muscles are part of the same muscle belly, but insert at different parts
- These muscles act together to the extend and move around the neck and head
- Individually, they rotate and laterally flex the neck
What are the muscles in the intermediate layer of intrinsic muscles in the back?
What is the primary responsibility of these muscles?
What do they consist of?
- The erector spinae are the main muscles in the intermediate layer of the intrinsic muscles in the back
- These are the main anti-gravity muscles
- They consist of 3 columns:
- Iliocostalis – runs down to the ileum and inserts mostly into ribs
- Longissimus
- Spinalis – closest to the spinous process
What are muscles of the deep layer of intrinsic back muscles called?
What are the 3 muscles from most superficial to deep?
What do these muscles do?
- The muscles of the deep layer of intrinsic back muscles are called transversospinalis
- These 3 muscles from superficial to deep are:
- Semispinalis
- Multifidus
- Rotatores
- These muscles are small muscles involved in the movement of the vertebral column
Where are deep neck muscles found?
What are the 4 deep neck muscles?
What do these muscles form when put together?
What does this structure do?
- Deep neck muscles are found deep to the semispinalis capitis
- The 4 deep neck muscles:
- Obliquus capitis superior
- Obliquus capitis inferior
- Rectus capitis posterior major
- Rectus capitis posterior minor
- When put together, these muscles for the sub-occipital triangle
- The sub-occipital triangle transmits the vertebral artery, vertebral vein, and the suboccipital nerve
Muscles of the back overview diagrams
