The back; Bones, Ligaments and Muscles Flashcards
How many bones makes up the vertebral column?
33 bones
What is special about the bones in the vertebral column?
The vertebral column consists of a series of irregular bones
What are the different vertebra separated by?
The vertebra are separated from each other by fibrocartilaginous intervertebral disks
What are the 5 regions of vertebra and how many vertebra are in each region?
Cervical Vertebra - x7 Thoracic Vertebra - x12 Lumbar Vertebra - x5 Sacral Vertebra - x5 Cocygeal Vertebra - x1 - 4
Remember; Breakfast at 7, Lunch at 12 and Dinner at 5
Why does the number of vertebra in the Cocygeal region vary?
As the number of vertebra that fuse together varies from one person to another.
Some people all 4 of their Coccygeal vertebra have fused together giving them only 1 bone and in others none have fused giving them 4 bones
What are the 6 primary functions of the vertebral column?
The vertebral column; - Enables upright posture - Supports body weight - Protects and transmits spinal cord and spinal nerves - Supports the skull and allows for its movement - Contributes to the rib cage - Locomotion: Provides attachment for trunk muscles
What are primary curvatures, when are they present and in what regions?
Primary curvatures are;
- Present in-utero where the foetus’ spine is fully curved dorsally (Kyphosis)
- Concave anteriorly (Kyphosis)
- Remains in thoracic and sacral regions after birth
What does Kyphosis mean?
A concave anteriorly
The curved part is pointing dorsally
What does Lordosis mean?
A concave posteriorly
The curved part is pointing anteriorly
What are secondary curvatures, when are they present and in what regions?
Secondary curvatures;
- Are not present in a foetus in-utero
- Are in the cervical and lumbar regions
- Do not develop until an infant lifts their head and stands to walk
What are the 10 main components to any typical vertebra, their functions?
Vertebral body - chunky bit at the front that takes most of the weight from the body/supportive function
Vertebral endplate/Intervertebral surface - part that is taking part in the joint between 2 vertebral bodies, covered in hyaline cartilage (secondary Cartilaginous) it will articulate with an intervertebral disk to form a intervertebral joint
Vertebral arch - Behind vertebral body
Sub parts;
- Pedical, means foot of vertebral arch - articulating / connected to vertebral body
- Lamina, plate or flat area used for ligament and muscle attachment
This vertebral arch encloses a vertebral foramen and when lots of these are stacked together these become continuous and for a vertebral canal in which our spinal cord runs in
Transverse processes - sticky bits out of sides
Spinous process - sticky bit out of back
Superior articular facet and inferior articular facet articulate with one another - vertebrae are a synovial joint and are prone to wear and tear these facet joints, arthritis (osseo and rhemetoid arthritis)
These facet joints are also known as zygapophyseal joints
Inferior veritable notch and superior veritable notch - when 2 stack together form an intervertebral foramen
Draw this diagram
What is bone-bone separated by in the vertebral column?
Bone to bone is separated by a fibrocartilaginous disk (secondary cartilaginous joint between vertebral bodies)
What are articular facets and joints susceptible too?
Articular facets and joint are susceptible to arthritis and back pain
What are the 4 main characteristics of the Cervical Vertebra?
They have Uncinate processes at lateral edges for synovial articulation with vertebra above. They help to deepen the socket between 1 cervical vertebrae and another
Transvers foramen - a whole in the transverse process which contains the vertebral artery and vein , going up through the holes in these vertebrae, being one of the ways to get blood to the brain
Its spinous process is bifid - bifocated at back - Main way to recognise a cervical vertebra
Superior Articular facets are flat, facing superiorly and posteriorly. They are directed postero-laterally.
- Movements can occur here due to the Superior articular facets being flat
What kind of movements can occur in the Cervical region?
Flexion, extension, rotation and lateral flexion
What are the 3 irregular vertebrae found in the cervical region?
C1 (the Atlas), C2 (Axis) and C7
What makes the Atlas/C1 vertebrae irregular?
No vertebral body
Has very big superior articular facets articulate with the occipital condyles (base of skull)
Its inferior articular facets articular with the Axis (C2)
Around back there is a groove behind the articular facets for vertebral artery which will come up and pass around the back of the articular facet to go up into the skull
What kind of joint occurs from the occipital bone in the head to the C1 vertebra and what kind of movement does this allow for?
The Atlanto-occipital joint allows for a little flexion extension in neck
What is unique about the Axis/C2 vertebra, what kind of joint occurs from here and what kind of movement does this allow for?
The Axis/C2 vertebra. has an Odontoid process/Dens which is a tooth-like, sticky up bit at front of C2 vertebra and is used for articulation with the anterior arch of the Atlas
Odontoid process/Dens - allows for rotation of head and neck at the Atlanta-axial joint (making up one of our pivot joints)
Odontoid peg takes the place of the vertebral body of C1, odontoid peg is derived form the vertebral body of C1
It superior articular facets are quite flat to articulate with the inferior facets of the atlas (atlanto-axial joint)
What are the 5 main characteristics of the Thoracic Vertebra?
Has a Heart shaped body and circular vertebral canal
Has a long, downward/inferiorly projected,
spinous process which overlaps 2 vertebrae points
Vertebral Body contains superior and inferior costal demi facets for the articulation with the heads of 2 pairs
of ribs because one rib articulates with half of a facet on the vertebrae above and half of a facet on the vertebra below itself - hence demi facets
Transverse processes has transverse costal facet that articulates with the tubercle of rib - Its transverse processes are very long and stick way out the side
Superior articular facets are flat and point straight backwards/postero-laterally, on a the arc of the circle
- This allows for 1 of the thoracic vertebra to rotate on the articular facets of another
What kind of movement occurs in the Thoracic vertebra and why doesn’t it have any different types of movement?
Main movement in thoracis vertebra is rotation, Due to them being packed very closely together you cannot flex or extend them
What are the 3 atypical vertebrae found in the Thoracic region and what makes them atypical?
T1, T11 and T12 because they have a full articular facet, not a demi articular facet like other thoracic vertebrae because the rib just articulates with 1 vertebrae at the top and bottom
What parts of the Thoracic vertebrae does the ribs articulate with?
Rib articulates with the;
- Demi facet on the body
- Facet on the transverse process (it has a long transverse process with a facet for articulation with the tubercle of its own rib)
What are the 3 main characteristics of the Lumbar Vertebra?
Lumbar vertebrae contain the largest vertebral body compared to the rest of the vertebra
Its Superior Articular Facets are concaved and facing postero-medially, interlocking with
inferior facets so if we stack 1 lumbar vertebrae on top of another this stops rotation, so we only get flexion and extension
Lumber spinous process is short, stumpy and thick quadrangular spinous process
Why should we avoid trying to distinguish lumbar vertebral from their large vertebral bodies when in the Dissection Room?
Between individuals don’t rely on the size of the lumbar vertebra being bigger as it wont coincide (our vertebrae all vary in size but are proportional to our own vertebrae)
I.e - Some people have larger thoracic vertebra than others lumber vertebra
What kind of movement is found in the lumbar vertebra and why?
Flexion and extension as its Superior Articular Facets are concaved and facing postero-medially, interlocking with inferior facets so if we stack 1 lumbar vertebrae on top of another this stops rotation
Extension is greatest movement, flexion and some lateral flexion, but no rotation
What are the 8 main characteristics of the Sacrum Vertebra?
Formed by fusion of 5 vertebrae
On the anterior surface we have the sacral promontory - When you look at the sacrum from above you can see that it sticks out quite a bit and this is the anterior projection of S1
At either side of the sacral promontory we have the Sacral ala (looks like wings)
Median, intermediate, lateral crests: Union of spinous,
articular and transverse processes, respectively
Anterior and Posterior foramen on the front and back of the sacrum and nerves go in and out foramena
On the Anterior foramen we have ventral rami (contains nerves) coming out
On the Posterior foramen we have dorsal rami (contains nerves) coming out
Sacral hiatus is where veritable arch of the of the lower sacral vertebrae hasn’t fused and has left a little gap
Cornu (meaning horn) parts at either side of hiatus
What would you expect to see in a scan of a juveniles sacrum?
In juvenile will see what looks like a fracture, just growing bones - don’t fuse until late teens early 20’s
What potential procedures does the Sacral Hiatus allow us to do?
Can use as a route to enter the vertebral canal - can stick a needle up and sample CSF, especially in juveniles
What is the Cauda equina?
frayed part spinal cord turns into
What hangs from the Sacrum?
The Coccygeal Vertebra
How many bones are in the Coccygeal vertebra?
Between 1-4 vertebrae a there is a great deal of variation in fusion
In a lot of people the lower coccygeal vertebrae never ossify and remain as cartilaginous masses
What are the 2 types of joints found in the vertebral column?
1). Zygapophyseal (facet) joints - synovial joints between articular processes
2). Symphysis or secondary
cartilaginous joint between
endplates and the intervertebral
discs
What is the intervertebral foramen?
Spinal nerves emerge from the intervertebral foramen
The intervertebral foramen a small space formed when the superior vertebral notch of one vertebra aligns with the inferior vertebral notch above of another vertebra with contribution from the intervertebral disc which forms part of the anterior border of the intervertebral foramen
What is the intervertebral disk composed of and what is its function?
Consists of an outer anulus fibrosus, which surrounds a central nucleus
pulposus
Nucleus pulposus;
• Gelatinous layer (made from 70-90% water)
• Absorbs compressive forces between
vertebrae (acts as a shock absorbent)
• Relative collagen content increase with age and dehydration of this mass.
Anulus fibrosus;
• Very strong, concentric lamellae (layed down one layer on top of another) of fibrocartilage
- Attached strongly and is kept in place by anterior and posterior longitudinal ligaments (which attach to the vertebral bodies of the vertebral column).
- It keeps the nucleus pulposus in place
Why do people shrink as they get older?
As you get older the nucleus pulposus will dehydrate causing a loss in mass and increase in collagen content
A great deal of the length of the vertebral column (20-25%) is made up by these intervertebral disks, so when they dehydrate we shrink
At what time of the day are we taller and why?
During day you are taller than you are at night, as you’ve been on your feet all day putting pressure through your intervertebral disks - only by a few cm
What else does the intervertebral contribute to in the spine?
The intervertebral disc also contributes to the shape of spinal curvatures
What happens when force is transmitted through the vertebrae?
The nucleus pulposus is being squeezed like squashing a tennis ball
What are bone and intervertebral discs an example of and what does this mean they require?
Bone and intervertebral disks are living tissues and need a blood supply
How are the different parts of the intervertebral disc supplied with blood?
We have a segmental blood supply to the vertebral bodies. From that segmental supply we get some little arteries that comes through into the periphery of disk, not through the centre of disk.
The annulus fibrosis is supplied by neighbouring capillaries
The nucleus pulposus is nourished by
diffusion from the periphery arteries located in the body of the vertebra
What may happen to the intervertebral discs to allow for movement between the vertebral bodies and what can this lead to?
Discs may deform to allow movement between the vertebral
bodies
This may put pressure on the nucleus pulposus
What can happen to the Annulus Fibrosis over wear, tear and age?
The annulus fibrosus may degenerate and weaken
What happens to the intervertebral disc when bending forward?
When bending forward and flexing the spine you get compression at the anterior of the disc and not at the posterior part of the disk - there is an uneven force through this disc
What can a deformed intervertebral disc, pressure on the nucleus pulposus. and a degenerating and weakening Annulus Fibrosis lead to?
A herniated/prolapsed disc
What vertebrae does the spinal cord stop at?
L1/L2
Why is the term ‘slipped disc’ anatomically incorrect and shouldn’t be used?
This term is wrong as the whole disk doesn’t slip out!
What part of the intervertebral disc herniates/prolapses? How does this happen and what can this lead to?
The part that herniates/prolapses is the Nucleus pulposus.
It squeezes its way out through a degenerately weakened anulus fibrosis (outside coating of nucleus pulposus). Once it herniates it can press on nervous structures
What regions can herniated/prolapsed discs occur in and why?
Occurs most common in lumber region (as this is where we do the majority of our movement of flexion and extension and a great deal of force is being put through)
However it can occur in the cervical region as well
At what position does a herniated disc come out?
The central position of the posterior longitudinal ligament
means that most disc herniations
are posterolateral, towards the
intervertebral foramen and not straight backwards.
Because of the direction the herniated disc comes out what does this mean about symptom?
Symptoms may only be unilateral (only affects one side of the body)
What nerves does the herniated disc affect around it and why?
Due to the disc forming the anterior aspect
of the foramen is will bulge out inferiorly and not superiorly hence the spinal nerve will most likely
emerge above the prolapsing
disc and escapes injury and the spinal nerves below the level of the herniated disc that will be affected.
I.e - Herniation of the intervertebral disc of L4/5 will not affect the L4 nerve it will affect L5 and downwards
If a patient has a defect in their L3 dermatome (area of skin that is mainly supplied by the spinal nerve L3) then what disk would you suspect has herniated?
The patients L2/3 intervertebral disk has herniated as it is the disk above where you are getting symptoms of the defect from
What must the vertebral bones be supported by?
Ligaments
What is the name of the ligament that attaches between the base of the skull and atlas?
The Anterior Atlanto-Occipital ligament runs between the base of the skull and atlas
What is the name of the ligament that attaches between the atlas and axis?
The Atlanto-Axial membrane/ligament runs between body of Atlas (C1) and the Axis (C2)
What are the Anterior Atlanto-Occipital ligament and the The Atlanto-Axial ligament part of?
The Anterior Atlanto-Occipital ligament and the The Atlanto-Axial ligament are part of the anterior longitudinal ligament.
It runs all the way from the Occipital bone down to the sacrum
What is the function of the Anterior longitudinal ligament and where does it run?
The is a broad band on the anterior surfaces of the bodies of vertebrae; — it runs from the Atlas to the sacrum — it limits extension and prevents hyperextension
Where do the main ligaments supporting the vertebral bodies run?
Within the vertebral canal we have more ligaments which run down the back of the vertebral body
Where does the Tectorial Membrane run and what is its function?
Tectorial Membrane;
— Extends between the
foramen magnum (the hole in the base of the skull through which the spinal cord passes) and C2 - Runs posterior to vertebra
— The tectorial ligament is continuous with the posterior longitudinal ligament
What is the features and function of the posterior longitudinal ligament?
The posterior longitudinal ligament is a narrow band on the posterior surfaces of the bodies of vertebrae — between C2 to sacrum — resists hyper-flexion
What is the Foramen Magnum?
The hole in the base of the skull through which the spinal cord passes.
Where does the longitudinal ligament run through and to?
Runs through the vertebral canal running on the posterior of all the vertebral bodies and carries on all the way down to the sacrum
What is the role and features of the ligaments lava?
Ligamental flavum - yellow ligament (looks yellow) - extends from one vertebral lamina to the lamina below;
— limit sudden flexion and support the curvatures
— continues superiorly as the Posterior Atlanto-
Axial and Atlanto-OccipitaI Membranes
If we look into the posterior wall of our vertebral canal we can see the ligamental flavum and we can see it runs from one lamina (1 vertebra to another) to the next then breaks then to the next and breaks.
They are said to be a paired structure with one on each side - However they very often just meet in the midline
What ligament runs between all
transverse
processes?
Intertransverse
ligaments
What are the 3 ligaments associated with the spinous processes, their functions and features ?
Supraspinous ligaments runs between tips of spines and run from sacrum closely associated spinous processes until it reaches C7
- continues with Ligamentum Nuchae
Ligamentum Nuchae (Nuchal Ligament) extends between external occipital protuberance and posterior edge of foramen magnum, down to C7 - Limits flexion, provides muscle attachment
Interspinous ligaments
- between all spinous processes
Ligamentum Nuchae is continuous with he Supraspinous ligaments
Why don’t we see the anterior curvature in the neck/lordosis of the neck?
As the curvature/lordosis is filled in by the Ligamentum Nuchae and all of the muscles associated with it
Where are the Alar ligaments and what is their function in C2?
Alar Ligaments:
Alar - ‘Looks like wings’
From sides of dens/odontoid peg to sides of foramen magnum
- Prevent excessive rotation
Where are the Apical ligaments and what is their function in C2?
From the very top/apex of the dens going up to the occipital bone we have an Apical ligament
Where are the Transverse ligaments and what is their function in C2?
Behind/posterior to the dens we have a transverse ligament - helps hold the dens in place by holding it close to the anterior arch and allows us to have put pivot joint there
Where are the Longitudinal fascicles and what is their function?
Longitudinal fascicles runs from C2 to the occipital bone
What makes up the cruciate ligament and what is their function?
Transverse ligament + superior and inferior longitudinal fascicles = cruciate ligament
Prevents excessive movement between the axis, atlas and occiput
Where do arteries that nourish the vertebra arise from?
Segmental arteries come around to form anastomotic rings that arise
from the vertebral arteries and posterior
intercostal and lumbar branches of aorta
They go into the intervertebral foramen on either side and penetrate the vertebral body and anastomose all around it
What parts drain the blood from the vertebra?
Venous plexuses
coalesce and drain to the veins equivalent to the above arteries
What are the 2 different types of Venous plexuses?
Venous plexuses outside the external canal we call the ‘external venous plexuses
Venous plexuses within the vertebral canal we call the ‘internal venous plexuses’
How are muscles of the back separated?
Muscles of the back are separated into layers and classified by their actions.
One classification we can do is Intrinsic and Extrinsic back muscles (related to embryology);
- Intrinsic back muscles - are ‘true’ back muscles
- Extrinsic back muscles - Are upper limb muscles that moves scapula and humorous (not true back muscles)
What are the 3 features of extrinsic back muscles?
The extrinsic muscles are;
- superficial
- involved with movements of
the upper limbs and thoracic
wall - innervated by anterior rami/ventral rami of
spinal nerves
What are the 5 features of extrinsic back muscles?
Intrinsic muscles are;
- Located deep, between the spinous processes
and the angle of the ribs - adapted to provide support and movement in
resistance to the effect of gravity - move the vertebral column and trunk
- participate in moving the head
- innervated by the posterior/dorsal rami of spinal nerves
Why are intrinsic back muscles stronger than flexors?
Stronger than the flexors because extension (such as
lifting an object) is in opposition to gravity
What does innervated mean?
Supply (an organ or other body part) with nerves.
What muscles are present in the superficial layer of the back?
- Trapezius
- Latissimus dorsi
Where does the trapezius run from and attach to?
Extends from back of the skull, to ligamentum nuchae, to the spines of C7 to T12 then changes direction and goes up to the scapula and clavicle (laterally) to complete a triangular shape
What are the functions of the 3 different parts of the trapezius? and the final general function?
Superior part - lift the shoulders
Middle part - retracts scapula
Inferior part - depress scapula
Extends neck
Where does the motor innervation come from to m one the trapezium?
An accessory nerve (which is a cranial nerve that comes out of the skull)
What does Latissimus Dorsi mean?
Literally means ‘widest muscle of the back’
Where does the Latissimus Dorsi run from and too?
The Latissimus Dorsi comes all the way up from the iliac crest passing through in this area of attachment known as the Thoracolumbar fascia and extends up there and inserts into the humorous.
From the humerus it goes to the lower ribs before going from the spines of T6 to T 12 lower and back to the iliac crest.
What is the job of the Latissimus Dorsi?
It extends and adduct your shoulder (helps with chin ups, pull ups and rowing)
What is the Latissimus Dorsi innervated by?
Innovated by a nerve called the Thoracodorsal nerve (a branch of the brachial plexus)
- You can simplify it and say it’s the nerve to the Latissimus Dorsi but Thoracodorsal is more common
What 5 muscles are in the next layer which is deeper to the trapezius and Lastissimus Dorsi?
Levator scapulae
Rhomboid major and minor:
Serratus posterior superior
Serratus posterior inferior
What is the function and position of the Levator scapulae?
Levator scapulae is a muscle which comes up the very top up to the neck and elevates the scapula
What is the function and position of the Rhomboid Major and Minor?
Are 2 roughly ‘square’ shaped muscles.
They retract and elevate the scapula as well, and bring the scapula backwards
Major - lower
Minor - Higher
What is the function and position of the Serratus posterior superior?
Serratus posterior superior - helps elevate the ribs during inspiration
They are tissue paper thin and very small, you will very likely damage them when you try to find them
These muscles are accessory muscles of respiration and they attach to the ribs
What is the function and position of the Serratus posterior inferior?
Serratus posterior inferior - helps depress the ribs during expiration
They are tissue paper thin and very small, you will very likely damage them when you try to find them
These muscles are accessory muscles of respiration and they attach to the ribs
What are the 5 features of the deepest layer of intrinsic back muscles?
- Run from skull, through cervical,
thoracic and lumbar regions to pelvis - Keep the vertebral column upright and in extension against gravity
- Arranged in 3 layers - Superficial, Intermediate, Deep
- Move the back and trunk
- Are innervated by Dorsal Rami of spinal nerves
What muscles are found in the superficial layer of the intrinsic muscles and what are their function?
Splenius Capitis - Part attaches to head
Splenius Cervicis - Part attaches to neck
- Same muscle, different parts
If you contract one side your head on one side will go laterally inferior (on top of shoulder) with a little rotation
If the Splenius Capitis and Cervicis
act together the neck is extended
What intrinsic muscles are found in the intermediate layer and what is it made up of?
Erector Spinae Erector spinae group of 3 muscles;
Iliocostalis - Goes up from the illium attaching to the ribs and all the way up neck
Longissimus - Muscle in between them which is pretty. Long, goes all the way up to the head
Spinalis - Muscle lies next to the spinous processes, lies very close to spinous processes
What are the Illiocostalisthoracic or spinalouslumborum muscles?
These aren’t different muscles they are sub parts of the erector muscles
I.e - There is 1 spinalis muscle which has 1 thoracic part and 1 cervices part
What are the intrinsic muscles that run in the deep layer of the back?
Transversospinalis muscles;
Semispinalis;
- Most impressive of the 3
- It runs about half of the length of the vertebral column, hence semispinalis
- It has a part which attaches to the neck and a part which attaches to the head
- So it has semispinalous-cervicous and Semispinalous-capitus
- Deep to our errector spinae
- Running half of the length of the vertebral column
Multifidus;
- It is small
- Goes from lamina down to transverse processes
- It helps rotate the vertebral column
Rotatores;
- Comes from lamina down to the transverse process, so the vertebra below
- Helps rotate the spine
- Deepest muscle of the back
What is the final group of muscles in the deep layer of the intrinsic back muscles and what is its functions and subunits of this?
Levatores costorum;
- help elevate ribs
- Accessory muscles of respiration
- They aren’t really back muscles but are innovated by dorsal rami of spinal nerves so we include them
Subdivisions;
- Rotatores brevis (short rotatores) - Goes from 1 transverse process to the rib below
- Rotatores longus (long rotatores) - goes from 1 transverse process to the rib 2 below
What are the function and a feature of intertransverse muscles?
Intertransverse muscles which are small but they help with lateral flexion
What are the features of interspinous muscles?
Interspinous muscles - very small and very distinct
What are the 4 deep neck muscles and where are they located?
Obliquus capitis superior - which goes from the transverse process of C1 up to the occipital bone
Obliquus capitis inferior - which goes from the spinous process of C2 out to the transverse process of C1
Rectus capitis posterior
major - which goes from the spinous process of C2 up to the occipital bone
Rectus capitis posterior
minor - which goes from the vestigial spinous process of C1 up to the occipital bone
What are deep neck muscles just beneath?
Deep to semispinalis capitis
What muscles make up the Sub-occipital Triangle ?
Obliquus capitis superior, Obliquus capitis superior and Rectus capitis posterior major
Why is The Sub Occipital Triangle a handy little landmark?
Because in the base of that triangle you should find the vertebral artery and sub-occipital nerve, so if you need to anesthetise the back of the head or for some reason get into the vertebral artery, you will find it in this sub-occipital triangle.
