1st Midterm: Development of the Spine/Cervical Spine Flashcards
During the 2nd week the inner cell mass develops into a _________ _________ ________
Bilaminar Embryonic Disc
The cells of the upper BED layer are called ___________
Epiblast
From where or what part of the BED does the prechordal plate develop?
Hypoblast
The process by which the inner cell mass is converted into a trilaminar embryonic disc is called?
Gastrulation
From where does the intro-embryonic ectoderm come from? Epi or hypoblast?
Epiblast
The tip of the primitive streak is called?
The primitive knot
What develops from the tip of the primitive streak?
Notochordal process
The notochord is a cellular rod that develops between what two layers?
Ectoderm & Endoderm
The primitive axis of the embryo is formed from what structure?
Notochord
The somites form what part of the skeleton?
The axial skeleton
The notochord induces the development of what system of the body?
Central Nervous System
What is the process called when the central nervous system is formed from the notochord?
Neurulation
Neuroectoderm -> __________ ->___________->_________ ->__________
Neural Plate, Neural Groove, Neural Tube, Neural Crest Cells
Approx how many days is somatic development?
20-30
Each somite can differentiate in what 3 parts?
Sclerotome
Dermatome
Myotome
The ventormedial part of the somite is the ________
Sclerotome
The _________ is the dorsolateral part of the somite?
Dermatome
How many spinal nerves will innervate each somite?
1 spinal nerve
The Sclerotome is a condensation of what type of cells?
Mesenchymal
During the 4th week, mesenchymal cells derived from the Sclerotome migrate to what 3 areas?
Around the notochord to form the centrum of the vertebra
Around the Neural Tube to form the Neural Arch
In the body wall to form the ribs in the thoracic region.
Describe how many as well as the location of the chondrification centres during the 5&6th weeks of development.
Mesenchymal Verterbra:
2 centres in each Centrum
2 centres on each side of the Neural Arch
Ossification of typical vertebrae ends by ___ yoa
25
The halves of the vertebral arches usually fuse during the first how many years of life?
3-5
After puberty how many secondary ossification centres appear? Where are they located?
5
1 for the tip of the s.process
1 for each t.p
2 rim epiphyses one superior and one inferior rim of vertebral bodies.
The main features of this syndrome are short neck, low hairline, and restricted neck movements?
Klippel-Feil (Brevicollis) Syndrome
What is the severe type of Spina Bifida?
Cystica
Name the types of Spina Bifida Cystica
- Meningocele
- Meningomyelocele
- Myeloschisis
what type of SB has no nervous tissue in the cyst?
Meningocele
What type of SB has nervous tissue in the cyst and will impair function?
Meningomyelocele
Hemivertebra results from?
Failure of one of the two chondrification centres of the vertebral body to appear and subsequent failure of half of the vertebra to form.
This condition is the result of the failure of fusion of the Neural Folds and Neural Arch, because of faulty induction of underlying Notochord or because of Teratogenic Agents..
Rachischisis
Each Myotome divides into a small dorsal and large ventral division each called?
Small dorsal Epaxial/Epimere Divison
Large ventral Hypaxial/Hypomere Divison
The Myoblasts of the Epaxial Division form all what muscles of the spine?
Extensors
Myoblasts of the Hypaxial Division form what muscles?
Anterior muscles of the neck
Flexor muscles of the Spine
Quadratus Lumborum
Pelvic Diaphragm muscles
The derivatives of the Hypaxial/Hypomere division are innervated by branches from what Spinal Nerves?
The Ventral Primary Rami of Spinal Nerves
The Occiput consists of these 4 parts:
- Squamous portion
- Two lateral portions
- One basilar portion
What characteristic of the occiput is unique in newborns compared to adults?
All four parts are separate in the newborn with all four parts centred around the Foramen Magnum
What part of the occiput is the largest and expanded portion? Where is it located?
Squamous part - located posterior and above the f.magnum
An aka for Inion
External Occipital Protuberance
Where does the Nuchal Ligament attach?
EOP
What line is for the galea aponeurotic a attachment?
Highest (Supreme) Nuchal Line
What makes the supreme nuchal line unique?
Not always present in all bodies.
This structure extends inferiorly from the EOP to the F.Magnum?
External Occipital Crest
This line serves as an attachment for the Trapezius and SCM
Superior Nuchal Line
This line serves as an attachment for the sub occipital muscles?
Inferior Nuchal Line
What is the area above the highest nuchal line named? What is a unique feature of this structure?
Planum Occipitale - Smooth part of the occiput
What is the main difference between the Planum Occipitale and the Planum Nuchale?
Occipitale is smooth where the nuchale has ridges.
The cranial surface of the occiput is deeply _________ so that it can fit these two parts of the brain?
Concave
Cerebral and Cerebellar
The concavity of the cranial surface of the occiput is divided into how many fossae?
4
The superior 2 fossae of the occiput house what lobes of the cerebral hemispheres?
Occiptal
What fossae house the two cerebellar hemispheres?
The two inferior fossae
What structure is extending superior form the IOP?
Sulcus for the superior sagittal sinus
This structure is an extension of dura mater proper that separates the two cerebral hemispheres?
Falx Cerebri
What is the function of the Tentorium Cerebelli?
This is an extension of the dura mater proper that separates the cerebral hemispheres above from the cerebellar hemispheres below.
The margins of what sulci serve as the attachment for the Tentorium Cerebelli?
Sulci for the Transverse Sinus
In what direction must we extend from the IOP to find the Sulcus for the Occipital Sinus?
Inferiorly
Another term for a large dilated vein?
Sinus
Where are dural sinuses formed?
Between the two layers of the cranial dura mater.
The lateral portions of the occiput aka ________ ________.
Condylar portions
Where are the condylar portions located in relation to the F.Mag?
Laterally on each side of the F.Mag.
The occipital condyles are directed how in space?
Anteriorly and medially
What type of connective tissue lines the occipital condyles
Hyaline Cartilage
Where is the Hypoglossal Canal located in relation to the occipital condyles?
Antero-lateral aspect of the condyles.
What runs through the Hypoglossal Canal?
Hypoglossal Nerve
The Jugular process that is located lateral to the condyles is the attachment point for this muscle?
Rectus Capitis Lateralis
The Jugular notch transmits what three nerves?
Cranial Nerves IX, X, and XI
Describe the location of the basilar portion of the Occiput?
It is anterior to the F.Mag where it meets the Basilar Portion of the Sphenoid bone.
What two bones make up the Clivus?
Occiput and Basilar Portion of the Sphenoid bone
What is the name of the tubercle that is on the inferior surface of the basilar portion of the Occiput?
Pharyngeal Tubercle
The primary part of each vertebra consist of these parts?
Body
Vertebral (Neural) Arch
7 Processes
What are the typical cervical vertebrae?
C3-C6
Normally, all seven cervical vertebrae form this tip e of curve?
Lordotic Curve, convex anteriorly
Lateral lips that project superiorly on either side of the body are called?
Uncinate Processes
What is the Uncovertebral Joint of Luschka?
An articulation where the lateral indentations on the inferior aspect of the bodies, the Uncinate Fossa, articulate with the uncinate process of the v.body below.
What part of the vertebra do the pedicles connect?
The vertebral arch to the body of the vertebra
In what direction do the pedicles project?
Posterolaterally
What structure travels through the transverse foramina of C1-C6 but not through C7?
Verterbal Artery
What structure does the Vertebral Artery pass through before it goes through the foramen magnum and the brain stem?
The posterior Atlanto-Occipital Membrane
The two superior articular facets face what directions?
Posteriorly, Superiorly and slightly medially
The articular processes when stacked up on top of one another form what structure?
Articular Pillar
What structure forms the posterior boarder of the Neural Arch?
Lamina
How are the lamina of adjacent vertebrae attached to each other?
Ligamentum Flavum
The tubercles at the end of the SP allow for the attachment of what structures?
Ligamentum Nuchae and Interspinalis muscles.
What is the typically size posterior to anterior in diameter of the cervical canal?
12-13 mm
Name the structure that forms the SUPERIOR border or roof of the IVF
Inferior notch of the pedicle of the vertebra above
The uncinate process of lower vertebra and uncinate ross of the upper vertebra form what part of the IVF?
Anterior Border
This structure make sup the inferior border or floor of the IVF
Superior notch of the pedicle of the vertebra below.
What is the unique characteristic of C6?
Carotid Tubercles - located on the right and left anterior tips of the TPs. Named because of their close proximity to the common carotid artery.
What is the last freely moveable vertebra upon flexion and extension?
C6
Where are the primary ossification centers found in the Atlas? The secondary centres?
One in each lateral mass
Secondary in the anterior arch
What arch is bigger in the Atlas posterior or superior?
Posterior
What structure attaches to the anterior tubercle of the anterior arch or our Atlas?
ALL anteriorly
Longus Colli muscles laterally
Where on the Atlas is the articular facet for dens located?
Posterior aspect of Anterior Arch
What articulation allows for rotation of C1 around C2?
Atlas and Dens of C2
Where is the Groove for the Vertebral Artery located on the Atlas?
Posteromedially of Lateral masses on the superior aspect of the posterior arch.
What other important structure emerges from the Groove for the Vertebral Artery?
Dorsal primary ramus of C1 Nerve (suboccipital)
What connects C0 to C1?
Posterior Atlanto-Occipital Membrane
What can happen to the Atlanto-Occipital Membrane?
It can ossify creating a “bridge” known as Posterior Ponticus. Bridge can be partial or complete.
If the ossification of the AO membrane is complete a hole is formed called?
Arcuate Foramen
There is controversy surrounding this condition relating to the ossification of the AO Membrane?
Vertebro-Basilar Arterial Insufficiency VBAI
The superior articular facets of Atlas are what shape?
Kidney bean or peanut shape
What is the primary movement of the Atlanto-occipital joint?
AP rocking for flexion/extension
How are the inferior articular facets different than the superior on the Atlas?
They are more oval or circular shape
What cervical vertebra is the widest?
C7
How man primary ossification centres does the Axis have?
5
- 1 in the body
- 2 in the neural arch
- 2 in the dens
How many secondary ossification centres are there and where are they located on the Axis?
2
- 1 in the dens
- 1 in the inferior aspect of the body
The Dens is made up of 3 ossification centres. Describe how they come together to form the Dens.
Two laterally placed and one apical secondary centre.
What structure is located on the anterior surface of the dens?
Articular Facet for Fovea Dentis
This ligament attaches to the posterior aspect of the Dens
Transverse Ligament of Atlas
This ligament attaches the superior tip (apex) of the dens to the occiput?
The Apical Ligament
Describe the function of the transverse ligament?
It connects the two lateral masses of C1 and holds the dens against the anterior arch of the Atlas
These ligaments attach the lateral aspect of the dens to the Occiput
Alar Ligaments
What two conditions exist in which the dens is not attached to the body?
Os Odontoideum - dens fails to fuse with the body of C2
Odontoid Fracture - acquired condition in which the dens is broken away from the body of C2
What is the mechanism of failure in Os Odontoideum?
Failure of the 2dary ossification centre in the apex of the dens to fuse with the 1ary centre of the body.
What condition related to the Dens would show up as jagged edges on a radiograph?
Odontoid Fracture
This structure of the Axis is thick from A to P and S to I
Pedicles
Is the Superior Articular Surfaces of Axis part of the Articular Pillar?
No - they lie anterior to the pillar which begins with the inferior articular process of C2
The inferior articular surfaces of the Axis face what directions?
Anterior, inferior, and lateral
Why is C7 atypical?
Its spinous process is NOT bifid
What does not travel through the TP’s of C7?
Vertebral artery
What is a cervical rib?
When the anterior tubercle on the anterior root of the C7 TP fails to fuse to the TP it can remain this distinct structure.
Define Transitional Vertebrae of the Spine
Areas of structural transition between two adjacent, varying regions of the spine. For example: C7 & T1 or T12 & L1
What shape are the occipital condyles?
Convex
C0/C1 are what type of joints?
Synovial