Week 3.1 - Osteology Flashcards
Name the curvatures of the spine
- Cervical and lumbar are secondary curvatures
- Thoracic and sacral and primary curvatures
State 3 distinguishing features of a typical cervical vertebrae
- Bifid spinous process
- Transverse foramen
- Large vertebral foramen
Which cervical vertebrae are atypical?
-1, 2, 7
What is different about atlas?
-No body or spinous process (concentric ring)
What is the main distinguishing feature of axis?
-Odontoid process (the dens)
What is the main distinguishing feature of C7 which makes it atypical?
-Prominent spinous process which is not bifid
Which movement of the head does atlas permit?
-Yes movement
Which movement of the head does axis permit?
-No movement
Why are there many ligaments between the vertebrae?
-To strengthen
On an anteroposterior radiograph of the cervical spine, from which vertebrae can you see?
-C3
On an lateral radiograph of the cervical spine, from which vertebrae can you see?
-C1
Describe a burst fracture (Jefferson fracture)
-Between 2-4 fractures within C1 (atlas) resulting from occiput condyles being driven into C1 eg head first fall from a height/diving into shallow water
Describe a hangmans fracture
- Bilateral fracture of C2
- Caused by hyperextension of the head on the neck -> compresses the brain stem
What does the skull refer to?
-Cranium + Mandible
How many bones in the skull?
-22
How are most bones of the skull joined?
-Fibrous joint (symphysis) known as a suture
What is the only movable joint in the skull?
-TMJ
What is the name for the major opening into the skull?
-Foramen magnum
How are sutures specialised for their function?
-Serrated edges allows bones to firmly interlock with one another resisting force in one direction
What gives the skull its protective function?
- The bones are flat bones which means they are dense and strong
- They are arranged in a trilaminar structure with 2 plates of compact bone and 1 middle layer of spongy bone
What is thought to be the function of the layer of spongy bone in the skull?
-Reduce the weight of the cranium
Is the cranium the same thickness all the way around?
-No it varies in thickness eg occiput and frontal bone are thick and pterion is thin
How does the mandible form?
-Two separate bones which fuse together by a midline fibrou joint known as the mental symphysis
What is the calvaria?
-Bony housing of the brain made up by 8 bones
What are the main bones of the cranial cap?
- Frontal
- Parietal
- Occipital
- Temporal
Describe the sutures of the cranial cap
-Coronal, saggital and lamboid suture with point lines bregma and lambda
What is the cranial fossa?
-The cranial floor
How is the cranial fossa divided and state the cranial nerves associated with each part?
- Anterior fossa 1
- Middle fossa 2-6
- Posterior fossa 7-12
State the main bones of the cranial fossa
- Frontal
- Ethmoid
- Sphenoid
- Temporal
- Occipital
- Palatine plate
What is the purpose of the foramina in the cranial fossa?
- Lessen weight of skull
- Allow anatomical structures to pass in and out of cranial cavity
Where is the frontal bone?
- Anterior of skull vault
- Contributes to superior orbit
Where is the ethmoid bone?
-Midline of anterior cranial fossa
What is specialised about the ethmoid bones?
- Contains cribriform plate to allow passage of olfactory nerves
- Contains ethmoidal air cells
Describe the sphenoid bone
Where is it located?
- Butterfly shaped bone (greater and lesser wings) with central body containing sphenoid sinus
- Median of middle cranial fossa, forms back of orbit
Where is the parietal bone?
-Forms a large part of the roof and sides of cranial cavity
Describe the temporal bone
-6 parts to the bone:
squamous, mastoid, tympanic, styloid process, zygomatic process, petrous part
To which sense does the parietal bone contribute?
-Hearing (and balance)
Describe the occiput
-4 parts arranged around foramen magnum:
Squamous (posterior)
L+R Condylar (edges of foramen)
Basilar (anterior)
What are the differences between a neonate and adult skull?
- Cranial sutures are open
- Adjacent bones held together by thick connective tissue matrix in the bregma and lamba regiones and are known as fontanelles
Explain how the neonate skull is specialised for full-term birth
- Open sutures allow movement during partum
- Cranial bones pushed together and serrated edges temporarily interlock to protect brain
Explain how the neonate skull can cause problems at pre-term birth
- Cranial sutures too wide open
- Pressures from birthing process do not result in interlocking of sutures leaving a probability of brain damage
How many cervical vertebrae?
-7
