Osteology and Radiology of the Skull and Cervical spine Flashcards
Which regions of the spine maintain the primary and secondary curvature?
Primary: Thoracic, sacral and coccygeal
Secondary: cervical and lumbar
What are the seven processes (projections) off the vertebral arch?
1 Spinous process
2 transverse processes
2 articulate processes
What is another term for an articulate process?
Zygapophyses
Name three primary functions of the cervical spine
- Support skull
- Allow for skull movement
- Transmit nervous and vascular structures
How many spinal nerves and cervical vertebra do you have?
8 spinal nerves and 7 cervical vertebra
Describe the characteristics of a typical cervical vertebra
Smallest of the vertebra
- bifid spinous process
- transverse foramen IN transverse process which allows for a conduit for vertebral artery and vein
- Large triangular vertebral foramen to allow for innervation of the upper limb
- small dome shaped body
What are uncinate processes and what is their function?
They are the upward lips of the edges of the cervical vertebra’s body and they restrict the amount of lateral flexion that can be done by the cervical vertebra
Which cervical vertebra are atypical? What are their ‘special names’ if any?
C1: ATLAS
-no body and no spinous process
C2: AXIS
-has an odontoid process called dense (which articulates with a facet on C1)
C7: no special name :(
- no bifid spinous process and no transverse foramen in its transverse processes
- spinous process called vertebral prominence (extra long)
Name the ‘3 lines of the cervical region’ from anterior-posterior
- Anterior
- Posterior
- Spinolaminar
What is a fracture of the atlas called? How might it occur and how does it typically present?
Jefferson’s fracture (C1)
Head first fall from height (i.e diving into pool)
Pain but typically no neural signs
What is a fracture of the axis called? How might it occur and how does it typically present?
Hangman’s fracture (C2)
Hyper extension of the head on the neck
Which bones compose the skull?
Cranium + mandible
Which joint is the ONLY movable joint of the skull in an adult and where is it?
Temperomandibular joint
The articulation between the mandible (jaw) and the cranial base
What are sutures?
Fibrous joints which interlock the bones that compose the skull
How many bones are there in the skeleton of the head?
22 discrete bones
Name three general functions of the skull
- Encloses/protects brain and special sensory organs (Estes, ears, tongue, nose)
- Creates specialized environment for brain to thrive
- Site for muscle attachments and meninges
Which areas of the cranium are especially thick and especially thin?
Thick: occipital and frontal bones
Thin: pterion, squamous part of temporal bone (covered by thick muscle)
Which bones does the cranial bone form? What lies between them?
Cranial bones form the calvaria (vault of the neurocranium) and the cranial base.
The Cranium has a tri-lamina bony structure
2 plates of thick and resilient compact bone (an outer and inner plate)
1 middle layer of spongy bone/ “diploe layer” which reduces the weight of the cranium
Describe the overall structure of the mandible
Formed by the union of R and L mandible bones joined by the mental symphisis (midline fibrous joint)
Which part(s) of the mandible do and don’t articulate with the skull?
Does articulate with skull: Condylar process
Doesn’t articulate with skull: coronoid process
What makes the sutures of the skull especially strong?
Bony edges are serrated which allows them to interlock (making it less likely for them to easily unlock when force is applied in one direction)
Name the four sutures that join the cranium and the three ‘points’ where the sutures join
Sutures: coronal, sagittal, lambdoid, squamous
Sutures join at the:
- Bregma: coronal and sagittal
- Lambda: lambdoid and sagittal
- Pterion: joins temporal, frontal, parietal and occipital bones
What are the cranial fossa? Name them and the nerves associated with them
The floor of the cranial cavity is divided into three depressions/fossa
- Anterior fossa: CN I and II
- Middle fossa: CN II-VI
- Posterior fossa: CN VII-XII
Where is the CNII foramen?
On the junction between the anterior and middle fossa
What determines the number of a cranial nerve?
CN are numbered 1-12 based on how they exit the cranial base from an anterior-posterior direction
Which bones are associated with the anterior cranial fossa?
Frontal, ethmoid and sphenoid
Which holes are associated with the anterior cranial fossa and what are their associated nerves?
Olfactory foramina in cribriform plate (CNI) Optic canal (CNII)
Which bones are associated with the middle cranial fossa?
Sphenoid and temporal
Which holes are associated with the middle cranial fossa and what are their associated nerve(s) and/or vessel(s)?
- Superior orbital fissure: “Live frankly to see absolutely no insult”
-Lacrimal and frontal divisions of ophthalmic nerve V1
-Trochlear n IV
-Superior division of oculomotor n III
-Abducens VI - Foramen rotundum (CN V2 - maxillary nerve)
- Foramen ovale (CN V3 - motor/muscles of mastication)
4, Foramen spinosum (MMA enters the cranial cavity via this foramen)
Which bones are associated with the posterior cranial fossa?
Temporal, occipital and bits of sphenoid and parietal
Which holes are associated with the posterior cranial fossa and what are their associated nerve(s) and/or vessel(s)?
- Foramen magnum - spinal cord and spinal roots of the accessory nerve (CN XI)
- Internal acoustic meatus (CN VII, VIII - vestibulocochlear n (transmits sound from inner ear to brain))
- Jugular foramen (CN IX, X, XI) + Internal jugular vein
- Hypoglossal canal (CN XII - hypoglossal n to the tongue)
What is the major opening of the skull?
Foramen magnum
Where does the facial nerve exit the skull?
*Where does its come from directly prior and what does it do right after?
Comes from the internal acoustic meatus and through the middle ear and then out the stylomastoid foramen!
*the foramen is between styloid and mastoid processes of the temporal bone
It then passes through the parotid gland and gives off 5 branches (to Zanzibar by motor car)
Why is the cranial base at an increased risk of fracture?
As there are a large number of foramina on the skull floor/cranial base which weakens it
Which general nerves enter and exit the foramina at the cranial base?
Enters: sensory and sympathetic fibres
Exits: motor and parasympathetic outflow
What does the frontal bone form?
The upper border of the orbital margins and roof of orbit
Where is the ethmoid bone and what nerve does it allow passageway of to the brain?
Ethmoid bone is NESTED in the midline in the anterior fossa and allows for passage of olfactory nerve CNI from nasal mucosa to the brain (through the holes in the cribriform plate and crista galli)
What is the topmost part of the ethmoid bone?
What symptoms could a damaged ethmoid lead to?
Crista galli
Poor sense of smell (if olfactory nerve is separated), nose bleeds and CSF leak
Which bone of the skull is ‘bat shaped’? Where is it and which sinuses does it contain?
Sphenoid bone; sits at the upper aspect of the nasal cavity
Contains the sphenoid sinuses (most posterior of the paranasal sinuses)
Which nerve and vessel threads through the sphenoid bone?
Optic nerve and ICA