Anatomy Flashcards
Describe the passage of CSF
- Produced by choroid plexi in each ventricle
- Lateral ventricles
- Interventricular foraminae (of Monro)
- Third ventricle
- Cerebral aqueduct (of Sylvius)
- Fourth ventricle
- 1 median foramen (of Magendie), 2 lateral foramenae (of Luschka)
- Sub-arachnoid space (incl. cisterns)
- Reabsorbed by arachnoid granulations
How much CSF is produced per day?
500mL
What is the normal volume of CSF?
150mL
What communicates between the lateral and third ventricles?
Interventricular foramenae (of Monro)
What communicates between the third and fourth ventricles?
Cerebral aqueduct (of Sylvius)
What communicates between the fourth ventricle and the sub-arachnoid space?
1 median foramen (of Magendie) and 2 lateral foraminae (of Luschka)
Explain why there can be blood in the ventricular system in a sub-arachnoid bleed
The ventricular system and the sub-arachnoid space communicate via the foramenae in the fourth ventricle
What are the three brain herniation syndromes in traumatic brain injury?
- Sub-falcine
- Trans-tenthorial
- Tonsillar
What structure is likely to be compromised in a sub-falcine herniation syndrome and what is the clinical presentation?
Medial frontal cortex (mimics anterior cerebral artery ischaemia)
What structure is most commonly compromised in transtentorial herniation and what is the clinical syndrome?
Occulomotor nerve (ipsilateral loss of pupillary constriction)
What structure is most likely to be compromised in tonsillar herniation and what is the clinical syndrome?
Medulla (loss of respiratory function)
What ligaments make up the three column model of vertebral column injury?
- Anterior longitudinal ligament
- Posterior longitudinal ligament
- Ligamentum flavum
What ligament connects the lateral masses of C1? What movement does it prevent?
Transverse ligament. Prevents anterior atlanto-axial translation by contact the dens.
Define the borders of the three column model of vertebral column injury
Anterior column — anterior longitudinal ligament to anterior two-thirds of vertebral body
Middle column — posterior third of vertebral body to posterior longitudinal ligament
Posterior column — posterior to posterior longitudinal ligament (includes pedicles, facets, ligamentum flavum)
According to the three column model of vertebral column injury, how many columns must be affected to produce an unstable fracture?
greater than one
Describe the course of the vertebral artery
Subclavian artery
Transverse foramen of C6
Transverse foramen of C1
Postero-medial “dog leg” over posterior arch of C1
Foramen magnum
Joins contralateral vertebral artery to form basilar artery
Most common site for vertebral artery injury
Segment between C1 foramen and foramen magnum (performs postero-medial turn over C1 posterior arch)
What is the distinction between intracranial and extracranial vertebral artery? What is the consequence of this?
All intracranial arteries lack external elastic lamina and have thinner intima. Consequence: increased likelihood of sub-arachnoid bleeding in intracranial vertebral artery dissection
Key sensory point: C2
At least one cm lateral to the occipital protuberance at the base of the skull. Alternately, it can be located at least 3 cm behind the ear.
Key sensory point: C3
In the supraclavicular fossa, at the midclavicular line.
Key sensory point: C4
Over the acromioclavicular joint.
Key sensory point: C5
On the lateral (radial) side of the antecubital fossa just proximal to the elbow (see image below).
Key sensory point: C6
On the dorsal surface of the proximal phalanx of the thumb.
Key sensory point: C7
On the dorsal surface of the proximal phalanx of the middle finger.
