Meninges, blood vessels & lymphatics Flashcards
What are the 3 menigeal layers, brefily describe them
- Dura (2 tough fiberous membranes) - Arachnoid (a soft translucent membrane surrounding the brain which doesnt go into the sulci) - Pia (thin membrane closely adhered to the brain surface which dives into ever sulci)
What are the two layers of dura called?
- The periosteal layer - The meningeal layer
Describe the formation of the dural venous sinuses
- periosteal dura stays adhered to skull - meningeal dura folds down into sulci/ fissures in the skull to create a space - venous blood flows in this space
What are the names of the dural folds and dural venous sinuses that go down the longitudinal fissure and above cerebellum?
- Falx ceribri is fold between hemispheres of the brain, it creates the superior SAGGITAL sinus - The tenortium ceribelli is fold at ceribellum, it forms the transverse and so sigmoid sinuses
Describe the collection and drainage of the dural venous sinuses (inc cavernous sinus)
- inferior saggital meets great cerebral vein and drains into straight sinus - staight sinus, superior sigmoid and occipital sinus meet at the confluence of sinuses on the back part of the skull - these drain L and R into transverse sinuses - Transverse become sigmoid sinuses which drain into the inferior vena cava - many veins (notably the opthalmic vein) drain into the cavernous sinus, which drains into the IJC via the inferior and superior petrosal sinuses.
How is the scalp drained? (4)
- through emissary veins into the dural venous sinuses and eventually IJC - superior temporal, posterior auricular and occipital veins drain into the EJV and into the subclavian vein
How is the face drained?
- much of face drains into the facial vein and straight into IJV - Opthalmic veins drain from orbit into cavernous sinus - much of maxilla and nasal cavity drains into the pterygoid plexus (below base of skull but behind mandible) - this drains straight into IJV via maxillary vein but also into the cavernous sinus
Why is the area around the nose and eyes a danger zone?
Because this is the area of greatest drainage into the cavernous sinus, so route for infection to spread into brain and increase risk of cavernous sinus thrombus.
What is a cavernous sinus thrombus, what is its significance?
The thrombus can be causes by any stagnantion but commonly from infection. It compresses the nerves within the cavernous sinus (occulomotor, opthlamic, throclear, abducens and maxillary nerves), as well as increasing ICP and causing headaches ect.
At what level in the neck does the common carotid artery bifucate?
at upper boarder of thyroid cartilage
What arteries supply the brain? describe their route
- vertebral artery- comes off common carotid and traves through transverse foramen on C1-6 - ICA doesnt have any branches in the neck, it enters carotid canal, makes S shape, then through cavernous sinus
Some anatomists like freaking out poor medical students
What are the 8 branches of the ECA as they arise?
some anatomists like freaking out poor medical students: 1. Superior thyroid 2. ascending pharygeal 3. lingual 4. facial 5. occipital 6. posterior auricular 7. maxillary 8. superficial temporal
What are the 2 significant branches of the maxillary artery?
- sphenopalantine: to nose, bleeds in nose bleeds
- middle meningeal: runs under pterion so at risk if you get hit in temple- causes epidrual haemorrhage
What are the 3 main types of intra cranial haemorrhage, where is the bleed and what do they look like on a CT?
- epidural/ extradural: between skull and periosteal dura, looks like a lemon/ eggs 2. subdural: between meningeal dura and arachnoid, looks like bannana 4. subarachnoid, between arachnoid and dura dont need to know CT appearance
What does epidrual look like lemon and subdural look like a banana?
because epidrual bleeds are confined within the boundaries of the suture lines so once the fill this space they start filling upwards into the brain to make eggshape
What vessels commonly bleed in an epidural, sudural and subarachnoid haemorhage?
epidural= middle meningeal artery subdural= bridging veins subarachnoid= circle of willis
What are bridging veins and when are they commonly ruptured?
Veins draining arachnoid into the venous sinuses. They commonly weaken with age and so can rupture from falls, shakes, trauma ect
Describe the layout of the contents of the cavernous sinus.
Remeber by CAT OTOM
Do emissary veins have valves?
No- they dont need them as drain downwards under gravity and are only small
What part of the body drains into the right lymphatic duct and what part drains into thoracic duct?
The right arm, right side of face and right side of upper body drains into right lymphatic duct.
The left arm, left head, left torso and both legs drain into the thoracic duct
What are the two main causes of enlarged lymph nodes (lymphadenopathy)?
Infection
Malignancy
What is the differnce between infected and cancerous lymph nodes?
Infected= mobile, tender, regular
Cancerous= hard, matted, irregular, non tender
Do nodes drain superficial to deep or deep to superficial?
superficial to deep
What are the 5 main budles of lymph nodes on the head (not neck)?
- Submental
- Sub mandibular
- Pre auricular
- post auricular/ mastoid
- occipital
Describe the distribution of the lymph nodes of the neck
Superficial cervical lymph nodes at top of SCM.
Anterior carvical nodes at base and anterior side of SCM.
Posterior cervical lymph nodes behind/ on trapezius
Deep cervical lymph nodes along & deep to SCM.
Supraclavicular nodes in supraclavicular fossa- at base of SCM on posterior side.
What is waldeyers ring?
a collection of lymphatic tissue surrounding the entrance to the laryngopharynx
What are the 4 tonsils called that make up the waldeyers ring?
Superior- adenoid (roof of nasal cavity)
- Tubual tonsil (floor of nasal cavity)
Lateral- palatine tonsils (lateral side of oral cavity)
Inferior- Lingual tonsil (base of oral cavity)
Whatre the names of the two deep cervical lymph nodes
The jugulo- digastric and jugulo- omohyoid
