Extracranial vasculature of head and neck and CNS Flashcards
Where does the external carotid arise from the common carotid?
Upper border of thyroid cartilage C4
Abi’s mneunonic for extneral carotid
Some anatomists like freaking out poor medial students
From bottom to top
Superior thyroid - supplies superior part of thyroid and larynx
Ascending pharyngeal - supplies the tonsils
Lingual - floor of mouth, incl tongue
Facial - around inferior border of manible looping over submandibular gland towards medial angle of the eye and provides major arterial supply to the face
Occipital
Posterior auricular
Maxillary artery - embedded in parotid gland. Deep structures of the face
Superficial temporal - arises between temporomandibular joint and auricle to supply temple and scalp
What does the maxillary give rise to?
Middle meningeal - extradural haemorrhage & pterion
Discuss subclavian
Left from arch, right from brachiocephalic trunk
In relation to the scalene muscles, subclavian gets divided into three segments - prescalene, retroscalene and postscalene
- Prescalene
- Vertebral - merge at pontomedullary junction to form basilar
- Internal thoracic - descends anterior chest wall (ant wall and breast)
- Thyrocervical trunk - inferior thyroid artery - supplies larynx, pharynx, trachea, oesophagus, thyroid parathyoid
- Retroscalene
* Costocervical trunk - posterior cervical muscles and upper thorax - Postscalene
* Dorsal scapular - trapezius, lev scap, rhomboid
VIT C and D
vertebral, internal thoracic, thyrocervical, costocervical, dorsal scapular
Pulses
Carotid in neck
- Common carotid: posterolateral to larynx External carotid: lateral to larynx between thyroid cartilage and hyoid bone
Facial over jaw
Superficial temporal over zygomatic process
Where does the common carotid typically bifurcate?
C3/4 - into internal and external
Blood supply of thyroid gland
Superior thyroid - external carotid
Inferior thyroid - subclavian thyrocervical trunk
Discuss veins of face and neck
Deep veins = internal jugular and subclavian
Superficial veins = external and anterior jugular
Discuss external jugular
drains external cranium and deep structures of the face
formed from posterior auricular branch and retromandibular braches joining inferior to outer ear
then descends neck in superficial fascia
passes underneath clavicle and drains into subclavian vein
Discuss anterior jugular vein
Paired veins draining anterior neck
Empty into subclavian
Internal jugular vein
Begins as continuation of sigmoid sinus
Leaves via jugular foramen
Descends in carotid sheath (deep)
IJV combines with the subclavian vein to form the brachiocephalic vein
2 brachiocephalic veins form the vena cava
Central Lines
Also known as central venous catheterisation, this procedure involves the insertion of a sterile tube (catheter) into either the subclavian or internal jugular veins, permitting blood sampling and long-term administration of drugs and artificial nutrition. Central lines have greater longevity, security and variety of uses compared to peripherally placed catheters.
Jugular Venous Pressure
The JVP is commonly examined during cardiovascular exams. It is normal to observe pulsations from the internal jugular vein within the neck, particularly when the patient is lying down.
Higher pressure = higher in the neck
The JVP can be differentiated from the carotid pulse by being a double waveform, variable with respiration, lost on pressure and by not being palpable
What is the superficial ring of lymph nodes that drains the lymph from scalp, face and neck
Submental
Submandibular
Parotid
Mastoid
Occipital
Some say pears marry oranges
All ultimately pass to deep cervical along internal jugular vein –> then to jugular lymphatic trunk –> drains thoracic duct on left and the internal jugular vein on the right
Which nodes drain from the tongue?
Submental and submandibular
What are the deep lymph nodes?
Everything drains into them
Located around the IJV
They are the jugulodigastric, deep cervical and jugular omohyoid
Discuss retropharyngeal lymph nodes
The retropharyngeal lymph nodes lie behind the superior pharynx and are responsible for draining the nasopharynx and auditory meati. Infections of the space in which these nodes are located can cause the formation of a retropharyngeal abscess, which can lead to airway obstruction and frequently require surgical drainage.
Discuss tonsils
Waldeyer’s Tonsillar Ring is a ring of lymphatic tissue that surrounds the naso- and oropharynx, consisting of the two adenoid tonsils (located in the roof of the nasopharynx), two tubal tonsils (located at the opening of the Eustachian tube), two palatine tonsils (the common tonsils, located between the palatoglossal and palato- pharyngeal arches) and one lingual tonsil (at the posterior base of the tongue).
You have 2x tubal and lingual and 1x pharyngeal and 1x lingual
Important in fighting infection
Discuss lymph drainage of the tongue
Which space do the cerebral veins run in?
Subarachnoid - then pierce the meninges to drain into the dural venous sinuses
Which layers of dura do dural venous sinuses lie? What do they all ultimately drain into? Do they have valves?
Periosteal and meningeal mater
Internal jugular vein
no
Discuss great cerebral vein
The internal structures of the forebrain drain into this
There are 2 internal cerebral veins - one for each hemisphere - join to form great cerebral vein
Drains into straight sinus
Where do the superficial cerebral veins lie?
Describe location of confluence of sinuses
Adjacent to internal occipital protuberance
Order of sinuses
Superior sagittal + striaght -> confluence -> transverse -> sigmoid -> internal jugular vein at jugular foramen
Which sinuses are found in the falx cerebri of dura mater?
Superior, straight, inferior
What veins does the cavernous sinus drain? Where can it be found?
Ophthalmic
Either side of sella turcica
Describe superior or inferior petrosal sinuses
Cavernous sinus -> superior or inferior petrosal -> internal jugular
Where do internal carotids originate from? At what level?
The internal carotid arteries (ICA) originate at the bifurcation of the left and right common carotid arteries, at the level of the fourth cervical vertebrae (C4).
What do the internal carotids travel in?
What else travels in this?
Carotid sheath
Part of deep cervical fascia
Surrounds:
- Common carotid artery
- Internal carotid artery
- Internal jugular vein
- Vagus nerve
Where do internal carotids enter the brain?
Carotid canal of temporal bone
What does each ICA give rise to?
Ophthalmic artery - supplies structures of each orbit, frontal and ethmoid sinuses, dorsum of nose and anterior scalp
Posterior communicating - circle of Willis
Anterior choroidal - motor control and vision
Anterior cerebral - frontal lobes and superior medial parietal lobes (runs in great longitudinal fissure). Regions that correspond to motor and sensory cortices.
Continues as middle cerebral - lateral fissure (separating frontal and parietal from temporal). Supplies lateral frontal, parietal and temporal. Doesnt do lower limb. Also does auditory cortex and insula
*remember top of brain controls bottom of body (lower limb)
Discuss regional blood supply to the cerebrum
The anterior cerebral arteries supply the anteromedial portion of the cerebrum.
The middle cerebral arteries are situated laterally, supplying the majority of the lateral part of the brain.
The posterior cerebral arteries supply both the medial and lateral parts of the posterior cerebrum.
Where do the vertebral arteries arise from? Where do they travel? Where do they enter skull?
Subclavian
Transverse foramen (not C7)
Foramen magnum
Discuss vertebral artery branching
Meningeal branch – supplies the falx cerebelli, a sheet of dura mater.
Anterior and posterior spinal arteries – supplies the spinal cord, spanning its entire length.
Posterior inferior cerebellar artery – supplies the cerebellum and choriod plexus of 4th venticle
Then converge to form basilar at medullopontine junction
Produces pair of AICAs - supply cerebellum
Pontine arteries
Superior cerebellar
Ultimately forms posterior cerebral which supplies visual cortex of occipital lobe and inferomedial temporal lobe.
Which aspect of the medulla do the vertebral arteries pass over?
Ventral
What does the labyrinthine artery arise from and what does it supply?
From AICA
Supplies the inner ear
Draw the circle of Willis
