Extracranial vasculature of head and neck and CNS

Question 1

Where does the external carotid arise from the common carotid?

Answer 1

Upper border of thyroid cartilage C4

Question 2

Abi’s mneunonic for extneral carotid

Answer 2

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

Question 3

What does the maxillary give rise to?

Answer 3

Middle meningeal - extradural haemorrhage & pterion

Question 4

Discuss subclavian

Answer 4

Left from arch, right from brachiocephalic trunk

In relation to the scalene muscles, subclavian gets divided into three segments - prescalene, retroscalene and postscalene

1. 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

2. Retroscalene
   * Costocervical trunk - posterior cervical muscles and upper thorax
3. Postscalene
   * Dorsal scapular - trapezius, lev scap, rhomboid

VIT C and D

vertebral, internal thoracic, thyrocervical, costocervical, dorsal scapular

Question 5

Pulses

Answer 5

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

Question 6

Where does the common carotid typically bifurcate?

Answer 6

C3/4 - into internal and external

Question 7

Blood supply of thyroid gland

Answer 7

Superior thyroid - external carotid

Inferior thyroid - subclavian thyrocervical trunk

Question 8

Discuss veins of face and neck

Answer 8

Deep veins = internal jugular and subclavian

Superficial veins = external and anterior jugular

Question 9

Discuss external jugular

Answer 9

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

Question 10

Discuss anterior jugular vein

Answer 10

Paired veins draining anterior neck

Empty into subclavian

Question 11

Internal jugular vein

Answer 11

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

Question 12

Central Lines

Answer 12

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.

Question 13

Jugular Venous Pressure

Answer 13

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

Question 14

What is the superficial ring of lymph nodes that drains the lymph from scalp, face and neck

Answer 14

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

Question 15

Which nodes drain from the tongue?

Answer 15

Submental and submandibular

Question 16

What are the deep lymph nodes?

Answer 16

Everything drains into them

Located around the IJV

They are the jugulodigastric, deep cervical and jugular omohyoid

Question 17

Discuss retropharyngeal lymph nodes

Answer 17

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.

Question 18

Discuss tonsils

Answer 18

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

Question 19

Discuss lymph drainage of the tongue

Question 20

Which space do the cerebral veins run in?

Answer 20

Subarachnoid - then pierce the meninges to drain into the dural venous sinuses

Question 21

Which layers of dura do dural venous sinuses lie? What do they all ultimately drain into? Do they have valves?

Answer 21

Periosteal and meningeal mater

Internal jugular vein

no

Question 22

Discuss great cerebral vein

Answer 22

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

Question 23

Where do the superficial cerebral veins lie?

Question 24

Describe location of confluence of sinuses

Answer 24

Adjacent to internal occipital protuberance

Question 25

Order of sinuses

Answer 25

Superior sagittal + striaght -> confluence -> transverse -> sigmoid -> internal jugular vein at jugular foramen

Question 26

Which sinuses are found in the falx cerebri of dura mater?

Answer 26

Superior, straight, inferior

Question 27

What veins does the cavernous sinus drain? Where can it be found?

Answer 27

Ophthalmic

Either side of sella turcica

Question 28

Describe superior or inferior petrosal sinuses

Answer 28

Cavernous sinus -> superior or inferior petrosal -> internal jugular

Question 29

Where do internal carotids originate from? At what level?

Answer 29

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).

Question 30

What do the internal carotids travel in?

What else travels in this?

Answer 30

Carotid sheath

Part of deep cervical fascia

Surrounds:

• Common carotid artery
• Internal carotid artery
• Internal jugular vein
• Vagus nerve

Question 31

Where do internal carotids enter the brain?

Answer 31

Carotid canal of temporal bone

Question 32

What does each ICA give rise to?

Answer 32

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)

Question 33

Discuss regional blood supply to the cerebrum

Answer 33

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.

Question 34

Where do the vertebral arteries arise from? Where do they travel? Where do they enter skull?

Answer 34

Subclavian

Transverse foramen (not C7)

Foramen magnum

Question 35

Discuss vertebral artery branching

Answer 35

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.

Question 36

Which aspect of the medulla do the vertebral arteries pass over?

Answer 36

Ventral

Question 37

What does the labyrinthine artery arise from and what does it supply?

Answer 37

From AICA

Supplies the inner ear

Question 38

Draw the circle of Willis

Answer 38