3. Blood vessels of the H&N

Question 1

which 3 arteries supply the H and N

Answer 1

1. vertebral a. (post. neck and post. parts of brain)
2. ICA (brain, eyes and forehead)
3. ECA (head and neck external to cranium)

Question 2

name 3 vessels arising from the thyrocervical trunk, and the areas they supply

Answer 2

1. inferior thyroid a. (lower thyroid lobes)
2. ascending and transverse cervical aa. (neck)
3. suprascapular a. (post. scapula)

Question 3

describe the course of the vertebral aa.

Answer 3

L and R subclavian aa. … ascend through transverse foramina of cervical vertebrae (exc. C7)… enter cranial cavity via foramen magnum… converge to form basilar a.

Question 4

where does the CCA bifurcate into ICA and ECA

Answer 4

level of upper border of thyroid cartilage (C4) within carotid triangle

Question 5

what is the carotid body and carotid sinus, and where are these found

Answer 5

1. carotid sinus
   - dilated portion of CCA and ICA
   - contains baroRs which detect stretch as measure of aBP - glossopharyngeal n. transmits info to brain to regulate BP
2. carotid body
   - cluster of nervous cells external to carotid sinus
   - act as peripheral chemoRs: detect O2 content of blood and relay info to brain to regulate breathing rate

Question 6

what is a carotid sinus massage and where is it performed

Answer 6

apply pressure on carotid sinus (in carotid triangle)… increase vagus input to heart… terminate supraventricular tachycardia

Question 7

describe the course of the ICA

Answer 7

no branches in neck… enters cranial cavity via carotid canal in petrous part of temporal bone… turns medially and horizontally… courses through cavernous sinus… givers rise to 3 branches inc. ophthalmic a. (to orbit)

Question 8

where does the ECA terminate

Answer 8

within parotid gland - branches into 2 terminal aa.: superficial temporal a. and maxillary a.

Question 9

name the branches of the ECA

Answer 9

1. superior thyroid
2. lingual
3. facial
4. ascending pharyngeal
5. maxillary
6. superficial temporal
7. posterior auricular
8. occipital

Question 10

describe the blood supply to the scalp

Answer 10

3 branches of ECA:

• superficial temporal
• posterior auricular
• occipital

2 branches of ICA (ophthalmic a.):

• supraorbital
• supratrochlear

Question 11

describe the blood supply to the nasal septum

Answer 11

Branches from both ICA and ECA, eg

• septal br. of sphenopalatine a. (from maxillary a.) - responsible for severe post. nosebleeds
• anterior ethmoidal aa. (from ophthalmic a.)

Rich anastamosis of aa. forms Kiesselbach’s area - common site for epistaxis.

Question 12

name the artery supplying the dura and skull

Answer 12

middle meningeal a.

Question 13

describe the course of the middle meningeal a. - which type of injury may cause it damage

Answer 13

arises from maxillary a… enters middle cranial fossa via foramen spinosum… divides into ant. and post. branches… ant. branch runs over pterion

skull fracture at pterion can rupture middle meningeal a., causing extradural haematoma

Question 14

how can infections from the scalp spread intracranially

Answer 14

veins of scalp connect to diploic veins of skull via valveless emissary veins in loose CT, and thus to dural venous sinuses

Question 15

how can infections around the orbit spread intracranially

Answer 15

the ophthalmic veins drain structures of the orbit and drain mostly via the facial vein with which they
anastamose. However, these ophthalmic veins also communicate with the cavernous sinus (through the
back of the orbit), and, as the veins are valveless, venous blood can pass in either direction (i.e.
intracranially to the cavernous sinus, or towards the facial vein). Infection involving the eye/orbit, or the
area of the face (danger triangle) can therefore potentially track intracranially via these venous structures towards the cavernous sinus.

Question 16

which vessel drains the majority of the external head/neck - describe its course

Answer 16

EJV:

i. union of posterior auricular v. (drains scalp sup. and post. to outer ear) and superficial temporal v. (drains face) post. to angle of mandible…
ii. descends down neck (receiving other vv.) within superficial fascia, anterior to SCM…
iii. passes under clavicle and drains into subclavian v.

Question 17

what does the IJV drain

Answer 17

• brain, meninges, face and scalp
• continuation of sigmoid sinus… exits skull via jugular foramen… descends neck within carotid sheath (lateral to CCA)… combines with subclavian vein to form brachiocephalic vein
• during descent receives: facial, lingual, occipital, superior and middle thyroid veins

Question 18

which vessels are typically ruptured in a subdural hemorrhage - what is their function and why are they susceptible to rupture

Answer 18

• Bridging veins: cross the subdural space, from neural tissue into superior sagittal sinus
• Are stretched as brain shrinks with age - more susceptible to rupture in head trauma

Question 19

describe the drainage of cerebral veins

Answer 19

1. Cerebral veins drain into superior or inferior sagittal sinuses (or others)…
2. sagittal sinuses drain into confluence of sinuses (via straight sinus for inferior)…
3. drains into transverse sinus…
4. drains into sigmoid sinus…
5. becomes internal jugular vein as exits skull base via jugular foramen…
6. combines with subclavian vein to become brachiocephalic vein