Blood Supply to the Head & Orbit

Question 1

What is the ascending aorta?

Answer 1

The ascending aorta arises from the aortic orifice from the left ventricle and ascends to become the aortic arch. It is 2 inches long in length and travels with the pulmonary trunk in the pericardial sheath.

Question 2

What does the right common carotid feed into?

Answer 2

Head & Neck

Question 3

What does the right subclavian artery feed into?

Answer 3

Right upper limb

Question 4

What does the left common carotid artery supply?

Answer 4

Left side of the head and neck

Question 5

What does the left subclavian artery supply?

Answer 5

Left upper limb
Sometimes doesn’t have a name as it has multiple branches on it such as the left axillary artery and left brachial artery.

Question 6

What is the thoracic aorta?

Answer 6

The thoracic (descending) aorta spans from the level of T4 to T12. Continuing from the aortic arch, it initially begins to the left of the vertebral column but approaches the midline as it descends. It leaves the thorax via theaortic hiatus in the diaphragm, and becomes the abdominal aorta

Question 7

Where do the carotid arteries extend?

Answer 7

Up the neck lateral to the oesophagus and trachea

Question 8

Where do the carotid arteries split?

Answer 8

2 become 4 at C4. Internal deeper and closer to the midline, external common carotid is on the outside.

Question 9

What do the carotid arteries border?

Answer 9

Superior border is jawline/mandible, lateral border is the SCM, medially is midline of neck so carotid triangle and the Anterior triangle are the same

Question 10

Where are baroreceptors?

Answer 10

Baroreceptors are in this area (carotid bodies) and if massaged it can help slow heart rate down by stimulating the baroreceptors by pressing on the common carotid

Question 11

What is it called where arteries meet and balloon?

Answer 11

Sinus

Question 12

What is the carotid triangle the same as?

Answer 12

The anterior triangle of the neck

Superiorly– inferior border of the mandible (jawbone).
Laterally– anterior border of the sternocleidomastoid.
Medially– sagittal line down the midline of the neck.

Question 13

What is the carotid sinus?

Answer 13

Where the internal carotid and common carotid are dilated. This is where baroreceptors are.

Question 14

What does the external carotid artery supply?

Answer 14

Most lateral, supplies areas of the head and neck external to the cranium

Question 15

What is the mnemonic to remember the external carotid arteries?

Answer 15

Some
Anatomy
Lecturers
Freak
Out
Poor
Medical
Students

Question 16

What are the branches of the External Carotid Arteries?

Answer 16

Some -
Superior Thyroid Artery

Anatomists -
Ascending Pharyngeal Artery

Like -
Lingual Artery

Freaking -
Facial Artery

Out -
Occipital Artery

Poor -
Posterior Auricular Artery

Medical -
Maxillary Artery (largest)

Students -
Superficial Temporal Artery

Question 17

What are the two terminal branches (end arteries) of the external carotid arteries?

Answer 17

Maxillary Artery & Superficial Temporal Artery

Question 18

What does the Maxillary artery supply?

Answer 18

Mandibular (1st part)
Pterygoid (2nd part)
Pterygopalatine (3rd part)

Question 19

What does the superficial temporal artery supply?

Answer 19

It’s a branch of the external carotid arteries that supplies superficial structures of the face

Question 20

What do the internal carotid arteries supply?

Answer 20

Entering the cranial cavity via the carotid canal in the petrous part of the temporal bone. Within the cranial cavity, the internal carotid artery supplies:

• The brain
• Eyes (ipsilateral)
• Forehead

Question 21

Where are the internal carotid arteries in the neck?

Answer 21

Deeper in the neck

Question 22

What are the vertebral arteries?

Answer 22

Paired vessels arising from the subclavian arteries.

Thinner than the carotid arteries = more fragile. They run up the neck on the side of the vertebra in a ring to make them more protected as encased in a bit of bone from the cervical vertebra.

Question 23

Where do the vertebral arteries ascend?

Answer 23

Posterior (behind) the carotids, encased in transverse processes of the cervical vertebrae

Travel up and enter the cranium through the foramen magnum

Question 24

Where do the vertebral arteries meet? What do they form?

Answer 24

Meet at the base of the brainstem to form the basilar artery. This sits on the pons.

Question 25

What is the Circle of Willis?

Answer 25

A circular anastomoses that supplies blood to the brain and surrounding structures. Small variations can exist however the general composition is 3 cerebral arteries and 2 communicating arteries Bunch of blood vessels that meet together in a ring, called an anastomoses

Question 26

Why does the Circle of Willis exist?

Answer 26

The arrangement of the brain's arteries into the circle of Willis is believed to create redundancy (analogous to engineered redundancy) for  collateral circulation in the cerebral circulation. If one part of the circle becomes blocked or narrowed (stenosed) or one of the arteries supplying the circle is blocked or narrowed, blood flow from the other blood vessels  can often preserve the cerebral perfusion well enough to avoid the symptoms of ischemia

Question 27

Where is the Circle of Willis?

Answer 27

Tucked in against the brainstem with the lobes surrounding it

Question 28

What structures are included in the Circle of Willis?

Answer 28

Anterior spinal arteries = Dive back to feed the anterior part of the spine Anterior inferior cerebellar artery = Front, lower part of the cerebellum Pontine arteries = Arteries that feed the pons – cranial nerves come from here and the pontine respiratory group etc Superior cerebellar arteries = Goes to top of cerebellum Posterior Cerebral = Goes to back of the cerebrum Posterior communicating arteries = Link lower arteries into the circle Middle cerebral artery = Commonly affected in strokes, contralateral blood supply Ophthalmic artery = Part of the eyes Anterior communicating artery = Link left and right together

Question 29

What's included in the ACA (Anterior Cerebral Artery)?

Answer 29

- Medial frontal lobe - Superomedial parietal lobe - Internal capsule (carries both ascending and descending pathways to and from the cerebral cortex from the brainstem

Question 30

Where does the Middle Cerebral Artery supply?

Answer 30

The most of lateral surface of hemisphere i.e temporal lobe, part of parietal and frontal lobes

Question 31

What does the Posterior Cerebral Artery supply?

Answer 31

- Midbrain and thalamus – Occipital lobe and visual cortex - Inferomedial temporal lobe - Brainstem

Question 32

What is total circulation stroke (TACS)?

Answer 32

Anterior cerebral artery

Question 33

How is TACS diagnosed?

Answer 33

Total Anterior Circulation Stroke (TACS) Anterior and Middle Cerebral Arteries All 3; - unilateral weakness or sensory deficit of the face, arm and leg - Homonymous Hemianopia - Higher cerebral dysfunction (dysphasia, visuospatial disorder)

Question 34

How is Partial Anterior Circulation Stroke (PACS) diagnosed?

Answer 34

2 of these 3; - unilateral weakness or sensory deficit of the face, arm and leg - Homonymous Hemianopia - Higher cerebral dysfunction (dysphasia, visuospatial disorder)

Question 35

What is PACS?

Answer 35

Partial Anterior Circulation Stroke If furrowing of the vessels, not enough blood to keep them all functioning from Anterior Middle cerebral arteries Infarct, that’s a big clot, that disintegrates clots, but it disintegrates all other clots but we have microclots everywhere that we need = bleed

Question 36

What is Lacunar Syndrome (LACS)?

Answer 36

internal structures of brain that communicate with other lobes, between the lobes are communications called internal capsules. If these (Internal capsule) are affected it is a Lacunar Stroke.

Question 37

How do we diagnose Lacunar Syndrome (LACS)?

Answer 37

One of the following; - Pure sensory stroke - Pure motor stroke - Sensori-motor stroke - Ataxic hemiparesis

Question 38

What is Posterior Circulation Syndrome (POCS)?

Answer 38

Issue with the posterior cerebral artery issue

Question 39

How is What is Posterior Circulation Syndrome (POCS) diagnosed?

Answer 39

One of the following: - Cranial nerve palsy and contralateral motor/sensory deficit - Bilateral motor/sensory deficit - Conjugate eye movement disorder e.g. gaze palsy - Cerebellar dysfunction e.g. ataxia, nystagmus, vertigo - Isolated homonymous hemianopia or cortical blindness`

Question 40

What is the Ophthalmic Artery?

Answer 40

First branch of the ICA once it leaves the cavernous sinus

Question 41

Where does the Ophthalmic Artery enter the orbit?

Answer 41

Through the optic canal inferior and lateral to the optic nerve

Question 42

What's the pathway of the Ophthalmic Artery?

Answer 42

At its origin from the internal carotid artery, the ophthalmic artery lies within the subarachnoid space. As the ophthalmic artery runs forward within the space through the optic canal, it lies within the dural-arachnoid sheath of the optic nerve. On emerging from the optic canal, the artery pierces the meningeal sheath and comes to lie outside it. In the orbital cavity the artery runs forward for a short distance lateral to the optic nerve and medial to the lateral rectus muscle, the abducent and oculomotor nerves, and the ciliary ganglion. The artery then turns medially and crosses above the optic nerve, accompanied by the nasociliary nerve. Here it lies inferior to the superior rectus muscle. On reaching the medial wall of the orbit, it runs forward with the nasociliary nerve above the medial rectus muscle and below the superior oblique. At the medial end of the upper eyelid the ophthalmic artery divides into the supratrochlear and dorsal nasal arteries

Question 43

What are the 11 branches of the Ophthalmic artery?

Answer 43

Central retinal a. Ciliary arteries Lacrimal a. Muscular branches Supraorbital a. Posterior ethmoidal a. Anterior ethmoidal a. Meningeal a. Medial palpebral a. Supratrochlear a. Dorsal nasal a.

Question 44

What's the central retinal artery?

Answer 44

The first branch of the Ophthalmic artery. Burrows into optic nerve and travels with the optic nerve. Comes out and splits into superior and inferior retinal arteries. Can get complete occlusion which is called Central Retinal Artery Occlusion.

Question 45

Where is the central retinal artery?

Answer 45

It's the first branch of the ophthalmic artery and lies inferolateral to the optic nerve close to the optic canal. It runs forward beneath the optic nerve and turn upward to pierce the dura and arachnoid sheaths of the optic nerve. Runs forward within the optic nerve, with the central retinal vein. Enters the eyeball and divides into a superior and inferior branch. Each of these branches then divides into a superior, inferior, nasal and temporal branch.

Question 46

What do the long posterior ciliary arteries supply?

Answer 46

Long = front of the eye Usually 2, pierce sclera and run forward to ciliary body/UVEA structures (anterior part of the eye) Supply choroid, ciliary body, iris = UVEA. Middle Vascular Layer

Question 47

What do the short posterior ciliary arteries supply?

Answer 47

Short = back of the eye Pierce sclera around entrance of Optic Nerve (ON) Supply choroid 15-20% cilioretinal artery

Question 48

What is the anterior ciliary artery?

Answer 48

Supplies the sclera and conjunctiva via tendon insertions of the EOMs Comes from the Muscular Artery

Question 49

What does the Lacrimal artery supply?

Answer 49

Lacrimal gland and then moves forward to the eyelids and conjunctiva.

Question 50

What does the Lacrimal artery run near?

Answer 50

Runs in close association with the LR and runs with the Lacrimal Nerve (CN V, Ophthalmic branch)

Question 51

Where does the lacrimal artery arise?

Answer 51

Arises from the ophthalmic artery before entering the orbital cavity. Runs forward with the lacrimal nerve, on the superior border of lateral rectus.

Question 52

What do the Muscular branches of the Ophthalmic artery supply?

Answer 52

Supply the EOM's. There's normally 2 to each EOM apart from the SR where there's only one.

Question 53

Which are the highly examined branches of the Ophthalmic Artery?

Answer 53

Central Retinal Ciliary Arteries Lacrimal Muscular

Question 53

What ciliary artery comes off of the muscular branches?

Answer 53

Anterior ciliary arteries - the arteries to the rectus muscles give origin to the anterior ciliary arteries

Question 54

What nerve runs alongside the supraorbital artery?

Answer 54

Supraorbital nerve

Question 55

What does the supraorbital artery supply?

Answer 55

Roof of orbit and most superior parts of the orbit (not the recti to obliques, lacrimal supplies eyelids) such as the LPS. And skin and soft tissue around the temporal side of the eye. The supraorbital artery supplies the levator palpebrae superioris, the diploe of the frontal bone, the frontal sinus, the upper eyelid, and the skin of the forehead and the scalp.

Question 56

How does the Supraorbital artery travel?

Answer 56

Arises from the Ophthalmic artery as it crosses the optic nerve. It passes superiorly round the medial borders of the superior rectus and levator palpebrae superioris muscles. The artery then runs forward with the supraorbital nerve between the levator and the roof of the orbit.

Question 57

How does the supraorbital artery leave the orbit?

Answer 57

It leaves the orbit by passing through the supraorbital notch or foramen and ascends to the scalp deep to the frontalis muscle. Its terminal branches anastomose with branches of the supratrochlear and superficial ternoral arteries

Question 58

Where does the posterior ethmoidal artery arise from?

Answer 58

The ophthalmic artery when the latter reaches the medial wall of the orbit.

Question 59

How does the posterior ethmoidal artery travel?

Answer 59

Passes medially between the upper border of the medial rectus muscle and the SO to enter the posterior ethmoidal canal.

Question 60

What does the Posterior Ethmoidal artery supply?

Answer 60

The posterior ethmoidal air sinuses, the dura of the anterior cranial fossa and the upper part of the nasal muscosa

Question 61

What does the Anterior Ethmoidal Artery supply?

Answer 61

During this long course the artery supplies the anterior and middle ethmoidal air cells, the frontal air sinus, the meninges, the mucous membrane of the anterior part of the nasal cavity, and the skin of the nose.

Question 62

Which is larger, the anterior or posterior ethmoidal artery?

Answer 62

Posterior ethmoidal artery

Question 63

Where does the Anterior Ethmoidal Artery arise? & what route does it follow?

Answer 63

It arises from the ophthalmic artery and enters the anterior ethmoidal canal accompanied by the anterior ethmoidal nerve. The artery then enters the anterior cranial fossa and passes into the nose through the cribriform plate of the ethmoid. It then descends in a groove on the deep surface of the nasal bone to enter the face between the nasal bone and the upper nasal cartilage.

Question 64

What is the Meningeal artery?

Answer 64

This small artery runs posteriorly through the superior orbital fissure to supply the meninges in the middle cranial fossa (middle of head / around the eye)

Question 65

When on a slit lamp, what needs to be lined up with the black dot on the lamp?

Answer 65

The lateral canthus

Question 66

What artery is near the medial canthus?

Answer 66

Near medial canvas are palpebral ligaments where the eyelids are attached at each end (one medial and one lateral). The medial palpebral supplies the medial ligament.

Question 67

How do the Medial Palpebral arteries travel?

Answer 67

The two medial palpebral arteries arise from the anterior part of the ophthalmic artery below the pulley for the superior oblique muscle. They descend behind the lacrimal sac and pierce the orbital septum above and below the medial palpebral ligament. Each artery passes laterally to enter the upper and lower eyelid and divides into two branches, which form the peripheral and marginal arterial arches. The arches run laterally between the orbicularis oculi muscle and the tarsal plates.

Question 68

What does the medial palpebral artery supply?

Answer 68

The medial ligament and branches supply the eyelids and conjunctiva

Question 69

Where is the supratrochlear artery?

Answer 69

Runs above the trochlea, above the SO. Continues into lids and supplies the blood flow to eyelid (but mainly this comes from lacrimal artery) and does blood supply around the trochlea.

Question 70

How does the supratrochlear artery leave the orbit?

Answer 70

Leaves the orbit by piercing the orbital septum above the pulley for the superior oblique muscle

Question 71

Which structure is immediately inferior to the supratrochlear artery?

Answer 71

The Trochlea

Question 72

What does the supratrochlear artery supply?

Answer 72

It is accompanied by the supratrochlear nerve and supplies the skin of the forehead and scalp & blood supply around the trochlea

Question 73

What are the features of the dorsal nasal artery?

Answer 73

The dorsal nasal artery, a terminal branch of the ophthalmic artery, pierces the orbital septum. It passes above the medial palpebral ligament and then descends to the side of the nose. It gives off branches to the lacrimal sac and anastomoses with the facial artery.

Question 74

What are the two terminal branches of the Ophthalmic artery?

Answer 74

Supratrochlear & Dorsal Nasal

Question 75

What is the blood-ocular barrier system?

Answer 75

The blood–aqueous barrier & The blood–retinal barrier (BRB).

Question 76

What are tight junctions in the blood retinal barrier called?

Answer 76

Zona Occludens Inner Zona Adherans Outer

Question 77

What is the Blood Retinal Barrier?

Answer 77

A particularly tight and restrictive physiological barrier that regulates ion, protein and water flux into and out of the retina.

Question 78

What does the BRB consist of?

Answer 78

Consists of inner and outer components, the inner BRB being formed of tight junctions between retinal capillary endothelial cells and the outer BRB of tight junctions between retinal pigment epithelial cells.

Question 79

What are the two most frequent and relevant retinal diseases?

Answer 79

Diabetic Retinopathy Age-Related Macular Degeneration (AMD)

Question 80

How is Diabetic Retinopathy initiated?

Answer 80

Initiated by an alteration of the inner BRB and neovascular AMD is a result of an alteration of the outer BRB

Question 81

What happens in macular degeneration (wet form)?

Answer 81

Blood vessel structures start to break down and thus get bleeding

Question 82

Can you reverse macular degeneration or diabetic retinopathy?

Answer 82

No - can manage them to stop them from getting worse

Question 83

How do we manage the treatment of retinal disease?

Answer 83

Treatment of retinal diseases must also deal with the BRB either by using its specific transport mechanisms or by circumventing it through intravitreal injections.

Question 84

Athernosclerosis is what?

Answer 84

Swelling at the bifurication of the common carotid arteries, carotid sinus, produces turbulent flow. Increase risk of Atheronma (fatty material that clogs arteries) formation in this area with the internal carotid most susceptible.

Question 85

What is Atheroslcerotic?

Answer 85

Atherosclerotic thickening of the tunica intima of the carotid arteries will reduce blood flow to the brain, resulting in the variety of neurological symptoms;