AH&N Vasculature

Question 1

Where do the carotid arteries bifurcate?

Answer 1

At the superior margin of the thyroid cartilage (c4) they split into the external and internal carotid artery. Occurs in the carotid triangle.

Question 2

What is carotid sinus hypertrophy?

Answer 2

Contains baroreceptors, detect stretch as a measure of bo, glossy pharyngeal nerve, brain, regulate bp.
Hypersensitive to stretch, external pressure on the carotid sinus can cause slowing of the HR & a decrease in bp, brain underperfused & syncope results therefore checking pulse at carotid triangle is not advised.
External to the carotid sinus is a cluster of cells, carotid body, peripheral chemoreceptors detecting the O2 content of the body & relaying this info to the brain to regulate breathing rate.

Question 3

What does the external carotid artery supply?

Answer 3

Supplies the area of the head & neck external to the cranium.

Question 4

Describe the path of the external carotid artery.

Answer 4

Arise from common carotid
Travels up neck posterior to mandibular neck and anterior to the lobule of the ear.
Artery ends with the parotid gland by division into superficial temporal artery & the maxillary artery.
Before terminates it gives off 6 branches:
Superior thyroid artery, lingual artery, facial artery, ascending pharyngeal artery, occipital artery, posterior auricular artery.

Question 5

Describe the blood supply to the scalp.

Answer 5

The posterior auricular, occipital, and superficial temporal arteries ( along with two branches of the internal carotid artery; supra-orbital & supratrochlear)

Question 6

Why do injuries to the scalp cause excessive bleeding?

Answer 6

The walls of the arteries are tightly and closely bound to the underlying connective tissue of the scalp. This prevents them from constricting to limit blood loss following injury or laceration.
Numerous anastomoses
Deep lacerations can involve the epicranial aponeurosis which is worsened by the opposing pulls of the occipital and frontalis muscles.

Question 7

Describe the path of the internal carotid artery.

Answer 7

Do not supply any structures in the neck, entering the cranial cavity via the carotid canal in the petrous part of the temporal bone. Supplies: brain, eyes, forehead

Question 8

What does swelling at the bifurcation of the common carotid artery cause? And what is the treatment?

Answer 8

Produces turbulent blood flow, increase risk of atheroma forming, internal carotid more susceptible than others.
Atherosclerotic thickening of the tunica intima of these arteries will reduce blood flow to the brain: symptoms: headache, dizziness, muscular blood flow and if blood flow is completely excluded, ischaemia.
In severe cases the artery can be opened and atheromatous tunica intima removed: carotid endarterectomy

Question 9

What arteries give rise to the thyrocervical trunk?

Answer 9

Right and left subclavian arteries.

Question 10

What are the three branches of the thyrocervical trunk?

Answer 10

1st branch: inferior thyroid artery- supplies thyroid gland
2nd branch: transverse cervical artery- supplies the trapezius and rhomboid muscles
3rd branch: suprascapular artery- supplies the posterior shoulder area

Question 11

Describe the path of the subclavian arteries.

Answer 11

Left and right vertebral arteries medial to anterior scalene muscle.
Ascend up the posterior side of the neck through foramen transversarium.
Enter the cranial cavity via the formen magnum and converge.
Give rise to the basilar arteries which supply the brain.

Question 12

Where do the right and left common carotid arteries arise from?

Answer 12

The right common carotid artery arises from the bifurcation of the brachiocephalic trunk.(right subclavian artery is other branch), occurs at level of right sternoclavicular joint.
The left common carotid artery branches from the arch of the aorta.

Question 13

Venous drainage of the brain & meninges?

Answer 13

Supplied by the dural venous sinuses.

Question 14

Venous drainage of the scalp & face?

Answer 14

Drain by veins synonymous with the arteries of the face & scalp, these drain into the internal & external jugular veins.

Question 15

Venous drainage of the neck?

Answer 15

️anterior jugular veins

Question 16

Which two veins form the external jugular vein and what do they drain?

Answer 16

Posterior auricular vein- drains the area of scalp superior and posterior to the outer ear.
Retromandibular vein- itself formed by the maxillary & superficial temporal veins which drain the face.
Combine immediately posterior to the angle of mandible & inferior to the outer ear.

Question 17

Describe the course of the external jugular vein.

Answer 17

Descends down the neck within the superficial fascia.
Runs anteriorly to the SCM crossing it in an oblique posterior and inferior direction.
Vein passes under the clavicle and drains into the subclavian vein.

Question 18

Describe the course of the anterior jugular veins.

Answer 18

Vary from person to person, they are paired veins which drain the anterior aspect of the neck, often communicate via a jugular venous arch.
Descend down the midline of the neck draining into the subclavian vein.

Question 19

Describe the course of the internal jugular vein.

Answer 19

Begins in the cranial cavity, as a continuation of the sigmoid sinus.
Initial part is dilated: superior bulb- vein exits skull via jugular foramen.
In neck it descends within the carotid sheath deep to the SCM & lateral to the common carotid artery at bottom to neck posterior to sternal end of the clavicle.
Then combines with the subclavian vein to form the brachiocephalic vein.
Immediately before its termination there is the inferior bulb, it has a valve that stops backflow of blood.
During descent it receives blood from the facial, lingual, occipital, superior and middle thyroid veins. These drain from the anterior face, trachea, thyroid, oesophagus, larynx & muscles of the neck.

Question 20

Why is JVP clinically useful?

Answer 20

When the heart contracts a pressure wave passes upwards, there are no valves in the brachiocephalic or subclavian veins- so pulsations in the IJV are a fairly accurate indication of right atrial pressure.

Question 21

What are dural venous sinuses?

Answer 21

Spaces between the periosteal & meningeal layers of dura mater which are lined by endothelial cells.
They collect venous blood from the veins that drain the brain & bony skull & ultimately drain into the IJV.

Question 22

What are the cavernous sinus?

Answer 22

Clinically important pair of dural sinuses.
Located next to the lateral aspect of the body of the sphenoid bone.
Receives blood from: superior & inferior ophthalmic veins, middle superficial cerebral veins & from other dural venous sinus; the sphenoparietal sinus.
Internal carotid artery crosses the sinus, allows for cooling of the arterial blood before it reaches the brain.and abducens nerve crosses.

Question 23

What nerves are located in the lateral wall of each cavernous sinus?

Answer 23

Occulomotor, trochlear, ophthalmic & maxillary.

Question 24

What happens if the cavernous sinus gets infected?

Answer 24

If infected nerves are at risk of damage.
Facial vein is connected to cavernous sinus via the superior ophthalmic vein.
Facial vein is valveless, blood can reverse direction and flow from the facia, vein to the cavernous sinus, which is a potential pathway by which infection of the face can spread to the venous sinuses.

Question 25

What does the lymphatic system do?

Answer 25

Drain tissue fluid, plasma proteins and other cellular debris back into the bloodstream & is also involved in immune defence.
Once this collection of substances enters the lymphatic vessels: lymph
Lymph is subsequently filtered by lymph nodes & directed into the venous system.

Question 26

What do the superficial lymphatic vessels drain?

Answer 26

Drain lymph from the scalp, face & neck into the superficial ring of lymph nodes at the junction of the neck & head.

Question 27

Describe the path of the deep lymphatic vessels.

Answer 27

Arise from the deep cervical lymph nodes. They converge to form the left & right jugular lymphatic trunks:
Left jugular lymphatic trunk- joins the thoracic duct at the root of the neck
Right jugular lymphatic trunk- empties into the right lymphatic duct at the root of the neck.

Question 28

Name the superficial lymph nodes.

Answer 28

Occipital: 1-3, back of the head at the lateral boxer of the trapezius muscle and collect lymph from the occipital area of scalp
Mastoid/post auricular: 2, lie on insertion of the SCM into the mastoid process and collect lymph from the posterior neck, upper ear & back of the auditory meatus.
Pre-auricular: 1-3 anterior to auricle of ear and collect lymph from superficial area of face and temporal region.
Parotid: superficial to parotid, collect lymph from nose, nasal cavity, external acoustic meatus, tympanic cavity. Also deep parotid drain nasal cavities and nasopharynx.
Submental: superficial to mylohyoid muscle, collect lymph from central lower lip, floor of mouth and apex of tongue.
Submandibular: 3-6, in submaxillary triangle, collect from cheeks, lateral aspects of nose, upper lip, lateral parts of lower lip, gums & ️anterior tongue. Receive from submental and facial lymph nodes.
Facial: maxillary/infraorbital, buccinator & supramandibular