Head And Neck Week 3 Flashcards
What are the major vessels in the neck?
Jugular veins
Carotid arteries
Which arteries arise from the subclavian artery at the base of the neck?
Internal thoracic, thyrocervical and vertebral arteries
What is similar about the internal carotid artery and the vertebral artery
They both supply the brain
Give off no branches in the neck
Does the common carotid artery give off branches in the neck?
No
Which arteries branch off from the thyrocervical trunk?
Suprascapular
Ascending cervical
Transverse cervical
Inferior thyroid
Where do the vertebral arteries arise from?
Subclavian artery
Describe the path of the vertebral arteries
Originate from the subclavian artery
Ascends through the transverse foramina of the cervical vertebrae 6-1
And enters the subarachnoid space just between the atlas and the occipital bone
Passes through foramen magnum
Curves around the medulla
Meets the other vertebral artery to form the basilar artery (circle of Willis) - runs along the anterior aspect of the brainstem
Which artery does the right common carotid originate from and where?
The brachiocephalic
Behind the right sternoclavicular joint
Where does the left common carotid originate?
Arch of the aorta
Which common carotid artery is longer?
The left because it arises from arch of aorta - courses for about 2cm through the superior mediastinum before entering the neck
What are the common carotid arteries enclosed in in the neck?
Carotid sheath
What are the contents of the carotid sheath?
Carotid artery
IJV
Vagus nerve
Deep cervical lymph nodes
Where is the carotid sheath found?
Deep to the sternocleidomastoid muscle
What forms the carotid sheath?
Prevertebral layer of cervical fascia - posteriorly
Pretracheal layer - anteromedially
Investing layer - anterolaterally
How does the carotid sheath differ over the artery and over the vein?
Thicker over the artery compared to the vein
Where does the sympathetic trunk lie in relation to the carotid sheath?
Posteromedially
How do the contents lie in the carotid sheath?
Artery medially
Vein laterally
Nerve posteriorly and between the vessels
At what point do the common carotid arteries bifurcate?
The superior surface of thyroid cartilage
What does the common carotid artery divide into?
External carotid
Internal carotid
What important structures are located at the bifurcation of the common carotid artery?
Carotid sinus (Baroreceptors) Carotid body (O2 peripheral chemoreceptors)
What is the clinical important of the carotid sinus?
Carotid massage can help to alleviate supra-ventricular tacchycardia
Why should you not attempt a carotid massage on healthy individuals?
Can cause bradycardia and a severe drop in blood pressure
Which artery is the major blood supply to the extra-cranial structures of the head and neck?
External carotid artery
What are the names of the terminal branches of the external carotid artery?
Maxillary artery
Superficial temporal artery
Where does the external carotid artery become the maxillary artery and superficial temporal?
Behind the neck of the mandible
In the parotid gland
What are the branches of the external carotid artery?
Some Anatomists Like Freaking Out Poor Medical Students S- Superior thyroid artery A - Ascending pharyngeal artery L- Lingual artery F - Facial artery O- Occipital artery P - Posterior auricular artery M - Maxillary artery S- Superficial temporal artery
The bifurcation of the common carotid artery is a common site for what pathology?
Atheroma formation
Causes narrowing - stenosis of the artery
Limit blood supply to the brain
The circle of Willis allows the other common carotid artery to compensate
Therefore may be no symptoms
Why do atheromas tend to form at the bifurcation of the common carotid artery?
Bifurcation causes turbulent flow
Damages endothelium
Leads to atherosclerotic changes
What may result from atherosclerosis of the common carotid artery?
Rupture of the clot –> embolus
Can become lodged in a cerebral artery
Leading to TIA or stroke
What are the boundaries of the carotid triangle?
Superior - Posterior belly of digastric muscle
Lateral - Anterior border of sternocleidomastoid
Medial - Superior belly of omohyoid
What is the carotid triangle?
A subdivision of the anterior triangle of the neck
What are the contents of the carotid triangle?
Internal jugular vein
Bifurcation of common carotid artery
Why is the carotid triangle important clinically?
Important for surgical approach to the carotid arteries or internal jugular vein - e.g. Carotid endarterectomy
Can access vagus and hypoglossal nerves
Carotid pulse can be palpated - but usually use more inferior pulses - Note: Dont feel for both carotid pulses at the same time, check for stenosis in both arteries before palpating
Carotid sinus massage - revert SVT
Draw and label a diagram showing the distribution of the external carotid artery and its branches
Check lecture
Which arteries supply the scalp?
Branches of internal carotid: Supraorbital Supratrochlear Branches of external carotid: Superficial temporal Posterior auricular Occipital
Which artery supplies the skull and dura?
Middle meningeal artery
How many layers of dura mater are there intracranially?
Two:
Outer endosteal layer - continuous with periosteum
Inner meningeal layer - continuous inferiorly with theca of spinal cord
Where do the dural venous sinuses lie?
In between the periosteum layer and meningeal layer of dura mater
Why is the bone reflected with its overlying muscle and skin during a craniotomy?
To preserve its blood supply during the surgery and after repositioning - reintegration is more successful this way
Adult pericranium has poor osteogenic properties - little regeneration occurs after bone loss
Which arteries supply the face? Draw and label their distribution
Supraorbital and supratrochlear from internal carotid artery Transverse facial artery Angular artery Lateral nasal artery Maxillary artery Superior and inferior labial artery Facial artery
Where can the facial artery pulse be felt?
At the inferior border of the mandible anterior to the masseter muscle
From what artery does the middle meningeal artery originate ?
Maxillary artery
What are the dural venous sinuses?
Endothelium-lined spaces between periosteal and meningeal layers of dura
Form at dural septae
Receive blood from large veins draining the brain (cerebral veins)
Connect to the scalp veins via emissary veins
Name some of the dural venous sinuses. Draw and label their positioning on a skull
Superior sagittal Inferior sagittal Cavernous Sigmoid Transverse sinus