2. Blood, Lymph, and Osteology of the Head and Neck Flashcards
What is the main blood supply to the head and neck through?
Common carotid arteries and vertebral arteries.
What is the main venous drainage of the head and neck via?
Internal jugular vein. External jugular vein and anterior jugular vein draining superficial structures.
What do the major blood vessels supplying and draining the head and neck make up?
The upper systemic vascular loop.
What is the carotid sheath?
A fascial envelope of areaolar tissue.
What does the carotid sheath enclose?
Common carotid artery, internal jugular vein, vagus nerve (CN X).
Where is the carotid sheath found?
Deep to the sternocleidomastoid muscle.
What is the carotid sheath derived from?
Fusion of: the prevertebral layer of cervical fascia posteriorly + the pretracheal layer of cervical fascia anteromedially + the superficial layer of cervical fascia anterolaterally.
What do the common carotid artery, internal jugular vein, and vagus nerve lie within the carotid sheath?
Artery is medial, vein is layer, and nerve is between and posterior to the two vessels.
What lies outside the carotid sheath, medially and posterior to it?
Sympathetic trunk.
Where does the right common carotid artery originate from?
Bifurcation of the brachiocephalic trunk behind the right sternoclavicular joint.
What does the left common carotid artery originate from?
The arch of the aorta, it courses for 2cm in superior mediastinum before entering the neck.
Where do the common carotids terminate?
Midway between the angle of the mandible and the mastoid process of the temporal bone - upper border of the thyroid cartilage.
Where is the carotid sinus given rise to?
Where the common carotids dilate and then bifurcate into internal and external carotid arteries at C4.
Where are the baroreceptors?
The carotid sinus, detects changes in blood pressure.
What is a carotid massage?
Gentle rubbing of the carotid sinus that alleviate supra-ventricular tachycardia.
What is the location of the peripheral chemoreceptors?
The carotid body, detects arterial O2 concentrations.
Why is the carotid artery bifurcation a common site for atheroma formation?
Narrowing/stenosis of the artery.
What is a potential sequelae of carotid artery atheroma?
Rupture of the clot causing the embolus to travel to the brain in transient ischaemic attack or stroke.
How can the internal carotid artery be distinguished from the external?
Internal has no branches in the neck and enters the skull through the carotid canal. The external has 8 branches to the extra-cranial structures of the head and neck.
What are the eight branches of the external carotid artery?
Stop Alcohol Late Friday Or Puke More Saturday
Superior thyroid, ascending pharyngeal, lingual, facial, occipital, posterior auricular, maxillary, superficial temporal.
What happens to the external carotid artery in the parotid gland?
It divides into the maxillary and superficial temporal arteries, accompanied by the facial nerve (CN VII) and retromandibular vein.
Where do the vertebral arteries arise from?
The subclavian arteries on the left and right, ascend through the transverse foramen in cervical vertebrae 6 to 1.
What do the vertebral arteries supply?
The brain along with the internal carotid arteries.
What is the carotid triangle a subdivision of?
The anterior triangle of the neck.
What are the boundaries of the carotid triangle?
Superiorly - posterior belly of the digastric.
Laterally - sternocleidomastiod.
Medially - superior belly of omohyoid.
What are the contents of the carotid triangle?
Carotid sheath with common carotid artery, internal jugular vein, vagus nerve, and deep cervical lymph nodes; thyroid gland; larynx; pharynx; external carotid artery and some branches; hypoglossal and spinal accessory nerve; branches of cervical plexus.
What are the layers of the scalp?
SCALP: skin, connective tissue (dense), aponeurosis, loose connective tissue (with blood vessels), periosteum.
What is the blood supply to the scalp?
Rich with many anastomoses. From branches of external carotid arteries (superficial temporal, posterior auricular, occipital), supratrochlear and suborbital arteries (branches of opthalmic arteries, arise from internal carotid arteries).
Why does the scalp bleed profusely?
It has numerous anastomoses and walls of arteries are closely attached to connective tissue, limiting their constriction.
Why do deep laceration involving the epicranial aponeurosis cause profuse bleeding?
Opposing pull of occipitofrontalis.
Why does loss of blood to the scalp not lead to underlying bone necrosis?
The skull has a different blood supply, mostly from the middle meningeal artery.
What is the venous drainage of the scalp?
Superficial temporal veins, occipital veins, posterior auricular veins. Some deep parts drain into the pterygoid venous plexus.
Where do supraorbital and supratrochlear veins drain?
Untie at medial angle of eye to form angular vein then drains into facial vein.
How do the veins of the scalp connect to veins of the skull?
Connect to diploic veins of skull via valve-less emissary veins so connect to dural venous sinuses.
How can infection spread from scalp to meninges?
Through the dural venous sinuses, there is a relationship between scalp to skull then to cranial cavity.
What is the arterial supply of the dura and skull?
Anterior and posterior branches of the middle meningeal artery, branch of maxillary artery, which is a branch of external carotid artery.
How can extradural haemorrhage occur?
From fracture at the pterion of the skull as the middle meningeal artery runs close to here and this would cause bleeding deep to the cranium but superficial to the dura.
What are craniotomies?
Bone and skin flap are reflected inferiorly to preserve blood supply but gain access into the cranial cavity.
What are the dural venous sinuses?
Endothelium-lined space between the periosteal and meningeal layers of the dura which form at the dural septae and receive blood from large veins that drain the brain.
What are the veins that drain the brain and form dural venous sinuses?
Superior sagittal sinus, inferior sagittal sinus, cavernous sinus, sigmoid sinus (continues as internal jugular veins and exits skull through jugular foramen), and transverse sinus.
What is the arterial supply to the face?
All superficial arteries arise from external carotid artery, except supraorbital and supratrochlear (from internal carotid via opthalmic artery). Facial, superior and inferior labial, maxillary, lateral nasal, angular, transverse facial.
What is the distribution of supply of the facial artery?
Muscles of facial expression and face.
What is the distribution of supply of the superior and inferior labial artery?
Upper lip, side and septum of nose, lower lip.
What is the distribution of supply of the maxillary artery?
Deep structure of the face.
What is the distribution of supply of the lateral nasal artery?
Skin on ala and dorsum of nose.
What is the distribution of supply of the angular artery?
Superior cheek and lower eyelid.
What is the distribution of supply of the transverse facial artery?
Facial muscles and skin of temporal frontal and temporal regions.
What is the distribution of supply of the supratrochlear artery?
Muscles and skin of forehead and scalp, superior conjunctiva.
What is the distribution of supply of the supraorbital artery?
Muscles and skin of forehead and scalp, superior conjunctiva.
What is the venous drainage of the face?
Veins accompanying the arteries of the face. They drain into the facial vein, drains into internal jugular vein.
What is the cavernous sinus?
Plexus of extremely thin-walled veins on the upper surface of the sphenoid bone.
What is in the cavernous sinus?
Veins, internal carotid artery, oculomotor nerve CNIII, trochlear nerve CNIV, abducens CNVI, trigeminal CNV (1 opthalmic and 2 maxillary).
Do the veins of the face have valves?
No.
Which veins communicate at the medial angle of the eye?
Facial vein and superior opthalmic vein, drain into cavernous sinus.
Where does the deep facial vein drain?
Into the pterygoid plexus.