Organization of Head and Neck Flashcards
ways to organize head and neck
via cranial nerves or via vasculature
Motor CN function
move sets of muscles in the H&N
Involuntary motor CN function
Glands of H&N
Eye accommodation & constriction
Sensory CN function
convey sensation from regions of the H&N OR special senses
V1
Opthalmic branch of trigeminal CN (superior)
V2
Maxillary branch of trigeminal CN (middle)
V3
Mandibular branch of trigeminal CN (inferior)
Passageways of trigeminal nerves
Foramen ovale
superior orbital fissure
Foramen rotundum
internal region
consists of the brain, cranial meninges, and inner table of the skull
External/superficial region
everything else but brain, meninges, and inner table of skull
Are there anastomatic connections between internal and external regions and H&N?
YES
Carotid system
paired common carotid arteries ascend in the neck to divide into the internal and external carotid arteries, which supply the internal and external regions, respectively.
Subclavian system
vertebral arteries ascend from the subclavian arteries and distribute branches to neck structures and terminate within the head, where they supply the internal region (brain and internal cranium.)
How brain receives oxygen rich blood
two paired systems of arteries, the internal carotid and vertebral arteries that communicate freely with each other via the Circle of Willis.
Carotid sheath
ascial sheath through which the carotid artery, internal jugular vein, and vagus nerve pass vertically through the neck
Carotid body
sensitive to blood O2, CO2, pH, and temperature (chemoreception)
Carotid sinus
sensitive to arterial blood pressure changes (baroreception)
Sensory innervation from carotid body and sinus travels in ___
glossopharyngeal nerve (CN IX)/ General visceral afferent
Branches of external carotid from superior to inferior vessels
Superficial temporal Maxillary Posterior auricular Occipital Facial Lingual Ascending pharyngeal Superior thyroid
Inferior thyroid artery
branch of thyrocervical trunk
Superficial temporal artery branches again to give off ___
transverse facial artery, another contributor to face
maxillary artery pathway
asses antero-medially across the infratemporal fossa, the space between the mandible and the skeleton of the midface.
Infratemporal fossa
contains maxillary artery and the muscles of mastication and the nerves that innervate them (branches of V3).
internal carotid enters skill via
Carotid canal
Internal carotid artery pathway
travels superiorly within the carotid sheath to the base of the skull to pass through a canal in the bone to emerge into the middle cranial fossa.
Internal carotid artery supplies ____
eye, orbit, forehead, and much of the cerebrum.
Part of internal carotid artery
Cervical part
Petrous part (travels through petrous part of temporal bone)
Cavernous part (in cavernous sinus)
Cerebral part
Branches of cerebral part of internal carotid
anterior, medial, and ophthalmic branches
anterior cerebral part of artery supplies ____
medial aspects of the
anterior cerebral hemispheres
Middle cerebral part of artery supplies ____
temporal lobe, anterolateral frontal lobe, and parietal lobe
ophthalmic cerebral part of artery supplies ____
walls of orbit and structures within the orbit as well as skin anterior to the orbit (eyelid, skin around the eye)
central artery of retina passes into ___
Optic nerve, with which it enters the back of the eye to reach the retina
What does it mean that the central artery of retina is a true end artery?
its occlusion (obstruction) results in instant and complete blindness in the affected eye.
Subclavian arterial supply to brain
vertebral artery, cervical part, atlantic part, intracranial parts, internal carotid
Contribution of vertebral arteries to circle of willis
posterior cerebral and basilar arteries
Branches of internal carotid in circle of willis
anterior cerebral, middle cerebral, ophthalmic, and posterior communicating arteries
Circle of willis
high redundant so one part could be compromised and brain would still be alright
venous blood pathway in head and neck
returns from the head and neck via internal jugular, external jugular, vertebral, and inferior thyroid veins.
Are there more or less communications between internal and external venous systems compared with arteries?
MORE
Epidural hematoma
Artery between dura and skull breaks and bleeds into the epidural space so the periosteal dura is slowly pushed away from the bone to create lens-shaped defect in cross section.
subdural hematoma
Low-pressure venous bleeding from bridging veins that drain neural tissue into dural sinuses and cross the arachnoid space. When torn, blood dissects arachnoid from dura, and the blood layers out along the cerebral convexity. Brain shifts away from bleed and ventricles compress
Subdural hematomas common in what kind of injury?
acceleration/deceleration injuries that cause the brain to move relative to skull
Subarachnoid hemmorrhage
Extravasation of blood into the subarachnoid space between the pial and arachnoid membranes causing blood to be diffusely through the brain
Caused by trauma or aneurysm
Dura layers
outer (periosteal) and inner (meningeal) layers
dural venous sinuses
Endothelium-lined channels in the spaces where the layers of the dura diverge so
venous blood runs through them to drain from the brain out of the skull
Dural venous sinus names
Superior and inferior sagittal sinus, straight sinus, confluence of sinuses, great cerebral vein, 2 sigmoid sinuses, 2 superior petrosal sinuses, inferior petrosal sinus, cavernous sinus, and ophthalmic vein
Internal jugular vein (IJV)
main venous structure in the neck. It descends through the neck in the carotid sheath.
IJV originates as ____
continuation of the S-shaped sigmoid (dural venous) sinus
Where does IJV terminate?
Terminates superior to the sternoclavicular joint by uniting with the subclavian vein to form the brachiocephalic vein.
What prevents reflux of blood into IJV?
large valve near its termination
What is IJV used for clinically?
access location for central line placement
What is main landmark for identifying IJV?
sternocleidomastoid muscle
What surrounds IJV in chains in neck?
Lymph nodes
Are veins superficial or deep to arteries?
Superficial
