Flashcards in Anatomy of Face, scalp and parotid Deck (23):
what are the layers of the scalp?
FIVE functional layers:
C-connective tissue (dense, 2x layers incl nerves, vessels, and fat)
A-aponeurosis of occipitofrontalis 2 belly's
L-Loose connective tissue
P-pericranium (aka periosteum)
borders of the scalp?
external occipital protuberance posteriorly to the supraorbital margins anteriorly. Laterally to the level of the zygomatic arches.
middle layer of scalp is formed by the aponeurosis of which 2 muscles?
medially by the frontalis and occipitalis belly's
what is the purpose of the 4th scalp layer?
loose connective tissue allows movement of scalp over the periosteum (since first 3 layers of scalp are fused together)
what risk of infection do emissary veins pose?
while most of scalp drains to superficial veins, some emissary veins drain through secondary dense CT layer into diploic and then directly into venous sinuses
-->meningitis or encephalitis can develop
whats the difficulty with treating scalp wounds/lacerations?
-bleed profusely as there is rich vascularization in dense CT layer (anastamoses between internal and external carotid artery).
-medial aponeurosis of frontalis and occipitalis muscles causing wounds to pull apart
what are the tissue layers of the face?
Four layers (no loose connective tissue)
2. subcutaneous connective tissue
3. muscles of facial expression
general characteristics of facial muscles?
circulating orifices (sphincters) or radiation out from these orifices (dilators).
arise from bone/fascia and attach to skin of the face.
facial muscles are innervated by which cranial nerve?
VII (Facial nerve)
facial muscles are derived from which embryological pharyngeal arch>
second pharyngeal arch
which nerves are associated with head and neck dermatomes?
3 division of trigeminal nerve band accross the face and turn upwards to the scalp.
V-1 Opthalmic division services nose, forehead, eyes, and dorsal scalp.
V-2 Maxillary division services upper lip, cheek, and temples
V-3 Mandibular nerve divison services lower lip, chin, side of head, and anterior ear
Branches of cervical plexus provide sensory innerveation to the neck, posterior & inferior ear
Dorsal Rami of cervical spinal nerves C2 and C3 supply posterior scalp behind the ears and back of neck.
Auricular branch of vagus supplies external meatus and small area on posteromedial.
which bony landmark localized the trigeminal ganglion?
petrous part of temporal bone.
sources of arterial supply to the face?
bulk of face and scalp is supplied by EXTERNAL CAROTID ARTERY-->crosses the inferior border of mandible and sends off a branch called "FACIAL ARTERY".-->further branches to upper and lower lip, nose, and cheek (TORTUOUS course to medial angle of eye)
Internal Carotid Artery provides some supply to supraorbital and supratrochlear (central area of forehead and eye).
NB: anastomoses of internal and external carotid artery on the face.
branches of the external carotid artery to the face/head?
after ECA branches off common carotid artery, the FACIAL ARTERY branches off from ECA anteriorly to service most of the face;
SUPERFICIAL TEMPORAL ARTERY branches off over the zygomatic arch to service lateral aspect of scalp;
POSTERIOR AURICULAR ARTERY branches off behind the ear;
OCCIPITAL ARTERY branches to supply posterior scalp (occipital region)
Sources of venous supply to the face?
(mostly mirror the arteries)
FACIAL VEIN is major drainage for the face.
-->runs a straighter course than facial artery, slightly posterior and superficial to the artery
Some venous drainage into cranial veins via EMISSARY VEINS (recall this is problematic for infections of cavernous sinuses)
what is the risk implied with infections of skin of face and cavernous sinus?
cavernous sinus is a dural encased endothelial-lined space on either side of body of sphenoid.-->infections of face (nose and upper lip triangle) can spread to cavernous sinus and cause meningitis/encephalitis
lymphatic drainage from the face?
lymphatics from face and scalp drain into a ring of lymph nodes around the base of the skull.
-submental noes (under chin)
-mastoid nodes/posterior auricular nodes
describe anatomical position of parotid gland?
Superiorly:sits below zygomatic arch
Inferiorly:above the angle of the mandible
Posteriorly: infront of the ear
Anteriorly: behind the masseter muscle
superficial to styloid process
why are parotid infections so intensely painful?
parotid gland is a serous salivary gland wrapped tightly in parotid fascia.
-->no flexibility when pressure increases with inflammation/infection-->pain!!
describe the path of parotid duct?
runs accross masseter and dissapears anteriorly when it pierces buccinator and enters oral cavity near second upper molar
which nerve is at risk when performing surgery on parotid gland?
facial nerve plexus in close proximity to parotid gland
5 branches of facial nerve?
(tall zulus bare many children)