30 - 201 - CUTANEOUS SURGICAL ANATOMY Flashcards
fibromuscular layer connecting the facial muscles
superficial musculoaponeurotic system (SMAS)
ideal location of undermining in relation to SMAS
Incisions and undermining within the subcutaneous fat above SMAS will not result in damage to motor nerves
- The SMAS is an important landmark because most major arteries and nerves run within or deep to it.
- Dissection above the SMAS allows the dermatologic surgeon to safely avoid neurovascular structures.
provide sensory innervation to the face
three branches of the trigeminal nerve (cranial nerve V)
three main danger zones
- areas where the temporal and marginal mandibular branches of the facial nerve and** spinal accessory nerve** lie superficial and can be easily injured
result of damage to the temporal branch of the facial nerve
ipsilateral eyebrow ptosis and obscuring of the superolateral visual field
marginal mandibular branch of the facial nerve is vulnerable to damage where?
along the inferior edge of the body of the mandible
Damage to the marginal mandibular branch of the facial nerve will result in what?
asymmetrical smile
landmark for the spinal accessory nerve
posterior triangle of the neck and may be identified by Erb’s point
borders of SMAS
- Above: temporalis and frontalis muscles
- Below: platysma
- Anterior orbicularis oculi
- Posterior: trapezius
Cosmetic units are zones of tissue that share cutaneous features such as..
color, texture, pilosebaceous quality, pore size, and degree of actinic exposure
represent the major cosmetic units of the face.
forehead, temples, eyelids, nose, cheeks, upper and lower lips, chin, and ears
the area between the eyebrows
glabella
the deep sulcus below the glabella and uppermost portion of the nose
root of the nose
the area overlying the nasal bone
dorsum or bridge
the sides of the nose
lateral sidewalls
the nostril
nasal ala
the grooves that demarcate the alae superiorly from the lateral nasal sidewall and alae inferiorly from the lip, respectively
nasolabial crease
the mobile linear structure separating the alae inferiorly
columella
The central concavity within which the external auditory meatus lies
concha
lateral surface of the ear is rimmed by what part of the ear?
helix
a curved cartilaginous structure that begins at the crus just above the external auditory canal and continues around the ear to end at the fleshy lobule
superior and inferior portion of the concha
The concha is divided by the crus of the helix into a superior portion; the cymba; and an inferior portion, the cavum.
he posterior border of the concha is formed by another cartilaginous structure
antihelix
Superiorly, the antihelix originates from two legs (crus is Latin for leg): (1) the superior crus and (2) inferior crus.
region between the crura
triangular fossa
groove between the helix and antihelix
scaphoid fossa
triangulated cartilaginous structure just anterior to the auditory canal
tragus
triangulated end of the antihelix
antitragus
The inferior region between the tragus and antitragus
intertragic notch
cutaneous upper lip has a concave depression in the center
philtrum
divides the cutaneous lower lip from the chin
mental crease
boundary between the red mucosal surface of the lips and the cutaneous surface
vermillion border
raised contoured area of the inferior portion of the philtrum is a critical aesthetic landmark
Cupid’s bow
any anatomical structure that can be easily distorted when tension is placed on it
free margin
- When these regions become distorted, the resulting asymmetry can cause cosmetic and functional concerns
- An ectropion can result in epiphora, as well as conjunctival and corneal exposure leading to corneal scarring
- An eclabium may result in altered speech, an asymmetrical smile, or drooling.
what are free margins of the face
eyelid margin, alar rim, lip vermillion, and helical rim
another characteristic of the face that help guide surgical reconstruction and allow the structural camouflage of scar lines
RELAXED SKIN TENSION LINES
creases on the face that form over time because of factors such as loss of elastic tissue tone, lengthening of the collagenous fibrous septae that connect the dermis to the underlying facial muscles, development of excessive skin, gravity, and ultraviolet radiation exposure
RELAXED SKIN TENSION LINES
- RSTLs usually run perpendicular to the underlying muscles.
- In most situations, the long axis of the excision should be placed parallel to the RSTL because they are often in the direction of the least tension for a scar.
facial nerve location
- The facial nerve exits the skull through the stylomastoid foramen near the earlobe and immediately gives off the posterior auricular branch, which provides motor innervation to the occipital and posterior auricular muscles.
- It then enters the parotid gland at the midpoint of a line connecting the tragus with the angle of the mandible.
- Within the parotid gland, the facial nerve divides into the temporofacial and cervicofacial rami from which five branches arise.
- After leaving the parotid gland, the branches of the facial nerve lie deep to the SMAS and enter the muscles of facial expression from their deep surface.
- The branches of the facial nerve are therefore well protected during surgical procedures that are no deeper than fat.
- However, it is important to note that there can be minimal thickness of the fat layer at certain sites such as the temple and at other sites in older adult patients.
five main branches of facial nerve
(1) temporal,
(2) zygomatic,
(3) buccal,
(4) mandibular,
(5) cervical
what are the two branches of the facial nerve most susceptible to injury during dermatologic surgery? where are they most susceptible?
- **temporal branch **as it **crosses the zygomatic arch **
- marginal mandibular branch along the inferior border of the mandible
location of the Temporal branch of the facial nerve
Facial nerve as it crosses the middle third of the zygomatic arch
damage to temporal nerve
- Flattening of forehead,
- diminished wrinkles, skin tension lines,
- eyebrow and eyelid ptosis,
- visual field disturbance
location of the marginal branch of the facial nerve
Inferior border of the mandible, as the nerve crosses the angle of the mandible at the inferoanterior border of the masseter
damage to the marginal mandibular branch of the facial nerve
Contralateral and upward pull on the mouth; ipsilateral side presents with lip droop
location of Spinal accessory nerve
Posterior triangle of the neck, from the midpoint of the posterior border of the sternocleidomastoid
damage to spinal accessory nerve
- Paralysis of trapezius,
- winging of the scapula,
- shoulder drop,
- inability to shrug the shoulder,
- difficulty with arm abduction,
- chronic shoulder pain
The approximate course of the temporal branch of the facial nerve can be projected on the skin by what landmark?
earlobe to the lateral edge of the eyebrow and another line from the tragus to just above the and behind the highest forehead crease
landmark for Erb’s point
- drawing a line connecting the angle of the mandible with the mastoid process
- A vertical line is then drawn from the midpoint of this line **6 cm **inferiorly.
- The point at which this line intersects the posterior border of the sternocleidomastoid muscle is Erb’s point.
- the point at which the spinal accessory nerve emerges from behind the sternocleidomastoid
The marginal mandibular branch of the facial nerve exits the parotid gland where?
angle of the jaw
- It divides into two or more rami and travels anteriorly along the us of the mandible to supply the depressor anguli oris, the depressor labii inferioris, the mentalis, and part of the orbicularis oris.
- As it crosses the angle of the mandible at the inferoanterior border of the masseter, the marginal mandibular nerve is covered only by skin, subcutaneous fat, and fascia, which may be thin in this location, particularly in older adults
the trigeminal nerve exits the skull via three foramina
supraorbital, infraorbital, and mental foramina
located bilaterally in the midpupillary line
Branches of the Trigeminal Nerve
nerves that innervates the forehead and anterior scalp
Supraorbital (lateral) nerve, Supratrochlear (medial) nerve
nerve that innervates the Upper eyelid
Lacrimal nerve
innervates the Glabella, nasal root, nose bridge
Infratrochlear nerve (nasociliary)
innervates Eyelid, superior cheek
Infraorbital nerve
innervates Most of the temple, temporoparietal scalp, anterior ears, external ear canal, tympanic membrane
Auriculotemporal
innervates Buccinators, buccal mucosa, gingiva
Buccal nerve
innervates Lower lip, chin
mental nerve
eyebrows move medially and downward with contraction of what muscles?
corrugator supercilii muscles
lies between the supercilii muscles and draws the skin of the forehead inferiorly to create the horizontal creases at the root of the nose
procerus
surrounds the eye and consists of an orbital and palpebral portion
orbicularis oculi muscle
The orbicularis oculi muscle serves to close the eyes with the palpebral part with both reflexive and voluntary control and the orbital part with voluntary control.
central sphincter-like muscle around the mouth
orbicularis oris
This muscle helps purse the lips to form certain sounds and whistle
lip depressors
depressor anguli oris, depressor labii inferioris, and the mentalis
lip elevators
zygomaticus major, zygomatic minor, levator anguli oris, levator labii superioris, and levator superioris alaeque nasi
The blood supply of the face is almost entirely derived from branches of what artery?
external carotid artery
The continuation of the facial artery in the nasofacial sulcus is called?
angular artery
terminal branches of the internal carotid artery
ophthalmic artery branches, the supraorbital artery, and the supratrochlear artery
internal and external carotid systems join in two places
(1) where the supratrochlear branch and the dorsal nasal artery anastomose with the angular artery and
(2) where the forehead branches of the supraorbital and supratrochlear arteries anastomose with branches of the superficial temporal artery.
lymphatic drainage of the face
- posterior scalp - postauricular and occipital nodes
- lateral and superior face - forehead
- lateral eyelids - parotid nodes
- medial and inferior face, including the medial eyelids and lateral lips - submandibular nodes
- middle two thirds of the lower lip and the chin - submental nodes
