201: Cutaneous Surgical Anatomy Flashcards
What is the superficial musculoaponeurotic system (SMAS) and its significance in facial surgery?
The superficial musculoaponeurotic system (SMAS) is a fibromuscular layer that connects the facial muscles. It is significant because incisions and undermining above the SMAS do not damage motor nerves, allowing for safer surgical procedures.
What are the three main danger zones related to the facial nerve during surgery?
The three main danger zones are: 1. Temporal branch of the facial nerve - Damage can result in ipsilateral eyebrow ptosis and obscuring of the superolateral visual field. 2. Marginal mandibular branch of the facial nerve - Vulnerable to damage along the inferior edge of the mandible, resulting in an asymmetrical smile. 3. Spinal accessory nerve - Located in the posterior triangle of the neck, identifiable by Erb’s point.
What are cosmetic units and why are they important in facial surgery?
Cosmetic units are zones of tissue that share cutaneous features such as color, texture, and pore size. They are important in facial surgery because surgical defects are best reconstructed within a cosmetic unit or subunit, and scar lines can be hidden easily in junction lines between cosmetic units.
What are the five important concepts of head and neck anatomy relevant to surgery?
The five important concepts of head and neck anatomy are: 1. Superficial musculoaponeurotic system (SMAS) 2. Topography and cosmetic units 3. Free margins 4. Relaxed skin tension lines (RSTL) 5. Facial motor nerves susceptible to damage during dermatologic surgery.
A patient presents with an asymmetrical smile after a surgical procedure near the mandible. Which nerve is likely damaged?
The marginal mandibular branch of the facial nerve (CN VII) is likely damaged. This nerve is vulnerable along the inferior edge of the mandible, where it is only covered by skin, subcutaneous fat, and fascia, making it susceptible to injury.
What are the major cosmetic units of the face?
The major cosmetic units of the face are the forehead, temples, eyelids, nose, cheeks, upper and lower lips, chin, and ears.
What is the function of the superficial musculoaponeurotic system (SMAS)?
The SMAS coordinates a wide range of facial expressions by linking the facial expression muscles with each other and the overlying skin. It is an important surgical landmark because most major arteries and nerves run within or deep to it.
What are the three main danger zones of the face?
The three main danger zones are: 1. Temporal branch of the facial nerve - Damage can cause ipsilateral eyebrow ptosis and visual field obstruction. 2. Marginal mandibular branch of the facial nerve - Damage can result in an asymmetrical smile. 3. Spinal accessory nerve - Damage can lead to shoulder drop and difficulty abducting the arm.
How does the rich vascular supply of the face contribute to surgical outcomes?
The rich vascular supply from both the external and internal carotid arteries ensures reliable healing potential and viability of flaps and grafts in head and neck surgery.
What is the role of the superficial musculoaponeurotic system (SMAS) in facial surgery?
The SMAS is a fibromuscular layer that connects facial muscles, allowing for coordinated facial expressions. It serves as a critical structure for incisions and undermining during surgery.
Why is knowledge of facial anatomy critical for surgeons?
Knowledge of facial anatomy is essential for: 1. Communicating precisely with colleagues. 2. Performing safe and efficient procedures. 3. Achieving aesthetic and functional reconstruction. 4. Understanding lymphatic drainage. 5. Anticipating metastatic spread of cutaneous malignancies.
What is the clinical implication of the relaxed skin tension lines (RSTL) in facial surgery?
Understanding the relaxed skin tension lines (RSTL) is crucial for minimizing scarring and optimizing aesthetic outcomes in facial surgery. Incisions made parallel to these lines are less likely to result in noticeable scars.
What are the free margins of the face?
The free margins of the face include: - Eyelid margin - Alar rim - Lip vermillion - Helical rim
What are Relaxed Skin Tension Lines (RSTLs) and their significance in surgery?
RSTLs are creases that form over time due to factors like loss of elastic tissue tone and gravity. They guide surgical reconstruction and camouflage scar lines.
Why is it important to place the long axis of a surgical excision parallel to relaxed skin tension lines (RSTLs)?
Placing the long axis of a surgical excision parallel to RSTLs minimizes tension on the scar, allowing for better healing and structural camouflage of the scar lines.
What are the anatomical features of the nasal ala?
The nasal ala is composed of fibrofatty tissue without cartilage, making it vulnerable to distortion when tension is placed on it during surgery.
What are the anatomical features of the lips?
The lips have features like the philtrum, mental crease, vermillion border, and Cupid’s bow. These are critical for maintaining aesthetic landmarks during surgery.
What are the anatomical features of the ear?
The ear has features like the helix, concha, antihelix, triangular fossa, scaphoid fossa, tragus, antitragus, and intertragic notch.
What are the anatomical features of the nose?
The nose has features like the glabella, root, dorsum, lateral sidewalls, nasal tip, nasal ala, alar groove, nasolabial crease, and columella.
What are the free margins of the face and their clinical significance?
The free margins of the face include: Eyelid margin, Alar rim, Lip vermillion, Helical rim. Distortion can cause significant cosmetic and functional concerns.
What are the implications of ectropion resulting from distortion of facial margins?
Ectropion can lead to excessive tearing and increased risk of corneal scarring and irritation.
What surgical considerations should be taken into account regarding the philtrum?
When considering surgical procedures involving the philtrum, it is important to recognize its role as a critical aesthetic landmark.
How do relaxed skin tension lines (RSTLs) influence scar formation after surgery?
RSTLs influence scar formation by guiding the direction of surgical incisions to align with the least tension, which minimizes scar visibility.
What is the clinical significance of the vermillion border in lip surgery?
The vermillion border marks the boundary between the red mucosal surface and the cutaneous surface of the lips.
What role does the mental crease play in facial aesthetics?
The mental crease divides the cutaneous lower lip from the chin, contributing to the overall facial contour.
What are the five main branches of the facial nerve and their mnemonic?
The five main branches of the facial nerve are: 1. Temporal 2. Zygomatic 3. Buccal 4. Mandibular 5. Cervical. Mnemonic: ‘to Zanzibar by motor car.’
What is the significance of the temporal branch of the facial nerve in terms of susceptibility to injury?
The temporal branch of the facial nerve is most susceptible to injury as it crosses the middle third of the zygomatic arch.
What are the potential consequences of damage to the marginal mandibular nerve?
Damage to the marginal mandibular nerve can result in contralateral and upward pull on the mouth.
How can one approximate the course of the temporal branch of the facial nerve?
To approximate the course of the temporal branch, draw a line from the earlobe to the lateral edge of the eyebrow.
What muscles are innervated by the temporal branch of the facial nerve?
The temporal branch of the facial nerve innervates the frontalis, upper fibers of the orbicularis oculi, corrugator supercilia, and anterior and superior auricular muscles.
During a brow lift surgery, how can a surgeon avoid damaging the temporal branch of the facial nerve?
The surgeon should undermine just beneath the dermis in the superficial fat above the fascia.
A patient has difficulty closing their eyes after surgery near the orbit. Which muscle and nerve are likely affected?
The orbicularis oculi muscle is likely affected. The temporal branch of the facial nerve (CN VII) innervates this muscle.
What mnemonic can help remember the branches of the facial nerve?
They can be remembered with the mnemonic ‘To Zanzibar By Motor Car.’
Which muscle and nerve are likely affected if a patient has difficulty closing their eyes after surgery near the orbit?
The orbicularis oculi muscle, which closes the eyes, is likely affected. The temporal branch of the facial nerve (CN VII) innervates the upper fibers of the orbicularis oculi and may have been damaged.
How can the course of the temporal branch of the facial nerve be approximated?
The course of the temporal branch can be approximated by drawing a line from the earlobe to the lateral edge of the eyebrow and another line from the tragus to just above and behind the highest forehead crease.
What are the potential consequences of damaging the temporal branch of the facial nerve?
Damage to the temporal branch can cause flattening of the forehead, diminished visibility of wrinkles, eyebrow and eyelid ptosis, visual field disturbance, and may require corrective procedures like brow lift or blepharoplasty.
What are the potential consequences of damaging the marginal mandibular nerve during surgery?
Damage to the marginal mandibular nerve can result in contralateral and upward pull on the mouth, causing a grimace and lip droop on the affected side.
What are the potential consequences of damaging the buccal and zygomatic branches of the facial nerve?
Damage to these branches may cause localized weakness in facial expression but is less debilitating due to the interconnecting network of rami in the midface.
What are the five main branches of the facial nerve and their mnemonic?
The five main branches of the facial nerve are: 1. Temporal 2. Zygomatic 3. Buccal 4. Mandibular 5. Cervical
Mnemonic: ‘To Zanzibar by motor car.’
What is the significance of the temporal branch of the facial nerve in terms of surgical procedures?
The temporal branch of the facial nerve is significant because it is most superficial and susceptible to damage as it crosses the middle third of the zygomatic arch. Care must be taken to undermine just beneath the dermis in the superficial fat above the fascia during surgical procedures.
What are the potential cosmetic and functional losses resulting from damage to the temporal branch of the facial nerve?
Damage to the temporal branch can result in: - Flattening of the forehead with diminished visibility of wrinkles and skin tension lines. - Eyebrow and eyelid ptosis over time as the muscle becomes atrophied, potentially leading to visual field disturbance. - A brow lift and blepharoplasty may be required to correct these issues.
What muscles are innervated by the marginal mandibular nerve?
The marginal mandibular nerve innervates the following muscles: - Depressor anguli oris - Depressor labii inferioris - Mentalis - Part of the orbicularis oris
What are the consequences of damage to the marginal mandibular nerve?
Damage to the marginal mandibular nerve results in: - Contralateral and upward pull on the mouth. - The affected ipsilateral side of the mouth is fixed in a grimace with a lip droop.
How does the course of the temporal branch of the facial nerve approximate?
To approximate the course of the temporal branch: 1. Draw a line from the earlobe to the lateral edge of the eyebrow. 2. Draw another line from the tragus to just above and behind the highest forehead crease.
What is the clinical importance of the cervical branch of the facial nerve?
The cervical branch of the facial nerve is of minimal clinical importance because it innervates the platysma muscle, which also receives nerve fibers from the marginal mandibular nerve. Damage to this branch is less debilitating compared to other branches.
What are the branches of the facial nerve that are most susceptible to injury during surgical procedures?
The branches of the facial nerve that are most susceptible to injury are: - Temporal branch as it crosses the zygomatic arch. - Marginal mandibular branch along the inferior border of the mandible.
What is the anatomical relationship of the facial nerve branches to the SMAS?
The branches of the facial nerve lie deep to the Superficial Musculoaponeurotic System (SMAS) and enter the muscles of facial expression from their deep surface, providing protection during surgical procedures that do not penetrate deeper than fat.
What are the less debilitating injuries associated with the buccal and zygomatic branches of the facial nerve?
Injuries to the buccal and zygomatic branches are less debilitating because: - They form an interconnecting network across the midface. - Damage to these nerves may occur during surgical procedures, but any injury is less debilitating than an injury to the temporal nerve due to the multiple rami in the buccal and zygomatic branches.
What are the consequences of an injury to the spinal accessory nerve?
Injury to the spinal accessory nerve can lead to: 1. Paralysis of the trapezius with winging of the scapula 2. Shoulder drop 3. Inability to shrug the shoulder 4. Difficulty with abducting the arm 5. Chronic shoulder pain
How can you approximate the location of the spinal accessory nerve?
To approximate the location of the spinal accessory nerve: 1. Draw a line connecting the angle of the mandible with the mastoid process. 2. From the midpoint of this line, draw a vertical line 6 cm inferiorly. 3. The intersection of this line with the posterior border of the sternocleidomastoid muscle indicates Erb’s point, which is where the spinal accessory nerve emerges.
What is the clinical implication of the Hutchinson sign?
The Hutchinson sign indicates that vesicles on the nasal tip may suggest involvement of the eye, as the nasociliary branch of V1 sends branches to both the nasal tip and the cornea.
What are the branches of the trigeminal nerve (CN V) and their areas of innervation?
The trigeminal nerve (CN V) has three main branches: | Branch | Area Innervated | |—————-|————————————-| | Ophthalmic (V1)| Forehead, anterior scalp | | Maxillary (V2) | Lateral nose, lower eyelid, superior cheek, anterior temple | | Mandibular (V3)| Lower lip, chin, mandibular and preauricular cheek, anterior ear, central temporal scalp |
What are the potential consequences of damaging the spinal accessory nerve during a neck dissection?
Damage to the spinal accessory nerve can lead to paralysis of the trapezius muscle, resulting in winging of the scapula, shoulder drop, inability to shrug the shoulder, difficulty abducting the arm, and chronic shoulder pain.
A patient has vesicles on the nasal tip and complains of eye pain. What is the clinical implication, and which nerve is involved?
The presence of vesicles on the nasal tip (Hutchinson sign) indicates that the eye may be involved because the nasociliary branch of the ophthalmic nerve (V1) sends branches to both the nasal tip and the cornea.
How can the location of Erb’s point be approximated, and why is it clinically significant?
Erb’s point can be approximated by drawing a line connecting the angle of the mandible with the mastoid process, then drawing a vertical line 6 cm inferiorly from the midpoint of this line. It is significant because it marks the emergence of several important sensory nerves and the spinal accessory nerve.
What are the branches of the ophthalmic nerve (V1), and what areas do they innervate?
Branches of the ophthalmic nerve (V1) include the supraorbital and supratrochlear nerves (forehead and anterior scalp), infratrochlear nerve (glabella, nasal root, and bridge), lacrimal nerve (upper eyelid), and external nasal nerve (dorsal nose).
What are the main branches of the maxillary nerve (V2), and what areas do they innervate?
The main branches of the maxillary nerve (V2) are the zygomaticofacial nerve (lateral canthus), zygomaticotemporal nerve (anterior temporal region), and infraorbital nerve (eyelid and superior cheek).
What is the anatomical explanation for the Hutchinson sign in herpes zoster?
The Hutchinson sign occurs because the nasociliary branch of the ophthalmic nerve (V1) sends branches to both the nasal tip and the cornea, indicating potential eye involvement.
What are the main branches of the mandibular nerve (V3), and what areas do they innervate?
The main branches of the mandibular nerve (V3) are the auriculotemporal nerve (temple, scalp, anterior ear), buccal nerve (buccal mucosa, gingiva), and mental nerve (lower lip, chin).
What are the potential consequences of damaging the spinal accessory nerve in the posterior triangle of the neck?
Damage can lead to paralysis of the trapezius muscle, resulting in winging of the scapula, shoulder drop, difficulty abducting the arm, and chronic shoulder pain.
What are the consequences of an injury to the spinal accessory nerve?
Injury to the spinal accessory nerve can lead to: 1. Paralysis of the trapezius with winging of the scapula 2. Shoulder drop 3. Inability to shrug the shoulder 4. Difficulty with abducting the arm 5. Chronic shoulder pain.
How can you approximate the location of the spinal accessory nerve?
To approximate the location of the spinal accessory nerve: 1. Draw a line connecting the angle of the mandible with the mastoid process. 2. From the midpoint of this line, draw a vertical line 6 cm inferiorly. 3. The intersection of this line with the posterior border of the sternocleidomastoid muscle indicates Erb’s point, where the spinal accessory nerve emerges.
What are the branches of the trigeminal nerve and their respective areas of innervation?
The trigeminal nerve (CN V) has three main branches: | Branch | Area Innervated | |—————-|————————————-| | Ophthalmic (V1)| Forehead, anterior scalp | | Maxillary (V2) | Lateral nose, lower eyelid, superior cheek, anterior temple | | Mandibular (V3)| Lower lip, chin, mandibular and preauricular cheek, anterior ear, central temporal scalp |
What are the major cutaneous branches of the mandibular nerve (CN V3)?
The major cutaneous branches of the mandibular nerve (CN V3) include: | Branch | Function | |———————-|—————————————————| | Auriculotemporal nerve| Innervates the temple, anterior ears, and parts of the external ear canal | | Buccal nerve | Supplies skin over the buccinators, buccal mucosa, and gingiva | | Mental nerve | Supplies sensation to the lower lip and chin |
What are the branches of the ophthalmic nerve (CN V1) and their functions?
The branches of the ophthalmic nerve (CN V1) and their functions are: | Branch | Function | |———————-|—————————————————| | Supraorbital nerve | Supplies the forehead and anterior scalp | | Supratrochlear nerve | Supplies the forehead and anterior scalp | | Infratrochlear nerve | Supplies the glabella, nasal root, and bridge | | Lacrimal nerve | Supplies sensation to the upper eyelid | | External nasal nerve | Supplies the dorsal nose |
What are the two main branches of the maxillary nerve (CN V2) and their functions?
The two main branches of the maxillary nerve (CN V2) and their functions are: | Branch | Function | |———————-|—————————————————| | Zygomaticofacial nerve| Supplies a small area of the lateral canthus | | Zygomaticotemporal nerve| Supplies skin of the anterior temporal region |
What are the primary muscles involved in facial expression and their functions?
The primary muscles of facial expression include: | Muscle | Function | |——–|———-| | Frontalis | Elevates the eyebrows and covers the forehead | | Occipitalis | Covers the posterior scalp | | Orbicularis oculi | Closes the eyes with both reflexive and voluntary control | | Orbicularis oris | Purses the lips for sounds and whistling | | Zygomaticus major/minor | Elevates the corners of the mouth | | Depressor anguli oris | Depresses the corners of the mouth | | Buccinator | Aids in mastication by keeping food between the teeth | | Risorius | Retracts the corners of the mouth |
How does the blood supply to the face primarily derive?
The blood supply of the face is almost entirely derived from branches of the external carotid artery. Key branches include: | Artery | Description | |——–|————-| | Facial artery | Branches off the external carotid artery, supplies the lips and face | | Angular artery | Continuation of the facial artery, anastomoses with the ophthalmic artery | | Posterior auricular artery | Supplies the postauricular scalp and other areas | | Maxillary artery | Supplies the lower eyelids and infraorbital cheek |
What is the significance of the facial veins lacking valves?
Facial veins lack valves, which allows blood to flow in either direction. This characteristic has clinical significance because: - It facilitates the spread of infections from the face to the cavernous sinus through anastomoses with the ophthalmic vein and angular vein. - The absence of valves can lead to complications in facial infections, making them potentially more dangerous.
What are the lymphatic drainage patterns of the face?
The lymphatic vessels of the face generally drain from superficial to deep and from medial to lateral. Key drainage patterns include: | Area | Drains to | |——|———–| | Posterior scalp | Postauricular and occipital nodes | | Lateral and superior face, forehead, lateral eyelids | Parotid nodes | | Medial and inferior face, medial eyelids, lateral lips | Submandibular nodes | | Middle 2/3 of lower lip and chin | Submental nodes |
Where do the internal and external carotid systems meet?
The internal and external carotid systems meet at: 1. The anastomosis of the supratrochlear branch and the dorsal nasal artery with the angular artery. 2. The anastomosis of the forehead branches of the supraorbital and supratrochlear arteries with branches of the superficial temporal artery, which supply both the nasal tip and the cornea.
What is the clinical significance of the angular vein in the central face?
The angular vein communicates with the ophthalmic vein and the deep facial vein, allowing infections in the central face to travel to the cavernous sinus, posing a risk of cavernous sinus thrombosis.
What are the muscles of the scalp, and what is their function?
The scalp has two muscles: the frontalis (anteriorly), which elevates the eyebrows, and the occipitalis (posteriorly). These muscles are joined by the galea aponeurotica, a thick fascia over the scalp.
What is the role of the orbicularis oris muscle, and which nerves innervate it?
The orbicularis oris is a sphincter-like muscle around the mouth that helps purse the lips for sounds and whistling. It is innervated by the buccal and marginal mandibular branches of the facial nerve.
What are the lymphatic drainage patterns of the face, and why are they clinically significant?
The lymphatic drainage patterns are: posterior scalp to postauricular and occipital nodes, lateral and superior face to parotid nodes, medial and inferior face to submandibular nodes, middle 2/3 of lower lip and chin to submental nodes.
What are the lymphatic drainage patterns of the face, and why are they clinically significant?
The lymphatic drainage patterns are: posterior scalp to postauricular and occipital nodes, lateral and superior face to parotid nodes, medial and inferior face to submandibular nodes, and middle lower lip and chin to submental nodes. These patterns are significant for understanding the spread of infections and malignancies.
What are the muscles responsible for elevating the lips, and which nerve innervates them?
The lip elevators include zygomaticus major, zygomaticus minor, levator anguli oris, levator labii superioris, and levator superioris alaeque nasi. They are innervated by the buccal branch of the facial nerve.
What is the significance of the galea aponeurotica in scalp anatomy?
The galea aponeurotica is a thick fascia that joins the frontalis and occipitalis muscles over the scalp, playing a role in scalp mobility and expression.
What are the main arteries supplying the face, and what is their clinical significance?
The main arteries are branches of the external carotid artery (facial artery, angular artery, posterior auricular artery, maxillary artery) and internal carotid artery (ophthalmic artery, supraorbital artery, supratrochlear artery). Their anastomoses ensure reliable healing and pose risks for infection spread.
What are the muscles responsible for depressing the lips, and which nerve innervates them?
The lip depressors include depressor anguli oris, depressor labii inferioris, and mentalis. They are innervated by the marginal mandibular branch of the facial nerve.
What is the role of the buccinator muscle, and which nerve innervates it?
The buccinator muscle aids in mastication by keeping food between the teeth and is innervated by the buccal branch of the facial nerve.
What are the main branches of the facial artery, and what areas do they supply?
The facial artery gives off the inferior labial artery (lower lip), superior labial artery (upper lip), and angular artery (nasofacial sulcus).
What are the anatomical features of the forehead, and which muscles are involved in its movement?
The forehead has features like the procerus muscle (creates horizontal creases at the root of the nose) and the frontalis muscle (elevates the eyebrows).
What are the anatomical features of the eyelids, and which muscles control their movement?
The eyelids are controlled by the orbicularis oculi muscle, which has an orbital portion (voluntary control) and a palpebral portion (reflexive and voluntary control).
What are the primary muscles involved in elevating the eyebrows and their functions?
The primary muscles involved in elevating the eyebrows are:
- Frontalis - elevates the eyebrows and covers the forehead.
- Corrugator supercilii - moves the eyebrows medially and downward.
Describe the role of the orbicularis oculi muscle in eye movement.
The orbicularis oculi muscle surrounds the eye and consists of:
- Orbital portion: closes the eyes with voluntary control.
- Palpebral portion: closes the eyes with both reflexive and voluntary control.
What is the function of the orbicularis oris muscle?
The orbicularis oris muscle is a central sphincter-like muscle around the mouth that helps purse the lips to form certain sounds and whistle.
Identify the main arteries that supply the face and their origins.
The main arteries that supply the face are:
- Facial artery - branches from the external carotid artery, supplying the lips and face.
- Angular artery - a continuation of the facial artery that anastomoses with the ophthalmic artery.
- Maxillary artery - supplies the lower eyelids and infraorbital cheek.
Explain the significance of the angular vein in facial infections.
The angular vein communicates with the deep facial vein and pterygoid plexus, allowing for easy access for infections to travel along the ophthalmic vein to the cavernous sinus due to the absence of valves in facial veins.
What are the lymphatic drainage patterns of the face?
The lymphatic vessels of the face generally drain:
- From superficial to deep
- From medial to lateral and caudad
Specific drainage includes:
- Posterior scalp: drains to postauricular and occipital nodes.
- Lateral and superior face: drains to parotid nodes.
- Medial and inferior face: drains to submandibular nodes.
- Lower lip and chin: drains to submental nodes.
Where do the internal and external carotid systems meet?
The internal and external carotid systems meet at:
1. The anastomosis of the supratrochlear branch and the dorsal nasal artery with the angular artery.
2. The anastomosis of the forehead branches of the supraorbital and supratrochlear arteries with branches of the superficial temporal artery to the nasal tip and cornea.
What is the role of the buccinator muscle in facial expression?
The buccinator muscle plays a crucial role in facial expression by:
- Keeping food positioned between the teeth during chewing.
- Assisting in blowing and sucking actions.
How does the blood supply to the face primarily derive?
The blood supply to the face is almost entirely derived from branches of the external carotid artery, which includes the facial artery and its branches that supply various facial structures.
What are the key functions of the zygomaticus major and minor muscles?
The zygomaticus major and minor muscles are responsible for:
- Zygomaticus major: elevates the corners of the mouth, contributing to smiling.
- Zygomaticus minor: assists in elevating the upper lip, aiding in facial expressions of happiness.
