201: Cutaneous Surgical Anatomy

Question 1

What is the superficial musculoaponeurotic system (SMAS) and its significance in facial surgery?

Answer 1

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.

Question 2

What are the three main danger zones related to the facial nerve during surgery?

Answer 2

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.

Question 3

What are cosmetic units and why are they important in facial surgery?

Answer 3

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.

Question 4

What are the five important concepts of head and neck anatomy relevant to surgery?

Answer 4

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.

Question 5

A patient presents with an asymmetrical smile after a surgical procedure near the mandible. Which nerve is likely damaged?

Answer 5

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.

Question 6

What are the major cosmetic units of the face?

Answer 6

The major cosmetic units of the face are the forehead, temples, eyelids, nose, cheeks, upper and lower lips, chin, and ears.

Question 7

What is the function of the superficial musculoaponeurotic system (SMAS)?

Answer 7

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.

Question 8

What are the three main danger zones of the face?

Answer 8

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.

Question 9

How does the rich vascular supply of the face contribute to surgical outcomes?

Answer 9

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.

Question 10

What is the role of the superficial musculoaponeurotic system (SMAS) in facial surgery?

Answer 10

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.

Question 11

Why is knowledge of facial anatomy critical for surgeons?

Answer 11

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.

Question 12

What is the clinical implication of the relaxed skin tension lines (RSTL) in facial surgery?

Answer 12

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.

Question 13

What are the free margins of the face?

Answer 13

The free margins of the face include: - Eyelid margin - Alar rim - Lip vermillion - Helical rim

Question 14

What are Relaxed Skin Tension Lines (RSTLs) and their significance in surgery?

Answer 14

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.

Question 15

Why is it important to place the long axis of a surgical excision parallel to relaxed skin tension lines (RSTLs)?

Answer 15

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.

Question 16

What are the anatomical features of the nasal ala?

Answer 16

The nasal ala is composed of fibrofatty tissue without cartilage, making it vulnerable to distortion when tension is placed on it during surgery.

Question 17

What are the anatomical features of the lips?

Answer 17

The lips have features like the philtrum, mental crease, vermillion border, and Cupid’s bow. These are critical for maintaining aesthetic landmarks during surgery.

Question 18

What are the anatomical features of the ear?

Answer 18

The ear has features like the helix, concha, antihelix, triangular fossa, scaphoid fossa, tragus, antitragus, and intertragic notch.

Question 19

What are the anatomical features of the nose?

Answer 19

The nose has features like the glabella, root, dorsum, lateral sidewalls, nasal tip, nasal ala, alar groove, nasolabial crease, and columella.

Question 20

What are the free margins of the face and their clinical significance?

Answer 20

The free margins of the face include: Eyelid margin, Alar rim, Lip vermillion, Helical rim. Distortion can cause significant cosmetic and functional concerns.

Question 21

What are the implications of ectropion resulting from distortion of facial margins?

Answer 21

Ectropion can lead to excessive tearing and increased risk of corneal scarring and irritation.

Question 22

What surgical considerations should be taken into account regarding the philtrum?

Answer 22

When considering surgical procedures involving the philtrum, it is important to recognize its role as a critical aesthetic landmark.

Question 23

How do relaxed skin tension lines (RSTLs) influence scar formation after surgery?

Answer 23

RSTLs influence scar formation by guiding the direction of surgical incisions to align with the least tension, which minimizes scar visibility.

Question 24

What is the clinical significance of the vermillion border in lip surgery?

Answer 24

The vermillion border marks the boundary between the red mucosal surface and the cutaneous surface of the lips.

Question 25

What role does the mental crease play in facial aesthetics?

Answer 25

The mental crease divides the cutaneous lower lip from the chin, contributing to the overall facial contour.

Question 26

What are the five main branches of the facial nerve and their mnemonic?

Answer 26

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.'

Question 27

What is the significance of the temporal branch of the facial nerve in terms of susceptibility to injury?

Answer 27

The temporal branch of the facial nerve is most susceptible to injury as it crosses the middle third of the zygomatic arch.

Question 28

What are the potential consequences of damage to the marginal mandibular nerve?

Answer 28

Damage to the marginal mandibular nerve can result in contralateral and upward pull on the mouth.

Question 29

How can one approximate the course of the temporal branch of the facial nerve?

Answer 29

To approximate the course of the temporal branch, draw a line from the earlobe to the lateral edge of the eyebrow.

Question 30

What muscles are innervated by the temporal branch of the facial nerve?

Answer 30

The temporal branch of the facial nerve innervates the frontalis, upper fibers of the orbicularis oculi, corrugator supercilia, and anterior and superior auricular muscles.

Question 31

During a brow lift surgery, how can a surgeon avoid damaging the temporal branch of the facial nerve?

Answer 31

The surgeon should undermine just beneath the dermis in the superficial fat above the fascia.

Question 32

A patient has difficulty closing their eyes after surgery near the orbit. Which muscle and nerve are likely affected?

Answer 32

The orbicularis oculi muscle is likely affected. The temporal branch of the facial nerve (CN VII) innervates this muscle.

Question 33

What mnemonic can help remember the branches of the facial nerve?

Answer 33

They can be remembered with the mnemonic 'To Zanzibar By Motor Car.'

Question 34

Which muscle and nerve are likely affected if a patient has difficulty closing their eyes after surgery near the orbit?

Answer 34

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.

Question 35

How can the course of the temporal branch of the facial nerve be approximated?

Answer 35

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.

Question 36

What are the potential consequences of damaging the temporal branch of the facial nerve?

Answer 36

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.

Question 37

What are the potential consequences of damaging the marginal mandibular nerve during surgery?

Answer 37

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.

Question 38

What are the potential consequences of damaging the buccal and zygomatic branches of the facial nerve?

Answer 38

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.

Question 39

What are the five main branches of the facial nerve and their mnemonic?

Answer 39

The five main branches of the facial nerve are: 1. Temporal 2. Zygomatic 3. Buccal 4. Mandibular 5. Cervical ## Footnote Mnemonic: 'To Zanzibar by motor car.'

Question 40

What is the significance of the temporal branch of the facial nerve in terms of surgical procedures?

Answer 40

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.

Question 41

What are the potential cosmetic and functional losses resulting from damage to the temporal branch of the facial nerve?

Answer 41

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.

Question 42

What muscles are innervated by the marginal mandibular nerve?

Answer 42

The marginal mandibular nerve innervates the following muscles: - Depressor anguli oris - Depressor labii inferioris - Mentalis - Part of the orbicularis oris

Question 43

What are the consequences of damage to the marginal mandibular nerve?

Answer 43

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.

Question 44

How does the course of the temporal branch of the facial nerve approximate?

Answer 44

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.

Question 45

What is the clinical importance of the cervical branch of the facial nerve?

Answer 45

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.

Question 46

What are the branches of the facial nerve that are most susceptible to injury during surgical procedures?

Answer 46

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.

Question 47

What is the anatomical relationship of the facial nerve branches to the SMAS?

Answer 47

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.

Question 48

What are the less debilitating injuries associated with the buccal and zygomatic branches of the facial nerve?

Answer 48

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.

Question 49

What are the consequences of an injury to the spinal accessory nerve?

Answer 49

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

Question 50

How can you approximate the location of the spinal accessory nerve?

Answer 50

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.

Question 51

What is the clinical implication of the Hutchinson sign?

Answer 51

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.

Question 52

What are the branches of the trigeminal nerve (CN V) and their areas of innervation?

Answer 52

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 |

Question 53

What are the potential consequences of damaging the spinal accessory nerve during a neck dissection?

Answer 53

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.

Question 54

A patient has vesicles on the nasal tip and complains of eye pain. What is the clinical implication, and which nerve is involved?

Answer 54

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.

Question 55

How can the location of Erb’s point be approximated, and why is it clinically significant?

Answer 55

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.

Question 56

What are the branches of the ophthalmic nerve (V1), and what areas do they innervate?

Answer 56

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).

Question 57

What are the main branches of the maxillary nerve (V2), and what areas do they innervate?

Answer 57

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).

Question 58

What is the anatomical explanation for the Hutchinson sign in herpes zoster?

Answer 58

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.

Question 59

What are the main branches of the mandibular nerve (V3), and what areas do they innervate?

Answer 59

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).

Question 60

What are the potential consequences of damaging the spinal accessory nerve in the posterior triangle of the neck?

Answer 60

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.

Question 61

What are the consequences of an injury to the spinal accessory nerve?

Answer 61

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.

Question 62

How can you approximate the location of the spinal accessory nerve?

Answer 62

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.

Question 63

What are the branches of the trigeminal nerve and their respective areas of innervation?

Answer 63

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 |

Question 64

What are the major cutaneous branches of the mandibular nerve (CN V3)?

Answer 64

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 |

Question 65

What are the branches of the ophthalmic nerve (CN V1) and their functions?

Answer 65

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 |

Question 66

What are the two main branches of the maxillary nerve (CN V2) and their functions?

Answer 66

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 |

Question 67

What are the primary muscles involved in facial expression and their functions?

Answer 67

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 |

Question 68

How does the blood supply to the face primarily derive?

Answer 68

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 |

Question 69

What is the significance of the facial veins lacking valves?

Answer 69

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.

Question 70

What are the lymphatic drainage patterns of the face?

Answer 70

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 |

Question 71

Where do the internal and external carotid systems meet?

Answer 71

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.

Question 72

What is the clinical significance of the angular vein in the central face?

Answer 72

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.

Question 73

What are the muscles of the scalp, and what is their function?

Answer 73

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.

Question 74

What is the role of the orbicularis oris muscle, and which nerves innervate it?

Answer 74

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.

Question 75

What are the lymphatic drainage patterns of the face, and why are they clinically significant?

Answer 75

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.

Question 76

What are the lymphatic drainage patterns of the face, and why are they clinically significant?

Answer 76

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.

Question 77

What are the muscles responsible for elevating the lips, and which nerve innervates them?

Answer 77

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.

Question 78

What is the significance of the galea aponeurotica in scalp anatomy?

Answer 78

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.

Question 79

What are the main arteries supplying the face, and what is their clinical significance?

Answer 79

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.

Question 80

What are the muscles responsible for depressing the lips, and which nerve innervates them?

Answer 80

The lip depressors include depressor anguli oris, depressor labii inferioris, and mentalis. They are innervated by the marginal mandibular branch of the facial nerve.

Question 81

What is the role of the buccinator muscle, and which nerve innervates it?

Answer 81

The buccinator muscle aids in mastication by keeping food between the teeth and is innervated by the buccal branch of the facial nerve.

Question 82

What are the main branches of the facial artery, and what areas do they supply?

Answer 82

The facial artery gives off the inferior labial artery (lower lip), superior labial artery (upper lip), and angular artery (nasofacial sulcus).

Question 83

What are the anatomical features of the forehead, and which muscles are involved in its movement?

Answer 83

The forehead has features like the procerus muscle (creates horizontal creases at the root of the nose) and the frontalis muscle (elevates the eyebrows).

Question 84

What are the anatomical features of the eyelids, and which muscles control their movement?

Answer 84

The eyelids are controlled by the orbicularis oculi muscle, which has an orbital portion (voluntary control) and a palpebral portion (reflexive and voluntary control).

Question 85

What are the primary muscles involved in elevating the eyebrows and their functions?

Answer 85

The primary muscles involved in elevating the eyebrows are: 1. **Frontalis** - elevates the eyebrows and covers the forehead. 2. **Corrugator supercilii** - moves the eyebrows medially and downward.

Question 86

Describe the role of the orbicularis oculi muscle in eye movement.

Answer 86

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.

Question 87

What is the function of the orbicularis oris muscle?

Answer 87

The **orbicularis oris** muscle is a central sphincter-like muscle around the mouth that helps purse the lips to form certain sounds and whistle.

Question 88

Identify the main arteries that supply the face and their origins.

Answer 88

The main arteries that supply the face are: 1. **Facial artery** - branches from the external carotid artery, supplying the lips and face. 2. **Angular artery** - a continuation of the facial artery that anastomoses with the ophthalmic artery. 3. **Maxillary artery** - supplies the lower eyelids and infraorbital cheek.

Question 89

Explain the significance of the angular vein in facial infections.

Answer 89

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.

Question 90

What are the lymphatic drainage patterns of the face?

Answer 90

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.

Question 91

Where do the internal and external carotid systems meet?

Answer 91

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.

Question 92

What is the role of the buccinator muscle in facial expression?

Answer 92

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.

Question 93

How does the blood supply to the face primarily derive?

Answer 93

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.

Question 94

What are the key functions of the zygomaticus major and minor muscles?

Answer 94

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.