Scalp & face + development of the face

🟣 Anatomy of the Scalp & Face – Notes

🖇 Scalp

📌 Definition: Hair-bearing part of the head.

📌 Boundaries:

• Anterior: Eyebrow → Glabella → Supraorbital margin
• Posterior: External occipital protuberance → Superior nuchal line
• Lateral: Superior temporal line → Zygomatic arch

📌 Layers (S.C.A.L.P):

1. Skin – with hair & sweat glands
2. Connective tissue – rich blood vessels 🚨 bleeding source
3. Aponeurosis – occipitofrontalis tendon
4. Loose areolar tissue – fat, allows free movement 🚨 danger space for infection
5. Pericranium – periosteum of skull

🖇 Occipitofrontalis Muscle

📌 Two bellies connected by aponeurosis:

• Frontal belly → elevates eyebrow, wrinkles forehead (surprise)
• Occipital belly → pulls scalp backward, smooths forehead

📌 Nerve supply:

• Frontal belly → Temporal branch of CN VII
• Occipital belly → Posterior auricular branch of CN VII

🖇 Nerve Supply of Scalp & Face

📌 Motor: Facial nerve (CN VII) → all muscles of facial expression

📌 Sensory: Trigeminal nerve (CN V)

• V1 (ophthalmic): forehead, nose, medial eye
• V2 (maxillary): upper lip, zygomatic region
• V3 (mandibular): chin, lower lip, temporal region

📌 Exceptions:

• Angle of mandible → Great auricular nerve (C2, C3)
• Posterior scalp → Greater, Lesser, Third occipital nerves

🖇 Muscles of Facial Expression

📌 Orbicularis oculi

• Orbital part → strong closure (squinting)
• Palpebral part → gentle closure (blinking)
• Lacrimal part → aids tear flow
  🚨 Origin & insertion: medial palpebral ligament → same ligament

📌 Buccinator

• Prevents food pocketing between cheek & gums
• Helps blowing & whistling
• Supplied by buccal branch of CN VII

📌 Orbicularis oris

• Encircles mouth → closes/open lips
• Actions: kissing, whistling

🖇 Applied Anatomy – Bell’s Palsy

📌 Cause: LMN lesion of Facial nerve (CN VII)
📌 Signs:

• Inability to close eye → dryness, corneal damage
• Drooping mouth, deviation to healthy side
• Can’t whistle, blow, or retain saliva

🖇 Development of the Face

📌 Formed around Stomodeum
📌 Processes:

• Frontonasal: nose, philtrum
• Maxillary (1st arch): upper lip (except philtrum), cheek, nasolacrimal duct, palate
• Mandibular (1st arch): lower lip & chin

🚨 Key Exam Questions

1. Layer of scalp causing severe hemorrhage → Connective tissue
2. Function of loose areolar tissue → allows free movement of scalp
3. Motor supply to facial muscles → Facial nerve (CN VII)
4. Sensory supply to face/scalp → Trigeminal nerve (CN V)
5. Sensory over angle of mandible → Great auricular nerve
6. Action of occipitofrontalis → surprise (frontal), smoothing (occipital)
7. Key role of buccinator → prevents food pocketing
8. Orbital vs palpebral part of orbicularis oculi → strong vs gentle closure
9. Development: Maxillary & Mandibular → First pharyngeal arch