Face and scalp Flashcards
What are the five layers of the scalp, and which is considered the “danger area”?
SCALP:
S: Skin
C: Connective tissue (dense)
A: Aponeurosis (Epicranial aponeurosis)
L: Loose connective tissue (danger area)
P: Pericranium (periosteum)
The loose areolar connective tissue is considered the “danger area” of the scalp because it contains emissary veins that connect the scalp’s veins to the intracranial venous sinuses. This means that infections in the scalp can spread to the cranial cavity and meninges, which can lead to meningitis.
What are the main arteries supplying the scalp?
The scalp receives blood from branches of the external carotid artery (occipital, posterior auricular, superficial temporal) and the internal carotid artery (supratrochlear, supraorbital arteries)
How are facial muscles organized, and what is their nerve supply?
Facial muscles are organized into sphincteric (e.g., orbicularis oculi, orbicularis oris) and dilator muscles. They are all supplied by the facial nerve (CN VII) via its five branches (temporal, zygomatic, buccal, marginal mandibular, cervical)
How does facial weakness differ between Bell’s palsy and a stroke?
Bell’s palsy (LMN lesion): Affects the entire half of the face (cannot close eyes or elevate eyebrows on the affected side).
Stroke (UMN lesion): Affects only the lower half of the face (can close eyes and elevate eyebrows)
What are the divisions of the trigeminal nerve (CN V) and the areas they supply?
V1 (Ophthalmic): Forehead, upper eyelids, nose.
V2 (Maxillary): Cheeks, upper lip, upper teeth.
V3 (Mandibular): Lower lip, chin, lower teeth, motor supply to muscles of mastication
Where is the danger area of the face, and why is it clinically significant?
The danger area is around the nose and upper lip. Infections here can spread to the cranial cavity via venous connections (cavernous sinus), potentially leading to serious complications
What are the anatomical relations of the parotid gland, and what nerve innervates it?
Location: Wedge-shaped, between the ramus of the mandible and mastoid process.
Innervation: Parasympathetic supply from the glossopharyngeal nerve (CN IX) via the otic ganglion.
Relations: Contains facial nerve (CN VII), retromandibular vein, external carotid artery
What are the consequences of a blunt injury to the scalp, and where does blood accumulate?
Blood can accumulate in the subcutaneous, subaponeurotic, or subperiosteal layers. Main arteries involved are branches of the external carotid artery. Control of bleeding from the scalp is possible by applying circumferential pressure
What is the main arterial supply to the face, and where can pulses be palpated?
The facial artery supplies the face and can be palpated along the inferior border of the mandible.
The superficial temporal artery supplies the scalp and can be palpated just anterior to the ear at the zygomatic arch
Why is the facial nerve significant in parotid gland surgery?
The facial nerve (CN VII) passes through the parotid gland, making it vulnerable to injury during parotidectomy for tumor removal
How are the facial muscles functionally organized around the mouth and eyes?
Sphincteric muscles: Close apertures, e.g., orbicularis oculi (eyes) and orbicularis oris (mouth).
Dilator muscles: Open apertures, e.g., levator labii superioris (raises the upper lip), depressor anguli oris (lowers corners of the mouth)
Describe the course of the facial artery and its clinical relevance.
The facial artery arises from the external carotid artery, crosses the lower border of the mandible near the masseter muscle, ascends to the medial angle of the eye, and terminates as the angular artery. Its pulse can be felt at the lower mandible
How is collateral circulation established when the external carotid artery is ligated?
Collateral circulation occurs via anastomoses between branches of the external carotid artery (ECA) and the internal carotid artery (ICA), particularly in areas like the scalp where supraorbital and supratrochlear arteries (from ICA) meet branches of the ECA
How is venous drainage of the face and scalp organized, and why is it clinically important?
The facial vein drains into the internal jugular vein.
It communicates with the cavernous sinus via the ophthalmic vein, making infections in the danger area of the face (nose and upper lip) potentially serious
What is trigeminal neuralgia and what part of the trigeminal nerve is most commonly affected?
Trigeminal neuralgia is characterized by sudden, severe facial pain, often triggered by touch. The maxillary nerve (V2) is most commonly affected, followed by the mandibular (V3) and ophthalmic (V1) nerves
How is head pain referred, and which nerves are involved?
Head pain is often referred to the distribution areas of the trigeminal nerve (CN V) or upper cervical nerves. The trigeminal nerve provides sensory innervation to the anterior head, while the upper cervical nerves (C1-C4) innervate the posterior regions
Describe the pathway of the parotid duct and its significance.
The parotid duct (Stenson’s duct) emerges from the anterior edge of the parotid gland, crosses the masseter muscle, then pierces the buccinator muscle, and opens into the oral cavity opposite the second upper molar as the parotid papilla
Why is the loose connective tissue layer of the scalp called the “danger area”?
Infections in the loose connective tissue layer can spread through emissary veins into the cranial cavity, potentially leading to serious complications such as meningitis
What are the key clinical features of Bell’s palsy?
Facial drooping on the affected side.
Inability to close the eye, leading to dry eye or excessive tearing.
Drooping of the mouth corner, causing drooling and difficulty in speech.
Weakness or paralysis of the facial muscles
Why is the pterion clinically significant?
The pterion is the thinnest part of the skull where four bones meet. The middle meningeal artery runs just deep to it, making this area vulnerable to epidural hematomas if injured
Why must surgeons be cautious during parotid gland surgery?
The facial nerve (CN VII) runs through the parotid gland, and injury to this nerve during parotidectomy can cause permanent facial paralysis
What are the clinical signs of injury to the facial nerve?
Signs include inability to close the eyes, drooping of the mouth, facial asymmetry, and difficulty speaking or eating due to paralysis of facial muscles
Where can the superficial temporal artery pulse be palpated, and why is it clinically important?
The superficial temporal artery can be palpated anterior to the ear, just above the zygomatic arch. This is often used by anesthesiologists to monitor the pulse during surgery
