Face, scalp and parotid Flashcards
What are the margins of the scalp?
From external occipital protuberance posteriorly to supraorbital margins anteriorly
Extends to the level of the zygomatic arches laterally
What are the layers of the scalp, from external to internal?
Skin
Dense connective tissue
Aponeurotic layer (of occipitofrontalis)
Loose connective tissue
Pericranium
Which layer of the scalp allows it to move?
Loose connective tissue
Which two muscles form the aponeurotic layer of the scalp?
Occipitalis and frontalis
What are the actions of occipitalis and frontalis?
Move the scalp and raise the eyebrows
What happens when a laceration to the scalp divides the aponeurosis?
Wound will gape, as occipitalis and frontalis will pull in opposite directions
In which layer of the scalp is the neurovascular plane found?
Dense connective tissue
Why does a scalp laceration bleed so profusely?
1: There is a rich vascular arrangement within the scalp, with many anastamoses between branches of the internal and external carotid arteries
2: The dense connective tissue has fibrous septa, that adhere to vessels and prevent constriction
What are the layers of the face?
Skin
Dense connective tissue
Muscles of facial expression
Pericranium
Whta do the facial muscles attach to?
Arise from bone or fascia and attach to skin of face
How are the facial muscles organised?
Organised to surround the facial orifices; either act as sphincters or dilators
Describe the general properties of sphincter and dilator facial muscles?
Sphincters: circular, name ‘ocularis’
Dilators: span out from corners, name ‘depressor’ or ‘levator’
Which cranial nerve supplies the facial muscles?
CN VII
Facial nerve
What is the embryological origin of the facial muscles?
Second pharyngeal arch
Describe the dermatomes of the head and neck?
Which nerves supply the dermatomes of the head and neck posterior to the ears?
Dorsal rami or cervical spinal nerves (C2 and C3)
Where is the ganglion of the trigeminal nerve found?
Petrous part of temporal bone
Which cranial nerve is responsible for sensation of the face?
CN V
Trigeminal nerve (V1, V2 & V3)
Which two major arteries give branches that supply the face?
Internal carotid
External carotid
List the arterial branches to the face that arise from the internal carotid artery? What do the supply?
Supraorbital branches
Supratrochlear branches
Both supply the centre of the forehead
Which gives off a greater blood supply to the face: the internal carotid or the external carotid?
External carotid
List the branches of the external carotid artery that supply the face?
Facial artery
Superficial temporal artery
Occipital artery
Posterior auricular artery
Which branch of the external carotid artery gives the most extensive blood supply to the face?
Facial artery
Describe the course of the facial artery?
Winds over inferior angle of mandible
Has tortuous course over the face to the medial angle of the eye
Sends branches off to nose, cheeks, etc.
Describe the course of the superficial temporal artery?
Runs over zygomatic arch
What does the superficial temporal artery supply?
Side of scalp
What is the major venous drainage of the face?
Facial vein
How can the facial vein be distinguished from the facial artery?
The facial vein is much less tortuous
Describe the venous drainage of the face?
Veins accompany the arteries and mirror them
In which area of the face may communication between the venous drainage of the face and cavernous sinus occur?
Describe the lymph drainage of the face and scalp?
Lymph drains into a ring of lymph nodes which surround the base of the skull
Submental nodes, submandibular nodes, pre-auricular and parotid nodes, mastoid nodes and occipital nodes
All drain into deep cervical nodes
What is the parotid gland?
A serous salivary gland
Where does the parotid gland sit?
Below zygomatic arch
In front of mastoid process and ear
Above angle of mandible
Behind masseter
Overlies styloid process of temporal bone
What encloses the parotid gland?
Thick parotid fascia
How does saliva travel from the parotid gland to the oral cavity?
Parotid duct
Describe the course of tje parotid duct?
Emerges from anterior border of gland onto masseter
Then turns inwards and pierces buccinator to enter the oral cavity near the second molar
List the structures that lie within the parotid, superficial to deep?
- CN VII
- Retromandibular vein
- External carotid artery
Parotid lymph nodes are scattered throughout
Describe the pathway of the facial nerve?
Exits skull via stylomastoid foramen > goes through auditory meatus, and has a short course through the temporal bone > gives off posterior auricular arch (to occipitalis) > enters substance of parotid gland > creates plexiform arrangement - pes anserinus > gives off five terminal branches
What are the five terminal branches of the facial nerve?
Temporal
Zygomatic
Buccal
Mandibular
Cervical
(Tall Zulus Bear Many Children)
How is the retromandibular vein formed?
By superficial temporal and maxillary veins
What happens to the external carotid artery once it enters the parotid gland?
Divides into maxillary and superifical temporal arteries
Describe the risks associated with surgery in the parotid area?
Facial nerve lesion > partial or complete paralysis of facial muscles ipsilaterally, flattening of nasolabial folds, no movement of eyes
What is the most common cause of facial nerve palsy?
Bell’s palsy (unknown cause, maybe post-viral)
