26 - Anatomy of the Scalp, Face and Parotid Flashcards
Extent of the scalp
External occipital protuberance posterioraly, extends to the supra-orbital margins.
Laterally to the zygomatic arches.
Layers of the scalp
Skin Connective tissue (dense) Aponeurosis (of occipitofrontalis) Loose areolar tissue Pericranium (periosteum of skull)
Shape of occipitofrontalis
Two muscle bellies, separated by an aponeurosis.
Frontalis over the face, occipitalis over the occipital part of the skull
Significance of the structure of the loose areolar tissue of the scalp
Very good for infection.
Infections of the scalp often localise here, then spread through diploic veins into deeper layers of the skull.
Layers of dura
Periosteal layer (lies against skull, an endosteal layer) Meningeal layer (lies against arachnoid, splits from periosteal layer to form dural septa (falx, etc)
Neurovascular plane of the scalp location
Dense connective tissue layer
Neurovascular plane of the scalp location
Anastamosis of internal and external carotid arteries.
Why do scalp lacerations bleed heavily? 1 2 3 4
1) Rich anastamosis between internal and external carotid arteries.
2) Frontalis belly and occipitalis belly will pull wounds open, because of centrally-placed aponeurosis of occipitofrontalis muscle.
3) Fibrous septa through structure of connective tissue. Arteries are attached to these, holding arteries open
4) Hard to compress arteries, as they aponeurose circumferentially.
Layer of scalp through which emissary veins travel
Dense connective tissue
Layers of skin of face
Four (same as skull, without loose connective tissue layer).
No aponeurosis like in scalp. Instead has muscles of facial expression
Origins and attachments of muscles of facial expression
All originate on bone, attach to skin of face.
All arrange around orifices and either encircle orifices to act as sphincters, or radiate out from orifice to act as a dilator.
Muscle encircling mouth (sphincter)
Orbicularis oris
Number of pharyngeal arches
Initially six, number five never develops (so five in the end)
Facial supply of the trigeminal nerve
Travel in bands, which point upwards to scalp.
Opthalmic division supplies superior scalp, face until tip of nose, just below eyes.
Maxillary division - Temples down to between tip of nose and upper lip.
Mandibular division - Mid-scalp to between lower lip and mandible.
Sensory supply of posterior scalp
Dorsal rami of cervical spinal nerves (C2 and C3 - C1 has no cutaneous branches). C2 is above ear. C3 below ear, onto back of neck).
Part of skull near which the trigeminal ganglion sits
Petrous part of temporal bone.
Face supplied by internal carotid artery
Centre of face above eyes (supra-trochlear and supra-orbital branches of ophthalmic artery, which is a branch of the internal carotid)
Superficial blood supply of face
Internal and external carotid arteries
Most-important branch of the external carotid supplying the face
Facial artery
Path of the facial artery
Branches from the external carotid.
Travels over inferior border of the mandible.
Tortuous course over face towards the medial border of the eye.
Blood supply of the sides of the scalp
Superficial temporal artery
Blood supply of the posterior scalp
Posterior auricular artery (behind ear) Occipital artery (occipital region)
Four branches of the external carotid supplying face and scalp
1) Facial artery
2) Superficial temporal artery
3) Posterior auricular artery
4) Occipital artery
Major venous drainage from the face
Facial vein
Path of the facial vein
Runs posterior, superficial to artery.
Has a straighter course than the facial artery
Venous drainages of the face
1
2
1) Facial vein (major path of drainage).
2) Drainage into skull through emissary veins into the cavernous sinus (goes via superior, inferior opthalmic veins, deep facial veins).
Lymphatic drainage of head
Drain into a ring of lymph nodes around the base of skull (submental nodes, submandibular nodes, pre-auricular and parotid nodes, upper and deep cervical nodes, mastoid nodes, occipital nodes)
Location of the parotid gland 1 2 3 4 5
Below zygomatic arch. Above angle of the mandible. In front of the ear. Behind masseter. Superficial to styloid process
Parotid duct
Emerges from front of gland, travels along masseter, pierces buccinator to enter oral cavity.
Where does the parotid duct enter the oral cavity?
Opposite the second, upper molar
Structures, superficial to deep, contained within parotid gland
1
2
3
1) Facial nerve
2) Retromandibular vein
3) External carotid artery
External course of CNVII
1
2
3
1) Exits skull through stylomastoid foramen (between styloid process and mastoid process)
2) Pierces parotid gland.
3) Within parotid gland, splits into six branches: Posterior auricular nerve, temporal, zygomatic, buccal, mandibular and cervical
Facial path of CNVII 1 2 3 4 5
1) Sends branch to occipitofrontalis
2) Facial nerve (exits skull just behind parotid gland)
3) Penetrates parotid gland, forms a plexus (called pes anserinus)
4) Splits into five terminal branches, which emerge from anterior border of parotid gland
5) Temporal, zygomatic, buccal, mandibular, cervical
Retromandibular vein
Formed by union of superficial temporal and maxillary veins
Path of external carotid within parotid gland
Penetrates parotid, divides into two terminal branches (superficial temporal and maxillary)
Maxillary artery
Deeper branch of the external carotid.
Gives rise to middle meningeal artery
Appearance of people with damaged facial nerve
Drooping lower eyelid, drooping mouth, flattening of naso-labial fold.
Most common cause of Bell’s palsy
Idiopathic. No known aetiology.
