L7: Scalp, face and parotid

Question 1

Scalp - 5 layers

Answer 1

Skin
Dense CT (contain neurovascular structures)
Aponeurotic layer
Loose CT (facilitates scalp movement over calvaria, infection tends to localise and spread through this layer because of its consistency)
Pericranium
(first 3 layers anchored tightly together)

Question 2

Innervation of scalp

Answer 2

Trigeminal nerve and ant. rami (C1-3) and post. rami (C2-3) of cervical plexus

Question 3

Blood supply of scalp

Answer 3

Arterial:
- Post 2/3 of scalp by external carotid a
(superficial a temporal, post auricular a
- Ant 1/3 by internal carotid a (ophthalmic
branch)
(supratrochlear a, supraorbital a)
Venous:
Similar pattern to arterial

Question 4

Lymphatics of scalp

Answer 4

Lymphatics:
Lymph nodes (submental, submandibular, parotid, mastoid, occipital)
Drain to deep cervical nodes

Question 5

Clinical: anaesthesia for suturing

Answer 5

• Anterior scalp: put slightly ant to laceration (nerve goes ant to post)
• Posterior scalp: put slightly post to laceration (nerve post to ant)
• Lateral scalp (nerve from below)

Question 6

Muscles of facial expression and innervation

Answer 6

Platysma, occipitofrontalis, auricularis muscles, orbicularis occuli

ALL supplied by facial nerve [VII]

Question 7

Platysma

Answer 7

From lower part of mandible to upper part of clavicle, through superficial fascia of neck

Question 8

Occipitofrontalis

Answer 8

2 bellies with long aponeurosis crossing superior skull

Ant belly = frontalis, post belly = occipitalis

Question 9

Auricularis muscles

Answer 9

Posterior, superior, anterior around ear

Generally cannot use

Question 10

Orbicularis occuli

Answer 10

Around eye
Orbital part (around palpebrae) - closes eye hard
Palpebrae part - close eye softly

Question 11

Buccinator and lip muscles

Answer 11

Buccinator: cheek muscles (parotid duct perforates it to enter mouth)

Upper and lower lip muscles (e.g. orbicularis oris)

Question 12

Muscles around nose

Answer 12

Nasalis is the main one

Question 13

Sensory innervation of face

Answer 13

ALL branches of trigeminal n [V]

Ophthalmic [V1] = innervates upper 1/3 of face
–> supraorbital, supracochlear, lacrimal, infratrochlear, external nasal

Maxillary [V2] = innervates middle 1/3
–> zygomaticotemporal, infraorbital, zygomaticofacial

Mandibular [V3] = innervates lower 1/3
–> auricotemporal (goes up), buccal (upper teeth), mental (chin)

e.g. toothache radiates back via infraorbital n to face

Question 14

Parotid gland anatomy

Answer 14

Superficial part on mandible ramus (in front of ear, below zygomatic arch)
Deep part wraps around mandible ramus
Surrounded by investing fascia

Question 15

Parotid gland innervation

Answer 15

Sensory: V3 to gland, C2 to parotid fascia
Secretomotor:
- Parasymp = mainly IX (and V3)
- Sympa = superior cervical ganglion via
external carotid a

Question 16

Parotid duct path

Answer 16

From the deep part, exits gland on anterior margin of superficial part
Runs along masseter and dives into buccinator on ant. edge of masseter
Opens next to 2nd molar

Question 17

Parotid duct surface anatomy

Complications of injury

Answer 17

Line from lower tragus (ear) to cheilion (corner of mouth)
Make a box in the middle 1/3 of line, above and below 1.5cm
95% of parotid ducts within box

Complications of injury: sialocoele, salivary fistula

Question 18

Facial nerve

Answer 18

Exits skull via stylomastoid foramen (giving off posterior auricular n, n to occipital part of occipitofrontalis and n to post belly of digastric and stylohyoid)
Splits into temporozygomatic and cervicofacial branches

Question 19

Temporozygomatic branches

Answer 19

1. Temporal branch (supplies ant and sup auricularis muscle and crosses zygomatic arch to innervate frontalis)
2. Zygomatic branch (crosses zygomatic arch and supplies frontalis, o. occuli and muscles below eye - paralysis impairs blinking)
3. Buccal branch (buccinator muscles and muscles of upper lip)

Question 20

Cervicofacial branches

Answer 20

1. Marginal mandibular (muscles of lower lip after travelling along lower border of mandible)
2. Cervical (supplies platysma)

Question 21

Injury to temporal branch

Injury to marginal mandibular branch

Answer 21

Temporal branch = ptosis of brow

Marginal mandibular branch = lip drooping and over time, upper lip elevates to compensate leading to resting snarl face

Question 22

Injury to facial nerve

Answer 22

= Bells palsy
One side of face droops
May also affect taste and how you produce tears and saliva

Question 23

Relations of facial nerve

Answer 23

Runs between mastoid process and styloid process
Penetrates parotid gland between superficial and deep parts
Then crosses superficial to retromandibular vein, external carotid artery, mandible, masseter muscle