L1: general organisation of the head and neck region

Question 1

List the muscles of facial expression

Answer 1

Orbicularis oculi
Occipitofrontalis 
Orbicularis oris 
Buccinator 
Dilator muscles (zygomaticus muscles & risorius)
Platysma

Question 2

List the muscles of mastication

Answer 2

Masseter
Temporalis
Pterygoids (lateral and medial)

Question 3

Describe the action and nerve innervation of orbicularis oculi

Answer 3

Orbital – squeezes the eye shut
Palpebral – closes the eyelid
Nerve – facial nerve

Question 4

Describe the action and nerve innervation of occipitofrontalis

Answer 4

Action – elevates eyebrows & wrinkles the forehead

Nerve – facial nerve

Question 5

Describe the action and nerve innervation of orbicularis oris

Answer 5

Action – brings lips together/purses lips

Nerve – facial nerve

Question 6

Describe the action and nerve innervation of buccinator

Answer 6

Action – compresses the cheeks during mastication

Nerve – facial nerve

Question 7

Describe the action and nerve innervation of the dilator muscles

Answer 7

Zygomaticus – draws the angles of the mouth laterally and superiorly (smile)
Risorius – pulls the corner of the mouth laterally
Nerve – facial nerve

Question 8

Describe the action and nerve innervation of platysma

Answer 8

Action – depresses angles of the mouth & tenses skin on neck
Nerve – facial nerve

Question 9

Describe the action and nerve innervation of masseter

Answer 9

Action – main elevator of the mandible (palpable when contracted)
Nerve – mandibular division of the trigeminal nerve

Question 10

Describe the action and nerve innervation of temporalis

Answer 10

Action – elevates the mandible & posterior fibres retract the jaw
Nerve – mandibular division of the trigeminal nerve

Question 11

Describe the action and nerve innervation of the lateral pterygoid

Answer 11

Action – bilateral contraction assists in depressing the mandible & protrudes mandible
Nerve – mandibular division of the trigeminal nerve

Question 12

Describe the action and nerve innervation of the medial pterygoid

Answer 12

Action – bilateral contraction assists in elevating the mandible & protrudes mandible
Nerve – mandibular division of the trigeminal nerve

Question 13

Describe the action and nerve innervation of sternocleidomastoid

Answer 13

Action – rotates the head to contralateral sides & laterally flexes neck
Nerve – accessory nerve

Question 14

Describe the action and nerve innervation of trapezius

Answer 14

Action – upper fibres elevate shoulder & rotates scapula when abducting shoulder beyond 90 degrees
Nerve – accessory nerve

Question 15

List the five key extracranial branches of the facial nerve

Answer 15

Temporal
Zygomatic 
Buccal
Marginal mandibular 
Cervical 
‘To Zanzibar By Motor Car’

Question 16

Describe the boundaries & contents of the anterior triangle

Answer 16

Medial - midline of the neck
Superior - inferior margin of mandible
Lateral – interior margin of sternocleidomastoid
Roof – investing fascia
Floor – visceral fascia
Contents – suprahyoid muscles, internal jugular vein, carotid artery, infrahyoid muscles & hyoid bone

Question 17

Describe the boundaries & contents of the posterior triangle

Answer 17

Anterior – posterior border of the sternocleidomastoid
Posterior – anterior border of the trapezius muscle
Inferior – middle 1/3 of the clavicle
Roof – investing layer of fascia
Floor – prevertebral fascia
Contents – external jugular vein, scalenes, trunks of brachial plexus, subclavian artery + vein & omohyoid

Question 18

Describe the boundaries & contents of the carotid triangle

Answer 18

Superior – posterior belly of the digastric muscle
Lateral – medial border of the sternocleidomastoid muscle
Inferior – superior belly of the omohyoid muscle
Contents – common carotid artery, internal jugular vein & hypoglossal + vagus nerves

Question 19

Describe the cervical fascia

Answer 19

Superficial cervical fascia
3 deep cervical fascial layers:
-investing layer
-pretracheal layer (posteriorly known as the buccopharyngeal layer)
-prevertebral layer
(carotid sheath is the 4th layer – formed by parts of all three layers of deep cervical fascia)

Question 20

Where is the retropharyngeal space? What disease is at risk of developing if there is an infection here?

Answer 20

Deep neck space that lies between the buccopharyngeal fascia and prevertebral fascia
Up until 3/4 years old, lymph nodes are here -> drain areas of the nose, oral cavity & upper pharynx
Retropharyngeal infections may spread inferiorly into the thorax, risking the development of mediastinitis (rare BUT life-threatening)