1) General organisation of H&N Flashcards
What are the major muscle groups in the head?
Muscles of facial expression
Buccinators (muscles of cheek)
Occipitofrontalis muscle
Muscles of mastication
What are the actions of facial muscles?
Move the skin & change facial expressions
Sphincters & dilators (open & close eyes, mouth)
Buccinators keep cheeks taut & aid chewing
What is the innervation of the muscles of mastication?
Mandibular division of the Trigeminal nerve (CNViii)
What does the facial nerve (CNVII) innervate?
Platysma (superficial muscle of neck & chin)
Muscles of facial expression
Buccinators
Muscles of the ear
Occipitofrontalis muscle
(CN VII enters the parotid gland where it divides into extra-cranial branches)
Name a non-traumatic cause of facial paralysis
Inflammation of CN VII near its exit from cranium at stylomastoid foramen
Describe Bell’s palsy
Inflammation causes oedema & compression of facial nerve in intracranial facial canal
Affected area sags, facial expression distorted, face appears passive or sad
What injuries can occur to the branches of the facial nerve?
Branches are superficial
Injured in wounds, cuts & childbirth
Parotid gland surgery or disease (pain in auricle of ear, external acoustic meatus, temporal region & TMJ)
What is the arterial supply to the face?
Facial artery (main supply) External carotid artery (branches)
Describe the facial artery
Artery winds round inferior border of mandible.
Pulse can be palpated
Lots of anastomoses, if lacerated both facial arteries must be compressed
Describe the venous drainage of the face
Facial vein (main) drains into the Internal Jugular vein Superficial temporal, maxillary & other veins form the EJV Both IJV & EJV drain into subclavian vein
Describe the fascia surrounding structures in the neck
Covered by layer of subcutaneous superficial fascia
Compartmentalised by deep cervical fascial layers
(determine direction infection may spread)
Describe the superficial cervical fascia
Fatty connective tissue
Lies between dermis of skin & investing layer of deep cervical fascia
Thin anteriorly
Contains cutaneous nerves, blood & lymph vessels and anterolaterally the Platysma
Describe the platysma
Broad thin sheet of muscle, tenses the skin
Develops from 2nd pharyngeal arch
Supplied by branches of facial nerve (CN VII)
Covers anterolateral aspect of neck
Inferiorly, gap anterior to larynx & trachea
Depresses the mandible, draws corners of mouth inferiorly (grimace)
Describe the layers of the deep cervical fascia in the neck
3 layers:
Investing
Pretracheal
Prevertebral
Condenses around common carotid arteries, IJVs & Vagus nerve to form CAROTID SHEATH
What are the functions of the deep cervical fascia in the neck?
Support (viscera e.g. thyroid gland, muscles, vessels & deep lymph nodes)
Limit the spread of abscesses from infections
Slipperiness allows structures to move and pass over one another (swallowing, turning head)
Describe the investing layer of deep cervical fascia
Most superficial
Surrounds entire neck deep to skin
Encloses: SCM, Trapezius, Submandibular & Parotid salivary glands
Describe the pretracheal layer of deep cervical fascia
Thin layer, anterior part of neck only
Inferiorly extends into thorax & blends with fibrous pericardium, laterally blends with carotid sheath
Muscular layer: encloses Infrahyoid muscles
Visceral layer: Thyroid gland, trachea, oesophagus
Describe the prevertebral layer of deep cervical fascia
Innermost layer of deep fascia
Sheath for vertebral column & assoc. muscles
From base of cranium of 3rd thoracic vertebrae
Extends laterally as axillary sheath (axillary vessels & brachial plexus)
What is the carotid sheath?
Tubular, fibrous structure
Base of cranium to root of neck
Contains: Common carotid artery, IJV, CN X (Vagus)
What are cleavage planes?
Layers of deep cervical fascia form natural cleavage planes
Separation of tissues during surgery
If an infection occurs between the investing layer and muscular part of the pretracheal layer surrounding the infrahyoid muscles, where will it spread?
Won’t spread beyond the manubrium
If an infection occurs between the investing layer and visceral pretracheal layers, where will it spread?
Into the thoracic cavity anterior to the pericardium
Where will pus from an abscess behind the prevertebral layer extend?
Laterally in the neck
May perforate fascial layer and enter retropharyngeal space
Bulge in pharynx (retropharyngeal abscess) causing dysphagia (difficulty swallowing) & dysphonia (difficulty speaking)
What is the retropharyngeal space?
Potential space between prevertebral fascia and superficial fascia surrounding pharynx
Major route of spread of infection from neck to thorax
Space runs to diaphragm
Name the borders of the anterior triangle of the neck
Anterior - mid-line Posterior - anterior border of SCM Superior - inferior border of mandible Apex - jugular notch in the manubrium Roof - superficial cervical fascia & platysma Floor - pharynx, larynx, thyroid gland
What are the 4 triangles within the anterior triangle?
Submandibular (digastric) triangle
Submental triangle
Carotid triangle
Muscular (omotracheal) triangle
Contents of the submandibular (digastric) triangle
Submandibular gland & lymph nodes
Hypoglossal & mylohyoid nerves
Parts of facial artery & vein
Contents of the submental triangle
Submental lymph nodes
Small veins which unite to form ant. jugular vein
Contents of the carotid triangle
Carotid sheath (CCA, IJV, Vagus N, Deep cervical lymph nodes) Thyroid gland Larynx & Pharynx ECA & some branches Hypoglossal & spinal accessory nerves Branches of cervical plexus
Contents of the muscular (omotracheal) triangle
Sternothyroid
Sternohyoid
Thyroid
Parathyroid
Name the borders of the posterior triangle of the neck
Anterior - posterior border of SCM
Posterior - anterior border of Trapezius
Inferiorly - middle third of clavicle, between trapezius & SCM
Apex - where SCM & Trapezius meet on sup. nuchal line of occipital bone
Roof - Investing layer of deep cervical fascia
Floor - Muscles covered by prevertebral deep cervical fascia
What are the 2 triangles within the posterior triangle?
Occipital triangle
Omoclavicular (subclavian) triangle
Contents of the occipital triangle
Spinal accessory nerve (CN XI) Trunks of brachial plexus Part of EJV Posterior branches of cervical plexus Cervicodorsal trunk Cervical lymph node
Contents of the omoclavicular (subclavian) triangle
3rd part Subclavian artery
Part of subclavian vein
Suprascapular artery
Supraclavicular lymph nodes
What is the function of the hyoid bone?
Anterolateral part of neck:
Attachments for Suprahyoid muscles superiorly, Infrahyoid muscles inferiorly
(muscles steady or move hyoid & larynx)
Name the suprahyoid muscles
Mylohyoid
Geniohyoid
Stylohyoid
Digastric muscles (ant. & post. bellies joined by tendon & fibrous sling)
What are the functions of the suprahyoid muscles?
Constitute the floor of the mouth
Support hyoid - base for tongue to function
Elevate hyoid & larynx (swallowing & tone prod.)
Name the infrahyoid muscles
Superficial plane:
Sternohyoid
Omohyoid (sup. & inf. bellies joined by tendon & fibrous sling)
Deep plane:
Sternothyroid
Thyrohyoid
What are the functions of the infrahyoid muscles?
“strap muscles” - (ribbon-like)
Anchor the hyoid, sternum, clavicle & scapula
Depress the hyoid & larynx (swallowing & speaking)
Work with suprahyoids to steady hyoid & provide firm base for tongue
What are the muscles of mastication?
Masseter
Temporalis
Medial pterygoid
Lateral pterygoid
