1 - Organisation Flashcards by Grace Duane

Why do lacerations to the scalp result in profuse bleeding?

Pull of occipitofrontalis muscle prevents closure of bvs
Bvs adhered to dense connective tissue so vasoconstriction prevented
Blood supply to scalp has many anastomoses

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Why does loss of blood supply to scalp not result in bone necrosis?

Skull’s blood supply from middle meningeal artery

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Which nerves innervate the scalp?

Trigeminal: Opthalmic: Supraorbital and supratrochlear
Maxillary: Zygomaticotemporal
Mandibular: Auriculotemporal
Cervical: Greater and lesser occipital

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Describe the layers of the scalp

Skin
Dense connective tissue- contains neurovascular bundle, bleeds profusely
Aponeurotic - contains occipitofrontalis
Loose connective tissue - Infections can spread to meninges via emissary veins
Pericranium - Attached to bones, stuck on at sutures

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What arteries supply the scalp?

External carotid: Superficial temporal
Posterior auricular 
Occipital 
Internal carotid: 
Opthalmic: 
Supraorbital 
Supratrochlear

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Where do facial muscles originate from?

2nd pharyngeal arch

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What is the function of orbicularis oculi?

Palpebral part gently closes eyelid

Orbital part forcefully closes eyelid

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What are the consequences of facial nerve palsy with respect to the eye?

Eye can’t shut, cornea dries out - Exposure keratitis

Lower eyelid droops- ectropion- lacrimal fluid pools instead of spreading across eye, so debris damages cornea

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What is the action and attachments of orbicularis oris?

Purses the lips

Arises from maxilla, inserts into mucous membranes and skin of lips

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What is the action and attachments of buccinator?

Pulls cheeks against teeth so food doesn’t accumulate

Originates from maxilla and mandible, blends with orbicularis oris into skin of lips

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What are the muscles of facial expression?

Occipitofrontalis
Orbicularis oculi
Orbicularis oris
Buccinator

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Where do the muscles of mastication develop from and what are they innervated by?

First pharyngeal arch

Innervated by mandibular branch of trigeminal nerve (V)

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What are the attachments and actions of masseter?

Superficial: Maxillary process of zygomatic bone
Deep: Zygomatic arch of temporal bone
Inserts into mandible
Elevates mandible to close mouth

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What are the attachments and actions of temporalis?

Originates from temporal fossa
Inserts as a tendon on mandible
Elevates mandible to close mouth and retracts mandible to pull jaw posteriorly

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What are the attachments and actions of medial pterygoid?

Superficial head: Maxilla
Deep head: Lateral pterygoid plate of sphenoid bone
Inserts on mandible, near angle of mandible
Elevates mandible closing mouth

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What are the attachments and actions of lateral pterygoid?

Superior head: Greater wing of sphenoid
Inferior head: Lateral pterygoid plate of sphenoid
Inserts as a tendon on neck of mandible
Bilaterally: Protract mandible, pushing jaw forwards
Unilaterally: Side to side movement of jaw

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What is the action of the suprahyoid muscles?

Elevate the hyoid bone, for swallowing

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What are the attachments, innervation and action of digastric?

Anterior belly: Mandible
Posterior: Mastoid process of temporal bone
Fibrous sling attaches to hyoid bone
Anterior innervation: Mandibular, trigeminal (V)
Posterior: Facial (VII)
Depresses mandible and elevates hyoid bone

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What are the attachments and actions of omohyoid?

Originates at scapula, running under SCM to attach to hyoid bone
Depresses hyoid bone

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What are the attachments, innervation and action of platysma?

Originates pectoral fascia, inserts into mandible
Innervated by cervical, facial nerve (VII)
Depresses the mandible

What are the attachments, innervation and action of sternocleidomastoid?

Originates sternal head and medial clavicle, inserts on mastoid process of temporal bone
Innervated by the accessory nerve
Laterally flexes head and neck

What are the attachments, innervation and action of trapezius?

Originates occipital lobe and spinous process of vertebrae. Inserts into lateral clavicle and scapula
Innervated by accessory nerve
Retraction, rotation, elevation and depression of scapula

What are the borders of the posterior triangle?

Anterior: Posterior SCM
Posterior: Anterior trapezius 
Inferior: Middle clavicle 
Roof: Investing fascia 
Floor: Prevertebral fascia

What is the danger of a stab wound in posterior triangle?

EJV travels through superficially
If cut, its lumen is held open by investing fascia
Air drawn into vein, produces cyanosis and stops blood flowing through RA

Which nerves run through the posterior triangle?

Accessory nerve Cevical plexus - phrenic nerve Brachial plexus

What are the borders of the anterior triangle?

``` Superior- Inferior mandible Lateral- Anterior SCM Medial - Sagittal line down midline of neck Roof: Investing fascia Floor: Visceral fascia ```

What are the contents of the anterior triangle?

``` Digastric Omohyoid Common cartoid (bifurcates here) IJV Cranial nerves: Facial (VII), glossopharyngeal (IX), vagus (X), accessory (XI) and hypoglossal (XII) Carotid triangle ```

What are the borders of the carotid triangle?

Superior: Posterior belly of digastric Lateral: Medial SCM Inferior: Superior belly of omohyoid (so hyoid bone)

What are the contents of the carotid triangle?

``` Common carotid artery, bifurcates here IJV Hypoglossal nerve Vagus nerve Carotid sinus ```

How does applying pressure to the carotid triangle lead to syncope?

Pressure on carotid sinus, baroreceptors sensitive to stretch Glossopharyngeal nerve feeds back to brain Brain becomes underperfused, causing syncope

From out to in, what are the fascial layers of the neck?

``` Superficial fascia Deep cervical fascia: Investing layer Pretracheal layer Prevertebral layer Carotid sheaths ```

What is contained within the superficial fascia layer?

Platysma EJV Fat - double chin Lymph nodes and neurovascular supply to skin

What is contained within the pretracheal layer and what does it fuse with?

``` Infrahyoid muscles Thyroid gland Trachea Oesophagus Fuses with pericardium and posteriorly with buccopharyngeal fascia ```

What is the danger of infection between investing and pretracheal fascia?

Infection can travel posteriorly to the anterior mediastinum

What is contained within the prevertebral layer?

Vertebral column Scalene muscles Brachial plexus + subclavian artery to form axillary sheath

What forms the carotid sheath?

Investing Pretracheal Prevertebral

What is contained in the carotid sheath?

Common carotid artery IJV Vagus nerve Cervical lymph nodes

Why is the carotid sheath a pathway for infection?

Runs from base of skull to thoracic mediastinum

Why is infection posterior to prevertebral fascia dangerous?

Infection can erode through prevertebral fascia and drain into retropharyngeal space, which extends to thorax so infection can reach mediastinum

Where does the neck extend to and from?

Lower mandible to suprasternal notch of manubrium and upper clavicle

Describe the typical presentation of a retropharyngeal abscess

``` Child under 5 Bulge on oropharynx Difficulty swallowing Stridor Reluctant to move neck Temperature ```

How is a thyroid lump distinguishable?

Lump will move on swallowing as thyroid gland is enclosed in pre-tracheal fascia and attached to hyoid bone

Describe retrosternal extension of the thyroid gland

As pre-tracheal fasica extends to thorax, thyroid can swell down Compresses trachea and venous blood vessels causing breathlessness, stridor and facial oedema

What complications occur due to facial injury damaging the parotid gland?

Facial nerve travels through parotid gland, can cause paralysis of facial muscles

What are the consequences of a parotid cancer?

Ipsilateral partoid enlargement resulting in facial nerve palsy

What is Bell's palsy?

Inflammation of the facial nerve, half the face is paralysed and droops Loss of taste in anterior 2/3 of tongue

Describe the venous drainage of the face

``` Facial vein (eye to mandible) drains into IJV Superficial temporal and maxillary vein drain into EJV EJV and IJV drain into subclavian vein ```

Where is the facial artery pulse felt?

Inferior mandible

Why do both sides of the face need to be compressed after a laceration?

Facial artery has many anastomoses with other arteries in face will bleed unless both sides compressed