3. Fasciae & spaces of the neck

**FASCIA and SPACES OF THE NECK:**

* Suprahyoid region: Spaces from skull base to hyoid bone (excluding orbit, sinuses & oral cavity) including parapharyngeal (PPS), pharyngeal mucosal (PMS), masticator (MS), parotid (PS), carotid (CS), buccal (BS), retropharyngeal (RPS) & perivertebral (PVS) spaces
* Infrahyoid region: Spaces below hyoid bone with some continuing into mediastinum including visceral space (VS), posterior cervical space (PCS), anterior cervical space (ACS), CS, RPS & PVS

**Superficial fascia:** Between the dermis and investing layer of deep fascia.

* Contains- Cutaneous nerves and vessels
* Lymphatics
* Fat
* Platysma muscle anteriorly

**Deep fascia:**

* **Consists of 3 layers-**
	+ **​**Investing (superficial layer)
	+ Pretracheal (middle layer)
	+ Prevertebral (deep layer)
* **Investing layer of deep fascia (superficial)**
	+ **​**Surrounds the entire neck, beneath the superficial layer
	+ Attachments:
		- inferiorly: Manubrium, superior border of clavicle, acromion, spine of scapula
		- superiorly: Superior nuchal line, zygomatic arches, angle of the mandible, mastoid process, spinous process of cervicle vertebrae
	+ Splits to enclose sternocleidomastoid, trapezius muscles and omohyoid in the suprahyoid region.
	+ Encloses and parotid and submandibular glands in the infrahyoid region.
	+ Forms the roof of the anterior and posterior triangles of the neck
* **Pretracheal fascia (middle)**
	+ Surrounds the visceral space and invests infrahyoid muscles
		- Trachea
		- Thyroid and parathyroid glands
		- Oesophagus
	+ Attachment:
		- inferior: to adventia of great vessels
		- superior: to thyroid cartilage, buccopharyngeal fascia of pharynx
	+ Blends laterally with the carotic sheath
* **Prevertebral fascia**
	+ Surrounds the perivertebral space from C1 to T3 vertebrae and associated muscles with longus colli and capitis, anterior middle and posterior scalenes and deep cervical muscles.
	+ Provides a slip of alar fascia anteriorly that separate the danger space from the retropharyngeal space.
	+ Described and having 2 laminae: anterior and posterior
	+ Attachment:
		- Superior: to the base of the skull
		- Inferior:
			* Anterior lamina to anterior longitudinal ligament and posterior oesophagus anteriorly
			* Posterior lamina to fascia over the thoracic vertebral column posteriorly
	+ Extends laterally as axillary sheath around axillary artery and brachial plexus
* **Carotid sheath**
	+ **​**Condensation of fascia around the great vessels of the neck with contribution from all other layers of deep cervical fascia.
	+ Extends from the base of the skull to the root of the neck
	+ United medially with the prevetebral fascia
	+ Contains:
		- Common carotid artery
		- Internal carotid artery
		- Internal jugular vein
		- Vagus nerve (CN X)
		- Deep cervical lymph nodes
		- Sympathetic fibres
	+ Communicates inferioryl with the medistinum

   **DEEP** **FASCIAL SPACES OF THE NECK AND NECK**

* **Perivertebral space**
* **Danger space**
	+ ​Critical space
	+ Extends from the base of the skull through to the thorax
* **​Retropharyngeal space:**
	+ **​**Largest and most significant space of the neck
	+ Potential space between the alar fascia and the buccophryngeal fascia
	+ From base of skull to the posterior mediastinum
	+ Permits movement of the pharynx, larynx, trachea and oesophagus during swallowing
	+ Infection originating in the pharyngeal area can spread to the retropharygeal space and and inferiorly to the mediastinum
* **Parapharygneal space**
* **Carotid space**
* **Visceral space**

* **Parotid space**
* **Masticator space**