Suprahyoid Neck Flashcards
What are the boundaries of the nasopharynx?
Anterior: Posterior nasal cavity at the nasal choana
Posterosuperior: Lower clivus, upper cervical spine, and prevertebral muscles
Inferior: Divided from the oropharynx by a horizontal line drawn along the hard and soft palates
Lateral wall: Composed of the torus tubarius (cartilaginous eustachian tube), the eustachian tube orifice, and the mucosa of the lateral pharyngeal recess (fossa of Rosenmuller)
What are the boundaries of the oropharynx?
Anterior: A ring structure of structures separates the oropharynx from the oral cavity. This ring includes the circumvallate papillae of the tongue the anterior tonsillar pillars, and the soft palate. The lingual tonsil is in the oropharynx and not the oral cavity.
Posterior: Superior and middle constrictor muscles
Inferior: Separated from the larynx by the epiglottis and glossoepiglottic fold and from the hypopharynx by the pharyngoepiglottic fold
Superior: The soft palate forms the roof of the oropharynx
What are the layers of deep cervical fascia in the suprahyoid neck?
- Superficial layer (investing fascia)
- Middle layer (buccopharyngeal fascia)
- Deep layer (prevertebral fascia)
What are the spaces defined by the three layers of deep cervical fascia?
- Parapharyngeal space
- Pharyngeal mucosal space
- Masticator space
- Parotid space
- Carotid space
- Retropharyngeal space
- Perivertebral space
All but two spaces of the suprahyoid neck are true fascia-enclosed spaces; that is, they are completely circumscribed by the three layers of deep cervical fascia. What are the two exempted space?
The parapharyngeal space and the pharyngeal mucosal space
These two spaces have complex fascial borders with multiple fascia constituting the space margins.
This is the central space of the deep face, around which most of the other important spaces are situated. The surrounding spaces include the pharyngeal mucosal, masticator, parotid, carotid, and lateral retropharyngeal spaces.
Parapharyngeal space (PPS)
Because the contents of the PPS are limited, few lesions actually arise in this space. Rather, most infections and tumors found in the PPS originate in one of the surrounding spaces.
What are the contents of the parapharyngeal space?
Fat
Internal maxillary artery
Ascending pharyngeal artery
Pharyngeal venous plexus
The PPS has no mucosa, muscle, bone, nodes, or normal salivary gland tissue wtihin its boundaries. As a result it is unusual for a disease process to originate in the PPS
What are the fascial margins of the PPS?
Medial fascial margin = made up of the middle layer of deep cervical fascia as it curves around the lateral sided of the pharyngeal mucosal space
Lateral fascial margin = formed by the medial slip of the superficial layer of deep cervical fascial as it curves around the deep border of the masticator and parotid spaces.
Posteriorly = made up of the anterior part of the carotid sheath, which is made up of all three layers of the deep cervical fascia
What are the contents of the pharyngeal mucosal space?
Mucosa Lymphoid tissue of Waldeyer's ring (adenoids, tonsils) Minor salivary glands Pharyngobasilar fascia Superior and middle constrictor muscles Salphingopharyngeus muscle Levator palatini muscle* Cartilagenous end of the eustachian tube*
- The levator palatini muscle and the eustachian tube originate outside the PMS from the skull base
This fascia attaches the superior constrictor muscle to the skull base.
Pharyngobasilar fascia
Along the superior aspect of the posterolateral margin of the pharyngobasilar fascia is a notch called ______.
Through this notch the levator palatini muscle and the eustachian tube pass on their way from the skull base to the PMS.
Sinus of Morgagni
The cartilaginous opening of the eustachian tube within the PMS is referred to as what?
Torus tubarius
What are the contents of the masticator space?
Muscles of mastication:
- Masseter muscle
- Temporalis muscle
- Medial pterygoid muscle
- Lateral pterygoid muscle
Masticator nerve branches (Proximal V3 motor branch)
Inferior alveolar nerve (V3 sensory branch)
Inferior alveolar vein and artery
Ramus and posterior body of the mandible
What are the bordering spaces of the masticator space?
Anterior = Buccal space
Posteromedial = Parapharyngeal space
Posterior = Parotid space
What are the contents of the parotid space?
Parotid gland Fascial nerve (CN VII) Retromandibular vein External carotid artery Intraparotid lymph nodes
This creates a surgical plane that divides the gland into superficial and deep lobes.
Intraparotid facial nerve
The intraparotid facial nerve is not routinely identified on either CT or MRI, even with high-resolution imaging.
Two vessels are usually seen in the parotid space.
What are these vessels?
The retromandibular vein is the lateral of the two, and the external carotid artery is just medial to it.
The facial nerve courses immediately lateral to the retromandibular vein.
The parotid space has lymph nodes within the glandular parenchym. Why?
Because of late encapsulation of the parotid gland in embryogenesis.
The normal parotid gland contains how many nodes?
20 to 30 nodes
It is also known as the Stenson’s duct.
The parotid duct
It emerges from the anterior PS, runs anteriorly over the surface of the masseter muscle, then arches medially through the buccal space to pierce the buccinator muscle at the level of they upper (maxillary) second molar.
All three layers of the deep cervical fascia condense to form the tenacious fascia surrounding the carotid space (CS), which is known as what?
Carotid sheath
What are the contents of the carotid space?
Common or internal carotid artery (level dependent)
Internal jugular vein
Cranial nerves IX, X, XI, XII: nasopharyngeal CS
Cranial nerve X only: oropharyngeal and infrahyoid CS
Symphathetic plexus
Lymph nodes
The internal carotid artery (ICA) arises from the common carotid artery at approximately what level?
At the level of the hyoid bone
The internal jugular vein usually runs posterolaterally with what vessel?
Internal carotid artery
What is the single most important nerve within the carotid space?
The vagus nerve
It is located in the posterior notch formed by the common and internal carotid arteries and internal jugular vein throughout the entire extracranial CS.
What cranial nerves are seen in the nasopharyngeal carotid space, but soon leave the CS at approximately at the level of the soft palate?
Glossopharyngeal, spinal accessory, and hypoglossal nerves (IX, XI, and XII)
The highest nodes of the deep cervical chain are found with the carotid sheath at the level of the oropharynx and known as _________.
Jugulodigastric nodes
What are the bordering spaces of the carotid space?
Lateral = Parotid space
Anterior = Parapharyngeal space fat
Medial = Lateral margin of the retropharyngeal space
What separates the parotid space from the carotid space?
Posterior belly of the digastric muscle and its associated superficial layer of the deep cervical fascia.
This is the potential space formed between the middle layer and the deep layer of deep cervical fascia.
Practically speaking, this space will be seen on cross-sectional imaging between the pharyngeal constrictor muscles anteriorly and the prevertebral muscles posteriorly.
Retropharyngeal space (RPS)
The lateral walls of the RPS are comprised of a slip of deep cervical fascia called what?
The alar fascia
A second slip of deep cervical fascia can be seen separating the RPS from the danger space.
What is the importance of the danger space?
The importance of the danger space is that it serves as a conduit for RPS infection and tumor to reach the mediastinum inferiorly.
What are the contents of the retropharyngeal space?
Fat
Lymph nodes
- Lateral nodes (nodes of Rouviere)
- Medial nodes
The lateral retropharyngeal nodal group (the nodes of Rouviere) is found in the high oropharynx and nasopharynx.
The nodes are considered normal if they measure how many cm in diameter?
If they are less than 1 cm in diameter
What divides the perivertebral space into the anterior (prevertebral) and posterior (paraspinal) portions?
The attachement of the deep cervical fascia to the transverse process of the vertebral body divides the perivertebral space.
What are the contents of the perivertebral space in the prevertebral portion?
Prevertebral muscles Scalene muscles - anterior, middle, and posterior muscles Brachial plexus Phrenic nerve Vertebral artery and vein Vertebral body
What are the contents of the perivertebral space in the paraspinal portion?
Paraspinal muscles
Posterior elements of the vertebral body
What are the bordering spaces of the PVS?
The prevertebral portion of the PVS sits directly behind the RPS/DS throughout the extracranial head and neck.
Anterolateral = carotid space
The posterior cervical space is directly lateral to the prevertebral and paraspinal portions
