DSNI Flashcards
(53 cards)
What is the most common source of DSNI in adults?
Odontogenic sources
Etiologies of DSNI
- Odontogenic
- Salivary gland infxn
- Penetrating trauma
- Surgical instrument trauma
- Spread from superficial infxn
- Necrotic malignant nodes
- Mastoiditis with resultant SCM abscess (Bezold’s)
- IVDA
- Congenital anomalies (TGDC, BCA)
Classification of fascia in the neck
Superficial cervical fascia
Deep cervical fascia
- Superficial layer
- Middle layer (muscular and visceral layers)
- Deep layer (alar and prevertebral fascia)
What fascial layer forms the carotid sheath?
All 3 deep cervical fascia layers
Contents of the superficial cervical fascia
- Fibrofatty layer that lies beneath the skin
- Covers adipose, sensory nerves, superficial vessels (EJ, AJ), lymphatics, platysma, muscles of facial expression
Superficial layer of the deep cervical fascia (“investing layer”)
-Completely surrounds the neck
Rule of 2’s
- 2 muscles that cross neck: SCM and trapezius
- 2 muscles above hyoid: masseter and ant digastric
- 2 salivary glands: partoid and SMG
- 2 fascial compartments: parotid and masticator spaces
Middle layer of the deep cervical fascia (“visceral fascia”)
2 divisions: muscular and visceral
- Muscular: straps
- Visceral: PT gland, thyroid gland, esophagus, trachea, larynx, pharyngeal constrictors, buccinator
2 planes from the visceral division
- Pretracheal fascia (overlies trachea)
- Buccopharyngeal fascia (lies posterior to and separates esophagus from deep layer of DCF)
Deep layer of the deep cervical fascia (“prevertebral fascia”)
2 divisions: prevertebral and alar
- Prevertebral: cervical vertebrae, phrenic n, paraspinous muscles
- Alar (b/w prevertebral and buccopharyngeal fascial): cervical SYMP trunk
What separates the RP space from the danger space?
The alar division of the deep layer of the DCF.
Ant to this is the RPS
Post to this is the danger space
Neck spaces are classified based on relationship to what anatomic landmark?
Hyoid bone
Strong fascial connections to the hyoid bone anteriorly function as a barrier to inferior spread
Classification of DSNI
Spaces involving the entire length of the neck
- Retropharyngeal space
- Danger space
- Prevertebral space
- Carotid space
Spaces limited to above the hyoid bone
- Parapharyngeal space
- Submandibular space
- Parotid space
- Masticator space
- Peritonsillar space
- Temporal space
Spaces limited to below the hyoid bone
- Anterior visceral space
- Suprasternal space
Retropharyngeal space location
- Skull base to tracheal bifurcation
- Medial to the carotid sheath
- Ant to the danger space (alar division)
- Post to the buccopharyngeal fascia of the visceral division
RPS conents
Nodes of Rouviere
Can cause abscess formation upon drainage from the paranasal sinuses or NP (esp in kids)
How can you tell if the infxn is in the RPS or in the danger space or prevertebral space?
- A midline raphe connects the alar division of the deep layer of the DCF to the buccopharyngeal fascia
- Thus, RPS infxns have OFF-MIDLINE presentation
- Danger and prevertebral space infxns are usu midline
How does one get a RPS infxn?
- Abscess from Node of Rouviere (<5 yo)
- Extension from parapharyngeal, prevertebral space
- Penetrating or blunt trauma, intubation
Danger space location
- Skull base to diaphragm
- Ant to the prevertebral space
- Post to retropharyngeal space and alar division of deep layer of DCF
- Medial to the transverse processes
Contents of the danger space
Cervical SYMP trunk
How does one get a danger space infxn?
Extension from
- RPS
- PPS
- Prevertebral space
Prevertebral space location
- Skull base to coccyx
- Ant to vertebral bodies
- Post to danger space
- Medial to transverse processes
What kinds of tissue is within the prevertebral space vs the danger space
Dense areolar tissue vs loose areolar tissue
Contents of prevertebral space
- Vertebral vessels
- Phrenic nerve
- Brachial plexus
- Muscles: paraspinous, prevertebral, scalene
How does one get a prevertebral space infxn
- Penetrating injury
- Direct extension from vertebrae (e.g. Pott’s abscess)
Carotid space contents
- Carotid
- IJ
- Vagus n
- SYMP plexus
How does one get a carotid space infxn
- Spread from PPS
- Penetrating trauma
- IVDA
