Aaron Rutman, MD Profile picture
May 24, 2022 22 tweets 12 min read Read on X
Pterygopalatine fossa🧵- inspired by ?s from med students in neuroanatomy lab & a resident w/ case of perineural tumor spread on same day! #meded #FOAMrad #medtwitter #medstudents #radiology #neurorad #HNrad #radres #neurology #ENT #temporalbone #neurosurgery #neuroanatomy
1/22
The PTERYGOPALATINE FOSSA (PPF) is a space deep in the face/skull base, bordered anteriorly by the maxilla (max sinus), posteriorly by the pterygoid base of the sphenoid, and medially by the perpendicular plate of the palatine bone. 2/22
It’s best to think of the PPF as a crossroads/intersection. Think about the roads that lead to and from it, and the cast of characters that pass through.

Some like to simplify/visualize the PPF as a cube or inverted pyramid.

3/22
The PPF is accessed from laterally via the PTERYGOMAXILLARY FISSURE (PMF), an open crevasse between the pterygoid base of the sphenoid and the post maxilla. On 3D images, It can be seen deep to the zygomatic process.
4/22
The PMF is the lateral exit route from PPF; the POST-SUP ALVEOLAR NERVE branches from the INFRAORBITAL nerve & travels along the lateral margin of maxilla before diving into the wall to innervate the maxillary molars (also innervates max sinus and post oral mucosa).
5/22
Within the PPF lives the PTERYGOPALATINE GANGLION (PPG) which contains post-synaptic parasympathetic cell bodies-->lacrimal gland and sinus/nasal/oral mucosa. Many other sympathetic and somatic nerves travel through the ganglion without synapsing.
6/22
There are two canals which travel in the AP plane through the sphenoid bone, and transmit nerves/vessels from the middle cranial fossa to the PPF: FORAMEN ROTUNDUM and the PTERYGOID (VIDIAN) CANAL. The pterygoid canal is more inf and medial.
7/22
The FORAMEN ROTUNDUM transmits V2, the MAXILLARY NERVE, from the middle cranial fossa to the PPF in the AP direction. The Maxillary nerve (V2) contains mainly sensory information from the mid-face.
8/22
The PTERYGOID CANAL transmits the NERVE OF THE PTERYGOID CANAL through the sphenoid from mid cranial fossa (ant to foramen lacerum) to the PPF. Contains preganglionic parasympathetic (from gr sup petrosal n) and post-ganglionic sympathetic (deep petrosal n) from ICA plexus.
9/22
Anterior/superior exit route from the PPF is the INFERIOR ORBITAL FISSURE (IOF). The IOF is formed by the sphenoid and maxilla, connecting the PPF to the floor of the orbital apex.
10/22
The IOF transmits the ZYGOMATIC and INFRAORBITAL NERVES (V2 branches); ZYGOMATIC n. supplies sensory info from skin over zygomatic/temporal bones (zygomaticotemporal and zygomaticofacial branches) & transmits postganglionic parasympathetic fibers to lacrimal nerve/gland.
11/22
The INFRAORBITAL NERVE branches from V2 in the PPF➡️goes through IOF➡️extends anteriorly➡️ infraorbital groove/canal at orbital floor➡️exits INFRAORBITAL FORAMEN of the maxilla; supplies sensory to skin of cheek/lower eyelid.
12/22
The middle and ant sup alveolar nerves variably branch from the infraorbital nerve to supply sensory information from the maxillary teeth.
13/22
The medial exit route of the PPF leads to the nasal cavity via the SPHENOPALATINE FORAMEN which is formed by the palatine and sphenoid bones. It transmits the NASOPALATINE NERVE, posterior superior nasal nerves, and sphenopalatine artery/vein.
14/22
The NASOPALTINE NERVE branches from V2 in PPF (just after from f. rotundum)➡️traverses sphenopalatine foramen➡️courses within nasal septum anteroinferiorly➡️goes through INCISIVE FORAMEN of the maxillary palate (somatic sensory & autonomic supply to nasal mucosa).
15/22
The POST SUP NASAL NERVES also branch from V2 in PPF, traverse sphenopalatine foramen, and supply posterior nasal septum and lateral nasal wall.
16/22
Posteriorly and medially, the PHARYNGEAL NERVE (branch of V2) exits the PPF to the nasopharynx via the PALATOVAGINAL CANAL. It contains somatic sensory info and autonomic motor supplying the sup nasopharyngeal mucosa.
17/22
Inferiorly, the GREATER and LESSER PALATINE NERVES exit the PPF via the GREATER and LESSER PALATINE FORAMINA to the greater/lesser palatine canals:
18/22
The greater palatine foramen is located at the lateral suture between the maxillary palate and palatine bone; lesser canals are within the horizontal plate of the palatine bone. Nerves contain somatic sensory and autonomic innervation to the palate and oral cavity.
19/22
Thats the PPF! Important because so many functions, (including including midface sensation, sinonasal and pharyngeal sensation, pharyngeal/sinonasal mucus and saliva production, and lacrimation) all pass through this small anatomic space.
20/22
Importantly, mucosal tumors such as squamous cell CA and adenoid cystic CA love to spread along the nerves (perineural spread). Staging of pharynx, palate, sinus, salivary gland tumors requires knowledge of nerve pathways; knowing the PPF is imperative!
21/22
Clinical Case: adenoid cystic CA of the left palate, with associated perineural spread involving the palatine nerves, PPF, post/sup alveolar n, infraorbital n, maxillary n, mandibular n, and Meckel's cave.
22/22

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More from @aaronrutman

Dec 8, 2022
HYPOTHALAMUS (HT)🧵-the control center of circadian rhythm, fatigue/wakefulness, hunger/satiety, sex drive, thirst/BP—and the command post for endocrine control via the HT-pituitary axis.
#meded #neuroradiology #neuroscience #radiology #neurology #neurosurgery #neuroanatomy
1/28
Quiz A: Histamine activity in the brain/brainstem contributes to alertness/wakefulness–hence: sleepy effects of benadryl. Histaminergic neurosecretory cell bodies are exclusively in the tuberomammillary nucleus of the TUBER CINEREUM (HT floor), with widespread projections.
2/28
The HT is a mysterious and complex—I get confused sighs from medical students when the topic arises—the small almond-sized morsel is the control center for endocrine/hormone regulation, and homeostasis of food/water consumption, sleep, BP, sex/attachment. The HT is boss!
3/28
Read 29 tweets
Mar 6, 2021
Neuroanatomy TOTD #15🧵
The inner ear #tweetorial--it packs a large functional punch for its small size-strap in!
#meded #FOAMed #FOAMrad #medtwitter #medstudents #radiology #neurorad #HNrad #radres #neurology #ENT #temporalbone #neurosurgery #neuroanatomy #neuroanatomyTOTD
1/24
To evaluate the t-bone, best to compartmentalize--external/middle/inner ear (IE). See previous #tweetorial of the ME. The IE is difficult as most structures are obliquely oriented (at different obliquities!)-and can be hard to see on standard views. 2/24
IE communicates with ME via oval&round windows (which allow for transmission&dissipation of sonic vibrations). IE houses sensory organs for hearing/balance/sensing motion. The cochlear&vestibular nerves (CNVIII) transmit signals to the brain via the int auditory canal (IAC). 3/24
Read 25 tweets
Jan 11, 2021
Neuroanatomy TOTD #14🧵
Got some requests to do one of the trickiest areas of human anatomy, the #temporalbone. So many named structures! #meded #FOAMed #FOAMrad #medtwitter #medstudents #radiology #neurorad #radres #neurosurgery #neuroanatomy #ENT #otolaryngology

1/21 Image
Whether learning t-bone anatomy as a medical student or evaluating a CT of the t-bone as a radres, it’s best to compartmentalize into external, middle, and inner ear. This thread🧵is on the middle ear: Inner ear to follow, some day:)

2/21 Image
The external ear extends from the external meatus to the TM. The TM should be thin and *almost* imperceptible on CT. Thickened and retracted TM suggests prior pathology (usually otitis media) and scarring.

3/21 Image
Read 22 tweets
Dec 2, 2020
Neuroanatomy TOTD #12

The green structure is the amygdala (amygdaloid body) and the yellow structure is the stria terminalis (ST).

1/18

#meded #FOAMed #FOAMrad #medtwitter #medstudents #radiology #neurorad #radres #neurology #neurosurgery #neuroanatomy #neuroanatomyTOTD Image
Time for a deep dive into limbic networks. Bear with me—this is a fun subject. I got carried away preparing slides—it’s hard to know when to stop!

2/18
The amygdala is an almond-shaped collection of gray nuclei/subnuclei deep to the uncus and ant to hippocampus in the med temporal lobe. Involved in multiple functions: memory modulation, emotional learning and responses, +important connections w/ the olfactory bulb/cortex.

3/18 Image
Read 18 tweets
Nov 15, 2020
Neuroanatomy TOTD #11🧵
➡️intracanalicular facial nerve. IAC cross section➡️4 nerves; ant-sup➡️facial, ant-inf➡️cochlear (7-up/coke-down). Post nerves➡️sup&inf vestibular #medtwitter #meded #FOAMed #FOAMrad #neurorad #radiology #radres #neurology #neurosurgery #neuroanatomy
1/11
Facial motor nucleus is in the pontine tegmentum; axons loop dorsally around the abducens nucleus, then course anterolaterally, exiting the brainstem at the CPA.
2/11
The nervus intermedius (NI) is composed of preganglionic parasympathetic fibers w/cell bodies in the sup salivatory nucleus, taste fibers w/cell bodies in the nucleus solitarius, and somatic sensory input from EAC/external ear, w/cell bodies in the spinal nucleus of CNV.

3/11
Read 11 tweets
Oct 30, 2020
Neuroanatomy TOTD #10🧵 
1/5 Small gray matter structure at the junction of the thalamus and midbrain is the subthalamic nucleus (STN).

#meded #FOAMed #FOAMrad #medtwitter #medstudents #radiology #neurorad #radres #neurology #neurosurgery #neuroanatomy #neuroanatomyTOTD Image
2/5...The STN is functionally a node within the basal ganglia (BG) INDIRECT LOOP. STN contains excitatory glutaminergic neurons➞output to the GABA neurons of GPi, which in turn have inhibitory effect on thalamic outputs to the motor cortex.
3/5...Loss of nigrostriatal input in Parkinsons Dz➞increased inhibitory output from GPi➞decreased thalamic stimulation of the motor cortex (through both direct and indirect loop circuits). Makes sense that DBS treatments were initially directed at disrupting activity in GPi.
Read 5 tweets

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