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Anatomy and Cerebral Circulation of the Rat
Published in Yanlin Wang-Fischer, Manual of Stroke Models in Rats, 2008
Yanlin Wang-Fischer, Ricardo Prado, Lee Koetzner
The external carotid artery (Figure 4.3a)1 begins at the level of the posterior corner (greater horn) of the hyoid bone, about 2 to 4 mm below the corner in adult rats, as a direct continuation of the common carotid. Before reaching the angle of the jaw, it branches into five major arteries: the occipital, superior thyroid, ascending pharyngeal, lingual, and ascending palatine (for detailed illustrations of these branches, see Reference 1). Note that the hyoid bone is shaped like a horseshoe and is suspended from the tips of the styloid processes of the temporal bones by the stylohyoid ligaments. It consists of five segments: a body; two greater corners, also called greater horns; and two lesser corners.
Diagnostic Musculoskeletal Ultrasound
Published in Mark V. Boswell, B. Eliot Cole, Weiner's Pain Management, 2005
Several pain syndromes can be imaged and guided with ultrasound to help with proper diagnosis and to decrease risks with interventional procedures. Eagle’s syndrome is caused by pressure on the internal carotid artery and glossopharyngeal nerve, by an abnormally elongated styloid process and/or a calcified stylohyoid ligament. Injection of the attachment of the stylohyoid ligament to the styloid with local anesthetic and steroid will serve as a therapeutic maneuver (Waldman, 2003). In our practice, we use dynamic ultrasound to evaluate the temporomandibular joint, surrounding musculature, and nerves. We also evaluate the vasculature with Doppler ultrasound. Ernest’s syndrome is an insertional tendonosis of the stylomandibular ligament.
Otalgia
Published in John C Watkinson, Raymond W Clarke, Christopher P Aldren, Doris-Eva Bamiou, Raymond W Clarke, Richard M Irving, Haytham Kubba, Shakeel R Saeed, Paediatrics, The Ear, Skull Base, 2018
The stylohyoid syndrome results in neuralgia secondary to an elongated styloid process or mineralization of the stylohyoid ligament. The condition was first reported by Eagle38 in 1937 and subsequently came to bear his name. The normal styloid process is approximately 2.5 cm long and is generally accepted to be elongated if its length exceeds 4 cm. An elongated styloid process is said to be present in 4% of the population, but it has been reported that only 4% of these people present with symptoms.39 Although Eagle originally described the syndrome as arising following tonsillectomy, later studies have concluded that tonsillectomy is not always an aetiological factor.40,41 Symptoms are postulated to occur as a result of compression of the hypoglossal nerve, impingement of the carotid vessels or inflammatory changes at the insertion of the stylohyoid ligament.41 In fact, the existence of this syndrome is controversial and the Headache Classification of the International Headache Society dismissed it as ‘not sufficiently demonstrated’.26 The symptoms are classically a dull pharyngeal pain, often located within the tonsillar fossa, with radiation to the ipsilateral ear, odynophagia and a foreign body sensation. Although there may not be any specific findings on examination, the styloid process may be palpable in the tonsillar fossa and this can aggravate symptoms. Local injection of local anaesthetic can temporarily relieve symptoms. Radiological diagnosis of an elongated styloid process can be made either by orthopantomography or CT scan. Conservative management with steroids and local anaesthetic along with carbamazepine have been suggested but surgical reduction of the styloid process is considered the preferred treatment.41,42 Excision can be performed either transorally through the tonsillar fossa or via an external transcervical approach.
Bilateral elongated styloid process (Eagle’s syndrome) - a case report and short review
Published in Acta Oto-Laryngologica Case Reports, 2022
Arun Panwar, Vaishali Keluskar, Shivayogi Charantimath, Lokesh Kumar S, Sridhar M, Jayapriya T
At the prenatal stage, the stylohyoid complex has four segments (superior portion of the hyoid corpus, SP, lesser cornua of the hyoid, and stylohyoid ligament). These are all derivatives of Reichert's cartilage (2nd branchial arch), which can be further divided into four parts based on the consequent development of the stylohyoid complex. Tympanohyal, being the first and most proximal segment, gives origin to the tympanic (proximal) segment of the SP, as well as the stapes. The second segment is called the stylohyal segment and gives rise to the distal portion of the SP. The third segment is ceratohyal and degenerates in utero, forming the stylohyoid ligament. The fourth and most distal segment is called the hypohyal segment and forms the lesser cornua of the hyoid. The stylohyoid process arises from the temporal bone immediately medial and anterior to the stylomastoid foramen, extends anteromedially, rarely shows any anatomical variations in its course, and is encircled on both sides by the internal carotid artery (ICA) and external carotid artery (ECA). The stylopharyngeus, styloglossus, and stylohyoid along with the two ligaments being stylohyoid ligament and stylomandibular ligament originate from the SP (6,7).