The hyoid bone is an integral part of the hypopharynx and the anterior movement of the hyoid complex improves the airway patency (Figure 6). From: Encyclopedia of Sleep, 2013
Richard L. Drake PhD, FAAA, in Gray's Anatomy for Students, 2020 The hyoid bone is a smallU-shaped bone in the neck between the larynx and the mandible. It has an anterior body of hyoid bone and two large greater horns, one on each side, which
project posteriorly and superiorly from the body (Fig. 8.250). There are two small conical lesser horns on the superior surface where the greater horns join with the body. The stylohyoid ligaments attach to the apices of the lesser horns. The hyoid bone is a key bone in the neck because it connects the floor of the oral cavity in front with the pharynx behind and the larynx below.Head and Neck
Hyoid bone
Head and neck : Overview and surface anatomy
Susan Standring MBE, PhD, DSc, FKC, Hon FAS, Hon FRCS, in Gray's Anatomy, 2021
Hyoid bone and laryngeal cartilages
The hyoid bone lies in the midline at the front of the neck at the level of the fourth cervical vertebra (Badshah et al 2017). It is suspended from the styloid processes by the stylohyoid ligaments and gives attachment to the suprahyoid and infrahyoid groups of muscles. The skeletal framework of the larynx is formed by a series of cartilages interconnected by ligaments and fibrous membranes and moved by a number of muscles (Ch. 41). The laryngeal cartilages are the single cricoid, thyroid and epiglottic cartilages, and the paired arytenoid, cuneiform, corniculate and tritiate cartilages.
Nose, oral cavity, pharynx, ear and larynx
Bari M. Logan MA, FMA, Hon MBIE, MAMAA, in McMinn's Color Atlas of Head and Neck Anatomy, 2017
The larynx with the pharynx, hyoid bone and trachea
In the side view in A the lateral lobe of the thyroid gland (20) has been displaced backwards to show the part of the origin of the inferior constrictor (17) that arises from the tendinous band (18) over cricothyroid (19). The lingual artery (1) lies just above the tip of the greater horn of the hyoid bone (2) and then passes deep to the posterior border of hyoglossus (3). The internal laryngeal nerve (30) runs just below the tip of the hyoid and pierces the thyrohyoid membrane (29) with the superior laryngeal branch (28) of the superior thyroid artery (27), behind which runs the external laryngeal nerve (16). Much of thyrohyoid (12) has been removed to show part of the origin of the inferior constrictor (17) from the lamina of the thyroid cartilage (13).
In B with the thyroid gland taken away, the lowest (cricopharyngeus) part of the inferior constrictor has been removed to show the recurrent laryngeal nerve (23) passing up behind the cricothyroid joint (34).
In C all muscles, vessels and nerves have been removed to display the thyrohyoid membrane (29), the cricothyroid membrane (38 and 39), and the cricotracheal ligament (40) attached to the first tracheal ring (41, which is here unusually broad).
In D most of the internal jugular vein (43) has been removed and the common carotid artery (44) has been displaced backwards to show the inferior thyroid artery (25) and recurrent laryngeal nerve (23).
from the right, with the cervical vertebral column removed as in A, after removal of the thyroid gland and part of the inferior constrictor from the front and the right, after removal of muscles in a neck dissection, from the right1Lingual artery
2Tip of greater horn of hyoid bone
3Hyoglossus
4Hypoglossal nerve
5Suprahyoid artery
6Nerve to thyrohyoid
7Tendon of digastric
8Digastric sling
9Body of hyoid bone
10Sternohyoid
11Superior belly of omohyoid
12Thyrohyoid
13Lamina of thyroid cartilage
14Laryngeal prominence
15Sternothyroid
16External laryngeal nerve
17Inferior constrictor
18Tendinous band
19Cricothyroid (straight part)
20Lateral lobe of thyroid gland
21Trachea
22Inferior laryngeal artery
23Recurrent laryngeal nerve
24Oesophagus
25Inferior thyroid artery
26Posterior pharyngeal wall
27Superior thyroid artery
28Superior laryngeal artery
29Thyrohyoid membrane
30Internal laryngeal nerve
31Cricothyroid (oblique part)
Arch of cricoid cartilage
33Inferior horn of thyroid cartilage
34Cricothyroid joint
35Epiglottis
36Lesser horn of hyoid bone
37Aperture for internal laryngeal nerve and superior laryngeal artery
38Conus elasticus (central part of cricothyroid ligament)
39Cricothyroid ligament (lateral part, cricovocal membrane)
40Cricotracheal ligament
41First tracheal ring (unusually large)
42Middle constrictor
43Internal jugular vein
44Common carotid artery
Cartilages of the larynx:
•Unpaired—thyroid, cricoid, epiglottic
•Paired—arytenoid, corniculate, cuneiform
Joints of the larynx: cricothyroid (B and C, 34), crico-arytenoid (page 192, E42), arytenocorniculate (page 192, E44).
Membranes and ligaments of the larynx:
•Extrinsic—thyrohyoid membrane (C29), hyo-epiglottic and thyro-epiglottic ligaments, cricotracheal ligament (C40).
•Intrinsic—quadrangular membrane (page 192, D37), whose upper margin forms the aryepiglottic fold (page 192, A3) and lower margin the vestibular (false vocal) fold (page 192, D28); cricothyroid ligament, whose upper margin (the vocal ligament,page 192, D32) forms the anterior part of the vocal fold (vocal cord). See notes onpage 193.
Theextrinsic muscles of the larynx (those connecting it to surrounding structures) can be divided into elevators and depressors—those directly attached to the thyroid and cricoid cartilages and which raise the larynx, e.g. during swallowing, and those that return it to the normal position:
Depressors: | sternothyroid (page 118, B48)—attached to thyroid cartilage |
upper oesophageal attachment (page 188, F47)—to cricoid cartilage | |
elastic recoil of trachea |
Theintrinsic muscles of the larynx move the vocal folds and alter the shape of the laryngeal inlet, and can be classified according to their main effects on the folds or the laryngeal inlet; i.e. they alter the shape of the rima of the glottis (the gap between the vocal folds of each side), or have a sphincteric action on the inlet:
Tensor: | cricothyroid (B19 and 31) |
Relaxor: | thyro-arytenoid (page 192, B20) |
Abductor: | posterior crico-arytenoid (page 192, A7) |
Adductor: | lateral crico-arytenoid (page 192, B21) |
transverse arytenoid (page 192, A5) | |
oblique arytenoid (page 192, A6) |
The vocalis part of the thyro-arytenoid may tighten segments of the vocal fold (as when singing a high note).
The thyroepiglottic, aryepiglottic and oblique arytenoid muscles constrict the inlet; their relaxation restores the normal shape.
Cricothyroid (B19 and 31) is the only external intrinsic muscle of the larynx; it is easily seen on the outside of the larynx in dissections of the front of the neck (as onpage 122, A9). The other intrinsic muscles are all inside the larynx and are only seen when the larynx itself is dissected (page 174).
The intrinsic muscles of the larynx are all supplied by the recurrent laryngeal nerve (A and B, 23) except for cricothyroid, supplied by the external laryngeal nerve (A and B, 16).
The mucous membrane of the larynx above the level of the vocal folds is supplied by the internal laryngeal nerve (A30), and below the vocal folds by the recurrent laryngeal nerve (A and B, 23).
The internal laryngeal nerve (A30) first enters the pharynx by piercing the thyrohyoid membrane (A29), and from there fibres spread into the larynx.
The recurrent laryngeal nerve (B23) lies immediately behind the cricothyroid joint (B34;page 192, B11) and enters the larynx by passing deep to the lower border of the inferior constrictor of the pharynx (A17).
VISCERAL SPACE
In Diagnostic Imaging: Head and Neck (Third Edition), 2017
Clinical Implications
Patients may be referred for cross-sectional imaging with either a midline neck mass ± lateral neck mass(es) from adenopathy. When protocoling such a study, it is important to remember that, if DTCa is a possible cause, consideration should be given to US, MR, or even NECT rather than CECT. Iodinated contrast can delay therapeutic ¹³¹I up to 6 months. Clinical indicators of possible thyroid cancer include young women with neck masses, particularly low neck masses and/or cystic lymph nodes, and masses associated with vocal cord paralysis.
There are 3 main considerations for a rapidly growing VS mass : (1) Hemorrhage or cystic degeneration of thyroid adenoma, (2) anaplastic thyroid carcinoma, and (3) thyroid lymphoma. The latter 2 lesions can appear quite similar on imaging, although lymphoma is more frequently a homogeneous lesion. Calcifications, cystic change, and hemorrhage are much less common in lymphoma than anaplastic carcinoma, which is typically heterogeneous and has a greater tendency to invade the trachea.
When imaging is required for preoperative evaluation of the complete extent of a multinodular goiter (MNG), 2 considerations must be kept in mind: (1) The scan is performed with the patient's arms by his or her side so as not to exaggerate the substernal extension that occurs with the patient's arms positioned over their head, and (2) up to 5% of MNGs harbor a focus of DTCa. While most often these are small foci that have not metastasized, the neck should be carefully evaluated for adenopathy and any invasive features of the thyroid contours that might make surgery complex.
Hyoid bone Superficial layer, DCF Thyroid cartilage Cricoid cartilage Thyroid gland Visceral fascia middle layer, DCF Manubrium Prevertebral fascia (deep layer, DCF) Alar fascia (deep layer, DCF) Retropharyngeal space Danger space Visceral fascia (middle layer, DCF)
Esophagus
Trachea
Sagittal graphic illustrates the craniocaudal extent of the visceral space (VS) in the anterior aspect of the neck. At the hyoid bone, the superficial and middle layers of deep cervical fascia (DCF) insert. The superficial layer encloses the strap muscles of the anterior neck and sternocleidomastoid muscles of the lateral neck. These muscles surround but are separate from the VS. The middle layer of DCF surrounds the VS. The larynx and cervical trachea and the hypopharynx and cervical esophagus form longitudinal columns within this space from the hyoid to the mediastinum.
Strap muscles
Middle layer, DCF
Superficial layer, DCF
Sternocleidomastoid muscle
Deep layer, DCF
Left thyroid lobe
Recurrent laryngeal nerve
Paratracheal node
Parathyroid gland
Cervical esophagus
Axial graphic depicts the anterior central location of the VS in the infrahyoid neck, between the carotid sheaths. Other important VS structures surround the larynx/trachea and the hypopharynx/esophagus, such as the thyroid gland, superior and inferior parathyroid glands, and level VI lymph nodes. The recurrent laryngeal nerves course superiorly to the larynx in the tracheoesophageal grooves.
Axial graphic depicts the thyroid gland in anterior VS wrapping around the trachea Axial CECT at the level of thyroid gland isthmus Coronal T1 MR shows
heterogeneous solid Coronal graphic shows the relationship of
thyroid Lateral graphic illustrates ascending course of RLNs in the tracheoesophageal groove of the VS. Left RLN Axial CECT in a patient with left RLN paralysis shows heterogeneous mass within the left thyroid lobe
Axial CECT shows tracheal adenoid cystic carcinoma invading the thyroid gland Axial CECT demonstrates right thyroid lobe enlargement with several focal areas of calcification Coronal CECT MPR shows ill-defined nonenhancement
within the enlarged right thyroid lobe Axial CECT demonstrates a large enhancing parathyroid adenoma in the right tracheoesophageal groove
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RETROPHARYNGEAL SPACE
In Diagnostic Imaging: Head and Neck (Third Edition), 2017
Clinical Implications
Small lesions of the RPS are typically not evident on clinical examination. It is only when lesions become significantly enlarged that bulging of a posterior pharyngeal wall is evident. It cannot be emphasized enough that the radiologist must consider the possibility of RPS metastatic nodal disease in all H&N cancer patients and must methodically search along the medial aspect of the cervical ICA. Nonnecrotic RPS nodes are more difficult to discern on CECT than MR, so vigilance is key.
Toxic patients with H&N infections, such as pharyngitis or tonsillitis, may be imaged to exclude the development of a, RPS abscess. This is a difficult clinical diagnosis because physical examination may not be fruitful. Thus, clinicians must rely largely on a high degree of clinical suspicion. The radiologist must exclude RPS abscess, or, if 1 is found, must delineate the entire craniocaudal extent and specifically exclude mediastinal involvement. Large abscesses may result in airway compromise, though it is rare that a patient presents with airway symptoms secondary to an RPS mass.
Hyoid bone Superficial layer, deep cervical fascia T2 vertebral body Visceral fascia (middle layer, deep cervical fascia) Esophagus Superior limit RPS + DS: Fasciae insert to central skull base Prevertebral fascia (deep layer, deep cervical fascia) Alar fascia (deep layer, deep cervical fascia) Retropharyngeal space Danger space Inferior limit true
RPS: Alar fascia merges with visceral fascia Sagittal graphic shows the deep cervical fascia (DCF) layers, which determine and delineate the contours of the retropharyngeal space (RPS). The anterior contour of the RPS is defined by the visceral fascia, the middle layer DCF, which separates the RPS from the pharyngeal mucosal space of SHN and visceral space of the IHN. The posterior contour is formed by the prevertebral fascia (deep layer DCF). The alar
fascia (also deep layer DCF) anatomically defines an anterior true RPS and more posterior danger space (DS), although this delineation is not typically evident at imaging. Inferiorly, the alar fascia blends with the visceral fascia at approximately T3, while superiorly the middle and deep layers of the DCF insert to the central skull base. Soft palate Cervical trachea Cervical esophagus Clivus
Retropharyngeal fat stripe
T1 vertebra
Sagittal T1 MR shows thin, hyperintense signal corresponding to normal fat within the retropharyngeal space. Contents include this thin fat stripe and the retropharyngeal lymph nodes in the lateral suprahyoid neck. It can be considered as a potential space that is most visible when distended by disease.
Axial graphic at level of oropharynx illustrates predominantly fat-filled RPS. The anterior contour is delineated by middle layer DCF
and the posterior contour by prevertebral fascia (deep layer DCF) . Alar fascia forms lateral margins and divider of RPS into anterior true RPS and posterior danger space.Axial CECT shows the typical appearance of RPS in a suprahyoid neck as a thin, low-density fat stripe
anterior to prevertebral muscles .Axial graphic at level of thyroid gland shows infrahyoid continuation of fat-filled RPS, now posterior to esophagus and again delineated anteriorly by visceral fascia (middle layer DCF)
. Posterior DS separates true RPS from prevertebral muscles and cervical vertebrae.Axial CECT shows RPS as an almost imperceptible fat stripe anterior to PVS and posterior to hypopharynx
. Laterally, RPS has a triangular contour immediately medial to internal carotid artery .Axial CECT shows a rare primary sarcoma of the RPS. Small areas of vascular enhancement are noted
. Note comparatively lower density relative to the pharynx anteriorly and prevertebral muscles posteriorly that helps correctly localize this mass.Midline sagittal CECT MPR demonstrates a RPS abscess
in a child. Infected & noninfected fluid collections are the most common source of RPS lesions. Infections are most often due to suppurative nodal disease in children and spread of spinal infection in adults.Sagittal CECT MPR demonstrates an enhancing soft tissue mass Axial T2 MR shows a hyperintense collection
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HYOID & VERTEBRAE
Tim D. White, Pieter A. Folkens, in The Human Bone Manual, 2005
Publisher Summary
The hyoid bone is an intermediary between the skull and postcranial skeleton. It combines skeletal elements of the second and the third pharyngeal arches associated with the gills of primitive fish. The hyoid bone is located in the neck and can be palpated immediately above the thyroid cartilage. It is suspended from the tips of the styloid processes of the temporal bones by the stylohyoid ligaments. The hyoid gives attachment to a variety of muscles and ligaments that connect it to the cranium, mandible, tongue, larynx, pharynx, sternum, and shoulder girdle. The hyoid ossifies from six centers: two for the body and one for each of the greater and lesser horns. In most modern vertebrates, the vertebrae have replaced the notochord as the principal means of support for the central part of the body. The sacrum and coccyx are vertebrae, but they function as the parts of the bony pelvis. This chapter describes the twenty-four movable vertebrae—the seven cervical, twelve thoracic, and five lumbar vertebrae. It introduces part common to most vertebrae.
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Multilevel pharyngeal surgeryfor obstructive sleep apnea
Kenny P. Pang, David J. Terris, in Sleep Apnea and Snoring, 2009
3.1 HYOID MYOTOMY (SUSPENSION)
Riley et al.22 first reported a skeletal approach to hypopharyngeal obstruction by using an adaptation of the laryngeal suspension procedure originally developed to minimize aspiration in patients who had had a supraglottic laryngectomy. In their original description, the infrahyoid musculature was removed from the hyoid bone, which was then suspended from the anterior mandibular arch using fascia lata. The technique was later simplified23 by approximating the hyoid bone antero-inferiorly to the thyroid cartilage (Figs 44.1 to 44.5). Essentially, the hyoid is releasedfrom its inferior attachments and advanced anteriorly and inferiorly over the thyroid cartilage. This applies tensionto the hyoepiglottic ligament, enlarging the hypopharynx (see figures).
3.1.1 TECHNICAL HIGHLIGHTS
•
The hyoid bone is exposed as in a thyroglossal cyst excision (Sistrunk procedure).
•The infrahyoid musculature is released from the body of the hyoid (Figs 44.1 and 44.2).
•The strap muscles are divided in the midline, and the thyroid cartilage exposed.
•Four non-absorbable #1-0 Ethibond (Johnson and Johnson) sutures are placed around the hyoid, through the thyroid cartilage to advance the hyoid bone (Fig. 44.3)
•Passive drainage (Penrose soft drain), and closure in layers.
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Functional Anatomy of the Airway
Lee Coleman, ... Sivam Ramanathan, in Benumof and Hagberg's Airway Management, 2013
1 Bones of the Larynx
The hyoid bone (Fig. 1-7) suspends and anchors the larynx during respiratory and phonatory movement. It is U shaped, and its name is derived from the Greek word hyoeides, meaning shaped like the letter upsilon. It has a body, which is 2.5 cm wide by 1 cm thick, and greater and lesser horns (cornu). The hyoid does not articulate with any other bone. It is attached to the styloid processes of the temporal bones by the stylohyoid ligament and to the thyroid cartilage by the thyrohyoid membrane and muscle. Intrinsic tongue muscles originate on the hyoid, and the pharyngeal constrictors are also attached there.4,12,34
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