ANATOMY/ FUNCTION OF THE ANATOMY/ FUNCTION OF THE HYOID APPARATUSHYOID APPARATUS

Dr. AsmaHouse Surgeon,ENT Department, Capital Hospital

Anterior view Sagittal SectionPosterior view

Thyroid cart.Thyroid cart.

Cricoid cart.

Arytenoid cart.

Epiglottis

Hyoid

Arytenoid cart.

Hyoid

Epiglottis

Cricoid cart.

Vocal Cord

Helps to support the tongue Serves as an attachment point for

several muscles that help to elevate the larynx during swallowing and speech.  

The hyoid bone (Lingual Bone) is unique in that it  is the only bone of the body that does not articulate with any other bone. 

It is supported by the muscles of the neck and in turn supports the root of the tongue.

Its name is derived from the Greek word hyoeides meaning "shaped like the letter upsilon" (υ). 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.

Segments The body or basihyalThe body or basihyal

The greater cornua The greater cornua

or thyrohyals or thyrohyals

The lesser cornua or The lesser cornua or ceratohyals ceratohyals

The body or basihyal Its anterior surface is convex and directed forward and upward.Its anterior surface is convex and directed forward and upward. The anterior surface gives insertion to the to a number of musclesThe anterior surface gives insertion to the to a number of muscles

The posterior surface is smooth, concave, directed backward and The posterior surface is smooth, concave, directed backward and downward, and separated from the epiglottis by the hyothyroid downward, and separated from the epiglottis by the hyothyroid membrane membrane

In early life the lateral borders are connected to the greater In early life the lateral borders are connected to the greater cornua by synchondroses; after middle life usually by bony union.cornua by synchondroses; after middle life usually by bony union.

The greater cornua or thyrohyals The greater cornua (cornua majora) project backward from the lateral The greater cornua (cornua majora) project backward from the lateral

borders of the body; they are flattened from above downward; each borders of the body; they are flattened from above downward; each ends in a tubercle to which is fixed the lateral hyothyroid ligament.ends in a tubercle to which is fixed the lateral hyothyroid ligament.

The lesser cornua or ceratohyals The lesser cornua (cornua minora) are two small, conical eminences, The lesser cornua (cornua minora) are two small, conical eminences,

attached by their bases to the angles of junction between the body and attached by their bases to the angles of junction between the body and greater cornua.greater cornua.

They are connected to the body of the bone by fibrous tissue, and They are connected to the body of the bone by fibrous tissue, and occasionally to the greater cornua by distinct diarthrodial jointsoccasionally to the greater cornua by distinct diarthrodial joints

Ossification

The hyoid is ossified from six centers: two for the body, and two for the body, and one for each cornu. one for each cornu.

Ossification commences in the greater cornua toward the end of fetal life, greater cornua toward the end of fetal life, in the body shortly afterward, in the body shortly afterward, and in the lesser cornua during the first or second year after and in the lesser cornua during the first or second year after

birth.birth.

Triangles of NeckTriangles of NeckLumps In NeckLumps In Neck

Sternocleidomastoid

Trapezius

Anterior triangle

LUMPS IN NECKLUMPS IN NECK

Triangles of Neck

Divided into anterior and posterior triangles by SCM.

Posterior Cervical Triangle

The Triangles are further divided into:

SubmandibularBetween digastric and mandibleBetween digastric and mandible Lymph nodesLymph nodes Submandibular or tail of parotid Submandibular or tail of parotid

salivary glandssalivary glands CalculusCalculus InfectedInfected TumourTumour ObstructionObstruction

Tense, painful swellingTense, painful swelling On eating, slowly resolves over On eating, slowly resolves over

hourshours Returns on next eatingReturns on next eating

Dental abcess (rare)Dental abcess (rare) SubmentalBetween hyoid and anterior belly of

digastric Lymph nodeLymph node Supra-hyoid thyroglossal cystSupra-hyoid thyroglossal cyst Dermoid cystDermoid cyst Dental abcess (rare)Dental abcess (rare)

Sternocleidomastoid

Trapezius

CarotidAnterior to SCM, between SCM and omohyoid Jugulo-digastric lymph nodesJugulo-digastric lymph nodes Branchial cystBranchial cyst Carotid body tumour (usually Carotid body tumour (usually

benign)benign) VagusVagus

SchwannomaSchwannoma NeuromaNeuroma ParagangliomaParaganglioma

PubertyPuberty Multinodular goitre Multinodular goitre

(MNG)(MNG) Later thyroiditisLater thyroiditis

Thyroglossal cystThyroglossal cyst

Laryngeal tumourLaryngeal tumour Lymph nodes – pre- and Lymph nodes – pre- and

para- trachealpara- tracheal

Muscular Between hyoid, SCM, and omohyoid, anterior to omohyoid ThyroidThyroid

NoduleNodule CystCyst CancerCancer

PapillaryPapillary FollicularFollicular MedullaryMedullary LymphomaLymphoma Anaplastic carcinomaAnaplastic carcinoma AdenomaAdenoma

Dominant nodule of MNGDominant nodule of MNG Diffuse enlargement (soft)Diffuse enlargement (soft)

GravesGraves Early thyroiditisEarly thyroiditis PhysiologicalPhysiological PregnancyPregnancy

SupraclavicularInferior to SCM and omohyoid

ThyroidThyroid Cervical ribCervical rib Lymph nodesLymph nodes

Especially metsEspecially mets Gastric carcinomaGastric carcinoma

Troisier’s sign – palpable Virchows node

Lung cancerLung cancer Breast cancerBreast cancer Others – less commonOthers – less common