Download VISCERA OF NECK Cervical viscera (3 layers) Endocrine layer

VISCERA OF NECK
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Cervical viscera (3 layers)
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Endocrine layer—thyroid and parathyroid glands (superficial)
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Respiratory layer—larynx and trachea
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Alimentary layer—pharynx and esophagus
ENDOCRINE LAYER
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Part of the body’s ductless, hormone-secreting glands
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Thyroid is body’s largest endocrine gland
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Produces thyroid hormone—controls rate of metabolism
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Calcitonin—controls Ca metabolism
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Affects all areas of body except the spleen, testes, and uterus
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Lies deep to sternothyroid and sternohyoid muscles
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Located anteriorly at level C5-T1
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Has right and left lobes, and an isthmus (between 2nd and 3rd tracheal rings)
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Surrounded by fibrous capsule
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Attached to cricoid cartilage and superior tracheal rings
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Pretracheal layer of deep cervical fascia covers this capsule
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ARTERIES
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Supplied by superior and inferior thyroid a.s
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Superior divides to anterior and posterior branches
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Inferior thyroid is largest branch off thyrocervical trunk from subclavian arteries
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Supply inferior poles of gland
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These anastomose all over the glandcollateral circulation between external
carotid and subclavian arteries
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10% have thyroid ima artery from brachiocephalic trunk, or subclavian, or
common carotid (right), or internal thoracic artery
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VEINS
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Three pairs of veins form the thyroid plexus
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Superior thyroid veins
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Middle thyroid veins
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Inferior thyroid veins
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Superior and middle drain to internal jugular veins
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Inferior drains to brachiocephalic veins posterior to manubrium
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LYMPH
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Lymph vessels run in interlobular CT, usually near arteries
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Pass to prelaryngeal, pretracheal, and paratracheal LNs.
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Prelaryngeals drain to superior cervicals
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Pretracheal and paratracheal drain to inferior deep cervicals.
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NERVES
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Superior, middle, and inferior cervical ganglia derived, which reach the gland
through cardiac, superior, and inferior thyroid periarterial plexuses that
accompany the arteries
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They are vasomotor, not secretomotorconstrict the blood vessels
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endocrine secretion regulated by pituitary
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Parathyroid glands
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Produce parathormone—controls metabolism of phosphorus and Ca
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Target kidneys, skeleton, intestine
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Lie external to thyroid capsule on medial half of the posterior surface of each lobe of the
thyroid, inside its sheath
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Superior parathyroids lie more than 1 cm superior to the point of entry of the inferior
thyroid arteries into the thyroid gland
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Usually at cricoid cartilage (inferior border)
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Inferior parathyroids lie more than 1 cm inferior to the arterial entry point
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Most people have 4
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VESSELS
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Inferior thyroid arteries and maybe some superior thyroid arteries, or laryngeal,
tracheal, esophageal arteries
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Parathyroid veins drain to thyroid plexus of veins
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Lymph nodes drain to deep cervicals and paratracheals
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NERVES
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Thyroid branches of cervical (sympathetic) ganglia
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Vasomotor rather than secretomotor
RESPIRATORY LAYER OF CERVICAL VISCERA
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Larynx and trachea
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Functions
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Routing air and food into the respiratory tract and esophagus respectively
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Patent airwayand way to seal it off temporarily
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Voice
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LARYNX
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“voice box”
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Composed of 9 cartilages and contain the vocal folds
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Located in anterior neck at C3-6 vertebrae
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Connects oropharynx with tracheaserves as a valve to maintain patent airway
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LARYNGEAL SKELETON
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9 cartilages
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3 are single: thyroid cricoid, epiglottic
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3 are paired: arytenoid, corniculate, cuneiform
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Thyroid cartilage
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Largest
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Superior border at C4
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Inferior 2/3rds of its laminae fuse anteriorly to form laryngeal
prominenceadam’s apple
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diverge superiorly to form the superior thyroid notch
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there is also an inferior thyroid notch
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superior horn and inferior horn
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superior border and horns attach to hyoid by thyrohyoid
membrane/median thyrohyoid ligament and lateral thyrohyoid
ligaments
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inferior horns articulate lateral surfaces of cricoid cartilage at
cricothyroid joints
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rotate and glide thyroid cartilage, which results in
changes in lengths of vocal folds
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cricoid cartilage
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posterior part is lamina, anterior part is arch
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thicker and stronger than thyroid cartilageonly complete ring of
cartilage to encircle the airway
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attaches to thyroid cartilage via median cricothyroid ligament and to
first tracheal ring via cricotracheal ligament
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arytenoid cartilages
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paired, 3 sided pyramidal cartilages that articulate with superior
border of cricoid lamina
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apex has corniculate cartilage on top
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attaches to ary-epiglottic fold
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vocal process has posterior attachment for vocal ligament
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VOCAL LIGAMENTS
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Junction of laminae of thyroid cartilage to vocal process of
arytenoid posteriorly
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Make up submucosal skeleton of vocal folds
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Conus elasticus and mucosa close tracheal inlet except for
central rima glottidesopening between vocal folds
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Epiglottic cartilage
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Consists of elastic cartilage, gives flexibility to epiglottis
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Thyroepiglottic and hyoepiglottic ligaments attach it
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Quadrangular membranemakes up vestibular ligamentforms
vestibular fold
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Aryepiglottic ligament formed from membrane forms aryepiglottic fold
Corniculate and cuneiform cartilages
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Nodules in posterior parts of aryepiglottic folds
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Cuneiforms don’t attach to other cartilages
INTERIOR OF LARYNX
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Extends from laryngeal inlet through which it communicates with
laryngopharynx at inferior border of cricoid
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Includes
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Laryngeal vestibule, middle part of laryngeal cavity, laryngeal ventricle
(with laryngeal saccules and mucus glands), infraglottic cavity
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Vocal folds control sound production
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Vocal ligament
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Vocalis muscle
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Vocal folds are sharp edged folds of mucus membrane overlying vocal
ligaments and thyroarytenoid musclessource of sound
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Glottis and rima glottides make up vocal folds and processes (rimaslit)
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Postpubertal males have deeper voices because their vocal folds are
longer
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Vestibular folds are protective infunctionenclose vestibular ligaments
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Space between them is rima vestibule
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Lateral recesses between vocal and vestibular folds are laryngeal ventricles
LARYNGEAL MUSCLES
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Extrinsic
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Move larynx as a whole
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Infrahyoid muscles
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Suprahyoid muscles and stylopharyngeus
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Intrinsic
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Later length of vocal folds and size and shape of the rima glottides
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All but one are supplied by recurrent laryngeal nerve off the vagus
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Cricothyroid supplied by external laryngeal nerve, one of two terminal
branches of superior laryngeal nerve
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See pg 1028 for muscle chart
ARTERIES
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Laryngeal arteries are branches of superior and inferior thyroid arteries
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Superior laryngeal artery accompanies internal branch of superior laryngeal
nerveinternal surface of larynx
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Cricothyroid artery off superior thyroid artery accompanies inferior laryngeal
nerve (terminal part of recurrent laryngeal nerve) and supplies mucus
membrane and muscles of inferior part of the larynx
VEINS
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Superior laryngeal vein and inferior laryngeal veins join superior and inferior
thyroid veins  left brachiocephalic vein
LYMPH
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Drain to superior deep cervicals
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Vocal folds drain to inferior deep cervical lymph nodes
NERVES
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Superior and inferior laryngeal branches of vagus nerves
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Superior laryngeal nerve arises from inferior vagal ganglion and divides into
two terminal branches within the carotid sheathinternal laryngeal nerve
(sensory and autonomic) and external laryngeal nerve (motor)
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Internal laryngeal nerve is larger and supplies sensory to the laryngeal
mucus membrane of the laryngeal vestibule and middle laryngeal
cavity, including superior surface of vocal folds
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External laryngeal nerve descends posterior to sternothyroid muscle,
contributes to inferior constrictor innervation, and supplies the
cricothyroid muscle
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Inferior laryngeal nerve is a continuation of the recurrent laryngeal nerve
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TRACHEA
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From larynx to thorax
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Tracheal cartilages support it (incomplete)
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Involuntary trachealis muscle between it and esophagussmooth muscle connects rings
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2.5 cm in diameter in adults, infants diameter of pencil
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Extends from inferior larynx to C6 and ends at level of sternal angle or T4-T5 IV
discdivides to right and left main bronchi
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Lateral to it are common carotids and lobes of thyroid gland
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Inferior to isthmus of thyroid gland is jugular venous arch and inferior thyroid veins
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Brachiocephalic trunk is related to right side of trachea
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Tracheal trauma may affect esophagus
ALIMENTARY LAYER OF CERVICAL VISCERA
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Digestive functions of body
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Pharyngeal constrictors direct food to esophagus
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Esophagus is beginning of alimentary canal
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PHARYNX
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Superior expanded part of alimentary system posterior to nasal and oral cavities
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Extends from cranial base to cricoid cartilage anteriorly and inferior border of C6
posteriorly
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Pharynx is widest opposite hyoid and narrowest at inferior end, where it is continuous
with esophagus
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Flat posterior wall of pharynx lies against prevertebral layer of deep cervical fasica
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INTERIOR
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3 parts
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Nasopharynx
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Respiratory functionposterior extension of nasal cavities
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Nose opens to this through two choanae
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Roof and posterior wall form continuous surface that lies
inferior to body of sphenoid and basilar part of occipital bone.
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Oropharynx
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Laryngopharynx
1043-1047 BLUE BOXES!!!
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Enters larynx by passing deep to inferior border of the inferior
pharyngeal constrictor and medial to lamina of thyroid cartilage
Divides to anterior and posterior branches
Anterior supplies lateral cricothyroid, thyroarytenoid, vocalis,
aryepiglottic, thyroepiglottic muscles
Posterior supplies posterior cricoarytenoid, transverse and oblique
arytenoid muscles
Inferior is primary motor nerve of larynx, as well as sensory fibers to
mucosa of infraglottic cavity