Pharynx, Larynx, and Neck

Pharynx

muscular tube extending from nasal and oral cavities to larynx and esophagus

Three parts of pharynx

nasopharynx, oropharynx, laryngopharynx

Epiglottis

flap of cartilage at the top of larynx that closes off the larynx during swallowing

Auditory tube

tube opening into the nasopharynx that connects the pharynx with the middle ear

Two types of pharyngeal muscles

constrictor muscles and longitudinal muscles

Function of constrictor muscles

attach pharynx to hyoid and squeeze food into the esophagus during swallowing

Function of longitudinal muscles

elevate pharynx and hyoid during swallowing

Somatic motor innervation of pharynx

CN X (vagus)

General sensory innervation of pharynx

CN IX (glossopharyngeal)

Structures found posterior to pharynx

internal jugular vein, internal carotid artery, external carotid artery, superior cervical ganglion

First step of swallowing

tongue collects food into a bolus and forces it into the oropharynx

Role of tongue during swallowing

collects food into bolus and blocks oral cavity as food traverses pharynx

Role of soft palate during swallowing

raises to block nasopharynx

Role of pharyngeal constrictors during swallowing

contract to squeeze food inferiorly through pharynx

Role of longitudinal muscles during swallowing

elevate hyoid and larynx

Role of epiglottis during swallowing

closes the entrance to the larynx to prevent food from entering airway

Final step of swallowing

food enters the esophagus

Cranial nerves involved in swallowing

V, IX, X, XII

Larynx

cartilaginous structure superior to trachea that contains vocal cords

Thyroid cartilage

adam’s apple

Cricoid cartilage

ring-shaped cartilage inferior to thyroid cartilage

Arytenoid cartilages

paired triangular cartilages that articulate with cricoid cartilage

Function of arytenoid cartilage

rotate to open or close rima glottis and adjust vocal fold tension

Thyrohyoid ligament

connects thyroid cartilage to hyoid bone

Cricothyroid ligament

connects thyroid and cricoid cartilages

Vocal ligaments

thickened superior edges of cricothyroid ligament that attach thyroid cartilage to arytenoid cartilages

Rima glottis

opening between vocal ligaments

Vocal folds

folds formed when mucosa covers the vocal ligaments

How speech sounds are produced

air forced through nearly closed vocal folds, causing them to vibrate and create sound waves

Effect of tightening vocal folds

higher-pitched sound

Why males have deeper voices

have larger and longer vocal folds, which vibrate at lower frequencies

Function of cricothyroid muscle

tilts thyroid cartilage forward to tighten vocal ligaments

Action needed for high-pitched sounds

contract cricothyroid muscle and nearly close the rima glottis

General sensory and somatic motor innervation of larynx

CN X (vagus)

Superior laryngeal nerve

branch of vagus nerve that contributes to laryngeal innervation

Recurrent laryngeal nerve

branch of vagus nerve that innervates structures of larynx

Number of cervical vertebrae

seven

C1 vertebra (Atlas) articulation

occipital condyles of skull

Transverse foramina

openings in transverse processes of cervical vertebrae

Atlas (C1)

first cervical vertebra that lacks vertebral body and supports the skull

Axis (C2)

second cervical vertebra containing the dens

Dens

superior projection of axis around which the atlas rotates

How the atlas and axis allow head movement

atlas rotates around the dens of the axis

Position of larynx relative to esophagus and pharynx

anterior to esophagus and pharynx

Position of trachea relative to larynx

inferior to larynx

Position of thyroid gland

anterior to thyroid cartilage of larynx

Function of thyroid gland

produce thyroid hormone to regulate metabolism, growth, and development

Parathyroid glands

fours glands located on posterior surface of thyroid gland

Function of parathyroid gland

produce parathyroid hormone to regulate calcium levels in blood

Borders of posterior triangle

sternocleidomastoid muscle, trapezius muscle, and clavicle

Sternocleidomastoid muscle attachment

mastoid process, clavicle, and sternum

Function of sternocleidomastoid muscle

tilts and rotates head and neck

Nerve innervating sternocleidomastoid and trapezius

CN XI (accessory)

Scalene muscles

muscles attaching cervical vertebrae to ribs that tilt and rotate neck

Structures passing between anterior and middle scalenes

brachial plexus and subclavian artery

Structure passing anteriorly to anterior scalene

phrenic nerve

Borders of anterior triangle

sternocleidomastoid, mandible, and midline of neck

Contents of anterior triangle

hyoid, larynx, thyroid gland, carotid sheath, infrahyoid muscles, and suprahyoid muscles

Common carotid artery

artery that splits into internal and external carotid arteries

Carotid sinus

swelling at split that contains blood pressure sensors

Structures within carotid sheath

internal jugular vein, common carotid artery, and vagus nerve

What do vertebral arteries travel through

transverse foramina in cervical vertebrae

How do vertebral arteries enter skull

through foramen magnum

Suprahyoid muscles attachment

attach to superior hyoid and skull

Function of suprahyoid muscles

elevate hyoid, larynx, and pharynx

Infrahyoid muscles attachment

inferior hyoid and sternum, larynx

Function of infrahyoid muscles

depress hyoid, larynx, and pharynx