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Anatomy

Blood Supply to the Head and Neck

  • Most arteries in the anterior cervical triangle arise from the common carotid artery or one of the branches of the external carotid artery.
  • Most veins in the anterior cervical triangle are tributaries of the large internal jugular vein.

 

The Common Carotid Arteries

  • The right common carotid artery begins at the bifurcation of the brachiocephalic trunk, posterior to the right sternoclavicular joint.
  • The left common carotid artery begins arises from the arch of the aorta and ascends into the neck, posterior to the left sternoclavicular joint.
  • Each common carotid artery ascends into the neck within the carotid sheath to the level of the superior border of the thyroid cartilage.
  • Here it terminates by dividing into the internal and external carotid arteries. 

The Internal Carotid Artery

  • This is the direct continuation of the common carotid artery and it has no branches in the neck.
  • It supplies structures inside the skull.
  • The internal carotid arteries are two of the four main arteries that supply blood to the brain.
  • Each artery arises from the common carotid at the level of the superior border of the thyroid cartilage.
  • It then passes superiorly, almost in a vertical plane, to enter the carotid canal in the petrous part of the temporal bone.
  • A plexus of sympathetic fibres accompany it.
  • During its course through the neck, the internal carotid artery lies on the longus capitis muscle and the sympathetic trunk.
  • The vagus nerve (CN X) lies posterolateral to it.
  • The internal carotid artery enters the middle cranial fossa beside the dorsum sellae of the sphenoid bone.
  • Within the cranial cavity, the internal carotid artery and its branches supply the hypophysis cerebri (pituitary gland), the orbit, and most of the supratentorial part of the brain. 

The External Carotid Arteries 

  • This vessel begins at the bifurcation of the common carotid, at the level of the superior border of the thyroid cartilage.
  • It supplies structures external to the skull.
  • The external carotid artery runs posterosuperiorly to the region between the neck of the mandible and the lobule of the auricle.
  • It terminates by dividing into two branches, the maxillary and superficial temporal arteries.
  • The stems of most of the six branches of the external carotid artery are in the carotid triangle. 

The Superior Thyroid Artery

  • This is the most inferior of the 3 anterior branches of the external carotid.
  • It arises close to the origin of the vessel, just inferior to the greater horn of the hyoid.
  • The superior thyroid artery runs anteroinferiorly, deep to the infrahyoid muscles and gives off the superior laryngeal artery. This artery pierces the thyrohyoid membrane in company with the internal laryngeal nerve and supplies the larynx.

 

The Lingual Artery

  • This arises from the external carotid artery as it lies on the middle constrictor muscle of the pharynx.
  • It arches superoanteriorly, about 5 mm superior to the tip of the greater horn of the hyoid bone, and then passes deep to the hypoglossal nerve, the stylohyoid muscle, and the posterior belly of digastric muscle.
  • It disappears deep to the hyoglossus muscle.
  • At the anterior border of this muscle, it turns superiorly and ends by becoming the deep lingual artery.

 

The Facial Artery

  • This arises from the carotid artery either, in common with the lingual artery, or immediately superior to it.
  • In the neck the facial artery gives off its important tonsillar branch and branches to the palate and submandibular gland.
  • The facial artery then passes superiorly under the cover of the digastric and stylohyoid muscles and the angle of the mandible.
  • It loops anteriorly and enters a deep groove in the submandibular gland.
  • The facial artery hooks around the inferior border of the mandible and enters the face. Here the pulsation of this artery can be felt (anterior to the masseter muscle).

 

The Ascending Pharyngeal Artery

  • This is the 1st or 2nd branch of the external carotid artery.
  • This small vessel ascends on the pharynx, deep to the internal carotid artery.
  • It sends branches to the pharynx, prevertebral muscles, middle ear and meninges.

 

The Occipital Artery

  • This arises from the posterior surface of the external carotid near the level of the facial artery.
  • It passes posteriorly along the inferior border of the posterior belly of digastric.
  • It ends in the posterior part of the scalp.
  • During its course, it is superficial to the internal carotid artery and three cranial nerves (CN IX, CN X and CN XI).

 

The Posterior Auricular Artery

  • This is a small posterior branch of the external carotid artery.
  • It arises from it at the superior border of the posterior belly of the digastric muscle.
  • It ascends posteriorly to the external acoustic meatus and supplies adjacent muscles, the parotid gland, the facial nerve, structures in the temporal bone, the auricle, and the scalp. 

The Internal Jugular Vein

 

  • This is usually the largest vein in the neck.
  • The internal jugular vein drains blood from the brain and superficial parts of the face and neck.
  • Its course corresponds to a line drawn from a point immediately inferior to the external acoustic meatus to the medial end of the clavicle.
  • This large vein commences at the jugular foramen in the posterior cranial fossa, as the direct continuation of the sigmoid sinus.
  • The dilation at its origin is called the superior bulb of the internal jugular vein.
  • From here it runs inferiorly through the neck in the carotid sheath.
  • The internal jugular vein leaves the anterior triangle of the neck by passing deep to the SCM muscle.
  • Posterior to the sternal end of the clavicle, it unites with the subclavian vein to form the brachiocephalic vein.
  • Near its termination is the inferior bulb of the jugular vein contains a bicuspid valve similar to that of the subclavian vein.
  • The deep cervical lymph nodes lie along the course of the internal jugular vein, mostly lateral and posterior.

 

Tributaries of the Internal Jugular Vein

  • This large vein is joined at its origin by the: inferior petrosal sinus, the facial, lingual, pharyngeal, superior and middle thyroid veins, and often the occipital vein.

Gross Features of the Tongue

  • The dorsum of the tongue is divided by a V-shaped sulcus terminalis into anterior oral (presulcal) and posterior pharyngeal (postsulcal) parts.
  • The apex of the V is posterior and the two limbs diverge anteriorly.
  • The oral part forms about 2/3 of the tongue and the pharyngeal part forms about 1/3.

 

Oral Part of the Tongue

  • This part is freely movable, but it is loosely attached to the floor of the mouth by the lingual frenulum.
  • On each side of the frenulum is a deep lingual vein, visible as a blue line.
  • It begins at the tip of the tongue and runs posteriorly.
  • All the veins on one side of the tongue unite at the posterior border of the hyoglossus muscle to form the lingual vein, which joins the facial vein or the internal jugular vein.
  • On the dorsum of the oral part of the tongue is a median groove.
  • This groove represents the site of fusion of the distal tongue buds during embryonic development.

 

The Lingual Papillae and Taste Buds

  • The filiform papillae (L. filum, thread) are numerous, rough, and thread-like.
  • They are arranged in rows parallel to the sulcus terminalis.
  • The fungiform papillae are small and mushroom-shaped.
  • They usually appear are pink or red spots.
  • The vallate (circumvallate) papillae are surrounded by a deep, circular trench (trough), the walls of which are studded with taste buds.
  • The foliate papillae are small lateral folds of lingual mucosa that are poorly formed in humans.
  • The vallate, foliate and most of the fungiform papillae contain taste receptors, which are located in the taste buds.

 

The Pharyngeal Part of the Tongue

  • This part lies posterior to the sulcus terminalis and palatoglossal arches.
  • Its mucous membrane has no papillae.
  • The underlying nodules of lymphoid tissue give this part of the tongue a cobblestone appearance.
  • The lymphoid nodules (lingual follicles) are collectively known as the lingual tonsil.

  •     Part of the axial skeleton; strong, flexible rod
        Supports the head
        Gives base to the ribs
        Encloses the spinal cord
        
    o    Vertebrae
        Consists of 34 bones composing the spinal column
    •    Cervical-7 bones
    •    Thoracic-12 bones
    •    Lumbar-5 bones
    •    Sacral- 5 bones.
    •    Coccygeal-4 to 5 bones

        In the adult the vertebrae of the sacral and coccygeal regions are united into two bones, the sacrum and me coccyx
        
    o    Curvatures-from a lateraI view there are four curves, alternately convex and concave ventrally
        Two convex curves are the cervical and lumbar
        Two concave curves are the thoracic and sacral

    o    Vertebra morphology

        Each vertebra differs in size and shape hut has similar components
        Body-central mass of bone
    •    Weight bearing
    •    Fonns anterior part of the vertebra
    •    Encloses the vertebral foramen
        Pedicles of the arch-two thick columns that extend backward from the body to meet with the laminae of the neural arch 

  •     Process (7)
    •    One spinous, two transverse, two superior articular, and two inferior articular
    o    Spinous process extends backward from the point of the union of thetwo laminae
    o    Transverse processes project laterally at either side from the junction of the lamina and the pedicle
    o    Articular processes arise near the junction of the pedicle and the lamina- superior processes project upward:inferior processes project downward
    •    Surfaces of the processes are smooth

    o    Inferior articular processes of the vertebra fit into the superior articular processes below
    o    Form true joints, but the contacts established serve to restrict movement

    Distinguishing features

    Cervical region- triangular shape

    •    All have foramina in the transverse process upper six transmit the vertebral artery
    •    Spinous processes are short
        o    C3 to C5 are bifurcated
        o    C7 is long-prominence felt at the back of the neck
    •    Have small bodies (except for C1 vertebra)
    •    C1 vertebra (atlas)
    o    No body
    o    Anterior and posterior arch and two lateral masses
    o    Superiorarticular processes articulate with the condyles of the occipital bone
    •    C2 vertebra (axis)-process on the upper surface of the body (dens) forms a pivot about which the axis rotates

    Thoracic region

    •    Presence of facets for articulation with the ribs (distinguishing feature)
    •    Processes are larger and heavier than those of the cervical region
    •    Spinous process is directed downward at a sharp angle
    •    Circular vertebral foramen

     Lumbar region
     
    •    Large and heavy bodies
    •    Four transverse lines separate the bodies of the vertebrae on the pelvic surface
    •    Triangular shape-fitted between the  halves of the pelvis
    •    Four pairs of dorsal sacral foramina communicate with four pairs of pelvic sacral foramina

    Sacral vertebrae 
    •    Five (sometimes six) vertebrae are fused in the adult to form the sacrum
    •    The sacrum articulates above with L5, laterally with the hip bones, and inferiorly with the coccyx.
    •    It has a roughly triangular appearance with a pelvic and dorsal surface, a lateral mass on each side, and a base and apex.
    •    An anesthetic for the spinal nerves may be injected extradurally through the sacral hiatus (caudal analgesia)
    •    The sacral canal (which contains the dura, cauda equina, and filum terminale) extends from the base to the sacral hiatus. 
    •    The apex of the sacrum may be fused with the coccyx.


    Coccygeal vertebrae

    •    Four to five modular pieces fused together
    •    Triangular shape with the base above and the apex below

    F Defects

    •    Lordosis-exaggerated lumbar concavity
    •    Scoliosis-lateral curvature of any region
    •    Kyphosis-exaggerated convexity in the thoracic region

 

Muscles of the Tongue

  • The tongue is divided into halves by a medial fibrous lingual septum that lies deep to the medial groove.
  • In each half of the tongue there are four extrinsic and four intrinsic muscles.
  • The lingual muscles are all supplied by the hypoglossal nerve (CN XII).
  • The only exception is palatoglossus, which is supplied by the pharyngeal branch of the vagus nerve, via the pharyngeal plexus.

 

Extrinsic Muscles of the Tongue

The Genioglossus Muscle

  • This is a bulky, fan-shaped muscle that contributes to most of the bulk of the tongue.
  • It arises from a short tendon from the genial tubercle (mental spine) of the mandible.
  • It fans out as it enters the tongue inferiorly and its fibres attach to the entire dorsum of the tongue.
  • Its most inferior fibres insert into the body of the hyoid bone.
  • The genioglossus muscle depresses the tongue and its posterior part protrudes it.

 

The Hyoglossus Muscle

  • This is a thin, quadrilateral muscle.
  • It arises from the body and greater horn of the hyoid bone and passes superoanteriorly to insert into the side and inferior aspect of the tongue.
  • It depresses the tongue, pulling its sides inferiorly; it also aids in retrusion of the tongue.

 

The Styloglossus Muscle

  • This small, short muscle arises from the anterior border of the styloid process near its tip and from the stylohyoid ligament.
  • It passes inferoanteriorly to insert into the side and inferior aspect of the tongue.
  • The styloglossus retrudes the tongue and curls its sides to create a trough during swallowing. 

 

The Palatopharyngeus Muscle

  • Superior attachment: hard palate and palatine aponeurosis.
  • Inferior attachment: lateral wall of pharynx.
  • Innervation: cranial part of accessory nerve (CN XI) through the pharyngeal branch of vagus (CN X) via the pharyngeal plexus.
  • This thin, flat muscle is covered with mucous membrane to form the palatopharyngeal arch.
  • It passes posteroinferiorly in this arch.
  • This muscle tenses the soft palate and pulls the walls of the pharynx superiorly, anteriorly and medially during swallowing. 

Intrinsic Muscles of the Tongue

The Superior Longitudinal Muscle of the Tongue

  • The muscle forms a thin layer deep to the mucous membrane on the dorsum of the tongue, running from its tip to its root.
  • It arises from the submucosal fibrous layer and the lingual septum and inserts mainly into the mucous membrane.
  • This muscle curls the tip and sides of the tongue superiorly, making the dorsum of the tongue concave.

 

The Inferior Longitudinal Muscle of the Tongue

  • This muscle consists of a narrow band close to the inferior surface of the tongue.
  • It extends from the tip to the root of the tongue.
  • Some of its fibres attach to the hyoid bone.
  • This muscle curls the tip of the tongue inferiorly, making the dorsum of the tongue convex.

The Transverse Muscle of the Tongue

  • This muscle lies deep to the superior longitudinal muscle.
  • It arises from the fibrous lingual septum and runs lateral to its right and left margins.
  • Its fibres are inserted into the submucosal fibrous tissue.
  • The transverse muscle narrows and increases the height of the tongue.

The Vertical Muscle of the Tongue

  • This muscle runs inferolaterally from the dorsum of the tongue.
  • It flattens and broadens the tongue.
  • Acting with the transverse muscle, it increases the length of the tongue.

The Lateral Wall of the Orbit

  • This wall is thick, particularly its posterior part, which separates the orbit from the middle cranial fossa.
  • The lateral wall is formed by the frontal process of the zygomatic bone and the greater wing of the sphenoid bone.
  • Anteriorly, the lateral wall lies between the orbit and the temporal fossa.
  • The lateral wall is partially separated from the roof by the superior orbital fissure.

o    English: all speech sounds produced by making exhaled air audible

o    Two ways of producing sound
    at larynx
    further up in vocal tract (tongue, lips)
    
o    How to produce sound at larynx
    changes in breathing: regulate airstream from lungs to atmosphere by changing movements of vocal folds, pharynx, soft-palate, tongue, lips and jaws
    
•    inhalation: take in greater volume more quickly, abduct folds

•    expiration: variable force; use muscles of inhalation to control rate of expiration, adduct

    How to vibrate vocal cords
    
•    NOT rhythmic contraction of laryngeal muscles: would be impossible b/c frequenceies of virbration
•    Changes in air pressure cause vibrations


    o    Adduct folds increase in subglottal pressure force folds apart folds sucked back together (Bernouilli effect)
•    The vibration of vocal cords disturbs airareas of low pressure (rarefaction) alternating with areas of high pressure (compression)
•    Changes in pressure sound at ears
•    Sine waves

    o    Changes in amplitudes: loudness

    o    Changes in frequency: pitch

    o    Normal sounds have fundamental frequency, overtones or harmonics

    o    Mass of folds: critical in voice
    Low pitch of lion’s roar: due to massive fibrous pad that forms part of vocal cords
    Men: more massive vocal cords
    Larger foldsslow vibrationdeeper voice

    o    Producing vowels and constants
    Most vowels are “voiced”: vocal folds produce sounds
    Consonants: can be “voiced” (Z) or “non-voiced” (S)
•    Use higher regions of vocal tract to control by stopping, restricting airflow from vocal folds; use lips, teethaperiodic sound

o    Vocal folds and resonators emphasize and deemphasize certain frequencies
    Never hear sounds produced at vocal foldsevery sound changed by passage thru vocal tract: sinuses/resonating chambers
    Howling monkeys: large hyoid bonepowerful resonator

    o    Age-related changes in voice
    
    Infant larynx is smaller, different proportions
•    Arytenoids are proportionately larger
•    Smaller vocal apparatushigher pitch
•    Larynx sits higher easier to breathe thru nose
    Abrupt change in larynx at pubertycan’t control voice
    Older adult: normal degenerative changes in lamina propria, ossification of thyroid cartilagechanges in fundamental frequency
    Lose your voice vocal fold are irritated
•    Can’t adduct foldsair escapes

o    Singing v. speaking
    Singing: greater thoracic pressure and uneven breathing with changes in resonators

    o    Whispering
    Intercartilaginous portions of vocal folds: open to allow air to escapelesser subglottal pressureslittle vibration of foldslittle tonal quality, low volume

    o    Falsetto
    Allowing only part of vocal folds to vibrate
    Increase range by training which part of vocal folds to vibrate

    o    Colds
    Mucus secretions add mass to folds—decrease in pitch, can’t adduct folds as well

    o    Surgeryscars, fibrotic changes can interfere with voice

The Tongue

  • The tongue (L. lingua; G. glossa) is a highly mobile muscular organ that can vary greatly in shape.
  • It consists of three parts, a root, body, and tip.
  • The tongue is concerned with mastication, taste, deglutition (swallowing), articulation (speech), and oral cleansing.
  • Its main functions are squeezing food into the pharynx when swallowing, and forming words during speech.

 

Gross Features of the Tongue

  • The dorsum of the tongue is divided by a V-shaped sulcus terminalis into anterior oral (presulcal) and posterior pharyngeal (postsulcal) parts.
  • The apex of the V is posterior and the two limbs diverge anteriorly.
  • The oral part forms about 2/3 of the tongue and the pharyngeal part forms about 1/3.

 

Oral Part of the Tongue

  • This part is freely movable, but it is loosely attached to the floor of the mouth by the lingual frenulum.
  • On each side of the frenulum is a deep lingual vein, visible as a blue line.
  • It begins at the tip of the tongue and runs posteriorly.
  • All the veins on one side of the tongue unite at the posterior border of the hyoglossus muscle to form the lingual vein, which joins the facial vein or the internal jugular vein.
  • On the dorsum of the oral part of the tongue is a median groove.
  • This groove represents the site of fusion of the distal tongue buds during embryonic development.

 

The Lingual Papillae and Taste Buds

  • The filiform papillae (L. filum, thread) are numerous, rough, and thread-like.
  • They are arranged in rows parallel to the sulcus terminalis.
  • The fungiform papillae are small and mushroom-shaped.
  • They usually appear are pink or red spots.
  • The vallate (circumvallate) papillae are surrounded by a deep, circular trench (trough), the walls of which are studded with taste buds.
  • The foliate papillae are small lateral folds of lingual mucosa that are poorly formed in humans.
  • The vallate, foliate and most of the fungiform papillae contain taste receptors, which are located in the taste buds.

 

The Pharyngeal Part of the Tongue

  • This part lies posterior to the sulcus terminalis and palatoglossal arches.
  • Its mucous membrane has no papillae.
  • The underlying nodules of lymphoid tissue give this part of the tongue a cobblestone appearance.
  • The lymphoid nodules (lingual follicles) are collectively known as the lingual tonsil.
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