THE NECK

Anterior triangle & fascia of the neck

Root of the neck; cervicothoracic relations

Pharynx and palate

Prevertebral region

Larynx


THE ANTERIOR TRIANGLE OF THE NECK

Text:  Gross Anatomy, K. W. Chung, 6th edition: pp. 321-332

Reference:  Clinically Oriented Anatomy, K.L. Moore, A.F. Dalley, 5th edition: pp. 1046-1055, 1065-1075; 6th edition:  pp. 982-992, 999-1011

Dissector:

Clemente’s Anatomy Dissector, 2nd edition:  pp. 337-349

Grant’s Dissector, P.W. Tank, 14th edition:  pp. 190-194

Borders of the anterior triangle of the neck (Clemente plate 436 fig. 693; Grant p. 752; Netter 3e 24, 4e 28)

are formed by the:

The anterior triangle of the neck can be further subdivided into (Clemente plate 436 fig. 693; Grant p. 752; Netter 3e 24, 4e 27-28):

Landmarks:

1) The tips of the transverse processes of C1 are more prominent than those of other cervical vertebrae (Clemente plate 437 fig. 694; Grant p. 751; Netter 3e 26, 4e 19). Palpate in the parotid space (Clemente plate 435 fig. 691; Grant p. 750, Netter 3e 26, 4e 13).

2) The hyoid bone: Its body is at the level of C3. It has a lesser and greater horns (cornua) bilaterally.

3) The thyroid cartilage lies at the levels of C4 and C5.

4) The cricoid cartilage lies at the level of C6 (Clemente plate 435; Grant p. 750; Netter 3e 12, 4e 65). The upper end of the trachea is palpable in the midline from the cricoid cartilage to the superior border of the manubrium.

5) The thyrohyoid membrane is pierced by the internal branches of the superior laryngeal nerve and vessels (Clemente plate 557; Grant p. 788-789; Netter 3e 76, 4e 71).

6) The cricothyroid membrane may be used for a high tracheostomy (Clemente plate 558; Grant p. 798; Netter 3e 73, 4e 77).

*The preferred site of tracheostomy is at tracheal cartilages 2-4 (below the cricoid cartilage and the isthmus of the thyroid gland).

SUPERFICIAL STRUCTURES

1) The platysma muscle (Clemente plate 438; Grant p. 746; Netter 3e 22, 4e 26)

2) The superficial (investing) layer of the deep cervical fascia (Clemente plate 446; Grant p. 747; Netter 3e 24, 4e 35):

The single investing layer anteriorly covers the anterior triangle of the neck and fuses with the opposite fascia in the midline.

3) The superficial veins lie superficial to the deep fascia

Anterior jugular veins (Clemente plate 450; Grant p. 748; Netter 3e 27, 4e 31):

4) Superficial cervical nerves (Clemente plate 441; Grant p. 754; Netter 20)

Sensory nerves from the cervical plexus:

The cervical branch of cranial nerve VII enters the platysma muscle on its deep surface near the angle of the mandible. This is a motor nerve.

INFRAHYOID MUSCLES (Grant p. 758-759, 761; Netter 3e 25, 4e 29)

The ansa cervicalis

Infrahyoid muscles (Clemente plate 447; Grant p. 758-759, 761; Netter 3e 25, 4e 29)

THE PHARYNX (Clemente plate 548; Grant p. 808-809; Netter 3e 64, 4e 63)

The pharynx is formed by the superior, middle and inferior constrictors which are attached by a posterior midline raphé with the same constrictors on the opposite side (Clemente plate 550; Grant p. 786, 787; Netter 3e 71, 4e 67 & 68). From superior to inferior, the constrictor muscles are stacked into one another.

THE SUPERIOR CONSTRICTOR MUSCLE

THE MIDDLE CONSTRICTOR MUSCLE lies behind the tongue and larynx (Clemente plates 550, 553; Grant p. 788, 791; Netter 3e 63, 4e 67). It is truly a constrictor and plays a major role in swallowing.

THE INFERIOR CONSTRICTOR MUSCLE attaches anteriorly to the cricoid and thyroid cartilages. The most inferior aspect is the cricopharyngeus which is the sphincter between the pharynx and the esophagus (Clemente plate 548; Grant p. 786, 788; Netter 3e 63-64, 4e 67-68).

Innervation (Clemente plate 551; Grant p. 787; Netter 3e 67, 72, 4e 71):

The carotid sheath

The thyroid gland

The carotid triangle

The posterior belly of the digastric (Clemente plate 439; Grant p. 761; Netter 3e 49, 4e 28, 32):

Relationships of the posterior belly of the digastric muscle:

1) between the posterior belly of the digastric muscle and the skin of the neck:

2) deep to the posterior belly of digastric

Cranial nerve X or the vagus nerve lies in the carotid sheath and sends out (Grant p. 837; Netter 3e 28, 72, 4e 69):

The superior laryngeal nerve from X divides into:

Spinal portion of XI or accessory nerve (Clemente plate 551; Grant p. 838; Netter 3e 28, 121, 4e 32): test by flexing head, turning head and shrugging shoulders

XII or hypoglossal nerve (Clemente plate 445; Grant p. 835; Netter 3e 67, 122, 4e 71, 128), running deep to the middle tendon of digastric to get to the digastric triangle (Clemente plates 460-461; Grant p. 789, fig. 8.16; Netter 3e 27, 4e 71), is motor to the tongue musculature.

C1 anterior rami fibers ("hitchhikers") form the superior root of the ansa cervicalis and send a branch to the thyrohyoid muscle (Clemente plates 443, 444; Grant p. 780; Netter 3e 28, 4e 32).

Arteries

The common carotid artery divides at the level of C3 (hyoid bone).

External carotid branches lie inferior to, deep to or superior to the posterior belly of the digastric.

Inferior to the posterior belly of the digastric:

1) The superior thyroid artery (Clemente plate 454, 474; Grant p. 770; Netter 3e 130, 4e 69) runs to the superior pole of the thyroid gland, anastomoses with its opposite counterpart and the inferior thyroid artery. Its branches are:

2) The lingual artery supplies the tongue (Clemente plate 535 fig. 855; Grant p. 781-782; Netter 3e 55, 130, 4e 59, 69)

3) The ascending pharyngeal artery (at the bifurcation of the common carotid artery) supplies the lateral wall of the pharynx and the nasopharynx (Clemente plate 474; Grant p. 764; Netter  3e 130, 4e 69).

Deep to the posterior belly of the digastric:

Superior to the posterior belly of the digastric:

The digastric triangle:

The Mylohyoid muscle (Clemente plate 534; Grant p. 760; Netter 23-24, 49)

The Hyoglossus muscle runs from the greater cornu of the hyoid bone and inserts into the tongue (Clemente plate 538; Grant p. 782; Netter 3e 55, 4e 59). Cranial nerve XII lies against its external surface and the lingual artery lies against its internal surface (Clemente plate 535 fig. 855; Grant p. 780; Netter 3e 55, 65, 67, 4e 59).

updated 10/28/2009


THE ROOT OF THE NECK

Text:  Gross Anatomy, K. W. Chung, 6th edition: pp. 332-337

Reference:  Clinically Oriented Anatomy, K.L. Moore, A.F. Dalley, 5th edition: pp. 1076-1089; 6th edition:  pp. 1012-1021; 1040-1044

Dissector:

Clemente’s Anatomy Dissector, 2nd edition:  pp. 349-352

Grant’s Dissector, P.W. Tank, 14th edition:  pp. 196-199

Scalene anterior muscle (Clemente plate 456; Grant p. 774-776; Netter 3e 26, 4e 30) :

Sternoclavicular joint (Grant p. 26; Netter 3e 208, 4e 30, 33)

The subclavian artery runs over the apex of the lung, posterior to the scalene anterior and superior to rib 1.

The subclavian artery can be divided into 3 parts:

The subclavian vein (Clemente plate 452; Grant p. 488, 772-773; Netter 3e 29, 194, 208, 4e 30) has 3 important differences from the artery:

Triangle of the vertebral artery:

Contents of the triangle of the vertebral artery:

Branches of the 1st part of the subclavian artery

1) The vertebral artery is the largest branch and lies in the transverse foramina of C1-C6 (Clemente plate 458; Grant p. 764-765; Netter 3e 130, 4e 136).

2) The thyrocervical trunk

3) The internal thoracic artery (Clemente plate 459 fig. 721; Grant p. 773; Netter 3e 29, 4e 33) runs in the pleura, posterior to the subclavian vein and enters the thorax on the posterior aspect of the sternum.

4) The costocervical trunk (Clemente plate 459; Grant p. 75, 764; Netter 3e 29, 4e 33, 136-138)

Phrenic nerve:

The trachea and esophagus (cervical portions)

updated 10/28/2009


THE PHARYNX AND THE PALATE

Text:  Gross Anatomy, K. W. Chung, 6th edition: pp. 393-400

Reference:  Clinically Oriented Anatomy, K.L. Moore, A.F. Dalley, 5th edition: pp. 1102-1116; 6th edition:  pp. 1032-1052; 1047-1050

Dissector:

Clemente’s Anatomy Dissector:  pp. 386-393

Grant’s Dissector, P.W. Tank, 14th edition:  pp. 237-240

The pharynx:

PHARYNGEAL WALL

4 layers (from exterior to interior)

1. Visceral fascia: also covers the external surface of the buccinator muscle (buccopharyngeal fascia) and the superior constrictor muscle. The common origin of these 2 muscles is the pterygomandibular raphé (Clemente plate 548; Grant p. 788-789; Netter 3e 64, 4e 65).

The pharyngeal plexus of veins:

The pharyngeal nervous plexus is formed by (Clemente plate 551; Grant p. 788-789; Netter 3e 67, 4e 71):

2. Skeletal muscular wall: 5 paired skeletal muscles.

3 muscles form the circular layer: the superior, middle and inferior constrictor muscles (Clemente plate 550; Grant p. 788; Netter 3e 64, 4e 67).

2 muscles are longitudinal and run from base of skull and palate vertically to attach to the thyroid cartilage: the stylopharyngeus and palatopharyngeus. Both insert into the thyroid cartilage on the internal aspect of the middle and inferior constrictors. They are separated superiorly by the superior constrictor muscle.

Stylopharyngeus (Clemente plate 550; Grant p. 787, 789; Netter 3e 64, 4e 68):

Palatopharyngeus (Clemente plate 553; Grant p. 795; Netter 3e 63, 4e 65, 67):

3. The fibrous internal muscular fascia

4. The mucosal lining

INTERIOR OF THE PHARYNX AND THE PALATE:

The interior of the pharynx is divided into naso-, oro-, and laryngopharynx (Clemente plate 549; Grant p. 790; Netter 3e 59, 4e 66).

The soft palate separates the nasopharynx from the oropharynx and acts as a flap-valve between these 2 regions to allow continuity between these 2 regions during respiration.

The nasopharynx:

The oropharynx lies inferior to the soft palate (Clemente plate 552; Grant p. 790; Netter 3e 59, 4e 63, 66) and superior to the root of the tongue.

Laryngopharynx lies posterior to the opening of the larynx at C3-4.

Between the anterior surface of the epiglottis and the posterior surface of the tongue are the valleculae separated by a glossoepiglottic fold (Clemente plate 539; Grant p. 790; Netter 3e 60, 4e 64). The vallecular fossae communicate with the piriform recesses lateral to the aryepiglottic folds. This is the territory of the internal branch of the superior laryngeal nerve (X), which is sensory for the cough reflex and also innervates the mucosa lining interior of larynx, superior to the vocal cords (also an area for eliciting the cough reflex; Clemente plate 554; Grant p. 800; Netter 3e 61, 4e 65).

The PALATE separates the oral from the nasal cavities.

The hard palate is formed anteriorly by the palatine processes of the maxilla and horizontal processes of the palatine bone (Clemente plate 498; Grant p. 682; Netter 8,10). It is covered over and under by mucoperiosteum. The rugae may be observed in the anterior 1/3 of the oral surface.

The soft palate lies posteriorly separating oropharynx from nasopharynx.

Innervation of the mucosa is by V2:

The greater palatine artery (Clemente plate 526; Grant p. 683-684; Netter 3e 37, 4e 40-41, 52) supplies the oral mucosa of the entire hard palate and ascends through the incisive foramen to supply a portion of the nasal septum and anastomose with the sphenopalatine artery (Clemente plate 524 fig. 830; Grant p. 683; Netter 3e 37, 4e 40).

Muscles of the soft palate (Clemente plates 471, 553; Grant p. 684; Netter 3e 63, 64, 4e 64-65)

Levator and tensor palati also open the auditory tube thus relieving pressure difference between the middle ear and the nose.

updated 10/28/2009


THE PREVERTEBRAL REGION

Text:  Gross Anatomy, K. W. Chung, 56th edition: pp. 336-337

Reference:  Clinically Oriented Anatomy, K.L. Moore, A.F. Dalley, 5th edition: pp. 482-488; 506-510; 1076-1077; 6th edition:  443-446, 457-460, 466-469, 476-477, 1012-1014

Dissector:

Clemente’s Anatomy Dissector, 2nd edition:  pp. 380-385

Grant’s Dissector, P.W. Tank, 14th edition:  pp. 234-236

The deep anterior cervical muscles are grouped according to their relationships with the cervical and brachial plexuses (Clemente plate 456; Grant p. 774-776; Netter 3e 26, 4e 30, 32).

Muscles lying medial to the plexuses include the:

Muscles lying lateral to the plexuses include the:

The scalene mass and the levator scapulae arise from the posterior tubercles of the cervical vertebrae and insert into ribs 1 and 2, and the superior angle of the scapula, respectively.

The prevertebral fascia (Clemente plate 446 fig. 705; Grant p. 774; Netter 3e 31, 4e 35) covers these prevertebral muscles, forming the fascia of the floor of the posterior triangle of the neck and is carried laterally by the brachial plexus and the subclavian artery to form the axillary fascia . This prevertebral fascia lies posterior to the retropharyngeal space and behind the danger plane.

updated 10/28/2009


THE LARYNX

Text:  Gross Anatomy, K. W. Chung, 6th edition: pp. 406-411

Reference:  Clinically Oriented Anatomy, K.L. Moore, A.F. Dalley, 5th edition: pp. 1089-1101; 6th edition:  pp.  1021-1032, 1044-1047

Dissector:

Clemente’s Anatomy Dissector, 2nd edition:  pp. 415-424

Grant’s Dissector, P.W. Tank, 14th edition:  pp. 252-255

The larynx is the organ for vocalization and lies between the levels of C4 and C6 vertebrae (Clemente plate 549; Grant p. 747; Netter 3e 59, 4e 63).

The cricoid cartilage

The thyroid cartilage

The cricothyroid muscle (Clemente plate 560 fig. 904; Grant p. 768, 802; Netter 3e 74, 4e 78):

The arytenoid cartilages

A cuneiform cartilage can also be found in the aryepiglottic fold, anterior to the arytenoid cartilage.

The vocal ligaments

This is why damage to the cricothyroid ligament in a tracheostomy may affect the vocal ligaments and the voice.

The epiglottis:

The quadrangular membrane

The intrinsic muscles of the larynx are all innervated by the recurrent laryngeal nerves (from cranial nerve X; Clemente plate 557; Grant p. 800, 802; Netter 3e 76, 4e 80) and are located on the posterior and lateral aspects of the larynx.

2 POSTERIOR MUSCLES:

The posterior cricoarytenoid muscle:

The arytenoideus muscle

5 LATERAL MUSCLES

attach to the anterior aspects of the arytenoid cartilages and adduct the vocal cords (Clemente plate 561 fig. 906; Grant p. 803; Netter 3e 74-75, 4e 78-79).

The lateral cricoarytenoid muscle attaches from the superior aspect of the arch of the cricoid to the anterior surface of the muscular process of the arytenoid cartilage.

The thyroarytenoideus muscle from the internal surface of the angle of the thyroid cartilage to the lateral aspect of the arytenoid cartilage. The portion adjacent to the vocal ligament is the vocalis muscle (Clemente plate 561 fig. 907; Grant p. 801; ; Netter 3e 74-75, 4e 78-79).

The thyroepiglotticus lies on the medial surface of the quadrangular ligament. It is formed by upper fibers of thyroarytenoideus, which join with aryepiglotticus to run to the epiglottis.

The aryepiglotticus lies on the superior border of the quadrangular ligament in the aryepiglottic fold .

Paralysis of one of the posterior cricoarytenoids causes a whisper to the quality of the voice. Tension is affected by the vocalis and cricothyroid muscles.

The aryepiglottic, thyroarytenoid and thyroepiglottic muscles:

This closes the superior laryngeal aperture and divert the swallowed food to the piriform recesses.

The INTERIOR OF THE LARYNX

The superior laryngeal aperture is obliquely oriented and bounded by the aryepiglottic folds and mucosa on the posterior aspect of the epiglottis.

The supraglottic cavity (Clemente plate 562; Grant p. 801, 804; Netter 3e 59, 4e 63) above the vocal folds has the vestibule (between the aryepiglottic folds and the vestibular folds - false vocal cords) and the ventricles (between the true and false vocal cords). Sensory innervation is by the internal (branch of the superior) laryngeal nerve, which pierced the thyrohoid membrane (Clemente plate 557; Grant p. 802; ; Netter 3e 76, 4e 76, 80).

The transition from stratified squamous epithelium superiorly to ciliated pseudostratified columnar epithelium inferiorly occurs at the level of the vocal cords and is a common site for cancer.

The infraglottic cavity is inferior to the vocal cords and continuous with the trachea. Its sensory innervation is by the recurrent laryngeal nerves (mixed-motor to all laryngeal muscles except for the cricothyroid muscle) which pierced the cricothyroid membrane.

The blood supply is by the laryngeal branches of the superior and inferior thyroid arteries (Clemente plate 557; Grant p. 770-771; Netter 3e 72, 4e 76) accompanying the internal (Clemente plate 557; Grant p. 802; Netter 3e 72, 4e 76) and recurrent (Clemente plate 557; Grant p. 802; Netter 3e 76, 4e 80) laryngeal nerves, respectively.

updated 10/28/2009



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