Anterior Cervical Triangle The anterior triangle of the neck is bounded by
1. the anterior border of the SCM 2. the anterior midline of the neck. 3. the mandible.
1 Anterior Cervical Triangle
The anterior triangle is subdivided into four smaller triangles for descriptive purposes 1. Submental triangle 2. Submandibular (digastric) triangle 3. Carotid triangle 4. Muscular (omotracheal) triangle
2 The submental triangle
inferior to the chin is an unpaired suprahyoid area bounded by : 1. the body of the hyoid bone inferiorly 2. the right and left anterior bellies of the digastric muscles laterally.
3 The submental triangle
The floor of the submental triangle is formed by the two mylohyoid muscles, which meet in a median fibrous raphe. The apex of the submental triangle is at the mandibular symphysis The base is formed by the hyoid bone.
4 The submental triangle
This triangle contains: 1. several small submental lymph nodes. 2. small veins that unite to form ' the anterior jugular vein.
5 6 7 The submandibular triangle
It is a glandular area between the inferior border of the mandible and the anterior and posterior bellies of the digastric and the stylohyoid muscle Above by the lower border of the mandible
Some people refer to it as the "digastric triangle." The floor of the submandibular triangle is formed by the mylohyoid muscle, hyoglossus muscle, and middle constrictor of the pharynx. 8 Anterior of the triangle
contains the submandibular salivary gland the facial deep to the gland The vein and the submandibular LN superficial to the gland The hypoglossal nerve runs on the hypoglossal muscle deep to the gland Maylohyiod nerve and vessel runs inferior surface of this muscle
9
10 Posterior par of the triangle
lies the carotid sheath, with the carotid arteries, internal jugular vein, vagus nerve The lower part of the parotid gland projects into the triangle.
The submandibular gland consists of a mixture of serous and mucous acini. It lies beneath the lower border of the body of the mandible and is divided into superficial and deep parts by the mylohyoid muscle.posterior border of the muscle
12 Superficial surface fills the same space of the between the mandible and the investing layer of fascia It has three surface lateral, medial and inferior.the lateral lies against the submandibular fossa of the mandible overlaping the front of the medial ptrygoid insertion Being deeply grooved posteriorly by the facial artery which hook under the mandible to reach the face
13 the inferior or superficial surface is covered by skin,platysma,and investing fascia and is crossed by the facial vein and the cervical branch of the facial nerve and also by the marginal mandibular branch of the facial nerve. Sumandibular lymph node lie not only in contact with surface of the gland but also within its substance.
14 The medial surface lie against the myelohyoid and its vessels but at the back it overlap the hyoglossus and lingual nerve and the submandibular ganglia nad hypoglossal nerve and the deep lingual vein
15 The deep part of the gland extend forward for a variable distance Sometimes few milimeters between mylohyoid and hyoglossus muscle with lingual nerve above it the submandibular duct and the hyopoglossal nerve below it
16 Submandibular Gland
The deep part of the gland lies beneath the mucous membrane of the mouth on the side of the tongue. The submandibular duct emerges from the anterior end of the deep part of the gland and runs forward beneath the mucous membrane of the mouth. It opens into the mouth on a small papilla, which is situated at the side of the frenulum of the tongue
17 submandibular duct
,approximately 5 cm long, arises from the portion of the gland that lies between the mylohyoid and the hyoglossus muscles. Passing from lateral to medial, the lingual nerve loops under the duct that runs anteriorly, opening by one to three orifices on a small sublingual papilla beside the base of the lingual frenulum. The orifices of the submandibular ducts are visible, and saliva can often be seen trickling from them (or spraying from them during yawning .)
18 19 The submandibular gland
1. nearly fills this triangle. 2. Approximately half the size of the parotid gland. 3. the submandibular gland is usually palpable as a soft mass between the body of the mandible and the mylohyoid muscle.
20 The submandibular gland
4. Submandibular lymph nodes lie on each side of the submandibular gland and along the inferior border of the mandible. 5. The submandibular duct approximately 5 cm in length, passes from the deep process of the
21 Nerve Supply
Parasympathetic secretomotor supply is from the facial nerve via the chorda tympani, and the submandibular ganglion. The postganglionic fibers pass directly to the gland.
22 Submandibular Ganglion
The submandibular ganglion is a parasympathetic ganglion that lies deep to the submandibular salivary gland and is attached to the lingual nerve by small nerves( and .)66-11 Preganglionic parasympathetic fibers reach the ganglion from the facial nerve via the chorda tympani and the lingual nerves. Postganglionic secretomotor fibers pass to the submandibular and the sublingual salivary glands
23 24 The arterial supply of the submandibular glands
is from the submental arteries. The veins accompany the arteries. The lymphatic vessels of the glands end in the deep cervical lymph nodes ,particularly the jugulo- omohyoid node. Developmentally the gland is almost certainly of ectodermal origin from the floor of the mouth
25 Clinical Notes
Submandibular Salivary Gland : Calculus Formation The submandibular salivary gland is a common site of calculus formation. This condition is rare in the other salivary glands. The presence of a tense swelling below the body of the mandible, which is greatest before or during a meal and is reduced in size or absent between meals, is diagnostic of the condition. Examination of the floor of the mouth will reveal absence of ejection of saliva from the orifice of the duct of the affected gland. Frequently, the stone can be palpated in the duct, which lies below the mucous membrane of the floor of the mouth.
26 Clinical Notes
Enlargement of the Submandibular Lymph Nodes and Swelling of the Submandibular Salivary Gland The submandibular lymph nodes are commonly enlarged as a result of a pathologic condition of the scalp, face, maxillary sinus, or mouth cavity. One of the most common causes of painful enlargement of these nodes is acute infection of the teeth. Enlargement of these nodes should not be confused with pathologic swelling of the submandibular salivary gland.
27 The end
28 Carotid Triangle
The carotid triangle lies behind the hyoid bone. It is bounded sjjperiorly by the posterior belly of the digastric, in-feriorly by tfie superior belly~oTthe omohyoid, ancTposteri-orly by the anterior_Dorder oLttie_sIernocTej?omastoid muscle (Fig. 11-7). Its floor is formed by portions of the" thyrohyoid, hyoglossus, and middle andjnferior constrictor muscles ^f j^hj^pfiarynx..
The triangle contains the carotid sheath,:with the conv. mon carotid artery dividing within the triangle into internal and external carotid arteries; numerous branches of the_ex-terria]_carotid_artery; the internal jugularjein jind its trlbu-taries; the hypoglossal nerve wTfrTTfs'clescending branch; the internal and external laryngeal nervesjlRe accessory and va-
gus nerves; and part of the chain of deep cervical lymph ;. 11-10). •" ~~———————-
"riq_
The internal jugular vein tends to be overlapped by the anterior border of the sternocleidomastoid muscle and is therefore hidden
29 The carotid triangle
It is a vascular area behind the hyoid bone bounded by: 1. the superior belly of the omohyoid,inferiorly 2. the posterior belly of the digastric, superiorly 3. the anterior border of the SCM .posteriorly 4. Floor is formed by portion of thyrohyoid, hyoglossal,and middle and inferior constrictor muscle of the pharynx
30 The carotid triangle
It is an important area because the common carotid artery ascends into and is where its pulse can be auscultated or palpated by compressing it lightly against the transverse processes of the cervical vertebrae.
31 At the level of the superior border of the thyroid cartilage, the common carotid artery divides into the internal And external carotid arteries. Found at this site are: 1. The carotid sinus 2. The carotid body
32 The carotid triangle
1. The carotid sinus, a slight dilation of the proximal part of the internal carotid artery; and may involve the common carotid. It is principally innervated by the glossopharyngeal nerve (CN IX) through the carotid sinus nerve, as well as by the vagus nerve, It is a baroreceptor (pressoreceptor) that reacts to changes in arterial blood pressure.
33 The carotid triangle 2.The carotid body,
a small, reddish-brown ovoid mass of tissue, lies on the medial (deep) side of the bifurcation of the common carotid artery in close relation to the carotid sinus. Supplied mainly by the carotid sinus nerve (CN IX) and by CN X, It is a chemoreceptor that monitors the level of oxygen in the blood. It is stimulated by low levels of oxygen and initiates a reflex, which increases the rate and depth of respiration, heart rate, and blood pressure.
34 35 The carotid sheath
a tubular, thickly matted fascial condensation on each side of the neck, extends from the base of the skull to the root of the neck.
36 The inferior part of the carotid sheath, contains the following clinically important structures: 1. The common carotid artery medially 2. The internal jugular vein laterally 3. The vagus nerve posteriorly.
** Superiorly, the common carotid is replaced by the internal carotid artery.
37 The carotid sheath
The ansa cervicalis usually lies on (or is embedded in) the anterolateral aspect of the sheath. Many deep cervical lymph nodes lie along the carotid sheath and the IJV.
38 The muscular triangle
is bounded by the superior belly of the omohyoid muscle, the anterior border of the SCM, and the median plane of the neck. This triangle contains the infrahyoid muscles and viscera of the neck, such as the thyroid and parathyroid glands.
39 Muscles in the Anterior Triangle
In the anterolateral part of the neck, the hyoid bone provides attachments for the suprahyoid muscles superior to it and the infrahyoid muscles inferior to it. These hyoid muscles steady or move the hyoid bone and larynx. .
40 Muscles in the Anterior Triangle
The suprahyoid muscles are superior to the hyoid bone and connect it to the skull.
they includes 1. the mylohyoid, 2. geniohyoid, 3. stylohyoid, 4. digastric
41 The suprahyoid muscles
1. Mylohyoid muscles: form the mobile but stable floor of the mouth and a muscular sling inferior to the tongue. These muscles support the tongue and elevate it and the hyoid bone when swallowing or protruding the tongue.
42 The suprahyoid muscles
2. Geniohyoid muscles are superior to the mylohyoid muscles, where they reinforce the floor of the mouth.
43 The suprahyoid muscles
3. The stylohyoid muscles: form a slip on each side, which is nearly parallel to the posterior belly of the digastric muscle.
44 The suprahyoid muscles
4. Digastric muscles: each of which has two bellies that descend toward the hyoid bone, are joined by an intermediate tendon. A fibrous sling derived from the deep cervical fascia allows intermediate tendon to slide anteriorly and posteriorly as it connects this tendon to the body and greater horn of the hyoid bone.
45 The suprahyoid muscles
Nerve supply of digastric muscle 1. Anterior belly: mylohyoid nerve, a branch of inferior alveolar nerve ( CN V ) 2. Posterior belly: facial nerve The difference in nerve supply between the two bellies of each digastric muscle results from the embryological origin of the anterior and posterior bellies from the 1st and 2nd pharyngeal arches, respectively. CN V is the nerve to the 1st arch, and CN VII supplies the 2nd arch
46 The The infrahyoid muscles often called strap muscles because of their ribbonlike appearance are inferior to the hyoid bone. These four muscles anchor the hyoid bone, sternum, clavicle, and scapula and depress the hyoid bone and larynx during swallowing and speaking. They also work with the suprahyoid muscles to steady the hyoid bone, providing a firm base for the tongue. The infrahyoid group includes the sternohyoid, omohyoid, sternothyroid, and thyrohyoid muscles, which are arranged in two planes: a superficial plane comprising the sternohyoid and omohyoid and a deep plane comprising the sternothyroid and
thyrohyoid 47 1-The sternohyoid,
a thin narrow muscle, lies superficially parallel and adjacent to the anterior median line. 2- The omohyoid muscle, lateral to the sternohyoid, has two bellies united by an intermediate tendon that connects to the clavicles by a fascial sling.
48 3-The sternothyroid
is wider than the sternohyoid, under which it lies. The sternothyroid covers the lateral lobe of the thyroid gland, attaching to the oblique line of the lamina of the thyroid cartilage immediately above,,jt. This muscle limits upward expansion of the thyroid gland; thus, tumors or goiters, which may enlarge it, cause it to expand anteriorly or inferiorly into the mediastinum. 4- The thyrohyoid appears to be the continuation of the ster-nothyroid muscle, running superiorly from the oblique line of the thyroid cartilage to the hyoid bone.
49
50
51 Vessels in the Anterior Triangle
The anterior triangle of the neck contains the carotid system of arteries—the common carotid artery and its terminal branches, the internal and external carotid arteries. It also contains the IJV and its tributaries and the anterior jugular veins
52
53 Carotid Arteries
. The common carotid artery and one of its terminal branches, the external carotid artery, are the main arterial vessels in the carotid triangle Branches of the external carotid (e.g., the superior thyroid artery) also originate in the carotid triangle. Each common carotid artery ascends within the carotid sheath with the IJV and vagus nerve to the level of the superior border of the thyroid cartilage, then terminates by dividing into the internal and external carotid arteries. Whereas the internal carotid has no branches in the neck, the external carotid has several.
54 The right common carotid artery
begins at the bifurcation of the brachiocephalic trunk The right subclavian artery is the other branch of the brachiocephalic trunk. From the arch of the aorta, the left common carotid artery ascends into the neck. Consequently, the left common carotid has a course of approximately 2 cm in the superior mediastinum before entering the neck. 55 The internal carotid arteries
The direct continuation of the common carotids, have no branches in the neck. They enter the skull through the carotid canals in the petrous parts of the temporal bones and become the main arteries of the brain and structures in the orbits. Each internal carotid artery arises from the common carotid artery at the level of the superior border of the thyroid cartilage
56 The proximal part of each internal carotid artery is the site of the carotid sinus, a slight dilation that may involve the terminal part of the common carotid artery. The wall of the sinus contains receptors that are sensitive to changes in blood pressure. An important regulator of blood-flow to the brain, the carotid sinus reacts to changes in head position and gravitational forces to keep the flow of blood nearly constant. The carotid body at the bifurcation of the common carotid artery is a chemoreceptor that responds to changes in the chemical composition of blood—specifically, the degree of oxygenation. 57 The external carotid arteries
for the main part supply structures external to the skull (the middle meningeal artery is an obvious exception). Each artery runs posterosuperiorly to the region between the neck of the mandible and the lobule (earlobe) of the auricle, where it is embedded in the parotid gland, and terminates by dividing into two branches, 1. the maxillary artery 2. the superficial temporal artery The other six branches of the external carotid artery are 1. the ascending pharyngeal, 2. superior thyroid, 3. lingual, 4. facial, 5. Occipital 6. posterior auricular arteries. 58 1-Ascending Pharyngeal Artery
. The ascending 'pharyngeal artery, the 1st or 2nd branch of the external carotid artery, ascends on the pharynx deep (medial) to the internal carotid artery and sends branches to the pharynx, prevertebral muscles, middle ear, and cranial meninges.
59 2-Superior Thyroid Artery.
The most inferior of the three anterior branches of the external carotid artery, the superior thyroid artery runs anteroinferiorly deep to the infrahyoid muscles to reach the thyroid gland. In addition to supplying this gland, it gives off branches to the infrahyoid muscles and SCM. It also gives rise to the superior laryngeal artery supplying the larynx
60 3-Lingual Artery
This artery arises from the external carotie where it lies on the middle constrictor muscle of the pharynx. It arches superoanteriorly and passes deep to the hypoglossal nerve (CN XII),the stylohyoid muscle, and the posterior belly of the digastric muscle. It disappears deep to the hyoglossus and turns superiorly at the anterior border of this muscle to become the deep lingual and sublingual arteries. 61 4- Facial Artery
. The facial artery arises from the external carotid artery, either in common with the lingual artery or immediately superior to it. The facial artery gives off a tonsillar branch (which, of the branches from five different arteries to the palatine tonsil, is the major one), as well as branches to the palate and submandibular gland. It then passes superiorly under cover of the digastric and stylohyoid muscles and the angle of the mandible. The facial artery loops anteriorly and enters a deep groove in the submandibular gland. It then hooks around the middle of the inferior border of the mandible (where its pulsations can be palpated) and enters the face. 62 5- Occipital Artery.
The occipital artery arises from the posterior aspect of the external carotid artery, superior to the origin of the facial artery. It passes posteriorly, parallel and deep to the posterior belly of the digastric muscle, forming its own groove in the base of the skull medial to that of the origin of the muscle, and ends in the posterior part of the scalp. During its course, it passes superficial to the internal carotid artery and CN IX through CN XI.
63 6- Posterior Auricular Artery
This artery, a small posterior branch of the external carotid artery ascends posteriorly between the external acoustic meatus and the mastoid process to supply the adjacent muscles, parotid gland, facial nerve, structures in the temporal bone, auricle, and scalp
64 Veins.
Most veins in the anterior triangle are tributaries of the IJV, usually the largest vein in the neck The IJV drains blood from the brain, anterior face, cervical viscera, and deep muscles of the neck. It commences at the jugular foramen in the posterior cranial fossa as the direct continuation of the sigmoid sinus From the dilation at its origin, the superior bulb of the IJV the vein runs inferiorly through the neck in the carotid sheath with the internal carotid, then the common carotid artery and vagus nerve.
65 The artery is medial and the vein is lateral, and the nerve lies posteriorly between these vessels The cervical sympathetic trunk lies posterior to the carotid sheath, and, although closely related, the trunk does not lie within the sheath but instead is embedded in the prevertebral fascia The IJV leaves the anterior triangle by passing deep to the SCM. The inferior end of the vein is deep to the gap between the sternal and clavicular heads of the SCM. Posterior to the sternal end of the clavicle, the IJV unites with the subclavian vein to form the brachiocephalic vein
66 and the inferior end of the IJV dilates to form the inferior bulb of the IJV. The inferior bulb contains a bicuspid valve that permits blood to flow toward the heart while preventing backflow into the vein, as might occur if inverted (standing on one's head or when intrathoracic pressure is increased). The tributaries of the IJV are the inferior petrosal sinus, facial lingual (often by a common trunk), pharyngeal, superior and middle thyroid veins. The occipital vein usually drains into the suboccipital venous plexus, drained by the deep cervical vein and the vertebral vein, but it may drain into the IJV.
67 The inferior petrosal sinus
leaves the skull through the jugular foramen and enters the superior bulb of the IJV. The facial vein empties into the IJV opposite or just inferior to the level of the hyoid bone. The facial vein may receive the superior thyroid, lingual, or sublingual veins. The lingual veins form a single vein from the tongue, which empties into the IJV at the level of origin of the lingual artery. The pharyngeal veins arise from the venous plexus on the pharyngeal wall and empty into the IJV at the level of the angle of the mandible. The superior and middle thyroid veins leave the thyroid gland and drain into the IJV. 68
Nerves.
Several nerves, including branches of cranial nerves, are in the anterior triangle: the transverse cervical nerve, the hypoglossal nerve, and branches of the glossopharyngeal and vagus nerves. The transverse cervical nerve (C2 and C3) supplies the skin covering the anterior triangle.This nerve winds around the lateral border of the_SCM just inferior to the great auricular nerve and crosses this muscle horizontally, deep to the platysma and EJV to reach the anterior triangle. Near the anterior border of the SCM, the transverse cervical nerve divides into superior and inferior branches that pass through the platysma and supply the skin covering the anterior triangle. 69 The hypoglossal nerve (CN XII): the motor nerve of the tongue, enters the submandibular triangle deep to the posterior belly of the digastric muscle to supply the intrinsic and four of the five extrinsic muscles of the tongue.). CN XII passes between the external carotid and jugular vessels and gives off the superior root of the ansa cervicalis and then a branch to the geniohyoid muscle In both cases, the branch conveys only fibers from the Cl spinal nerve, which joined its proximal part—no hypoglossal fibers are conveyed in these branches. For details about CN XII, Branches of the glossopharyngeal and vagus nerves are in the submandibular and carotid triangles CN IX is primarily related to the tongue and pharynx. In the neck, CN X gives rise to pharyngeal, laryngeal, and cardiac branches
70 71