الاسراء 2015
TRANSCRIPT
Bones of the Skull
The skull : is the bony casing ( a box ) of the head of humans and other vertebrates.
The human skull consists primarily of two parts :
A- the cranium (the protective casing of the brain), and
B- the bones of the face, which include the maxilla (upper jaw bone), mandible (lower jaw bone), zygomatic(cheekbones), and the nasal bones. AB
Closely associated with, but not strictly part of, the skull are the hyoid (a small bone at the back of the tongue) and the auditory ossicles (three tiny bones in each middle ear).
The 22 skull bones are made up of external and internal tables of compact bone separated by a layer of spongy bone called the diploe. The internal table is thinner and more brittle than the external table. The bones are covered on the outer surface with periosteum and inner surfaces with endosteum. These bones are connected togather by strong fibrous joint called sutures.
A- The cranium consists of the following 8 bones, two of which are paired (Figs. ): Frontal bone: 1 Parietal bones: 2 Occipital bone: 1 Temporal bones: 2 Sphenoid bone: 1 Ethmoid bone: 1
B- The facial bones are 14 in number consist of the following, two of which are single: Zygomatic bones: 2 Maxillae: 2 Nasal bones: 2 Lacrimal bones: 2 Vomer: 1 Palatine bones: 2 Inferior conchae: 2 Mandible: 1
It is unnecessary for students of medicine to know the detailed structure of each individual skull bone. However, students should be familiar with the skull as a whole and should have a dried skull available for reference as they read the following description.
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Lecture two
Paranasal Air-Sinuses Paranasal air-sinuses are air-
filled spaces, communicating with the nasal cavity, within cranial, and the facial bones of the skull. Humans possess a number of paranasal air-sinuses, divided into subgroups.
The subgroups of the paranasal air sinuses
1- the maxillary air sinuses, also called the maxillary antra (or Antrum of Highmore). They are the largest of the paranasal sinuses, are under the eyes, in the maxillary bones (cheek bones).
2- the frontal air-sinusover the eyes, in the frontal bone, which forms the hard part of the forehead.
Frontal air-SINUSES are absent at birth, they are generally fairly well developed between the seventh and eighth years, but only reach their full size after puberty.
The frontal air sinuses: Are situated behind the superciliary arches, are rarely symmetrical, and the septum between them frequently deviates to one or other side of the middle line.
Each opens into the anterior part of the corresponding middle meatus of the nose through the frontonasal duct which traverses the anterior part of the labyrinth of the ethmoid. These structures then open into the hiatus semilunaris in the middle meatus.
Their average measurements are as follows: 1- height, 3 cm.; 2- breadth, 2.5 cm.;3- depth from before backward, 2.5 cm.
3- the ethmoid air- sinus, which are formed from
several discrete air cells within the ethmoid bonee between the nose and the eyes.
4- the sphenoid air-sinus: found within the
sphenoid bone at the center of the skull base under the pituitary gland
Biological function of the paranasal air-sinuses :
The biological role of the sinuses is debated, but a number of possible functions have been proposed:
1- Decreasing the relative weight of the front of the skull, and especially the bones of the face. The shape of the facial bones is important, as a point of origin and insertion for the muscles of facial expression.
3- Providing a buffer against blows to the face.
4- Insulating sensitive structures like dental roots and eyes from rapid temperature fluctuations in the nasal cavity.
5- Humidifying and heating of inhaled air because of slow air turnover in this region.
6- Regulation of intranasal and serum gas pressures.
7-Immunological defense.
8-Regulating the temperature of the C.S.F. ( cerebrospinal fluid ) contacting the inner layer of the frontal air sinus.
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Lecture Three
The scalp
The scalp is the part of the head that extends from the superciliary arches anteriorly to the external occipital protuberance and superior nuchal lines posteriorly. Laterally it continues inferiorly to the zygomatic arch.
The scalp is a multilayered structure with layers that can be defined by the word itself: S-skin; C-connective tissue (dense); A-aponeurotic layer; L-loose connective tissue; P-pericranium (Fig. ).
Examining the layers of the scalp reveals that the first three layers are tightly held together, forming a single unit . This unit is sometimes referred to as the scalp proper and is the tissue torn away during serious 'scalping' injuries.
1- The skin :is the outer layer of the scalp (Figs. and ). It is similar structurally to skin throughout the body with the exception that hair is present on a large amount of it.
2- Connective tissue (dense) :
Deep to the skin is dense connective tissue. This layer anchors the skin to the third layer and contains the arteries, veins, and nerves supplying the scalp. When the scalp is cut, the dense connective tissue surrounding the vessels tends to hold cut vessels open. This results in profuse bleeding.
3-Aponeurotic layer : The deepest layer of the first three layers is the aponeurotic layer. Firmly attached to the skin by the dense connective tissue of the second layer, this layer consists of the occipitofrontalis muscle, which has a frontal belly anteriorly, an occipital belly posteriorly, and an aponeurotic tendon-the epicranial aponeurosis (galea aponeurotica)-connecting the two (Fig. ).
The frontal belly of occipitofrontalis begins anteriorly where it is attached to the skin of the eyebrows. It passes upward, across the forehead, to become continuous with the aponeurotic tendon.
The occipitofrontalis muscles move the scalp, wrinkle the forehead, and raise the eyebrows. The frontal belly is innervated by temporal branches of the facial nerve [VII] and the posterior belly by the posterior auricular branch.
Posteriorly, each occipital belly of occipitofrontalis arises from the lateral part of the superior nuchal line of the occipital bone and the mastoid process of the temporal bone. It also passes superiorly to attach to the aponeurotic tendon.
A layer of loose connective tissue separates the aponeurotic layer from the pericranium and facilitates movement of the scalp proper over the calvaria (Figs. And ). Because of its consistency, infections tend to localize and spread through the loose connective tissue.
4- Loose connective tissue
The pericranium is the deepest layer of the scalp and is the periosteum on the outer surface of the calvaria. It is attached to the bones of the calvaria, but is removable, except in the area of the sutures.
5- Pericranium
Lecture FourThe Innervation of the scalp
Arterial Supply
Venous and Lymphatic Drainage
The Innervation of the scalp1- Sensory innervation of the scalp is from two major sources, 1- cranial nerves or 2- cervical nerves,depending on whether it is anterior or posterior to the ears and the vertex of the head (Fig. ),
2- Motor supply A- The frontal branch of the facial nerve supplies the frontal bellies of the occipitofrontalis muscle, and
B- the auricular branch of the facial nerve supplies the occipital bellies of the muscle.
1-Supratrochlear nerve - A branch of the ophthalmic division of the trigeminal nerve; this nerve supplies the scalp in the medial plane at the frontal region, up to the vertex 2-Supraorbital nerve - Also a branch of the ophthalmic division of the trigeminal nerve; this nerve supplies the scalp at the front, lateral to the supratrochlear nerve distribution, up to the vertex 3-Zygomaticotemporal nerve - A branch of the maxillary division of the trigeminal nerve; it supplies the scalp over the temple region 4-Auriculotemporal nerve - A branch of the mandibular division of the trigeminal nerve; it supplies the skin over the temporal region of the scalp
Posterior to the ears and vertex, sensory innervation of the scalp is by cervical nerves, specifically branches from spinal cord levels C2 and C3 (Fig. ). These branches are1- the great auricular,2- the lesser occipital, 3- the greater occipital, and 4- the third occipital nerves.
Arterial SupplyThe scalp has a rich vascular supply. The blood vessels traverse the connective tissue layer, which receives vascular contribution from the internal and external carotid arteries. The blood vessels anastomose freely in the scalp. From the midline anteriorly, the arteries present as follows:
1- Supratrochlear artery 2- Supraorbital artery3- Superficial temporal artery 4- Posterior auricular artery 5- Occipital artery
1 & 2 :The supratrochlear and supraorbital arteries are 2 branches of the ophthalmic artery, which, in turn, is a branch of the internal carotid artery. These arteries accompany the corresponding nerves.
3- The superficial temporal artery is a terminal branch of the external carotid artery that ascends in front of the auricle. This artery, which supplies the scalp over the temporal region, travels with the auriculotemporal nerve and divides into anterior and posterior branches.
4- The posterior auricular artery is a branch of the external carotid artery that ascends posterior to the auricle.
5- The occipital artery is a branch of the external carotid artery; it is accompanied by the greater occipital nerve.
The veins of the scalp freely anastomose with one another and are connected to the diploic veins of the skull bones and the intracranial dural sinuses through several emissary veins. The emissary veins are valveless. The scalp veins, which are as follows, accompany the arteries and have similar names (see the image ))
Venous and Lymphatic Drainage
Lymphatic drainage
The part of the scalp that is anterior to the auricles is drained to the 1-parotid, 2-submandibular, and 3-deep cervical lymph nodes.
The posterior part of the scalp is drained to 1- the posterior auricular (mastoid) and 2- occipital lymph nodes.
Applied Anatomy1-Wounds in the scalp bleed profusely, because the fibrous fascia prevents vasoconstriction. However, wounds superficial to the aponeurosis gap much less than do wounds that cut through it, because aponeurosis holds the skin tight. During a difficult birth, bleeding may occur between the neonate's pericranium and calvaria, usually over 1 parietal bone,
2-The emissary veins do not have valves and open in the loose areolar tissue; therefore, infection can be transmitted from the scalp to the cranial cavity. The layer of loose areolar tissue is known as the dangerous area of the scalp. Metastatic spread of malignant lesions in front of the auricle is to the parotid and cervical groups of lymph nodes.
3-Anastomosis exists at the medial angle of the eye, between the facial branch of the external carotid artery and the cutaneous branch of the internal carotid artery. During old age, if the internal carotid artery undergoes atherosclerotic changes, the intracranial structures can receive blood from the connection of the facial artery to the dorsal nasal branch of the ophthalmic artery.
4-Because it contains numerous sebaceous glands, the scalp is one of the most common sites for sebaceous cysts.
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Lecture five & Six
are like elastic sheets that are stretched in layers over the cranium, facial bones, the openings they form, and the cartilage, fat, and other tissues of the head. These are the muscles of facial expression, acting singly and in combination.
The facial muscles
face-to-face meeting is an important initial contact between individuals. Part of this exchange is the use of facial expressions to convey emotions. In fact, a Physician can gain important information about an individual's general health by observing a patient's face.
These muscles control expressions of the face so they are sometimes referred to as muscles of 'facial expression'. They also act as sphincters and dilators of the orifices of the face (i.e. the orbits, nose, and mouth).
1- The orbital group :
Two muscles are associated with the orbital group-A- the orbicularis oculi and
B- the corrugator supercilii.
1- Orbicularis oculi
-Palpebral part Medial palpebral ligament
Lateral palpebral raphe
Facial nerve [VII]
Closes the eyelids gently
-Orbital part Nasal part of
frontal bone; frontal process of maxilla; medial palpebral ligament
Fibers form an uninterrupted ellipse around orbit
Facial nerve [VII]
Closes the eyelids forcefully
2- Corrugator supercilii
Medial end of the superciliary arch
Skin of the medial half of eye-brow
Facial nerve [VII]
Draws the eyebrows medially and downward
1- The orbital group :
1-Nasalis
Nerve supply Action
-Transverse part
Maxilla just lateral to nose
Aponeurosis across dorsum of nose with muscle fibers from the other side
Facial nerve [VII] Compresses nasal aperture
-Alar part Maxilla over
lateral incisorAlar cartilage of nose
Facial nerve [VII] Draws cartilage downward and laterally opening nostril
2-Procerus
Nasal bone and upper part of lateral nasal cartilage
Skin of lower forehead between eyebrows
Facial nerve [VII] Draws down medial angle of eyebrows producing transverse wrinkles over bridge of nose
3- Depressor septi
Maxilla above medial incisor
Mobile part of the nasal septum
Facial nerve [VII] Pulls nose inferiorly
2- The Nasal group
3- The Oral group
1-Depressor anguli oris
Oblique line of mandible below canine, premolar and first molar teeth
Skin at the corner of mouth and blending with orbicularis oris
Facial nerve [VII] Draws corner of mouth down and laterally
2-Depressor labii inferioris
Anterior part of oblique line of mandible
Lower lip at midline; blends with muscle from opposite side
Facial nerve [VII] Draws lower lip downward and laterally
3-Mentalis Mandible inferior
to incisor teethSkin of chin Facial nerve [VII] Raises and
protrudes lower lip as it wrinkles skin on chin
4-Risorius Fascia over
masseter muscleSkin at the corner of the mouth
Facial nerve [VII] Retracts corner of mouth
1-Zygomaticus major
Posterior part of lateral surface of zygomatic bone
Skin at the corner of the mouth
Facial nerve [VII] Draws the corner of the mouth upward and laterally
2-Zygomaticus minor
Anterior part of lateral surface of zygomatic bone
Upper lip just medial to corner of mouth
Facial nerve [VII] Draws the upper lip upward
3-Levator labii superioris
Infra-orbital margin of maxilla
Skin of upper lateral half of upper lip
Facial nerve [VII] Raises upper lip; helps form nasolabial furrow
4-Levator labii superioris alaeque nasi
Frontal process of maxilla
Alar cartilage of nose and upper lip
Facial nerve [VII] Raises upper lip and opens nostril
5-Levator anguli oris
Maxilla below infra-orbital foramen
Skin at the corner of mouth
Facial nerve [VII] Raises corner of mouth; helps form nasolabial furrow
6-Orbicularis oris From muscles in
area; maxilla and mandible in midline
Forms ellipse around mouth
Facial nerve [VII] Closes lips; protrudes lips
Other muscles or groups
Anterior auricular
Anterior part of temporal fascia
Into helix of ear Facial nerve [VII] Draws ear upward and forward
Superior auricular
Epicranial aponeurosis on side of head
Upper part of auricle
Facial nerve [VII] Elevates ear
Posterior auricular
Mastoid process of temporal bone
Convexity of concha of ear
Facial nerve [VII] Draws ear upward and backward
Occipitofrontalis
-Frontal belly Skin of
eyebrowsInto galea aponeurotica
Facial nerve [VII]
Wrinkles forehead; raises eyebrows
-Occipital belly Lateral part of
superior nuchal line of occipital bone and mastoid process of temporal bone
Into galea aponeurotica
Facial nerve [VII]
Draws scalp backward
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Lecture sevenThe oral cavity
Part one
The oral cavity, also known as the buccal cavity or the mouth, is the orifice through which an individual takes in food and water.it extends from the vermilion (red) border of the lips to the junction of the hard and soft palates in the roof of the mouth, and to the circumvallate papillae on the tongue.
The oral cavity
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The Oral Cavity is designed for: 1-articulation in speech and2- mastication of food, 3-the oral cavity also functions as an alternate airway passage.
The oral cavity is divided in:1-The vestibule: is the space between the teeth and the inner mucosal lining of the lips and checks.
2-The oral cavity proper: is the space contained within the upper and lower dental arches.
The entire oral cavity is lined by : a stratified squamous epithelium. The epithelial lining is divided into two broad types:
1-Masticatory epithelium covers the surfaces involved in the processing of food (tongue, gingivae and hard palate). The epithelium is keratinized to different degrees depending on the extent of physical forces exerted on it. 2-Lining epithelium, i.e. non-keratinised stratified squamous epithelium, covers the remaining surfaces of the oral cavity.
A. Boundaries1- Anterior - the lips 2- Posterior - the anterior tonsillar pillars 3-Roof - hard and soft palate Floor –4- mucosa overlying sublingual and submandibular glands. 5- Walls - buccal mucosa
PharynxA. Nasopharynx - extends from posterior choanae of the nose to the soft palate. Related posteriorly to the base of the skull. Contains adenoid tissue and the orifices of the eustachian tubes. This area is not accessible to direct inspection and must be examined by mirrors or optical instruments.
B. Oropharynx - that portion which is visible via the mouth. Extends from soft palate superiorly to vallecula inferiorly. Posterior and lateral walls are formed by the superior and middle pharyngeal constrictors
D. Hypopharynx - Is the portion of the pharynx that lies inferior to the tip of epiglottis. The posterior and lateral walls are formed by middle and inferior pharyngeal constrictors. It extends inferiorly to the cricopharyngeus, where the pharynx empties into the cervical esophagus. Anteriorly, it extends from the valleculae and contains the epiglottis and the larynx. Lateral to the larynx are the pyriform sinuses, two mucosal pouches whose medial borders are the lateral walls of the larynx. The posterior aspect of the hypopharynx contains the posterior pharyngeal wall and post cricoid mucosa.
B. Contents1- Alveolar processes and teeth 2- Anterior tongue to circumvallate papilla3- Orifice of parotid gland (Stenson's duct) in buccal mucosa opposite upper second molars 4-Orifice of submandibular duct (Wharton's duct) in anterior floor of mouth 5-Orifices of sublingual glands
The oral cavity has numerous functions:
1- One function is called oral competence, which is the ability to hold food and saliva in the mouth without drooling. The specialized lining of the mouth as well as the many saliva glands provide lubrication which aide in speech, swallowing and in the digestion of food.
2-The grinding and crushing of food, which occurs in the oral cavity, is also important for digestion. Once foods are prepared for swallowing, the oral cavity helps in swallowing as the tongue and the mouth push the food backward towards the swallowing tube - the oesophagus.
3-The grinding and crushing of food, which occurs in the oral cavity, is also important for digestion. Once foods are prepared for swallowing, the oral cavity helps in swallowing as the tongue and the mouth push the food backward towards the swallowing tube - the oesophagus.
4- Finally, our highly coordinated and specialized speech, which is so important to communication, would not be possible without the structures of the oral cavity.
The oral cavity consists of:
1-the lips, 2-commissures, 3-all surfaces (anterior 2/3 or oral, dorsal, ventral, border) of the tongue except the base of tongue, 4-lingual tonsils, 5-gums (alveolar ridge), 6-floor of mouth, 7-hard palate, 8-buccal mucosa, and 9-retromolar trigone.
Lecture EightThe oral cavity
Part twoThe tongue
13th,Dec. 2015
The tongue is a muscular organ in the mouth. The tongue is covered with moist, pink tissue called mucosa. Tiny bumps called papillae give the tongue its rough texture. Thousands of taste buds cover the surfaces of the papillae. Taste buds are collections of nerve-like cells that connect to nerves running into the brain.
The tongue
The tongueThe tongue consists of a buccal and a pharyngeal portion separated by a V-shaped groove on its dorsal surface, the sulcus terminalis. At the apex of this groove is a shallow depression, the foramen caecum,embryological origin of the thyroid gland. Immediately in front of the sulcus lie a row of large vallate papilliae.
The under aspect of the tongue bears the 1-median frenulum linguae; 2-the mucosa is thin on this surface and 3-the lingual veins can thus be seen on either side of the frenulum. The lingual nerve and the lingual artery are medial to the vein but not visible. 4-On either side of the base of the frenulum can be seen the orifice of the submandibular duct on its papilla. Inspect this in a mirror and note the discharge of saliva when you press on your submandibular gland just below the angle of the jaw.
The four common tastes are 1-sweet, 2-sour, 3- bitter, and 4-salty. 5-A fifth taste, called umami, results from tasting glutamate (present in MSG). The tongue has many nerves that help detect and transmit taste signals to the brain. Because of this, all parts of the tongue can detect these four common tastes; the commonly described “taste map” of the tongue doesn’t really exist.
Lecture NineThe oral cavity
Part ThreeThe tongue II20th,Dec. 2015
Blood supplyBlood is supplied from the lingual branch of the external carotid artery. There is little cross-circulation across the median raphe, which is therefore a relatively avascular plane
Branches of the lingual artery:Supply blood to the tongue
A- Dorsal lingual arteries: Supply the posterior part of the tongueB- Deep lingual artery: Supplies the anterior part of the tongue and communicates with the dorsal arteries at the apexC- Sublingual artery: Supplies the sublingual gland and the floor of the oral cavity
Venous drainage:Veins of the tongue are arranged in two sets, superficial and deep. Superficial vein drains the tip and under surface of the tongue, passes superficial to the hyoglossus accompanying the hypoglossal nerve and ends into internal jugular vein.
Deep vein drains the dorsum of tongue accompanying the lingual artery, passes deep to the hyoglossus and terminates into the internal jugular vein either directly or after joining the superficial vein.
Lymph drainage The drainage zones of the mucosa of the tongue can be grouped into three:the tip drains to the submental nodes;the anterior two-thirds drains to the submental and submandibular nodes and thence to the lower nodes of the deep cervical chain along the carotid sheath;the posterior one-third drains to the upper nodes of the deep cervical chain. There is a rich anastomosis across the midline between the lymphaticsof the posterior one-third of the tongue so that a tumour on one side readily metastasizes to contralateral nodes. In contrast, there is little crosscommunication in the anterior two-thirds, where growths more than 0.5in (12mm) from the midline do not metastasize to the opposite side of the neck till late in the disease.
Diagram of the lymph drainage of the tongue. Note two points.The anterior part of the tongue tends to drain to the nodes farthest Down the deep cervical chain, whereas the posterior part drains to the upper chain. (ii) The anterior two-thirds of the tongue drain unilaterally, the posterior one-third bilaterally.
Lymphatic drainage:
Lymphatics of the tongue consist of intra muscular and submucous plexuses, and are arranged in four sets—apical, marginal, central and dorsal (Fig ).Apical set:It drains the tip and frenulum linguae, descends with or without decussation and terminates as follows:(a) Some vessels pierce the mylohyoid and drain into submental lymph nodes; a few vessels pass downwards in front of hyoid bond and drain directly into jugulo-omohyoid lymph nodes.(b) Some vessels drain into submandibular nodes after piercing the mylohyoid.(c) A few vessels pass deep to the mylohyoid and terminate into jugulo-digastric or jugulo- omohyoid lymph nodes.
B- The Marginal set:The vessels drain the side of the tongue in front of sulcus terminalis and terminate as follows:(a) Some vessels drain into submandibular nodes after piercing the mylohyoid;(b) Some vessels pass deep to the mylohyoid and drain into jugulo-digastric and jugulo- omohyoid nodes.
C- The Central set:The vessels drain the dorsal surface of anterior two-thirds of tongue in front of vallate papillae. They descend between the two genioglossi with or without decussations and terminate as follows:(a) Most of the vessels drain into jugulo digastric or jugulo-omohyoid nodes without piercing the mylohyoid.(b) A few vessels pierce the mylohyoid and drain into submandibular nodes.
Dorsal (or basal) Set:It drains the posterior one-third of the tongue including vallate papillae.(a) Most of the vessels drain bilaterally into jugulo-digastric nodes after piercing the pharyngeal wall.(b) One vessel passes downward behind the tongue and hyoid bone, pierces the thyrohyoid membrane and drains directly into jugulo-omohyoid nodes.
Peculiarities of lymphatics:1. Lymphatics do not accompany the blood vessels.2. In the middle line of the tongue a free decussation takes place and the lymphatics pass bilaterally.3. Tip of the tongue presents richest lymph drainage. A cancer affecting the tip spreads to all cervical lymph nodes of both sides.4. A group of lymph nodes situated at the bifurcation of common carotid artery is known as the principal lymph nodes of the tongue.
The lymphatics of the mouthLymph from the upper lip, teeth, lateral parts of the anterior part of the tongue, and gingivae drains into the submandibular lymph nodes. Lymph from the lower lip and apex of the tongue drains into the submental lymph nodes. Lymph from the medial anterior portion of the tongue drains into the inferior deep cervical lymph nodes, and the posterior portion of the tongue drains into the superior deep cervical lymph nodes. The parotid glands drain their lymph into the superficial and deep cervical lymph nodes. The submandibular glands drain lymph into the deep cervical lymph nodes.
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Lecture TenThe Parotid
Gland
The parotid glandThe parotid gland: They are Paired unilobular glands. Pyramidal in shape divided non anatomically by the facial nerve into deep and superficial lobes• Accessory parotid tissue may extend along parotid duct into buccal space• 1- is the largest of the three main salivary glands in the head and numerous structures pass through it. 2-It is anterior to and below the lower half of the ear, superficial, posterior, and deep to the ramus of the mandible .3- It extends down to the lower border of the mandible and up to the zygomatic arch. 4-Posteriorly it covers the anterior part of the sternocleidomastoid muscle and continues anteriorly to halfway across the masseter muscle.
The facial nerve divides the gland into superficial and deep lobes and numerous structures pass through it.
The parotid duct emerges from the anterior border of the gland and passes forward over the lateral surface of the masseter The duct is about 2 in. (5 cm) long and passes forward across the masseter about a
fingerbreadth below the zygomatic arch. turns deeply into the buccal fat pad and pierces the buccinator muscle to enter the vestibule of the mouth opposite the upper second molar tooth..
Important relationshipsSeveral major structures enter and pass through or pass just deep to the parotid gland. These include :
1- the facial nerve [VII], 2- the external carotid artery and its branches, and 3- the retromandibular vein and its tributaries
1- the facial nerve [VII] :The facial nerve [VII] exits the skull through the stylomastoid foramen and passes into the deep substance of the parotid gland, where it usually divides into upper and lower trunks. These pass through the substance of the parotid gland, where there may be further branching and anastomosing of the nerves.
Five terminal groups of branches of the facial nerve [VII] branches-emerge from the upper, anterior, and lower borders of the parotid gland:
1- the temporal,
2- zygomatic, 3- buccal,
4- marginal mandibular, and 5- cervical
1
2
3
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2- the external carotid artery and its branches :The external carotid artery enters into or passes deep to the inferior border of the parotid gland . As it continues in a superior direction it gives off 1-the posterior auricular artery2- before dividing into its two terminal branches
A- the maxillary and
B- superficial temporal arteries emerges from the upper border of the gland after giving off the transverse facial artery.
3- the retromandibular vein and its tributaries :The retromandibular vein is formed in the substance of the parotid gland when the superficial temporal and maxillary veins join together (and passes inferiorly in the substance of the parotid gland. It usually divides into anterior and posterior branches just below the inferior border of the gland.
Arterial supply of the parotid gland :The parotid gland receives its arterial supply from the numerous arteries that pass through its substance.
Sensory innervation of the parotid gland is provided by the auriculotemporal nerve, which is a branch of the mandibular nerve [V3]. This division of the trigeminal nerve exits the skull through the foramen ovale.
The auriculotemporal nerve also carries secretomotor fibers to the parotid gland. the mandibular nerve [V3] and are just inferior to the foramen ovale.
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