1. Anatomy of Head.pdf

The Anatomy of Head and Neck The Head Anas Alhamed College of Medicine. University of Anbar. The Vertebral Column A typical vertebra consists of body and a vertebral arch, vertebral foramen, pedicles, laminae The vertebral arch gives rise to seven processes. arti...

The Anatomy of Head and Neck The Head Anas Alhamed College of Medicine. University of Anbar. The Vertebral Column A typical vertebra consists of body and a vertebral arch, vertebral foramen, pedicles, laminae The vertebral arch gives rise to seven processes. articular processes Intervertebral foramen  Cervical Vertebrae A. Typical cervical (3-6 vertebrae) vertebra, superior aspect. B. Atlas, or first cervical vertebra C. Axis, or second cervical vertebra D. Seventh cervical vertebra Characteristics of Typical Cervical Vertebrae Cervical Vertebra A typical cervical vertebra has the following characteristics The body is small and broad from side to side. The transverse processes possess a foramen transversarium for the passage of the vertebral artery and veins The spines are small and bifid. The vertebral foramen is large and triangular. The superior articular processes facets posteriorly and superiorly; the inferior processes facets anteriorly and inferiorly  Characteristics of the Atypical Cervical Vertebrae ❑ The 1st cervical vertebra, or atlas ✔ does not possess a body or a spinous process. ✔ It has an anterior and posterior arch. ✔ It has articular surfaces on its upper surface for articulation with the occipital condyles (atlanto-occipital joints) and articular surfaces on its inferior surface for articulation with the axis (atlantoaxial joints).  Characteristics of the Atypical Cervical Vertebrae The 2nd cervical vertebra, or axis ❑ has a peglike odontoid process (dens) that projects from the superior surface of the body (representing the body of the atlas that has fused with the body of the axis).  Characteristics of the Atypical Cervical Vertebrae ❑ The 7th cervical vertebra, or vertebra prominence , is so named because ✔ it has the longest spinous process. ✔ and the process is not bifid. ✔ The transverse process is large, but the foramen transversarium is small and transmits the vertebral vein or veins. Characteristics of a Typical Thoracic Vertebra A typical thoracic vertebra has the following characteristics The body is medium size and heart shaped. The vertebral foramen is small and circular. The spines are long and Motivated downward. The superior articular processes facets posteriorly and laterally, whereas the facets on the inferior articular processes face anteriorly and medially.  The Head The head is formed mainly by the skull with the brain and its covering meninges enclosed in the cranial cavity. The brain gives rise to 12 pairs of cranial nerves, which leave the brain and pass through foramina and fissures in the skull. All the cranial nerves are distributed to structures in the head and neck, except the 10th, which also supplies structures in the chest and abdomen. The special senses, the eye and the ear, lie within the skull bones or in the cavities bounded by them.  Bones of the Skull ✔ The skull is composed of several separate bones united at immovable joints called sutures. The connective tissue between the bones is called a sutural ligament. ✔ The mandible is an exception to this rule, for it is united to the skull by the movable temporomandibular joint. ✔ cranial & facial bones. ✔ The skull bones are made up of external and internal tables of compact bone separated by a layer of spongy bone called the diploë. internal table thinner than external table. Bones of Skull The cranium:8 Frontal bone (1), Parietal bones (2), Occipital bone (1), Temporal bones (2), Sphenoid bone (1), Ethmoid bone (1). The facial bones:14 Zygomatic bones (2), Maxillae (2), Nasal bones (2), Lacrimal bones (2), Vomer (1), Palatine bones (2), Inferior conchae (2), Mandible (1). External Views of Skull the Anterior View of the Skull The frontal bone, or forehead bone, curves downward to make the upper margins of the orbits. The superciliary arches can be seen on either side, and the supraorbital notch, or foramen, can be recognized. Within the frontal bone, just above the orbital margins, are two hollow spaces called the frontal air sinuses. Medially, the frontal bone articulates with the with the nasal & maxillary bones. Laterally, the frontal bone articulates with the zygomatic bone. Two nasal bones. The two nasal bones form the bridge of the nose. Their lower borders, with the maxillae, make the anterior nasal aperture. The nasal cavity is divided into two cavities by the bony nasal septum, which is largely formed by the vomer. The superior and middle conchae are shelves of bone that project into the nasal cavity from the ethmoid on each side; the inferior conchae are separate bones. Maxillary bone The two maxillae form the upper. jaw, the anterior part of the hard palate, part of the lateral walls of the nasal cavities, and part of the floors of the orbital cavities. The two bones meet in the midline at the intermaxillary suture and form the lower margin of the nasal aperture. Below the orbit, the maxilla is perforated by the infraorbital foramen. The alveolar process projects downward and, together with the fellow of the opposite side, forms the alveolar arch, which carries the upper teeth. Within each maxilla is a large, pyramid-shaped cavity lined with mucous membrane called the maxillary sinus. Zygomatic bone The zygomatic bone forms the prominence of the cheek and part of the lateral wall and floor of the orbital cavity. Medially, it articulates with the maxilla and laterally it articulates with the zygomatic process of the temporal bone to form the zygomatic arch. The zygomatic bone is perforated by two foramina for the zygomaticofacial and zygomaticotemporal nerves. Lateral View of the Skull The frontal bone forms anterior part of the side of the skull and articulates with the parietal bone at the coronal suture. The parietal bones form the sides and roof of the cranium and articulate with each other in the midline at the sagittal suture. They articulate with the occipital bone behind, at the lambdoid suture. The skull is completed at the side by the squamous part of the occipital bone. parts of the temporal bone, namely, the squamous, tympanic, mastoid process, styloid process, and zygomatic process. greater wing of sphenoid ✔ Note that the thinnest part of the lateral wall of the skull is where the anteroinferior corner of the parietal bone articulates with the greater wing of the sphenoid; this point is referred to as the pterion. Temporal and infratemporal fossa Identify the superior and inferior temporal lines, which begin as a single line from the posterior margin of the zygomatic process of the frontal bone and diverge as they arch backward. The temporal fossa lies below the inferior temporal line. The infratemporal fossa lies below the infratemporal crest on the greater wing of the sphenoid. The pterygomaxillary fissure is a vertical fissure that lies within the fossa between the pterygoid process of the sphenoid bone and back of the maxilla. It leads medially into the pterygopalatine fossa. The pterygopalatine fossa is a small space behind and below the orbital cavity. It communicates laterally with the infratemporal fossa through the pterygomaxillary fissure. medially with the nasal cavity through the sphenopalatine foramen, superiorly with the skull through the foramen rotundum, anteriorly with the orbit through the inferior orbital fissure. Superior View of the Skull Anteriorly, the frontal bone articulates with the two parietal bones at the coronal suture. Occasionally, the two halves of the frontal bone fail to fuse, leaving a midline metopic suture. Behind, the two parietal bones articulate in the midline at the sagittal suture. Posterior View of the Skull The parietal bones articulate … with the squamous part of the occipital bone at the suture lambdoid. On each side the occipital bone articulates with the temporal bone. In the midline of the occipital bone is a roughened elevation called the external occipital protuberance, which gives attachment to muscles and the ligaments. On either side of the protuberance the superior nuchal lines extend laterally toward the temporal bone. Inferior View of the Skull the anterior part of this aspect of the skull is seen to be formed by the hard palate. The palatal processes of the maxillae and the horizontal plates of the palatine bones can be identified. In the midline anteriorly is the incisive fossa and foramen. Posterolaterally are the greater and lesser palatine foramina. Above the posterior edge of the hard palate are the choanae (posterior nasal apertures). ▪ These are separated from each other by the posterior margin of the vomer and are bounded laterally by the medial pterygoid plates of the sphenoid bone. The inferior end of the medial pterygoid plate is prolonged as a curved spike of bone, the pterygoid hamulus. Posterolateral to the lateral. pterygoid plate, the greater wing of the sphenoid is pierced by the large foramen ovale and the small foramen spinosum. Between the greater wing of the sphenoid and the petrous part of the temporal bone, is a groove for the cartilaginous part of the auditory tube. The opening of the bony part of the tube can be identified. The mandibular fossa of the temporal bone and the articular tubercle form the upper articular surfaces for the temporomandibular joint.. The styloid process of the temporal bone projects downward and forward from its inferior aspect. The opening of the carotid canal can be seen on the inferior surface of the petrous part of the temporal bone. The medial end of the petrous part of the temporal bone is irregular and, together with the basilar part of the occipital bone and the greater wing of the sphenoid, forms the foramen lacerum. During life, the foramen lacerum is closed with fibrous tissue, and only a few small vessels pass through this foramen from the cavity of the skull to the exterior. The tympanic plate, which forms part of the temporal bone, is C shaped on section and forms the bony part of the external auditory meatus.. In the interval between the styloid and mastoid processes, the stylomastoid foramen can be seen. Medial to the styloid process, the petrous part of the temporal bone has a deep notch, which, together with a shallower notch on the occipital bone, forms the jugular foramen. The pharyngeal tubercle is a small prominence on the undersurface of the basilar part of the occipital bone in the midline. The occipital condyles should be identified; they articulate with the superior aspect of the lateral mass of the first cervical vertebra, the atlas. Superior to the occipital condyle is the hypoglossal canal for transmission of the hypoglossal nerve. The Cranial Cavity The cranial cavity contains the brain and its surrounding meninges, portions of the cranial nerves, arteries, veins, and venous sinuses. Vault of the Skull The internal surface of the vault shows the coronal, sagittal, and lambdoid sutures. In the midline is a shallow sagittal groove that lodges the superior sagittal sinus. On each side of the groove are several small pits, called granular pits, which lodge the lateral lacunae and arachnoid granulations Several narrow grooves are present for the anterior and posterior divisions of the middle meningeal vessels as they pass up the side of the skull to the vault Base of the Skull The interior of the base of the skull is divided into three cranial fossae: anterior, middle, and posterior. The anterior cranial fossa is separated from the middle cranial fossa by the lesser wing of the sphenoid, and the middle cranial fossa is separated from the posterior cranial fossa by the petrous part of the temporal bone. Anterior Cranial Fossa The anterior cranial fossa lodges the frontal lobes of the cerebral hemispheres. It is bounded anteriorly by the inner Surface of the frontal bone, and in the midline is a crest for the attachment of the falx cerebri. Its posterior boundary is the sharp lesser wing of the sphenoid, which articulates laterally with the frontal bone and meets the anteroinferior angle of the parietal bone, or the pterion. The medial end of the lesser wing of the sphenoid forms the anterior clinoid process on each side, which gives attachment to the tentorium cerebelli. The median part of the anterior cranial fossa is limited posteriorly by the groove for the optic chiasma. Anterior Cranial Fossa The floor of the fossa is formed by the orbital plates of the frontal bone laterally and by the cribriform plate of the ethmoid. The crista galli is a sharp upward projection of the ethmoid bone in the midline for the attachment of the falx cerebri. Alongside the crista galli is a narrow slit in the cribriform plate for the passage of the anterior ethmoidal nerve into the nasal cavity. Middle Cranial Fossa Lodge the temporal lobes of the cerebral hemispheres. It is bounded anteriorly by the lesser wings of the sphenoid and posteriorly by the superior borders of the petrous parts of the temporal bones. Laterally lie the squamous parts of the temporal bones, the greater wings of the sphenoid, and the parietal bones. The floor of each lateral part of the middle cranial fossa is formed by the greater wing of the sphenoid and the squamous and petrous parts of the temporal bone. Middle Cranial Fossa The sphenoid bone resembles a bat having a centrally placed body with greater and lesser wings that are outstretched on each side. The body of the sphenoid contains the sphenoid air sinuses, which are lined with mucous membrane and communicate with the nasal cavity; they serve as voice resonators. Anteriorly, the optic canal transmits the optic nerve and the ophthalmic artery, a branch of the internal carotid artery, to the orbit. The superior orbital fissure, which is a slit like opening between the lesser and the greater wings of the sphenoid, transmits the oculomotor, trochlear, lacrimal, frontal, nasociliary, and abducent nerves, superior ophthalmic vein. Middle Cranial Fossa The foramen rotundum, which is situated behind the medial end of the superior orbital fissure, perforates the greater wing of the sphenoid and transmits the maxillary nerve from the trigeminal ganglion to the pterygopalatine fossa. The foramen ovale lies posterolateral to the foramen rotundum. It perforates the greater wing of the sphenoid and transmits the large sensory root and small motor root of the mandibular nerve to the infratemporal fossa; the lesser petrosal nerve also passes through it. The small foramen spinosum lies posterolateral to the foramen ovale and also perforates the greater wing of the sphenoid. The foramen transmits the middle meningeal artery from the infratemporal fossa into the cranial cavity. Middle Cranial Fossa foramen lacerum The carotid canal opens into the side of the foramen lacerum above the closed inferior opening. Middle cranial fossa The tegmen tympani it forms the roof of the mastoid antrum, the tympanic cavity, and the auditory tube. This thin plate of bone is the only major barrier that separates infection in the tympanic cavity from the temporal lobe of the cerebral hemisphere. Middle cranial fossa The median part of the middle cranial fossa is formed by the body of the sphenoid bone. In front is the sulcus chiasmatis, which is related to the optic chiasma and leads laterally to the optic canal on each side. Posterior to the sulcus is an elevation, the tuberculum sellae. Behind the elevation is a deep depression, the sella turcica, which lodges the pituitary gland. The sella turcica is bounded posteriorly by a square plate of bone called the dorsum sellae. The superior angles of the dorsum sellae have two tubercles, called the posterior clinoid processes. Middle cranial fossa The cavernous sinus is directly related to the side of the body of the sphenoid. It carries in its lateral wall the 3rd and 4th cranial nerves and the ophthalmic and maxillary divisions of the 5th cranial nerve. The internal carotid artery and the 6th cranial nerve pass forward through the sinus. Posterior Cranial Fossa The posterior cranial fossa is deep and lodges the parts of the hindbrain.. Anteriorly, the fossa is bounded by the superior border of the petrous part of the temporal bone, and posteriorly it is bounded by the internal surface of the squamous part of the occipital bone. The floor of the posterior fossa is formed by the basilar, condylar, and squamous parts of the occipital bone and the mastoid part of the temporal bone. The roof of the fossa is formed by a fold of dura (the tentorium cerebelli) Posterior Cranial Fossa The foramen magnum occupies the central area of the floor and transmits the medulla oblongata and its surrounding meninges, the ascending spinal parts of the accessory nerves, and the two vertebral arteries. The hypoglossal canal is situated above the anterolateral boundary of the foramen magnum and transmits the hypoglossal nerve. The jugular foramen lies between the lower border of the petrous part of the temporal bone and the condylar part of the occipital bone. It transmits the following structures from before backward: the inferior petrosal sinus ;the 9th, 10th, and 11th cranial nerves; and the large sigmoid sinus. Posterior Cranial Fossa The internal acoustic meatus pierces the posterior surface of the petrous part of the temporal bone. It transmits the facial nerve and The vestibulocochlear nerve the internal occipital crest it is attached the small falx Cerebelli. Posterior Cranial Fossa On each side of the internal occipital protuberance is a wide groove for the transverse sinus.to reach the posteroinferior angle or corner of the parietal bone. The groove now passes onto the mastoid part of the temporal bone, and here the transverse sinus becomes the sigmoid sinus. As the sigmoid sinus descends to the jugular foramen The superior petrosal sinus runs backward along the upper border of the petrous bone in a narrow groove and drains into the sigmoid sinus. The body of the mandible angle of the mandible Mandible mental foramen mental spines mylohyoid line submandibular fossa subligual fossa digastric fossa The ramus of the mandible coronoid process condyloid process, or head mandibular notch mandibular foramen Lingula sphenomandibular ligament mandibular canal  Neonatal Skull Anterior fontanelle: is diamond shaped and lies between the two halves of the frontal bone in front and the two parietal bones behind. The fontanelle is replaced by bone and is closed by 18 months of age. Posterior fontanelle: is triangular and lies between the two parietal bones in front and the occipital bone behind. By the end of the first year the fontanelle is usually closed.  Comparison The bones of the skull are smooth and unilaminar The bones of the vault are not closely joined at sutures The tympanic part of the temporal bone is merely a C-shaped ring at birth. This means that the external auditory meatus is almost entirely cartilaginous in the newborn, and the tympanic membrane is nearer the surface. The mastoid process is not present at birth the mastoid antrum lies about 3 mm deep to the floor of the suprameatal triangle. The mandible has right and left halves at birth  Ligaments of the Mandible ✔ Temporomandibular Lig. ✔ Stylomandibular Lig. ✔ Sphenomandibular Lig. TMJ and Muscle Temporalis Lateral pterygoid m. Medial pterygoid m. Masseter m. SCALP Skin. Connective tissue. Aponeurosis (epicranial). Loss areolar tissue. Periosteum. Sensory Nerve Of Scalp Supratrochlear n. Supraorbital n. Zygomaticotemporal n. Auriculotemporal n. Lesser occipital n. Greater occipital n. Arterial Supply Of Scalp Supratrochlear a. Supraorbital a. Superficial temporal a. Posterior auricular a. Occipital a.  The supratrochlear and the supraorbital veins unite at the Venous Drainage of Scalp medial margin of the orbit to form the facial vein. The superficial temporal vein unites with the maxillary vein in the substance of the parotid gland to form the retromandibular vein. The posterior auricular vein unites with the posterior division of the retromandibular vein, just below the parotid gland, to form the external jugular vein. The occipital vein drains into the suboccipital venous plexus, which lies beneath the floor of the upper part of the posterior triangle, the plexus in turn drains into the vertebral veins or internal jugular vein. The veins of the scalp freely anastomose with one another and are connected to the diploic veins of the skull bones and the intracranial venous sinuses by the valveless emissary veins.  Muscle of the Scalp Occipitofrontalis Origin: It consists of four bellies, two occipital and two frontal, connected by an aponeurosis. Each occipital belly arises from the highest nuchal line on the occipital bone and passes forward to be attached to the aponeurosis. Each frontal belly arises from the skin and superficial fascia of the eyebrow and passes backward to be attached to the aponeurosis. Nerve supply: ∙ facial nerve. Action: The first three layers of the scalp can be moved forward or backward. The frontal bellies can raise the eyebrow in expression of surprise.  The Face Skin of the Face The skin of the face possesses numerous sweat and sebaceous glands. It is connected to the underlying bones by loose connective tissue, in which are embedded the muscle of the facial expression. Ophthalmic N. supplies the skin of the forehead, the upper eyelid, the conjunctive, Sensory Nerves of Face and the side of the nose down to and including the tip. Lacrimal n. Supraorbital n. Supratrochlear n. Infratrochlear n. External nasal n. Maxillary N. supplies the skin on the posterior part of the side of the nose, the lower eyelid, the cheek, the upper lip, and the lateral side of the orbital opening. Infraorbital n. zygomaticotemporal zygomaticofacial n. Mandibular N. supplies the skin of the lower lip, the lower part of the face, the temporal region, and part of the auricle. Mental n. Buccal n. auriculotemporal n. Facial artery arises from the external carotid Arterial Supply of artery. It curves around the inferior Face margin of the body of the mandible at the anterior border of the masseter muscle. It is here that the pulse can be easily felt. Submental a. Inferior labial a. Superior labial a. lateral nasal a. Superficial temporal artery smaller terminal branch of the external carotid artery, commence in the parotid gland. It ascends in front of the auricle to supply the scalp. Transverse facial a. A branch of the superficial temporal artery, arises within the parotid gland. It runs forward across the cheek just above the parotid duct. Ophthalmic Artery Supraorbital a. supratrochlear a.  Venous Drainage of the Face The facial vein is formed at the medial angle of the eye by the union of the supraorbital and supratrochlear veins. It is connected to the superior ophthalmic vein directly through the supraorbital vein. By means of the superior ophthalmic vein, the facial vein is connected to the cavernous sinus. This connection is of great clinical importance because it provides a pathway for the spread of infection from the face to the cavernous sinus. The facial vein descends behind the facial artery to the lower margin of the body of the mandible. It crosses superficial to the submandibular gland and it is joined by he anterior division of the retromandibular vein. The facial vein end by draining into the internal jugular vein. The facial vein receives tributaries that correspond to the branches of the facial artery. It is joined to the pterygoid venous plexus by the deep facial vein and to the cavernous sinus by the superior ophthalmic vein. The transverse facial vein joins the superficial temporal vein within the parotid gland.  The muscles of the face are embedded in the superficial Muscles of Face fascia. Arise from the bones of the skull and are inserted into the skin. The orifices of the face, namely, the orbit, nose, and mouth, are guarded by the eyelids, nostrils, and lips, respectively. The function of the facial muscles is to serve as sphincters or dilators of the structures. A secondary function of the facial muscles is to modify the expression of the face. Muscles of the eyelid Orbicularis oculi (sphincter). Levator palpebrae superioris (dilator). occipitofrontalis (dilator).  Muscle of the nostrils Compressors naris (sphincter). Dilator naris (dilator). Muscles of the lips Orbicularis oris (sphincter). Levator labii superioris alaeque nasi. Levator labii superioris. Zygomaticus minor and major. Levator anguli oris Risorius. Depressor anguli oris. Depressor labii inferioris. Mentalis. Muscle of the cheek Buccinator.  Sphincter Muscle of the Lip Orbicularis Oris Origin and insertion: The fibers encircle the oral orifice within the substance of the lips. Some fibers of the muscle arise from the maxilla above and the mandible below. Other fibers arise from the deep surface of the skin. Many of the fibers are derived from the buccinator muscle. Nerve supply: Buccal and mandibular branches of the facial nerve Action: Compress the lips together Muscle of the Cheek Buccinator Origin: From the outer surface of the alveolar margins of the maxilla and mandible opposite the molar teeth and from the pterygomandibular ligament. Insertion: the muscle fibers pass forward, forming the muscle layer of the cheek. The muscle is pierced by the parotid duct. At the angle of the mouth the central fibers decussate, those from below entering the upper lip and those from above entering the lower lip. The buccinator muscle thus blends and forms part of the orbicularis oris muscle. Nerve supply: Buccal branch of the facial nerve. Action: Compresses the cheeks and lips against the teeth.  Parotid Region The parotid region comprises the parotid salivary gland and the structures immediately related to it.  Parotid Gland Parotid gland The parotid gland is a lobulated mass surrounded by a connective tissue capsule. In addition, the gland is enclosed in a dense fibrous capsule derived from the investing layer of the deep cervical fascia. Glenoid process. Accessory part of parotid gland. Pterygoid process. Parotid duct. Structures within the parotid gland Facial nerve. Retromandibular vein. External carotid artery. Parotid lymph node. Facial nerve before parotid Muscular branches Facial Nerve (posterior belly of the digastric and the stylohyoid ) Posterior auricular n. (posterior and superior auricular muscles and the occipital belly of the occipitofrontalis) Facial nerve within parotid Temporal branch (anterior and superior auricular muscles, the frontal belly of the occipitofrontalis, the orbicularis oculi, and the corrugator supercilii ). Zygomatic branch (orbicularis oculi). Buccal branch (buccinator muscle and the muscles of the upper lip and nostril) Mandibular branch (muscles of the lower lip) Cervical branch to platysma.  Nerve Supply of the Parotid Gland Parasympathetic secretomotor supply arises from glossopharyngeal nerve. The nerves reach the gland via the tympanic branch, the lesser petrosal nerve, the otic ganglion, and the auriculotemporal nerve.  The Muscle of Mastication These consist of the masseter, temporalis, lateral and medial pterygoid muscles. Masseter ∙ Origin: From the lower border and medial surface of the zygomatic arch. ∙ Insertion: Its fibers run downward and backward to be attached to the lateral aspect of the ramus of the mandible. ∙ Nerve Supply: Mandibular division of the trigeminal nerve. ∙ Action: Raises the mandible to occlude the teeth in mastication. The Temporal and Infratemporal Fossae The temporal region is situated on the side of the head. The temporal fossa is bounded above by the superior temporal line on the side of the skull and below by the zygomatic arch. The infratemporal fossa is situated beneath the base of the skull, between the pharynx and the ramus of the mandible. The temporal and infratemporal fossae communicate with each other deep to the zygomatic arch. Temporal Fossa Temporalis muscle Deep temporal nerves. Auriculotemporal nerve. Superficial temporal a. Temporali s∙ Origin: The muscle is fan shaped and arises from the bony floor of the temporal fossa and from the deep surface of the temporal fascia. ∙ Insertion: the muscle fibers converge to a tendon, which passes deep to the zygomatic arch and is inserted on the coronoid process of the mandible and the anterior border of the ramus of the mandible. ∙ Nerve Supply: Deep temporal nerves, which are branches of the anterior division of the mandibular division of the trigeminal nerve. Action: the anterior and superior fibers elevate the mandible; the posterior fibers retract the mandible  deep temporal nerves The deep temporal nerves are two in number and arise from the anterior division of the mandibular nerve. They emerge from the upper border of the lateral pterygoid muscle and enter the deep surface of the temporalis muscle. auriculotemporal nerve The auriculotemporal nerve, a branch of the posterior division of the mandibular nerve, emerges from the upper border of the parotid gland and crosses the root of the zygomatic arch. It distributed to the skin of the auricle, the external auditory meatus, and the scalp over the temporal region. superficial temporal artery The superficial temporal artery, a terminal branch of the external carotid artery, emerges from the upper border of the parotid gland and crosses the root of the zygomatic arch in front of the auriculotemporal nerve and the auricle. It is here that its pulsation can be felt. It ascends onto the scalp and divides into anterior and posterior divisions.  Content of the Infratemporal Fossa The infratemporal fossa is occupied by the lateral and medial pterygoid muscles, the branches of the mandibular nerve, the otic ganglion, the chorda tympani, the maxillary artery, and the pterygoid venous plexus. Lateral pterygoid Origin: The upper head arises from the infratemporal surface of the greater wing of the sphenoid. The lower head arises from the lateral surface of the lateral pterygoid plate. Insertion: the two heads pass backward and are inserted into the front of the neck of the mandible and the articular disc of the TMJ joint. Nerve supply: Anterior division of the mandibular division of the trigeminal nerve. Action: Pulls the neck of the mandible forward during the process of opening of the mouth. Acting with the medial pterygoid of the same side, it pulls the neck of the mandible forward causing the jaw to rotate around the opposite condyle, as in the movement of chewing. Medial Pterygoid Origin: The superficial head arises from the tuberosity of the maxilla. The deep head arises from the medial surface of the lateral pterygoid plate. Insertion: the fibers run downward and laterally and are inserted into the medial surface of the angle of the mandible. Nerve supply: Mandibular division of the trigeminal nerve. Action: assists in elevating the mandible.  Mandibular Division of the Trigeminal Nerve The sensory and motor roots of the mandibular nerve emerge from the skull through the foramen ovale in the greater wing of the sphenoid bone. Immediately below the foramen, the small motor root of the mandibular nerve unites with the large sensory root. The mandibular nerve now descends and divides into a small anterior and a large posterior division. Branches from the Main Trunk Mandibular Nerve Meningeal branch Nerve to medial pterygoid Branches from Anterior Division The masseteric nerve. two deep temporal nerves. The nerve to lateral pterygoid muscle. The buccal nerve is a sensory nerve that runs forward and emerges on the cheek and supplies the skin over the cheek and the mucous membrane lining the cheek. Branches from Posterior division Auriculotemporal. Lingual. Inferior alveolar nerve mylohyoid nerve. The auriculotemporal nerve It receives postganglionic parasympathetic secretomotor fibers from the otic ganglion, which it conveys to the parotid gland. The lingual nerve runs downward and anterior to inferior alveolar nerve. At the lower border of the lateral pterygoid muscle it is joined by the chorda tympani nerve. The nerve supplies sensory branches to the anterior two-thirds of the tongue, the floor of the mouth, and the lingual gum. The inferior alveolar nerve which is made up of motor and sensory nerve fibers, descends on the lateral surface of the sphenomandibular ligament. It then enters the mandibular canal through the mandibular foramen and run forward below the teeth. Having supplied the teeth of the lower jaw, it emerges through the mental foramen to supply the skin of the face. The mylohoid nerve A branch of the inferior alveolar nerve, arises just above the mandibular foramen. It runs forward on the medial surface of the body of the mandible below the mylohyoid line. It lies superficial to the mylohoid muscle, which it supplies; it also supplies the anterior belly of the digastric muscle. Hard and Soft Palate  Otic Ganglion The otic ganglion is a small parasympathetic ganglion that is functionally associated with the glossopharyngeal nerve. It is situated just below the foramen ovale and is medial to the mandibular nerve.  Chorda Tympani The chorda tympani is a branch of the facial nerve in the temporal bone. It enters the infratemporal fossa through the Petrotympanic fissure and runs downward and forward to join the lingual nerve. The nerve carries preganglionic parasympathetic secretomotor fibers to the submandibular and sublingual salivary glands. It is also carries taste fibers from the anterior two-thirds of the tongue and the floor of the mouth. Maxillary Artery The maxillary artery is the largest terminal branch of the external carotid artery in the parotid gland. It arises behind the neck of the mandible and runs upward and forward, either superficial or deep to the lower head of the lateral pterygoid. It then leaves the infratemporal fossa by entering the pterygopalatine fossa. Branches in the Infratemporal Fossa The inferior alveolar artery follows the inferior alveolar nerve into the mandibular canal. ∙ The middle meningeal artery is an important artery that passes upward behind the mandibular nerve. The artery enters the skull through the foramen spinosum. It is distributed to the meninges within the skull. ∙ Small branches supply the lining of the external auditory meatus and the tympanic membrane. ∙ Numerous small muscular branches supply the muscle of mastication. Pterygoid Venous Plexus The pterygoid venous plexus is a venous network associated with the pterygoid muscle. It receives veins correspond to branches of the maxillary artery and its posterior end is drained by the maxillary vein. It communicates with the facial vein through the deep facial vein.  The Submandibular Region The submandibular region lies between the mandible and the hyoid bone. It contains the following structures: ∙ Muscles: digastric, mylohyoid, geniohyoid. hyoglossus, genioglossus, and styloglossus. ∙ Salivary glands: submandibular and sublingual. ∙ Nerves: Lingual, glossopharyngeal, and hypoglossal. ∙ Parasympathetic ganglion: Submandibular ganglion. ∙ Blood vessels: Facial artery and vein and lingual artery and vein. ∙ Lymph nodes: Submandibular group.  Hyoid Bone The hyoid bone is U shaped and consists of a body and two greater and two lesser cornua. It is mobile and lies in the neck just above the larynx and below the mandible. The hyoid bone forms a base for the tongue and is suspended in position by muscles that connect it to the mandible.  Muscles of the Submandibular Region Mylohyoid The mylohyoid is a flat triangular sheet of muscle arises from the mylohyoid line of the mandible. It is inserted into the body of the hyoid bone. It is supplied by the mylohyoid branch of the inferior alveolar nerve. Its action is to form a muscular sheet to support the tongue and the floor of the mouth. When the mandible is fixed, they elevate the floor of the mouth and the hyoid bone during the first stage of swallowing.  Muscles of the Submandibular Region Hyoglossus It is originated from the body and the great cornu of the hyoid bone. The muscle is quadrilateral and enters the side of the tongue where it ends when its fibers mix with those of other muscles of the tongue. It is supplied by the hypoglossal nerve. It depresses the tongue. Geniohyoid It is originated from the mental spine, behind the symphysis menti of the mandible. It is a narrow muscle that lies above the mylohyoid and inserted onto the body of the hyoid bone. Its medial surface lies in contact with the corresponding muscle of the opposite side. It is supplied by the first cervical nerve through the hypoglossal nerve.  Muscles of the Submandibular Region Genioglossus This muscle originated from the mental spine, behind the symphysis menti of the mandible. This fan-shaped muscle widen as it extends backward into the tongue. The superior fibers pass into the tip of the tongue, and middle fibers pass to the dorsum of the tongue and a few of inferior fibers are attached to the body of the hyoid bone. It is supplied by the hypoglossal nerve. It draws the tongue forward and protrudes the tip. Styloglossus This muscle is originated from the styloid process and the fibers pass downward and forward on the lateral surface of the superior constrictor muscle. The muscle is inserted in the side of the tongue. It is innervated by the hypoglossal nerve. It draws the tongue upward and backward  Salivary Glands Submandibular Glands The paired submandibular together with the paired sublingual and parotid glands and the numerous small glands scattered throughout the mouth cavity, constitute the salivary glands. The submandibular gland is a large gland that lies partially under the body of the mandible. It is composed of serous and mucous acini. The serous acini are predominating. It is made up of a large superficial part and a small deep part, which are continuous with each other around the posterior border of the mylohyoid muscle. The superficial part of the gland lies in the digastric triangle, reaching upward under the cover of the body of the mandible. Submandibular duct The submandibular duct emerges from the anterior end of the deep part of the gland. It passes forward along the side of the tongue, beneath the mucous membrane of the floor of the mouth. It opens into the mouth on the summit of a small papilla, which is situated at the side of the frenulum of the tongue. The submandibular duct and the deep part of the gland can be readily palpated through the mucous membrane of the floor of the mouth alongside the tongue. 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. Sublingual Gland The sublingual gland is the smallest of the three main salivary glands. It contains both serous and mucous acini, the later predominating. It lies beneath the mucous membrane of the floor of the mouth, close to the midline. Anteriorly the gland is related to its fellow of the opposite side and posteriorly to the deep part of the submandibular gland. Relations: Anteriorly: the gland of the opposite side. Posteriorly: the deep part of the submandibular gland. Medially: the genioglossus muscle, the lingual nerve, and the submandibular duct. Laterally: the gland is related laterally to the sublingual fossa of the medial surface of the mandible. Superiorly: the mucous membrane of the floor of the mouth, which is elevated by the gland to form the sublingual fold. Inferiorly: the gland is supported by the mylohyoid muscle. Nerve Supply The parasympathetic secretomotor supply of the submandibular and sublingual glands from the superior salivary nucleus of the facial nerve. The nerve fibers pass to the submandibular ganglion via the chorda tympani and the lingual nerve.  Nerves of the Submandibular Region Lingual nerve The lingual nerve is a branch of the posterior division of the mandibular nerve in the infratemporal fossa. The lingual nerve is joined the chorda tympani in the infratemporal fossa. It enters the submandibular region by passing forward and medially beneath the lower border of the superior constrictor muscle of the pharynx It ends by dividing into terminal branches, which Branches : supply the mucous membrane of the anterior two-thirds of the tongue and the floor of the mouth. Ganglionic branches : Sensory branches Communicating branches : Branches of Glossopharyngeal Nerve The tympanic branch supplies the lining of the middle ear and gives off the lesser petrosal nerve. The carotid branch to the carotid sinus and carotid body. The muscular branch supplies the stylopharyngeus muscle. The pharyngeal branches By means of these branches, the glossopharyngeal nerve gives sensory fibers to the mucous membrane of the pharynx, tonsils, and soft palate. The lingual branch supplies general sensory and special taste fibers to the mucous membrane of the posterior third of the tongue and the circumvallate papillae region of the anterior part of the tongue. Hypoglossal Nerve Branches in the Submandibular Region Muscular branches to all the muscle of the tongue except the palatoglossus, which is supplied by the pharyngeal plexus. It thus supplies the styloglossus, the hyoplgossus, the genioglossus, and the intrinsic muscles of the tongue. Communicating branch. The hypoglossal nerve communicates with the lingual nerve on the side of the tongue.  Blood Vessels of the Submandibular Region Facial artery The facial artery arises from the external carotid artery just above the tip of the greater cornu of the hyoid bone. It ascends and grooves the posterior border of the submandibular salivary gland. It then hooks around the lower border of the mandible to enter the face at the anterior margin of the masseter muscle. Branches in the Submandibular Region Ascending palatine artery. This ascends alongside the pharynx. Tonsillor artery. This artery perforates the superior constrictor muscle and provides the tonsil with its main blood supply. Glandular arteries. These supply the submandibular salivary glands. Submental artery. This artery runs forward along the lower border of the body of the mandible to supply the region of the chin and the lower lip. Facial vein The facial vein leaves the face by crossing the lower margin of the body of the mandible behind the facial artery. It is joined the anterior division of the retromandibular vein and drains into the internal jugular vein. Lingual artery The lingual artery arises from the external carotid artery opposite the tip of the greater cornu of the hyoid bone. It proceeds forward deep to the hyoglossus muscle to supply the tip of the tongue. Branches ∙ the dorsal lingual branches are two or three in number and ascend to the dorsum of the tongue. ∙ The sublingual artery supplies the sublingual salivary gland and neighboring structures Lingual vein The dorsal lingual veins join to form the lingual vein, which drains into the jugular vein.