Chapter 9: Head and Neck Anatomy

How many pairs of cranial nerves are connected to the brain?

12 pairs of nerves

In which type of dental examination would lymph nodes be palpated?

extraoral examination

Which cranial nerve innervates all muscles of mastication?

fifth nerve

What bone forms the forehead?

frontal bone

Identify the regions of the head

frontal, parietal, occipital, temporal, orbital, nasal, infraorbital, zygomatic, buccal, oral, and mental

The _______________ serves the posterior hard palate and the posterior lingual gingiva.

greater palatine nerve

What are the basic types of movement by the temporomandibular joint?

hinge and glide

The region of the head that is located below the orbital region is the _______________.

infraorbital region

Paired facial bones that help form the medial wall of the orbit are the _______________.

lacrimal bones

What is the term for enlarged or palpable lymph nodes?

lymphadenopathy

Name the only movable bone of the skull

mandible bone

Where is the mental foramen located?

mandible bone

Which division of the trigeminal nerve subdivides into the buccal, lingual, and inferior alveolar nerves?

mandibular division

The _______________ is the strongest and most obvious muscle of mastication.

masseter muscle

Which bones form the upper jaw and hard palate?

maxilla bone

What bone forms the back and base of the cranium?

occipital bone

The _______________ is the region of the head overlying the occipital bone and covered by the scalp.

occipital region

What type of sign or symptom may a patient who is experiencing temporomandibular disorder exhibit?

pain in the jaw

The _______________ is associated with the parotid salivary gland, which opens into the oral cavity at the parotid papilla.

parotid duct

Which of the major salivary glands is the largest?

parotid salivary gland

The _______________ produce saliva.

salivary glands

One of the cervical muscles that divide the neck region into anterior and posterior cervical triangles is the _______________.

sternocleidomastoid

A joint on each side of the head that allows for movement of the mandible is the _______________.

temporomadibular joint

_______________ is a disease process associated with the temporomandibular joint.

temporomandibular disease

What is the name of the horseshoe-shaped bone where the muscles of the tongue and the floor of the mouth attach?

Hyoid bone

Which artery is behind the ramus and has five branches?

Inferior alveolar artery

Which artery supplies the maxillary molars, premolar teeth, and gingiva?

Posterior superior alveolar artery

What is another name for the parotid duct?

Stensen's duct

Large papillae on the tongue are the _______________.

circumvallate lingual papillae

The eight bones that cover and protect the brain are the _______________.

cranium

Identify and locate the paranasal sinuses of the skull

-The paranasal sinuses are air-containing spaces within the skull that communicate with the nasal cavity. (A sinus is an air-filled cavity within a bone.) Functions of the sinuses include (1) producing mucus; (2) making the bones of the skull lighter; and (3) providing resonance, which helps produce sound. - The sinuses are named for the bones in which they are located, as follows: • Maxillary sinuses—the largest of the paranasal sinuses • Frontal sinuses—located within the forehead just above the left and right eyes • Ethmoid sinuses—irregularly shaped air cells separated from the orbital cavity by a very thin layer of bone • Sphenoid sinuses—located close to the optic nerves, where an infection may damage vision

Identify the action & components of the temporomandibular joint.

-The temporomandibular joint (TMJ) is a joint on each side of the head that allows movement of the mandible for speech and mastication (chewing) -The TMJ receives its name from the two bones that enter into its formation: the temporal bone and the mandible. The mandible is attached to the cranium by the ligaments of the TMJ. The mandible is held in position by the muscles of mastication. -The TMJ is made up of the following three bony parts: 1. The glenoid fossa, which is lined with fibrous connective tissue, is an oval depression in the temporal bone just anterior to the external auditory meatus. 2. The articular eminence is a raised portion of the temporal bone just anterior to the glenoid fossa. 3. The condyloid process of the mandible lies in the glenoid fossa.

Identify the bones of the cranium and face

Bones of the Cranium -Parietal bones: The two parietal bones form most of the roof and upper sides of the cranium. The two parietal bones are joined at the sagittal suture at the midline of the skull. The line of articulation between the frontal bone and the parietal bones is called the coronal suture. In a newborn, the anterior fontanelle is the soft spot where the sutures between the frontal and parietal bones have not yet closed. This spot disappears as the child grows and the sutures close. -Frontal Bone: The frontal bone forms the forehead, part of the floor of the cranium, and most of the roof of the orbits. (The orbit is the bony cavity that protects the eye.) The frontal bone contains the two frontal sinuses, with one located above each eye. -Occipital Bone: The occipital bone forms the back and base of the cranium. It joins the parietal bones at the lambdoid suture. The spinal cord passes through the foramen magnum of the occipital bone. -Temporal Bones: Each temporal bone encloses an ear and contains the external auditory meatus, which is the bony passage of the outer ear. The mastoid process is a projection on the temporal bone located just behind the ear. The mastoid process is composed of air spaces that communicate with the middle ear cavity. The lower portion of each temporal bone bears the glenoid fossa for articulation with the mandible. The styloid process extends from the undersurface of the temporal bone. -Sphenoid Bone: The sphenoid bone is made up of a body and paired greater and lesser wings. It forms the anterior part of the base of the skull. The sphenoid sinuses are located in the sphenoid bone just posterior to the eye. The pterygoid process, which extends downward from the sphenoid bone, consists of two plates. The lateral pterygoid plate is the point of origin for the internal and external pterygoid muscles. The medial pterygoid plate ends in the hook-shaped hamulus, which is visible on some dental radiographs. -Ethmoid Bone: The ethmoid bone forms part of the floor of the cranium, the orbit, and the nasal cavity. This complex bone contains honeycomb-like spaces and the ethmoid sinuses. The medial concha and superior concha, which are scroll-like structures, extend from the ethmoid bone. -Auditory Ossicles: The six auditory ossicles are the bones of the middle ear. Each ear contains one malleus, incus, and stapes. Bones of the Face -Zygomatic Bones: The two zygomatic bones, also known as the malar bones, form the prominence of the cheek and the lateral wall and floor of the orbit. The frontal process of the zygomatic bone extends upward to articulate with the frontal bone at the outer edge of the orbit. The zygomatic bones rest on the maxillary bones, and each articulates with the right or left zygomatic process. 106The temporal process of the zygomatic bone articulates with the zygomatic process of the temporal bone to form the zygomatic arch, which creates the prominence of the cheek. The zygomatic bones are useful in identifying maxillary radiographs. -Maxillary Bones: The two maxillary bones, also known as the maxillae (singular, maxilla), form the upper jaw and part of the hard palate. The maxillary bones are joined together at the midline by the maxillary suture. The zygomatic process of the maxillary bones extends upward to articulate with the zygomatic bone. The maxillary bones contain the maxillary sinuses. The alveolar process of the maxillary bones forms the support for the teeth of the maxillary arch. The maxillary tuberosity is a larger, rounded area on the outer surface of the maxillary bones in the area of the posterior teeth. The maxillary tuberosity is also a useful landmark for mounting maxillary radiographs. -Palatine Bones: The two palatine bones are not strictly considered facial bones but are discussed here for ease of learning. Each palatine bone consists of two plates: the horizontal and vertical plates. The horizontal plates of the palatine bones form the posterior part of the hard palate of the mouth and the floor of the nose. The vertical plates form part of the lateral walls of the nasal cavity. Anteriorly, they articulate (join) with the maxillary bone. -Nasal Bones: The two nasal bones form the bridge of the nose. Superiorly, they articulate with the frontal bone and make up a small portion of the nasal septum. -Lacrimal Bones: The two lacrimal bones make up part of the orbit at the inner angle of the eye. These small, thin bones lie directly behind the frontal processes of the maxillary bones. -Vomer: The vomer is a single, flat bone that forms the base for the nasal septum -Nasal Conchae: Each lateral wall of the nasal cavity consists of three projecting structures that extend inward from the maxilla, called the nasal conchae (singular, concha). Each concha extends scroll-like into the nasal cavity. The superior, middle, and inferior nasal conchae are formed from the ethmoid bone. -Mandible: The mandible forms the lower jaw and is the movable bone of the skull. The alveolar process of the mandible supports the teeth of the mandibular arch. The U-shaped mandible, which is the strongest and longest bone of the face, develops prenatally as two parts; in early childhood, however, it ossifies (hardens) into a single bone. This symphysis is located at the midline and forms the mental protuberance, commonly known as the chin. A mental foramen is located on the facial surface on the left and right between the apices of the first and second mandibular premolars. -Hyoid Bone: The hyoid bone is unique because it does not articulate with any other bone. Instead, the hyoid is suspended between the mandible and the larynx, where it functions as a primary support for the tongue and other muscles. The hyoid bone is shaped like a horseshoe and consists of a central body with two lateral projections. Externally, its position is noted in the neck between the mandible and the larynx. The hyoid is suspended from the styloid process of the temporal bone by two stylohyoid ligaments.

Identify and trace the routes of the blood vessels in the head and neck

Major Arteries of the Face and Oral Cavity -The aorta ascends from the left ventricle of the heart. The common carotid artery arises from the aorta and subdivides into the internal and external carotid arteries. The internal carotid artery supplies blood to the brain and eyes. The external carotid artery provides the major blood supply to the face and mouth. -External Carotid Artery: The branches of the external carotid artery are named according to the areas they supply. These branches supply the tongue, face, ears, and wall of the cranium. -Facial Artery: The facial artery is another branch of the external carotid. It enters the face at the inferior border of the mandible and can be detected by gentle palpation of the mandibular notch. The facial artery passes forward and upward across the cheek toward the angle of the mouth. Then it continues upward alongside the nose and ends at the medial canthus (inner corner) of the eye. The facial artery has six branches that supply the pharyngeal muscles, soft palate, tonsils, posterior tongue, submandibular gland, muscles of the face, nasal septum, nose, and eyelids. -Lingual Artery: The lingual artery is also a branch of the external carotid. It consists of several branches to the entire tongue, floor of the mouth, lingual gingiva, and a portion of the soft palate and tonsils. -Maxillary Artery: The maxillary artery is the larger of the two terminal branches of the external carotid. It arises behind the angle of the mandible and supplies the deep structures of the face. The maxillary artery divides into three sections: inferior alveolar, pterygoid, and pterygopalatine. The pterygoid artery supplies blood to the temporal muscle, masseter muscle, pterygoid muscles, and buccinator muscles. The inferior alveolar artery also comes from the maxillary artery. It enters the mandibular canal, along with the inferior alveolar nerve. Major Veins of the Face and Oral Cavity -The maxillary vein receives branches that correspond to those of the maxillary artery. These branches form the pterygoid plexus. The trunk of the maxillary vein passes backward behind the neck of the mandible. -The union of the temporal and maxillary veins forms the retromandibular vein. It descends within the parotid gland and divides into two branches. The anterior branch passes inward to join the facial vein. The posterior branch is joined by the posterior auricular vein and becomes the external jugular vein. -The external jugular vein empties into the subclavian vein. The facial vein begins near the side of the nose. It passes downward and crosses over the body of the mandible with the facial artery. It then passes outward and backward to unite with the anterior division of the retromandibular vein to form the common facial vein, which enters the internal jugular vein. -The deep facial vein courses from the pterygoid plexus to the facial vein. The lingual veins begin on the dorsum (top), sides, and undersurface of the tongue. They pass backward, following the course of the lingual artery and its branches, and terminate in the internal jugular vein. -The internal jugular vein, which corresponds to the common carotid artery, empties into the superior vena cava, which returns blood from the upper portion of the body to the right atrium of the heart.

Locate and identify the muscles of the head and neck

Major Muscles of the Neck -The two muscles of the neck are superficial and are easily palpated on the neck. These cervical muscles are the sternocleidomastoid and trapezius. These muscles can become painful when dental assistants use improper posture while assisting. Major Muscles of Facial Expression -The muscles of facial expression are paired muscles (left and right) that originate from the bone and insert on skin tissue. These muscles cause wrinkles at right angles to the action line of the muscle. The seventh cranial (facial) nerve innervates all the muscles of facial expression. Major Muscles of Mastication -The muscles of mastication are four pairs of muscles attached to the mandible that include the temporalis, masseter, internal (medial) pterygoid, and external (lateral) pterygoid. These muscles work with the TMJ to make all movements of the mandible possible. The mandibular division of the fifth cranial (trigeminal) nerve innervates all muscles of mastication. Muscles of the Floor of the Mouth -The muscles of the floor of the mouth are the digastric, mylohyoid, stylohyoid, and geniohyoid. These muscles are located between the mandible and the hyoid bone. Different nerve branches innervate the muscles on the floor of the mouth. Muscles of the Tongue -The tongue has two groups of muscles: intrinsic (within the tongue) and extrinsic. Intrinsic muscles are responsible for shaping the tongue during speaking, chewing, and swallowing. Extrinsic muscles assist in the movement and functioning of the tongue and include the genioglossus, hyoglossus, styloglossus, and palatoglossus. All muscles of the tongue, except the palatoglossus, are innervated by the hypoglossal nerve. The palatoglossus muscle is discussed with the palate. Muscles of the tongue and the floor of the mouth attach to the hyoid bone. Muscles of the Soft Palate - The soft palate has two major muscles called the palatoglossus and palatopharyngeus. The pharyngeal plexus innervates both of these muscles.

Describe locations of the major and minor salivary glands and associated ducts

Minor Salivary Glands -The minor salivary glands are smaller and more numerous than the major salivary glands. The minor glands are scattered in the tissues of the buccal, labial, and lingual mucosa; the soft palate; the lateral portions of the hard palate; and the floor of the mouth. Von Ebner's salivary gland is associated with the circumvallate lingual papillae on the tongue. Major Salivary Glands -The three large paired salivary glands are the parotid, submandibular, and sublingual glands. -The parotid salivary gland is the largest of the major salivary glands, but it provides only 25 percent of the total volume of saliva. It is located in an area just below and in front of the ear. Saliva passes from the parotid gland into the mouth through the parotid duct, also known as Stensen's duct. -The submandibular salivary gland, about the size of a walnut, is the second largest salivary gland. This gland provides 60 to 65 percent of the total volume of saliva. It lies beneath the mandible in the submandibular fossa, posterior to the sublingual salivary gland. The gland releases saliva into the oral cavity through the submandibular duct, also known as Wharton's duct, which ends in the sublingual caruncles. -The sublingual salivary gland is the smallest of the three major salivary glands. It provides only 10 percent of the total salivary volume. This gland releases saliva into the oral cavity through the sublingual duct, also known as Bartholin's duct. Other smaller ducts of the sublingual gland open along the sublingual fold. A stone, or sialolith, may block the salivary glands in the duct opening, preventing saliva from flowing into the mouth. Salivary stones may be removed surgically

Identify the location of the major lymph node sites of the body

Structure and Function -Lymph nodes are small round or oval structures that are located in lymph vessels. They fight disease by producing antibodies; this is part of the immune reaction. In acute infection, lymph nodes become swollen and tender as a result of the collection of lymphocytes gathered to destroy invading substances. Major lymph nodes of the body include cervical nodes (in the neck), axillary nodes (under the arms), and inguinal nodes (in the lower abdomen). Lymph nodes of the head are classified as superficial (near the surface) or deep. All nodes of the head drain the right or the left tissues in the area, depending on their location. Superficial Lymph Nodes of the Head -Five groups of superficial lymph nodes are found in the head: occipital, retroauricular, anterior auricular, superficial parotid, and facial nodes Deep Cervical Lymph Nodes -Deep cervical lymph nodes are located along the length of the internal jugular vein on each side of the neck, deep to the sternocleidomastoid muscle

Describe and locate the divisions of the trigeminal nerve

The trigeminal nerve is the primary source of innervation for the oral cavity. The trigeminal nerve subdivides into three main divisions: ophthalmic, maxillary, and mandibular. Maxillary Divison of Trigeminal Nerve -The maxillary division of the trigeminal nerve supplies the maxillary teeth, periosteum, mucous membranes, maxillary sinuses, and soft palate. The maxillary division subdivides to provide the following innervation: • The nasopalatine nerve, which passes through the incisive foramen, supplies the mucoperiosteum palatal to the maxillary anterior teeth. (Mucoperiosteum is periosteum that has a mucous membrane surface.) • The greater palatine nerve, which passes through the posterior palatine foramen and forward over the palate, supplies the mucoperiosteum, intermingling with the nasopalatine nerve. • The anterior superior alveolar nerve supplies the maxillary central, lateral, and cuspid teeth, along with their periodontal membranes and gingivae. This nerve also supplies the maxillary sinus. • The middle superior alveolar nerve supplies the maxillary first and second premolars, the mesiobuccal root of the maxillary first molar, and the maxillary sinus. • The posterior superior alveolar nerve supplies the other roots of the maxillary first molar and the maxillary second and third molars. It also branches forward to serve the lateral wall of the maxillary sinus. Mandibular Division of the Trigeminal Nerve -The mandibular division of the trigeminal nerve subdivides to provide the following innervation: • The buccal nerve (long buccal) supplies branches to the buccal mucous membrane and to the mucoperiosteum of the mandibular molars. • The lingual nerve supplies the anterior two thirds of the tongue and branches to supply the lingual mucous membrane and mucoperiosteum. • The inferior alveolar nerve subdivides into the following: • The mylohyoid nerve supplies the mylohyoid muscles and the anterior belly of the digastric muscle. • Small dental nerves supply the molar and premolar teeth, alveolar process, and periosteum.

The _______________ is the sixth cranial nerve, which serves the eye muscle.

abducens nerve

The space between the capsular ligament and the surfaces of the glenoid fossa and the condyle is the _______________.

articular space

_______________ pertains to structures that are closest to the inner cheek.

buccal

The _______________ is one of the cervical muscles that lift the clavicle and scapula to shrug the shoulder.

trapezius

The regions of the head include the frontal, parietal, occipital, temporal, orbital, nasal, infraorbital, buccal, oral, mental, and _______________.

zygomatic

Which bones form the cheek?

zygomatic bones