Lips and Tongue: Anatomy

Gross Anatomy of the Lips

Characteristics

• Philtrum: vertical indentation in the middle area of the upper lip Upper Lip Melasma
• Oral commissures: lateral borders of the oral cavity where upper and lower lips join
• Vermilion lip: pink portion of external lip
• Contain fewer melanocytes Melanocytes Mammalian pigment cells that produce melanins, pigments found mainly in the epidermis, but also in the eyes and the hair, by a process called melanogenesis. Coloration can be altered by the number of melanocytes or the amount of pigment produced and stored in the organelles called melanosomes. The large non-mammalian melanin-containing cells are called melanophores. Skin: Structure and Functions than the rest of the skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions
• Do not contain sweat glands Sweat glands Sweat-producing structures that are embedded in the dermis. Each gland consists of a single tube, a coiled body, and a superficial duct. Soft Tissue Abscess
• Lips are attached to the gums by the upper and lower labial frenula (frenulum labii).

Movement

Numerous muscles are responsible for movement of the lips.

• Lip elevation:
  • Levator labii superioris Levator labii superioris Facial Muscles: Anatomy
  • Levator labii superioris Levator labii superioris Facial Muscles: Anatomy alaeque nasi
  • Levator anguli oris
  • Zygomaticus minor Zygomaticus minor Facial Muscles: Anatomy
  • Zygomaticus major Zygomaticus major Facial Muscles: Anatomy
• Lip depression:
  • Risorius
  • Depressor anguli oris
  • Depressor labii inferioris
  • Mentalis Mentalis Facial Muscles: Anatomy

Neurovasculature

• Blood supply:
  • Supplied by branches of the facial artery ( external carotid artery External carotid artery Branch of the common carotid artery which supplies the exterior of the head, the face, and the greater part of the neck. Carotid Arterial System: Anatomy origin)
  • Superior labial artery: supplies upper lip Upper Lip Melasma
  • Inferior labial artery: supplies lower lip
• Innervation:
  • Supplied by branches of the trigeminal nerve Trigeminal nerve The 5th and largest cranial nerve. The trigeminal nerve is a mixed motor and sensory nerve. The larger sensory part forms the ophthalmic, mandibular, and maxillary nerves which carry afferents sensitive to external or internal stimuli from the skin, muscles, and joints of the face and mouth and from the teeth. Most of these fibers originate from cells of the trigeminal ganglion and project to the trigeminal nucleus of the brain stem. The smaller motor part arises from the brain stem trigeminal motor nucleus and innervates the muscles of mastication. The 12 Cranial Nerves: Overview and Functions
  • Infraorbital nerve (V2): innervates upper lip Upper Lip Melasma
  • Mental nerve (V3): innervates lower lip

Gross Anatomy of the Tongue

The tongue is a muscular projection that assists with chewing, speech, and taste. The tongue has variable Variable Variables represent information about something that can change. The design of the measurement scales, or of the methods for obtaining information, will determine the data gathered and the characteristics of that data. As a result, a variable can be qualitative or quantitative, and may be further classified into subgroups. Types of Variables innervation depending on which section is of interest and is supplied by a branch of the external carotid artery External carotid artery Branch of the common carotid artery which supplies the exterior of the head, the face, and the greater part of the neck. Carotid Arterial System: Anatomy.

Characteristics

• Made up of 3 parts:
  • Root (radix linguae)
  • Body (corpus linguae)
  • Tip (apex linguae)
• Consists of skeletal muscle, which allows for flexibility.

Movement

The tongue is moved by extrinsic and intrinsic muscles. Extrinsic muscles connect the tongue to surrounding structures, while intrinsic muscles do not have a bony origin or insertion.

• Extrinsic tongue muscles:
  • Genioglossus
  • Hyoglossus 
  • Styloglossus 
  • Palatoglossus 
• Intrinsic tongue muscles:
  • Verticalis linguae
  • Superior longitudinal
  • Inferior longitudinal
  • Transverse lingual

Neurovasculature

• Blood supply:
  • Supplied by branches of the external carotid artery External carotid artery Branch of the common carotid artery which supplies the exterior of the head, the face, and the greater part of the neck. Carotid Arterial System: Anatomy
  • The lingual artery branches directly off of the external carotid artery External carotid artery Branch of the common carotid artery which supplies the exterior of the head, the face, and the greater part of the neck. Carotid Arterial System: Anatomy to supply the tongue.
• Motor Motor Neurons which send impulses peripherally to activate muscles or secretory cells. Nervous System: Histology innervation:
  • Hypoglossal nerve: all tongue muscles except for the palatoglossus
  • Vagus nerve Vagus nerve The 10th cranial nerve. The vagus is a mixed nerve which contains somatic afferents (from skin in back of the ear and the external auditory meatus), visceral afferents (from the pharynx, larynx, thorax, and abdomen), parasympathetic efferents (to the thorax and abdomen), and efferents to striated muscle (of the larynx and pharynx). Pharynx: Anatomy: palatoglossus muscle
• Innervation of taste and sensation:
  • Anterior ⅔ of the tongue:
    • Taste: chorda tympani (cranial nerve (CN) VII)
    • Sensation: lingual nerve (CN V₃)
  • Glossopharyngeal nerve Glossopharyngeal nerve The 9th cranial nerve. The glossopharyngeal nerve is a mixed motor and sensory nerve; it conveys somatic and autonomic efferents as well as general, special, and visceral afferents. Among the connections are motor fibers to the stylopharyngeus muscle, parasympathetic fibers to the parotid glands, general and taste afferents from the posterior third of the tongue, the nasopharynx, and the palate, and afferents from baroreceptors and chemoreceptor cells of the carotid sinus. Pharynx: Anatomy: posterior ⅓ of the tongue
  • Internal branch of superior laryngeal nerve: base of the tongue

Microscopic Anatomy of the Lips

The microscopic anatomy of the lips consists primarily of 3 layers: the pars cutanea, pars intermedia, and pars mucosa. The pars cutanea is the outer layer of skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions, the pars intermedia is the pink portion of the lip, and the pars mucosa is inside the lip. These layers contain varying amounts of skeletal muscle.

• Pars cutanea:
  • Skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions ( stratified squamous epithelium Stratified squamous epithelium Surface Epithelium: Histology)
  • Hair follicles
  • Sebaceous glands
  • Sweat glands Sweat glands Sweat-producing structures that are embedded in the dermis. Each gland consists of a single tube, a coiled body, and a superficial duct. Soft Tissue Abscess
• Pars intermedia:
  • Stratified squamous epithelium Stratified squamous epithelium Surface Epithelium: Histology
  • No sebaceous glands or hair follicles
• Pars mucosa:
  • Nonkeratinized stratified squamous epithelium Stratified squamous epithelium Surface Epithelium: Histology
  • Labial glands
  • Small salivary glands Salivary glands The salivary glands are exocrine glands positioned in and around the oral cavity. These glands are responsible for secreting saliva into the mouth, which aids in digestion. There are 3 major paired salivary glands: the sublingual, submandibular, and parotid glands. Salivary Glands: Anatomy
• Muscles contained in all layers: 
  • Orbicularis oris Orbicularis oris Facial Muscles: Anatomy
  • Depressor labii inferioris
  • Levator labii

Microscopic Anatomy of the Tongue

The microscopic anatomy of the tongue comprises squamous epithelium Epithelium The epithelium is a complex of specialized cellular organizations arranged into sheets and lining cavities and covering the surfaces of the body. The cells exhibit polarity, having an apical and a basal pole. Structures important for the epithelial integrity and function involve the basement membrane, the semipermeable sheet on which the cells rest, and interdigitations, as well as cellular junctions. Surface Epithelium: Histology and nerve cells, which assist in the highly variable Variable Variables represent information about something that can change. The design of the measurement scales, or of the methods for obtaining information, will determine the data gathered and the characteristics of that data. As a result, a variable can be qualitative or quantitative, and may be further classified into subgroups. Types of Variables functions of the organ. 

• Stratified squamous epithelium Stratified squamous epithelium Surface Epithelium: Histology:
  • Dorsal surface: keratinized
  • Ventral surface: nonkeratinized
• The tongue contains:
  • Papillae
  • Taste buds:
    • Taste receptor Receptor Receptors are proteins located either on the surface of or within a cell that can bind to signaling molecules known as ligands (e.g., hormones) and cause some type of response within the cell. Receptors cells
    • Sustentacular cells → opens onto the surface → taste pore
• Glands: serous glands

Clinical Relevance

• Cleft tongue or lips: due to a lack of fusion of the lateral lingual swellings or lips. A cleft lip Cleft lip The embryological development of craniofacial structures is an intricate sequential process involving tissue growth and directed cell apoptosis. Disruption of any step in this process may result in the formation of a cleft lip alone or in combination with a cleft palate. As the most common craniofacial malformation of the newborn, the diagnosis of a cleft is clinical and usually apparent at birth. Cleft Lip and Cleft Palate usually presents as an opening in the upper lip Upper Lip Melasma that may extend into the nose Nose The nose is the human body’s primary organ of smell and functions as part of the upper respiratory system. The nose may be best known for inhaling oxygen and exhaling carbon dioxide, but it also contributes to other important functions, such as tasting. The anatomy of the nose can be divided into the external nose and the nasal cavity. Nose Anatomy (External & Internal). Along with cosmetic disfigurement, these disorders can result in feeding problems that may be severe. The treatment is usually surgical.
• Microglossia: small or rudimentary tongue. Microglossia is a rare congenital condition that presents with difficulty in eating and swallowing Swallowing The act of taking solids and liquids into the gastrointestinal tract through the mouth and throat. Gastrointestinal Motility. Relative microglossia is when the tongue is smaller in structure than the jaw Jaw The jaw is made up of the mandible, which comprises the lower jaw, and the maxilla, which comprises the upper jaw. The mandible articulates with the temporal bone via the temporomandibular joint (TMJ). The 4 muscles of mastication produce the movements of the TMJ to ensure the efficient chewing of food. Jaw and Temporomandibular Joint: Anatomy bones. There is no treatment for microglossia.
• Macroglossia Macroglossia The presence of an excessively large tongue, which may be congenital or may develop as a result of a tumor or edema due to obstruction of lymphatic vessels, or it may occur in association with hyperpituitarism or acromegaly. It also may be associated with malocclusion because of pressure of the tongue on the teeth. Wilms Tumor: enlarged tongue. Macroglossia Macroglossia The presence of an excessively large tongue, which may be congenital or may develop as a result of a tumor or edema due to obstruction of lymphatic vessels, or it may occur in association with hyperpituitarism or acromegaly. It also may be associated with malocclusion because of pressure of the tongue on the teeth. Wilms Tumor can be either congenital or acquired. Macroglossia Macroglossia The presence of an excessively large tongue, which may be congenital or may develop as a result of a tumor or edema due to obstruction of lymphatic vessels, or it may occur in association with hyperpituitarism or acromegaly. It also may be associated with malocclusion because of pressure of the tongue on the teeth. Wilms Tumor is often associated with Down syndrome Down syndrome Down syndrome, or trisomy 21, is the most common chromosomal aberration and the most frequent genetic cause of developmental delay. Both boys and girls are affected and have characteristic craniofacial and musculoskeletal features, as well as multiple medical anomalies involving the cardiac, gastrointestinal, ocular, and auditory systems. Down syndrome (Trisomy 21) and Hunter syndrome. Acquired macroglossia Macroglossia The presence of an excessively large tongue, which may be congenital or may develop as a result of a tumor or edema due to obstruction of lymphatic vessels, or it may occur in association with hyperpituitarism or acromegaly. It also may be associated with malocclusion because of pressure of the tongue on the teeth. Wilms Tumor may be seen in lingual tumors, myxedema Myxedema A condition characterized by a dry, waxy type of swelling (edema) with abnormal deposits of mucopolysaccharides in the skin and other tissues. It is caused by a deficiency of thyroid hormones. The skin becomes puffy around the eyes and on the cheeks. The face is dull and expressionless with thickened nose and lips. Edema, amyloidosis Amyloidosis Amyloidosis is a disease caused by abnormal extracellular tissue deposition of fibrils composed of various misfolded low-molecular-weight protein subunits. These proteins are frequently byproducts of other pathological processes (e.g., multiple myeloma). Amyloidosis, and angioedema Angioedema Angioedema is a localized, self-limited (but potentially life-threatening), nonpitting, asymmetrical edema occurring in the deep layers of the skin and mucosal tissue. The common underlying pathophysiology involves inflammatory mediators triggering significant vasodilation and increased capillary permeability. Angioedema.
• Ankyloglossia Ankyloglossia A severe congenital restriction of tongue movement, resulting from fusion or adherence of the tongue to the floor of the mouth. In partial ankyloglossia (tongue-tie) the lingual frenum is abnormally short, or is attached too close to the tip of the tongue. Omim: 106280. Physical Examination of the Newborn: condition characterized by fixation of the tongue to the floor of the mouth. Partial ankyloglossia Ankyloglossia A severe congenital restriction of tongue movement, resulting from fusion or adherence of the tongue to the floor of the mouth. In partial ankyloglossia (tongue-tie) the lingual frenum is abnormally short, or is attached too close to the tip of the tongue. Omim: 106280. Physical Examination of the Newborn is also known as tongue-tie. Patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship have difficulty with speaking and swallowing Swallowing The act of taking solids and liquids into the gastrointestinal tract through the mouth and throat. Gastrointestinal Motility. Ankyloglossia Ankyloglossia A severe congenital restriction of tongue movement, resulting from fusion or adherence of the tongue to the floor of the mouth. In partial ankyloglossia (tongue-tie) the lingual frenum is abnormally short, or is attached too close to the tip of the tongue. Omim: 106280. Physical Examination of the Newborn may be resolved by surgical intervention.