Muscles of facial expression

Muscles of face bring about different types of facial expressions, hence the name muscles of facial expression, the actions of many of them are implied by their names.

CHARACTERISTICS:

  1. Lie in superficial fascia and inserted into the skin.
  2. Morphological, they represent subcutaneous muscle of lower animals, called panniculus carnosus.
  3. Embryologically, develop from mesoderm of 2nd pharyngeal arch, hence supplied by facial nerve
  4. Functionally, perform all important functions of non-verbal communication in addition to closing and opening of orifices.

MUSCLES AROUND THE ORIFICE OF EYE

🔹️Orbicularis oculi

Consists of three parts:

  1. Orbital part: arises from medial palpebral ligament, frontal process of maxilla and adjoining part of frontal bone. Fibres form complete elliptical loops around the eyes.

It closes the eye tightly during intense sunlight and also for winking.

2. Palpebral part: arises from medial palpebral ligament and sweeps laterally over the upper and lower eyelids to be inserted into lateral palpebral ligament.

It closes the eyelids gently as in sleep or in blinking.

3. Lacrimal part: arises from posterior lacrimal crest and lacrimal fascia and passes laterally in front of tarsal plates of both eyelids to be inserted into lateral palpebral range.

It dilates the lacrimal sac , thus helping in the drainage of lacrimal fluid.

🔹️Corrugator supervision

It arises from medial end of superciliary arch, passes laterally and upwards to be inserted into the skin of eyebrow.

It drags the eyebrow medially and downwards producing vertical wrinkles on the the forehead.

🔹️Frontalis

It elevates the eyebrows and produces transverse wrinkles on the forehead.

🔹️Levator palpebra superioris

It elevates the upper eyelid.

MUSCLES AROUND NASAL CAVITY

🔹️Procerus

Arises from nasal bone, passes upwards to be inserted into the skin of lower part of the forehead.

It produces transverse wrinkles across the bridge of the nose.

🔹️Nasalis

Consists of 2 parts:

  1. Compressor naris: arises from maxilla close to nasal notch, passes upwards and medially to form aponeurosis across the bridge of the nose.

It compresses the nasal aperture.

2. Dilator naris: arises from maxilla for the margin of nasal notch and inserted into the lateral part Ala of nose.

Dilates the anterior nasal apertures.

🔹️DEPRESSOR SEPTI

It arises incisive fossa of the maxilla and is inserted into the lower mobile part of the nasal septum.

It fixes the nasal septum to allow dilation of anterior nasal aperture by dilator naris.

MUSCLES AROUND MOUTH

🔹️Orbicularis Oris

It has extrinsic and intrinsic portions. The major extrinsic portion is composed of interlacing fibres of the muscles which converge around the mouth for their insertion into the lips. The fibres of buccinator converge towards modulus and form chiasma.

The intrinsic portion consists of fibres running obliquely between the skin and mucous membranes of lips, incisive slips, which pass laterally into lips and interlace with fibres of peripheral part of orbicularis oris.

🔹️Nine muscles which converge around the mouth

  1. Levator labii superioris alaeque nasii: arises from frontal process of maxilla, inserted into Ala of nose. Elevates upper lip and dilates the nostrils.
  2. Levator labii superioris: arises from maxilla just above infraorbital frames and inserted into upper lip. Elevates upper lip.
  3. Levator anguli oris: arises from maxilla below infraorbital foramen, inserted into angle of mouth. Raises the angle of mouth.
  4. Zygomaticus minor: arises from zygomatic bone, inserted into upper lip. Elevates upper lip.
  5. Zygomaticus major: arises from zygomatic bone, inserted into angle of mouth. Draws angle of mouth upward and laterally.
  6. Depressor labii inferioris: arises from anterior oblique line of mandible, inserted into lower lip. Draws lower lip downward and laterally.
  7. Depressor anguli oris: arises from posterior part of oblique line of mandible, inserted into angle of mouth.
  8. Risorius: arises from parotid fascia, inserted into angle of mouth. Retracts angle of mouth gently.
  9. Buccinator: arises from outer surface of alveolar process of maxilla, pterygomandibular raphe, outer surface of alveolar process of mandible. It flattens the cheek and helps in blowing the cheek.

Muscle of chin: Mentalis

Arises from incisive fossa of mandible, inserted into lower lip.

It puckers the chin and protrudes the lower lip.

REFERENCE:

Vishram Singh: Textbook of Anatomy

WALDEYER’S LYMPHATIC RING

It is an uninterrupted circle of protective lymphoid tissue at the upper ends of the respiratory and alimentary tracts.

  • Also known as Nasal Associated Lymphoid Tissue (NALT).
  • Consists of the palatine, nasopharyngeal, lingual and tubal tonsils.
  • Produces B and T lymphocytes.
  • Involved in local defence.
  • Also produce lymphocytes to send to other lymph nodes.

PHARYNX

  • Length- 12cm
  • Width- 3.5cm in the upper portion and the lower portion of the pharynx is the narrowest portion of the GIT after the appendix.

Boundaries-

  • Superiorly- Base of the Skull
  • Inferiorly- Oesophagus
  • Posteriorly- Pre vertebral fascia
  • Anteriorly- Nasal cavity, Oral cavity, Larynx
  • Laterally- Medial pterygoid plate, Pterygomandibular raphe, Mandible, Tongue, Larynx, Thyroid and Cricoid cartilages, Middle ear cavity, Styloid process, CCA, ICA, ECA.

The pharynx is divided into 3 parts-

1.) Nasopharynx

  • Passage of air.
  • Located behind the nose.
  • Extends from the base of the skull to the soft palate.
  • Lines by ciliated columnar epithelium.
  • Supplied by pharyngeal branch of pterygopalatine ganglion.

2.) Oropharynx

  • Passage of food and air.
  • Extends from the soft palate to the epiglottis.
  • Lined by stratified squamous non keratinised epithelium.
  • Supplied by IX and X cranial nerves.

3.) Laryngopharynx

  • Passage of food.
  • Extends from the epiglottis to the cricoid cartilage.
  • Lined by stratified squamous non keratinised epithelium.
  • Supplied by the IX and X cranial nerves.

Muscles of the pharynx-

1.) Longitudinal Muscles

  • Stylopharyngeus
  • Palatopharyngeus – Makes the Passavant’s ridge
  • Salpingopharyngeus

2.) Circular Muscles

  • Superior constrictor
  • Middle constrictor
  • Inferior constrictor

The space between the base of the skull and the superior constrictor is called as the pharyngobasilar fascia or the SINUS OF MORGAGNI.

Killian’s dehiscence-

The inferior constrictor muscle splits into two- the stylopharyngeus and the cricopharyngeus.

The potential space between these two is called as the Killian’s dehiscence.

Incoordination in the area will lead to – ZENKERS DIVERTICULUM.

Lateral wall of nose

STRUCTURE

Lateral wall of nose has three owing projections called as conchae. These conchae increase the surface area

Lateral wall of the nose is partly made up of bone and partly by cartilage and partly made up of soft tissues

Lateral wall is subdivided into three parts

• Small depressed area in the anterior part is called vestibule which contains short and stiff hair called vibrissae

• Middle part is called as atrium of middle meatus and posterior part contains conchae and space separating conchae are called meatus

Conchae and meatuses

Nasal conchae are curved bony projection which are directed medially and downwards

● Superior concha and middle concha are made up of ethmoid bone and inferior concha is an independent bone

● Meatuses are the passages beneath overhanging conchae. Each meatus will communicate with nasal cavity proper

● Inferior meatus is present underneath the inferior concha and it’s largest of all meatuses. nasolacrimal duct opens into it and it’s opening is guarded by hasner’s valve

● Middle meatus lies underneath the middle concha. Frontal air sinus , anterior ethmoidal air sinus and maxillary sinus opens into it

● Superior meatus lies below the superior concha. It receives openings of Posterior ethmoidal air sinus

● Sphenoethmoidal recess is triangular fossa present just above superior concha it receives opening of sphenoid air sinus

BLOOD SUPPLY

● Anteriosuperior quadrant is supplied by anterior ethmoidal artery and assisted by posterior ethmoidal artery. Anterioinferior quadrant is supplied by branch of facial artery

● Posteriosuperior quadrant supplied by branches of sphenopalatine artery. Posterioinferior quadrant is supplied by greater palatine artery

● Venous drainage : Veins form plexus which anteriorly into facial vein and posteriorly into pharyngeal plexus of veins

● Nerve supply : Anteriosuperior quadrant is supplied by anterior ethmoidal nerve branch of opthalmic nerve. Anterioinferior quadrant is supplied by anterior superior alveolar nerve, branch of infraorbital and continuation of maxillary nerve

● Posteriosuperior quadrant is supplied by lateral posterior superior nasal branches of pterygopalatine ganglion. Posterioinferior quadrant is supplied by anterior palatine branch from pytergopalatine ganglion

Clinical significance

Hypertrophy of mucosa over inferior nasal concha is a common feature of allergic rhinitis which is characterised by sneezing , nasal blockage and excessive nasal discharge from nose. Drugs like Nasal decongestants and antihistamines may be given.

Reference : B.D chaurasia

Tongue (part -2)

Functions of tongue : deglutition, taste sensation, speech, mastication

Blood Supply

●Tongue is mainly supplied by lingual artery branch of external carotid artery, tonsilar branch of facial artery and Ascending pharyngeal artery branch of external carotid artery

● Venous drainage : dorsal lingual veins and deep lingual veins

● Sensory supply: lingual nerve supplies anterior 2/3rd of tongue, glossopharngeal nerve supplies posterior 1/3rd of tongue, Vagus nerve supplies posterior most part of tongue

● Motor supply : All extrinsic and intrinsic muscles of the tongue are supplied by hypoglossal nerve except palatoglossus supplied by vagus nerve

Clinical significance

● Ankyloglossia (tongue tie) : Occurs due to abnormal length of frenulum that extends to the tip of the tongue . Ankyloglossia can be corrected surgically.

● Fissured tongue: Occurs when small furrows present on dorsal surface of the tongue. They are generally painless and benign and often associated with other syndromes

● Geographic tongue: asymptomatic and benign characterized by presence of red patches with greyish white border covering dorsum of tongue

Interesting facts

● An average adult has 2000- 4000 taste buds

● You cannot see your taste buds with naked eye. Those tiny pink and white bumps you see are actually papillae

● Tongue muscles are only muscles in the body working independent of the skeleton

● An oversized tongue is indicative of sleep apnea disorder

● Children sense flavours more intensely compared to adults. Umami is new variant of taste , monosodium glutamate is chemical responsible for this taste

● Women have shorter tongue than men.

● Your tongue is germ free only of its pink. If it is white there is a thin film of bacteria on it

● Blue whale has largest tongue in animal kingdom and weighs 5400lbs

Reference: B.D chaurasia and interesting facts from google