Muscles of the Pharynx

• This consists of three constrictor muscles and three muscles that descend from the styloid process, the cartilaginous part of the auditory tube and the soft palate.

External Muscles of the Pharynx 

• The paired superior, middle, and inferior constrictor muscles form the external circular part of the muscular layer of the wall.
• These muscles overlap each other and are arranged so that the superior one is innermost and the inferior one is outermost.

• These muscles contract involuntarily in a way that results in contraction taking place sequentially from the superior to inferior end of the pharynx.
• This action propels food into the oesophagus.

• All three constrictors of the pharynx are supplied by the pharyngeal plexus of nerves, which lies on the lateral wall of the pharynx, mainly on the middle constrictor of the pharynx.
• This plexus is formed by pharyngeal branches of the glossopharyngeal (CN IX) and vagus (CN X) nerves.

The Superior Constrictor Muscle

• Origin: pterygoid hamulus, pterygomandibular raphe, posterior end of the mylohyoid line of the mandible, and side of tongue.
• Insertion: median raphe of pharynx and pharyngeal tubercle.
• Innervation: though the pharyngeal plexus of nerves.

• The pterygomandibular raphe is the fibrous line of junction between the buccinator and superior constrictor muscles.

The Middle Constrictor Muscle

• Origin: stylohyoid ligament and greater and lesser horns of hyoid bone.
• Insertion: median raphe of pharynx.
• Innervation: through the pharyngeal plexus of nerves.

The Inferior Constrictor Muscle

• Origin: oblique line of thyroid cartilage and side of cricoid cartilage.
• Insertion: median raphe of pharynx.
• Innervation: through the pharyngeal plexus of nerves.

• The fibres arising from the cricoid cartilage are believed to act as a sphincter, preventing air from entering the oesophagus. 

Gaps in the Pharyngeal Musculature

• The overlapping arrangement of the three constrictor muscles leaves 4 deficiencies or gaps in the pharyngeal musculature.
• Various structures enter and leave the pharynx through these gaps.

• Superior to the superior constrictor muscle, the levator veli palatini muscle, the auditory tube, and the ascending palatine artery pass through a gap between the superior constrictor muscle and the skull.
• Superior to the superior border of the superior constrictor, the pharyngobasilar fascia blends with the buccopharyngeal fascia to form, with the mucous membrane, the thin wall of the pharyngeal recess.

• Between the superior and middle constrictor muscles, the gateway to the mouth, though which pass the stylopharyngeus muscle, the glossopharyngeal nerve (CN IX), and the stylohyoid ligament.

• Between the middle and inferior constrictor muscles, the internal laryngeal nerve and the superior laryngeal artery and vein pass to the larynx.

• Inferior to the inferior constrictor muscles, the recurrent laryngeal nerve and inferior laryngeal artery pass superiorly into the larynx.

Classified on functional Basis

Secretion ,Protection and waterproofing, Absorbtion, Transport, Sensory

Secretion

Glandular epithelium’s 3 types:

- Exocrine - with ducts

- endocrine - without ducts

- mixed exo-endocrine

Exocrine glands: One cell

- goblet cells

- In lining epitheliums of respiratory tract and GIT

- Secretes musin (protein) Musin + water = mucus, Mucus is a lubricant

More than one cell

 Simple:  Has a single duct,

• Acinar - mucus glands of the penile urethra
• Tubular - cripts of Lieberkuhn
• Coiled tubular - sweat gland
• Spiral tubular - Gland of Moll
• Branched tubular - mucous glands of the pyloric region
• Branched acinar - sebaceous gland in the skin

Compound

• Consists of a branched duct with numerous secretory end organs
• Compound tubular - Brünners glands
• Compound alveolar - mammary, prostate, pancreas, parotid
• Compound tubuloalveolar - submandibular-, sublingual salivary glands

Endocrine glands

Secrete directly into the blood

One cell :  mast cells,  in soft CT,  near capillaries,

secrete - heparin - histamine

More than one cell

Cells can be arranged in the following ways:

• Cords - adrenal glands, parathyroid, anterior pituitary
• anastomosing cords with dilated blood capillaries in-between
• Isles - pancreas
• Follicles - thyroid
• cells line a follicle filled with non-cellular material

The Ear

• The ear contains the vestibulocochlear organ and consists of three main parts: external, middle, and internal.
• It has two functions, balance and hearing.

• The tympanic membrane (eardrum) separates the external ear from the middle ear.
• The auditory tube joins the middle ear or tympanic cavity to the nasopharynx.

The Lateral Pterygoid Muscle

• This is a short, thick muscle that has two heads or origin.
• It is a conical muscle with its apex pointing posteriorly.

• Origin: superior head—infratemporal surface and infratemporal crest of the greater wing of the sphenoid bone, inferior head—lateral surface of lateral pterygoid plate.
• Insertion: neck of mandible, articular disc, and capsule of temporomandibular joint.
• Innervation: mandibular nerve via lateral pterygoid nerve from anterior trunk, which enters it deep surface.

• Acting together, these muscles protrude the mandible and depress the chin.
• Acting alone and alternately, they produce side-to-side movements of the mandible.

Ligaments of the Joint

• The fibrous capsule is thickened laterally to form the lateral (temporomandibular) ligament. It reinforces the lateral part of this capsule.
• The base of this triangular ligament is attached to the zygomatic process of the temporal bone and the articular tubercle.
• Its apex is fixed to the lateral side of the neck of the mandible.

• Two other ligaments connect the mandible to the cranium but neither provides much strength.

• The stylomandibular ligament is a thickened band of deep cervical fascia.
• It runs from the styloid process of the temporal bone to the angle of the mandible and separates the parotid and submandibular salivary glands.

• The sphenomandibular ligament is a long membranous band that lies medial to the joint.
• This ligament runs from the spine of the sphenoid bone to the lingula on the medial aspect of the mandible.

Nerves of the Palate

• The sensory nerves of the palate, which are branches of the pterygopalatine ganglion, are the greater and lesser palatine nerves.
• They accompany the arteries through the greater and lesser palatine foramina, respectively.

• The greater palatine nerve supplies the gingivae, mucous membrane, and glands of the hard palate.

• The lesser palatine nerve supplies the soft palate.

• Another branch of the pterygopalatine ganglion, the nasopalatine nerve, emerges from the incisive foramen and supplies the mucous membrane of the anterior part of the hard palate.