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Anatomy

Levator Palpebrae Superioris Muscles

  • This is a thin, triangular muscle that elevates the upper eyelid.
  • It is continuously active except during sleeping and when the eye is closing.
  • Origin: roof of orbit, anterior to the optic canal.
  • Insertion: this muscle fans out into a wide aponeurosis that inserts into the skin of the upper eyelid. The inferior part of the aponeurosis contains some smooth muscle fibres that insert into the tarsal plate.
  • Innervation: the superior fibres are innervated by the oculomotor nerve (CN III), and the smooth muscle component is innervated by fibres of the cervical sympathetic trunk and the internal carotid plexus.

 

Illnesses involving the Levator Palpebrae Superioris

  • In third nerve palsy, the upper eyelid droops (ptosis) and cannot be raised voluntarily.
  • This results from damage to the oculomotor nerve (CN III), which supplies this muscle.
  • If the cervical sympathetic trunk is interrupted, the smooth muscle component of the levator palpebrae superioris is paralysed and also causes ptosis.
  • This is part of Horner's syndrome.

 

The Rectus Muscles

 

  • There are four rectus muscles (L. rectus, straight), superior, inferior, medial and lateral.
  • These arise from a tough tendinous cuff, called the common tendinous ring, which surrounds the optic canal and the junction of the superior and inferior orbital fissures.
  • From their common origin, these muscles run anteriorly, close to the walls of the orbit, and attach to the eyeball just posterior to the sclerocorneal junction.
  • The medial and lateral rectus muscles attach to the medial and lateral sides of the eyeball respectively, on the horizontal axis.
  • However, the superior rectus attaches to the anterosuperior aspect of the medial side of the eyeball while the inferior rectus attaches to the anteroinferior aspect of the medial side of the eye.

 

The Oblique Muscles

The Superior Oblique Muscle

  • This muscle arises from the body of the sphenoid bone, superomedial to the common tendinous ring.
  • It passes anteriorly, superior and medial to the superior and medial rectus muscles.
  • It ends as a round tendon that runs through a pulley-like loop called the trochlea (L. pulley).
  • After passing though the trochlea, the tendon of the superior oblique turns posterolaterally and inserts into the sclera at the posterosuperior aspect of the lateral side of the eyeball.

 

The Inferior Oblique Muscle

  • This muscle arises from the maxilla in the floor of the orbit.
  • It passes laterally and posteriorly, inferior to the inferior rectus muscle.
  • It inserts into the sclera at the posteroinferior aspect of the lateral side of the eyeball.

The Middle Ear

 

  • This part of the ear is in a narrow cavity in the petrous part of the temporal bone.
  • It contains air, three auditory ossicles, a nerve and two small muscles.
  • The middle ear is separated from the external acoustic meatus by the tympanic membrane.
  • This cavity includes the tympanic cavity proper, the space directly internal to the tympanic membrane, and the epitympanic recess, the space superior to it.
  • The middle ear is connected anteriorly with the nasopharynx by the auditory tube.
  • Posterosuperiorly, the tympanic cavity connects with the mastoid cells through the aditus ad antrum (mastoid antrum).
  • The tympanic cavity is lined with mucous membrane that is continuous with the mucous membrane of the auditory tube, mastoid cells, and aditus ad antrum.

Contents of the Tympanic Cavity or Middle Ear

  • This cavity contains the auditory ossicles (malleus, incus and stapes); the stapedius and tensor tympani muscles; the chorda tympani nerve (a branch of the facial nerve, CN VII); and the tympanic plexus of nerves.

Superior Constrictor Muscle

  • Origin: Hamulus, pterygo-mandibular raphe, and mylohyoid line of the mandible.
  • Insertion: Median raphe of the pharynx.
  • Nerve Supply: Vagus nerve via the pharyngeal plexus.
  • Arterial Supply: Ascending pharyngeal artery, ascending palatine artery, tonsillar branch of the facial artery, and dorsal branch of the lingual artery.
  • Action: Constricts the wall of the pharynx during swallowing.

 
Anterior 2/3 of tongue Posterior 1/3 of tongue
Motor Innervation All muscles by hypoglossal nerve (CN XII) except palatoglossus muscle (by the pharyngeal plexus)
General Sensory Innervation
Lingual nerve (branch of mandibular nerve CN V3) Glossopharyngeal nerve (CN IX)
Special Sensory Innervation
Chorda tympani nerve (branch of facial nerve) Glossopharyngeal nerve (CN IX)

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

Histology

Histology is the study of tissues.

A tissue is a group of cells with similar structure and function plus the extracellular substances located between the cells.

There are four basic types of tissues:

- Epitheliums

- Connective tissue

- Muscle tissue

- Nervous tissue

The Lips

  • These are mobile muscular folds that surround the mouth, the entrance of the oral cavity.
  • The lips (L. labia) are covered externally by skin and internally by mucous membrane.
  • In between these are layers of muscles, especially the orbicularis oris muscle.
  • The upper and lower lips are attached to the gingivae in the median plane by raised folds of mucous membrane, called the labial frenula.

Sensory Nerves of the Lips

  • The sensory nerves of the upper and lower lips are from the infraorbital and mental nerves, which are branches of the maxillary (CN V2) and mandibular (CN V3) nerves.

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