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Anatomy

Mesodermal Origin

Muscles

Innervation

Somitomeres 1, 2

Superior, medial and ventral recti

Oculomotor (III)

Somitomere 3

Superior oblique

Trochlear (IV)

Somitomere 4

Jaw-closing muscles

Trigeminal (V)

Somitomere 5

Lateral rectus

Abducens (VI)

Somitomere 6

Jaw-opening and other 2nd arch muscles

Facial (VII)

Somitomere 7

Stylopharyngeus

Glossopharyngeal (IX)

Somites 1, 2

Intrinsic laryngeals

Vagus (X)

Somites 2-5

Tongue muscles

Hypoglossal (XII)

The Arteries of the Face

  • The superficial arteries are derived from the external carotid arteries.

The Facial Artery

  • This is the chief artery of the face.
  • It arises from the external carotid artery and winds its way to the inferior border of the mandible, just anterior to the masseter muscle.
  • It hooks around the inferior border of the mandible and grooves the bone. Here the artery is superficial, just beneath the platysma and its pulsation can be felt.
  • In its course over the face to the medial angle of the eye, the facial artery crosses the mandible, buccinator muscle, and maxilla.
  • It lies deep to the zygomaticus major.
  • The facial artery ends by sending branches to the lip and side of the nose.
  • The part of the artery that runs along the side of the nose to supply the eyelids is called the angular artery.

The Superficial Temporal Artery

  • This artery is the smaller of the two terminal branches of the external carotid artery (the other is the maxillary artery).
  • It begins deep to the parotid gland, posterior to the neck of the mandible, and ascends superficial to the posterior end of the zygomatic process of the temporal bone. It then enters the temporal fossa.
  • The superficial temporal artery ends in the scalp by dividing into the frontal and parietal branches.
  • Pulsation of this artery can be felt by compressing the root of the zygomatic process of the temporal bone.

The Transverse Facial Artery

  • This small artery arises from the superficial temporal artery before it emerges from the parotid gland.
  • It crosses the face superficial to the masseter muscle, about a fingerbreadth inferior to the zygomatic arch.
  • It divides into numerous branches that supply the parotid gland and duct, the masseter muscle, and the skin of the face.
  • It anastomoses with branches of the facial artery.

The Auditory Ossicles

The Malleus

  • Its superior part, the head, lies in the epitympanic recess.
  • The head articulates with the incus.
  • The neck, lies against the flaccid part of the tympanic membrane.
  • The chorda tympani nerve crosses the medial surface of the neck of the malleus.
  • The handle of the malleus (L. hammer) is embedded in the tympanic membrane and moves with it.
  • The tendon of the tensor tympani muscle inserts into the handle.

The Incus

  • Its large body lies in the epitympanic recess where it articulates with the head of the malleus.
  • The long process of the incus (L. an anvil) articulates with the stapes.
  • The short process is connected by a ligament to the posterior wall of the tympanic cavity.

The Stapes

  • The base (footplate) of the stapes (L. a stirrup), the smallest ossicle, fits into the fenestra vestibuli or oval window on the medial wall of the tympanic cavity.

Functions of the Auditory Ossicles

  • The auditory ossicles increase the force but decrease the amplitude of the vibrations transmitted from the tympanic membrane.

  • Long bones (e.g.. femur and humerus)
  • Short bones (e.g.. wrist and ankle bones)
  • Flat bones (e.g.. ribs)
  • Irregular bones (e.g.. vertebrae)

The Soft Palate

  • This is the posterior curtain-like part, and has no bony support. It does, however, contain a membranous aponeurosis.
  • The soft palate, or velum palatinum (L. velum, veil), is a movable, fibromuscular fold that is attached to the posterior edge of the hard palate.
  • It extends posteroinferiorly to a curved free margin from which hangs a conical process, the uvula (L. uva, grape).
  • The soft palate separates the nasopharynx superiorly and the oropharynx inferiorly.
  • During swallowing the soft palate moves posteriorly against the wall of the pharynx, preventing the regurgitation of food into the nasal cavity.
  • Laterally, the soft palate is continuous with the wall of the pharynx and is joined to the tongue and pharynx by the palatoglossal and palatopharyngeal folds.
  • The soft palate is strengthened by the palatine aponeurosis, formed by the expanded tendon of the tensor veli palatini muscle.
  • This aponeurosis attaches to the posterior margin of the hard palate.

The Auditory Tube

  • This is a funnel-shaped tube connecting the nasopharynx to the tympanic cavity.
  • Its wide end is towards the nasopharynx, where it opens posterior to the inferior meatus of the nasal cavity.
  • The auditory tube is 3.5 to 4 cm long; its posterior 1/3 is bony and the other 2/3 is cartilaginous.
  • It bony part lies in a groove on the inferior aspect of the base of the skull, between the petrous part of the temporal bone and the greater wing of the sphenoid bone.
  • The function of the auditory tube is to equalise pressure of the middle ear with atmospheric pressure.

The Nasopharynx

  • The nasal part of the pharynx has a respiratory function.
  • It lies superior to the soft palate and is a posterior extension of the nasal cavity.
  • The nose opens into the nasopharynx via to large posterior apertures called choanae.
  • The roof and posterior wall of the nasopharynx form a continuous surface that lies inferior to the body of the sphenoid bone and the basilar part of the occipital bone.
  • In the mucous membrane of the roof of the posterior wall of the nasopharynx is a collection of lymphoid tissue, known as the pharyngeal tonsil (commonly known as the adenoids).
  • The pharyngeal orifice of the auditory tube is on the lateral wall of the nasopharynx, 1 to 1.5 cm posterior to the inferior concha, and level with the superior border of the palate.
  • The orifice is directed inferiorly and has a hood-like tubal elevation over it called the torus of the auditory tube or the torus tubarius (L. torus, swelling).
  • Extending inferiorly from the torus is a vertical fold of mucous membrane, known as the salpingopharyngeal fold.
  • The collection of lymphoid tissue in the submucosa of the pharynx, posterior to the orifice of the auditory tube, is known as the tubal tonsil.
  • Posterior to the torus and the salpingopharyngeal fold, there is a slit-like lateral projection of the pharynx called the pharyngeal recess.
  • It extends laterally and posteriorly.

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