The Eye and Orbit

• The orbit (eye socket) appears as a bony recess in the skull when it is viewed from anteriorly.
• It almost surrounds the eye and their associated muscles, nerves and vessels, together with the lacrimal apparatus.

• The orbit is shaped somewhat like a four-side pyramid lying on its side, with its apex pointing posteriorly and its base anteriorly.

Intrinsic muscles

    all innervated by recurrent laryngeal nerve except cricothyroid: external laryngeal nerve
    adductors of vocal folds: bring folds together at midline

    Transverse and oblique arytenoids: pull arytenoids together
    Lateral cricoartenoids: spin and slide arytenoids up
    only one abductor of vocal folds
    
    Posterior cricoarytenoids—down and up
    adjustors of shape and tension of vocal folds

    Cricothyroid muscle
    
o    superficial to lateral cricoarytenoid
o    tenses vocal folds by tilting thyroid cartilage forward and sliding forward

    Thyroartenoid and vocalis muscles
    
o    vocalis: sometimes treated as medial most fibers of thyroartenoid muscle
o    different fiber directions
    
    lateral: adduct
    medial: change shape of folds
    control voice by bring bringing together different parts of folds

o    as move from epithelium to vocalis muscle, fold becomes stiffer
o    near connections, vocal folds are stiffer
o    vocal fold: complex, multilayered vibrator

Internal Ear

• Osseous labyrinth: a complex system of cavities in the substance of the petrous bone.
• Membranous labyrinth: filled with endolymph, bathed in perilymph.

The Frontalis Muscle

• The frontalis muscle is part of the scalp muscle called the occipitalfrontalis.
• The frontalis elevates the forehead, giving the face a surprised look, and produces transverse wrinkles in the forehead when one frowns.

• Articulations

  Classified according to their structure, composition,and movability
  •    Fibrous joints-surfaces of bones almost in direct contact with limited movement
      o    Syndesmosis-two bones united by interosseous ligaments
      o    Sutures-serrated margins of bones united by a thin layer of fibrous tissue
      o    Gomphosis-insertion of a cone-shaped process into a socket

  •    Cartilaginous joints-no joint cavity and contiguous bones united by cartilage
      o    Synchondrosis-ends of two bones approximated by hyaline cartilage
      o    Symphyses-approximating bone surfaces connected by fibrocartilage

  •    Synovial joints-approximating bone surfaces covered with cartilage; may be separated by a disk; attached by ligaments 
      o    Hinge-permits motion in one plane only
      o    Pivot-permits rotary movement in which a ring rotates around a central axis
      o    Saddle-opposing surfaces are convexconcave. allowing great freedom of motion
      o    Ball and socket - capable of movement in an infinite number of axes; rounded head of one bone moves in a cuplike cavity of the approximating bone

  Bursae
  •    Sacs filled with synovial fluid that are present where tendons rub against bone or where skjn rubs across bone
  •    Some bursae communicate with a joint cavity 
  •    Prominent bursae found at the elbow. hip, and knee'

  Movements
  •    Gliding
      o    Simplest kind of motion in a joint
      o    Movement on a joint that does not involve any angular or rotary motions
  •    Flexion-decreases the angle formed by the union of two bones
  •    Extension-increases the angle formed by the union of two bones
  •    Abduction-occurs by moving part of the appendicular skeleton away from the median plane of the body
  •    Adduction-occurs by moving part of the appendicular skeleton toward the median plane of the body
  •    Circumduction
      o    Occurs in ball-and-socket joints
      o    Circumscribes the conic space of one bone by the other bone
  •    Rotation-turning on an axis without being displaced from that axis
   

Internal Muscles of the Pharynx

• The internal, chiefly longitudinal muscular layer, consists of 3 muscles: stylopharyngeus, palatopharyngeus, and salpingopharyngeus.
• They all elevate the larynx and pharynx during swallowing and speaking.

The Stylopharyngeus Muscle

• This is a long, thin, conical muscles that descends inferiorly between the external and internal carotid arteries.
• It enters the wall of the pharynx between the superior and middle constrictor muscles.

• Origin: styloid process of temporal bone.
• Insertion: posterior and superior borders of thyroid cartilage with palatopharyngeus muscle.
• Innervation: glossopharyngeal nerve (CN IX).

• It elevates the pharynx and larynx and expands the sides of the pharynx, thereby aiding in pulling the pharyngeal wall over a bolus of food.

The Palatopharyngeus Muscle

• This is a thin muscle and the overlying mucosa form the palatopharyngeal arch.

The Salpingopharyngeus Muscle

• This is a slender muscle that descends in the lateral wall of the pharynx.
• The over lying mucous membrane forms the salpingopharyngeal fold.

• Origin: cartilaginous part of the auditory tube.
• Insertion: blends with palatopharyngeus muscle.
• Innervation: through the pharyngeal plexus.

• It elevates the pharynx and larynx and opens the pharyngeal orifice of the auditory tube during swallowing.