NEET MDS Lessons
Anatomy
- 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 Lateral Wall of the Orbit
- This wall is thick, particularly its posterior part, which separates the orbit from the middle cranial fossa.
- The lateral wall is formed by the frontal process of the zygomatic bone and the greater wing of the sphenoid bone.
- Anteriorly, the lateral wall lies between the orbit and the temporal fossa.
- The lateral wall is partially separated from the roof by the superior orbital fissure.
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.
Vessels of the Palate
- The palate has a rich blood supply from branches of the maxillary artery.
Stylohyoid Muscle
- Origin: Posterior border of the styloid process of the temporal bone.
- Insertion: Body of the hyoid bone at the junction with the greater horn.
- Nerve Supply: Facial nerve (CN VII).
- Arterial Supply: Muscular branches of the facial artery and muscular branches of the occipital artery.
- Action: Elevates the hyoid bone and base of the tongue.
The Meatus of the Nose
Sphenopalatine Recess
- This space is posterosuperior to the superior concha.
- The sphenoidal sinus opens into this recess.
Superior Meatus
- This is a narrow passageway between the superior and middle nasal conchae.
- The posterior ethmoidal sinuses open into it by one or more orifices.
Middle Meatus
- This is longer and wider than the superior one.
- The anterosuperior part of this meatus lead into a funnel-shaped opening, called the infundibulum, through which the frontonasal duct leads to the frontal sinus.
- There is one duct for each frontal sinus and since there may be several, there may be several frontonasal ducts.
- When the middle concha is removed, rounded elevation called the ethmoidal bulla (L. bubble), is visible
- The middle ethmoidal air cells open on the surface of the ethmoidal bulla.
- Inferior to this bulla is a semicircular groove called the hiatus semilunaris.
- The frontal sinus opens into this hiatus anterosuperiorly.
- Near the hiatus are the openings of the anterior ethmoid air cells.
- The maxillary sinus also opens into the middle meatus.
Inferior Meatus
- This is a horizontal passage, inferolateral to the inferior nasal concha.
- The nasolacrimal duct opens into the anterior part of this meatus.
- Usually, the orifice of this duct is wide and circular.
The Temporomandibular Joint
- This articulation is a modified hinge type of synovial joint.
- The articular surfaces are: (1) the head or condyle of the mandible inferiorly and (2) the articular tubercle and the mandibular fossa of the squamous part of the temporal bone.
- An oval fibrocartilaginous articular disc divides the joint cavity into superior and inferior compartments. The disc is fused to the articular capsule surrounding the joint.
- The articular disc is more firmly bound to the mandible than to the temporal bone.
- Thus, when the head of the mandible slides anterior on the articular tubercle as the mouth is opened, the articular disc slides anteriorly against the posterior surface of the articular tubercle
3 basic functions
o protection of respiratory tract during swallowing food/air pathways cross.
epiglottis provides protection
o control intra-thoracic pressure (in coughing) - close off airway to build pressure then rapidly open to release stuff
o production of sound (in speaking, singing, laughing)
Important structures
o hyoid bone
o thyroid cartilage
o arytenoids cartilage: vocal and muscle process
sits on slope on posterior side of cricoid - spin and slide
o cricoid cartilage: signet ring
o thyroepiglottic ligament
Membranes and ligaments
o membrane: general; ligament: thickening of membrane
o folds: free edges of membranes or ligaments
o names: tell you where located
Important membranes:
quandrangular/vestibular membrane—from epiglottis to arytenoids
• inferior edge: false vocal fold
thyrohyoid membrane
conus elasticus = cricothyroid = cricovocal
• superior/medial edge = vocal fold
• vocal ligaments: true folds, top of cricothyroid membrane