Week 5: ENT 2 (anatomy of nose, mouth and throat) Flashcards
function of the nose
- Smell and taste
- Breathing- route for inspired air
- Filters inspired air trapping particle sin nasal hair and mucous
- Moistens (humidifies) and warms
- Resonating chamber for speech
anatomy of the nasal cavity
- External nose (vestibule) from the external nose to the nasopharynx
- Anterior nares= nostrils (apertures)
- Posterior nasal apertures (choanae)
external nose
- Made up of cartilage (near the nostrils) and bone
- Important bone = nasal bone (paired bone)
- Clinical correlates
- Prominence of nasal bone makes them susceptible to fracture in facial injury
vestibule
Lined with skin containing sebaceous/sweat glands and hair filters inspired air
nasal cavity
Has bony boundaries and is divided into left and right by midline septum
the nose has 2 lateral walls - describe their structure
- Irregular due to presence of bony projections (conchae/ turbinate’s)
- Superior (part of ethmoid)
- Middle (part of ethmoid)
- Inferior (other bone
- These creates meatuses
- Superior
- Middle
- Inferior
opening sunder the meatuses allows for
drainage of the
- Paranasal air sinus in nasal cavity
- Nasolacrimal duct in nasal cavity
Why does the nose have this irregular anatomy?
- slows airflow by causing turbulence of airflow
- increases surface area over which air passes
- doesn’t always require immediate intervention
bones whcih form the food of the nasal cavity
frontal bone
nasal bone
ethmoid bone (cribriform plate)
sphenoid
the nasal roof can be used to
access parts of the brain found ont he cranial floow
e.g. Transsphenoidal surgical approach- e.g. gaining access to the pituitary gland via the sphenoid bone
medial wall of the nasal cavity- the septum
- Consists of a bony and cartilaginous part
- Anterior= septal cartilage
- Posterior= perpendicular plate of the ethmoid bone and the vomer bone
if you dont treat a septal heamtoma what forms and why
saddle nose deformity
untreated septal haematoma e.g. caused by trauma leads to avascular necrosis of cartilaginous septum
nerve innervation of the nasal cavity
- V1- Ophthalmic
-
V2- Maxillary
- Majority of nasal cavity (particularly lateral wall) supplies by V2
- V3- mandibular
lining of the nasal vaity
Vestibule lined by skin
Deeper lined with mucus membrane - very vascular
- olfactory region
- respiratory region
olfactory region
- Olfactory mucous membrane
- Contains dendrites of olfactory nerves
- Covers over roof of the nasal cavity (including superior concha/superior part of the septum)
- Contains dendrites of olfactory nerves
Respiratory mucous membrane
- Pseudostratified columnar epithelium
- Rich in goblet cells
- Filters (mucous and cilia)
- Humidifies and warms(rich blood supply)
Rich blood supply to the nasal mucosa
Allows for warming and humidification of inspired air
- Mucosa and blood vessels are easily injured
- Nose bleed (epistaxis)
arterial supply of the nose includes
ophthalmic artery
maxillary artery
ophthalmic artery blood supply to the nose
Ethmoidal arteries (anterior and posterior)
- feed into Little’s / kiesselbachs plexus
maxillary artery branches supplying the nose
- Form a rich arterial anastomoses in the anterior septum (Keisselbachs plexus)
- Most common source of bleeding in epistaxis (e.g. picking of nose)
- Easily treatable with simple first aid measure- pinching nose
- Usually just one sided
-
Sphenopalatine artery
- Small proportion of nosebleeds
- Potentially more serious and difficult to reach(harder to reach to tamponade
- Bleeding in both nostrils
- Small proportion of nosebleeds
venous drainage of npse
- Form a rich arterial anastomoses in the anterior septum (Keisselbachs plexus)
- Most common source of bleeding in epistaxis (e.g. picking of nose)
- Easily treatable with simple first aid measure- pinching nose
- Usually just one sided
-
Sphenopalatine artery
- Small proportion of nosebleeds
- Potentially more serious and difficult to reach(harder to reach to tamponade
- Bleeding in both nostrils
*
- Small proportion of nosebleeds
paranasal sinuses: name
1. Frontal air sinuses (can have 2,3 or 4)
2. Ethmoid air sinuses
3. Maxillary air sinuses- most common infection due to gravity and draining mucus
4. Sphenoidal air sinuses
what are paranasal sinuses
- Air filled spaces that are extension of the nasal cavity
- Rudimentary or absent at birth
- Lined with respiratory mucosa
- Ciliated and secretes mucous
- Named according to the bone in which they are found
- Various functions – humidify and warm inspired air
- Reduce weight of the skull
- Drain into the nasal cavity via small channels (ostia in middle conchia) into a meatus
- Most in the middle meatus
- Infection of nasal cavity involving sinuses (sinusitis)
- Maxillary sinus most commonly infected
importnant anatomical relations of paranasal sinuses include
nasal cavity, orbit and anteriro cranial foss
- roots of upper teeth can progest into maxiallary sinus
sensory innervation of paranasal sinuses
from the trigeminal (V)
- Va (frontal, ethmoidal and sphenoid sinus)
- Vb (maxillary sinus)
Nasal cavity separate to oral cavity=
the hard and soft palate
- Tip of soft palate= uvula
how many teeth
32
area between lips and teeth
vestibule
palatoglossal and palatopharyngeal arches
(Mc Donald’s signs)
- Where tonsils sit within
salivary glands
x3 paiers
- parotid
- submandibular
- sublingual
parotid glands
- Lies anterior to the SCM and ear
- Behind the masseter and zygomatic arch
- Duct opens up in the upper region of the oral cavity- Stenson’s duct (near upper 2nd molar)
- produces 25% of all saliva
- serous consistency with lots of enzymes
sublingual gland
- Lie under the tongue
- 5% of saliva
- More mucous saliva and less enzymes than the parotid gland
submandibular gland
- Sits below the mandible and in submandibular triangle
- Produces a mixed saliva
- Serous
- Mucous
- Biggest contributor volume wise- 70% of all saliva
production of saliva
Exocrine structure of the salivary gland
- Acinus is where the saliva is produced
- Isotonic with plasma
- Isotonic solution passes out of the acinus due to myoacinus epithelial cells which contract the acinus to move saliva into the duct
- Once in the ductal region , ductal cells use transporters to move Na+ and Cl- out of the solution and K+ and HCO3- into the solution
- Producing a hypotonic solution near the end of the duct (removal of ions >secretion)
- The amount of modification by the ductal cells depends on how quickly the saliva is moving through the ductal system
- Basal level- most hypotonic solution
- When eating the solution moves through much quicker, less contact with ductal cells- smallest change to the tonicity of the isotonic solution (more secretion of HCO3- when active saliva production
tongue made up of
intrinsic and extrinsic muscles
intrinsic muscles of the tongue
- Intrinsic muscle (not attached to other muscles except other intrinsic muscles)
- 4 pair muscles
- Longitudinal
- Transverse
- vertical
- Motor innervation – hypoglossal nerve
- 4 pair muscles
extrinsic muscles of the tongue
- arise from other structures and insert into tongue
- Genioglossus
- Hyoglossus
- Styloglossus
- Motor innervation: hypoglossal nerve
- Palatoglossus
- Motor innervation (vagus nerve)
sensory supply of the tongue
- Divides tongue into
- Anterior 2/3
- Sensation- trigeminal (V3)
- Taste- facial
- Posterior 1/3
- Sensation and tase- glossopharyngeal
- Anterior 2/3
throat - pharynx divided into
-
Nasopharynx
- Behind nasal cavity
-
Oropharynx
- Behind oral cavity
-
Laryngopharynx
- Behind larynx
the nasopharynx- upper pharynx
- Pink part in the photo
- Behind the nasal cavity
- borders
- Base of skull- upper border
- C1,C2- posterior border
- Nasal cavity- anterior border
- Contains
- Pharyngeal tonsil e.g. adenoids
- glossopharangeal sensory supply
the oropharynx- middle pharnx
- Yellow part on photo
- Starts where the nasopharynx end
- Borders
- Soft palate to epiglottis
- Anterior- oral cavity
- Posterior (C2,C3)
- Contains
- Palatine tonsils
- glossopharangeal supply
palatine tonsils
collection of lymphoid tissue in the oropharyngeal mucosa. They form part of Waldeyer’s ring
function: preventing infection in the respiratory and digestive tracts by producing antibodies (B and T cells) that help kill infective agents
laryngopharynx- lower pharynx
- Blue part on photos
- Borders
- Oropharynx to oesophagus
- Epiglottis to cricoid cartilage
- Anterior- larynx
- Posterior (C4, C5, C6)
- Contains
- Piriform fossa
- pharyngeal branches of the vagus nerve
piriform fossa
Epiglottis (flap on right photo) acts as a director of flow of fluid and water into the piriform fossa into the oesophagus instead of the trachea
General overview of muscle arrangements in the pharynx
3x longitudinal muscles
- Stylopharyngeus
- Palatopharyngeus
- Salpingopharygeus
3x constrictors (circular)
Stylopharyngeus
- Originates from the styloid process and goes down to the posterior border of the thyroid cartilage
- Innervation- glossopharyngeal nerve (CN IX)
palatopharyngeys
- Originates from the hard palate and extends down to the attach to the posterior border of the thyroid gland
- Pharyngeal branch of vagus (CN X)
salpingopharyngeaus
- Originates from the cartilaginous part of ET- merges with the palatopharyngeus
- Pharyngeal branch of vagus (CN X)
Pharyngeal constrictors
X3 circular (more semi-circular) muscles all insert on the pharyngeal raphe)
- Superior pharyngeal constrictor
- Origin – pterygomandibular raphe
- Middle pharyngeal constrictor
- Origin- hyoid bone
- Inferior
- 2 parts
- Thyropharyngeal (origin- thyroid cartilage)
- Cricopharyngeal (origin- cricoid cartilage
- 2 parts
- All supplies by the vagus nerve
aim of pharngeal constrictors
- Constrict walls of pharynx when swallowing
General overview of nerve innervation of pharynx
-
Pharyngeal plexus
- Located mainly on surface of middle constrictor muscle
- Vagus, glossopharyngeal and cervical sympathetic nerve
-
Motor
- CNX -Vagus innervates all muscles
- Except stylopharyngeus (glossopharyngeal nerve (CN IX))
- CNX -Vagus innervates all muscles
-
Sensory
- Nasopharynx (glossopharyngeal nerve CN IX)
- Oropharynx ( glossopharyngeal nerve CN IX)
- Laryngopharynx (vagus nerve CNX)
swallowing
1) Oral stage
- Voluntary
- Tongue touching hard-palate
2) Pharyngeal phase
- Involuntary
- Tongue touching hard palate
- Soft palate elevation
- Dangerous stage- shared airway space
- Need to protect airway
- By shortening longitudinal muscles- elevate larynx and pharynx→ widening it
- Closure of epiglottis (sealing the airway)
- Need to protect airway
3) Oesophageal phase
- Relaxes upper oesophageal sphincter
- Rapid peristalsis
- Lower oesophageal sphincter relaxes and bolus goes into stomach
