The normal ear Flashcards
Name the 3 parts of the mammalian ear
- External (pinna and external ear canal)
- Middle (tympanic cavity/ membrane. bulla, ossicles (bones) connected to the nasopharynx)
- Inner ear (contained within petrous temporal bone)
Describe the external ear
- Auricular cartilage
- Scutiform
- Annular cartilage
- Bone acoustic process(ligament attaches here)
Describe the vasculature of the ear
- Auricular arteries (branch from the internal carotid)
- Venous drainage to internal maxillary vein
Which nerves give motor control to the muscles of the ear?
CN VII facial nerve -auriculopalpebral branch
Which nerves give sensory innervation to the ear?
- Branch of Cranial nerve 5 (trigeminal)
- Cervical segmental C2
Where is Henri’s pocket located?
On the caudal aspect of the pinna
What type of epidermis covers the external ear?
Thin, stratified keratinising
What is cerumen?
Secretion of the ear canal Contains: -Exfoliated cells -Sebaceous secretions -Ceruminous gland -secretion (aqueous) -Immunoglobulins (mainly IgG) -Lipid content= 50%
Describe the tympanic membrane
-Made of epithelium-stratified keratinising laterally and cuboidal mucosal medially.
In which species is there limited vision otoscopially of the tympanic membrane?
The horse
In which region of the tympanic membrane is the pars flaccida?
Dorsorostrally- adjacent to edge of malleus
What are the 3 compartments of the middle ear?
Epitympanum
Mesotympnum
Hypotympanum (fundus)
What is different about the middle ear of the cat?
Have an incomplete bony septum
What type of epithelium is found in the auditory tube?
-Pseudostratified, ciliated, columnar epithelium
What is the topographical course of cranial nerve 7?
Enters petrosal bone through the internal acoustic meatus and runs inside the facial canal
Emerges through stylomastoid foramen
