Intro/Outer Ear Flashcards
What landmark does the Squamous portion of the temporal bone contain? What shape is this portion? Where is it located?
Fan shaped portion that contains mandibular fossa (articulation for condylar process of mandible). It is superior to the external auditory meatus.
What landmarks does the Tympanic portion of the temporal bone contain? Where is it located?
Contains the opening for the external auditory meatus and styloid process. The lateral portion forms the external auditory canal. The tympanic portion is anterior and inferior to the external auditory meatus.
What landmarks does the Mastoid portion of the Temporal bone contain? Where is it located?
Contains mastoid process and air cells. It is posterior to the external auditory meatus.
What landmarks does the Petrous portion of the Tympanic bone contain? Where is it located? What are some features of this portion?
Contains the labryinth of cochlea, vestibular system, portions of VII, & VIII nerves, carotid canal, and jugular fossa. It is located medial to external auditory meatus. It is triangular in shape and is the hardest bone in the body.
What structures does the temporal bone encase?
Portion of external ear, middle ear, and inner ear, including the cochlea and vestibular apparatus and the seventh and eighth nerves.
Why is the term labyrinth used to describe the bony structure of the temporal bone?
It has cavities, channels and canals that house the end organs of hearing and balance (sense organs).
What is the bony labyrinth?
Provides support and protection for the delicate anatomical structures of hearing and balance.
What is the membranous labyrinth/
Contained within bony labyrinth, contains fluids and sense organs of hearing and balance.
What are the five bones that each temporal bone articulates with?
Sphenoid, mandible, occipital, ipsilateral parietal, and zygomatic.
What is the temporomandibular joint? What is pain in this joint confused with?
The articulation between the condylar process of the mandible and the mandibular fossa of the temporal bone- only movable joint between bones of the skull. Pain here can be confused with ear ache.
What is the first portion of the auditory system? What are it’s two parts?
The outer ear; it consists of the pinna/auricle and the external auditory meatus/ear canal.
What is the consistency of the auricle/pinna?
Fibrous cartilage covered with skin.
How many auricular muscles are there?
3 extrinsic, 6 intrinsic.
What are the three extrinsic auricular muscles?
Anterior, superior, and posterior muscles attach to the auricle and serve little/no function in humans.
What are the intrinsic auricular muscles?
6 muscles that contribute to the shape of the pinna.
What are the auricular muscles innervated by?
Branches of the facial nerve (VII).
What is the external auditory meatus? What is it’s role?
The tube like structure that conducts sound to the middle ear.
What is the diameter of the external auditory meatus? What shape is it?
Measures 2.5-3 cm in length ~1 in. 7-8 mm in diameter. It is larger at orifice and decreases as it approaches isthmus, where it opens up again to increase in diameter. Oval in shape.
What is the cartilaginous portion of the EAM? What shape does it take?
The lateral one-third to one-half of the EAM. Assists in diameter change with movement of mandible and pulling on auricle.
What does the subepithelial stroma contain?
Rich blood supply, hair follicles and ceruminal glands.
What are the two glands of the cartilaginous portion of the EAM?
Sebaceous, which produces oily substance that lubricates the canal, and ceruminous glands.
What is the epidermal lining of the EAM?
Covers ear canal and forms the lateral-most layer of the tympanic membrane.
What is the isthmus of the ear canal?
A constriction, which marks the junction of the cartilaginous framework with the bony framework.
What is the bony portion of the EAM? What is it formed by?
The medial one-half to two-thirds of the EAM. Formed by the tympanic portion of the temporal bone (floor and anterior wall, and inferior posterior wall of canal), the squamous portion of the temporal bone (roof and portion of the posterior wall), and the condoyle of the mandible (inferior anterior wall of canal at TMJ joint).
