Bones - Temporal Bone Flashcards
Anatomical structure of the temporal bone
Made up of how 5 parts, what are they?
1) Squamous
2) Zygomatic process
3) Tympanic
4) Styloid process
5) Petromastoid
The squamous part of the temporal bone
Surfaces?
Articulations with other bones?
Surfaces:
1) Temporal
2) Cerebral
Articulates with the sphenoid bone anteriorly and the parietal bone laterally.
The zygomatic process of the temporal bone
Bony landmarks?
Articulations?
1) Zygomatic process - arises from the lower part of squamous temporal bone - projects anteriorly - articulates with the temporal process of the zygomatic bone to form the zygomatic (palpable as the cheek bones).
2) Articular tubercle - located anterior to the boundary of the mandibular fossa, part of the temporomandibular joint.
3) Masseter muscle - one of the origins for this muscle is located on the lateral surface of the zygomatic process.
Tympanic part of the temporal bone
Location?
Bony landmarks?
Inferior to the squamous portion of the temporal bone and anterior to the petromastoid part of the bone.
It surrounds the external auditory opening, which leads into the external acoustic meatus of the external ear.
Styloid process of the temporal bone
Location?
Purpose?
Associated foramina?
Located immediately inferior to the external auditory opening.
Acts as a site of attachment for ligaments and muscles, such as the stylomandibular ligament of the TMJ.
Just posterior to the styloid process is the stylomastoid foramen - allows passage for the facial nerve and stylomastoid artery and vein.
Petromastoid part of the temporal bone
Bony landmarks?
Purpose?
Clinical relevance?
Foramina?
The petromastoid part can be separated into the petrous part of the temporal bone and the mastoid process.
On the lateral view, only the mastoid process can be observed - it is a site of attachment of many muscles, including the sternocleidomastoid.
Clinical importantance - mastoid air cells are located within the mastoid process - they act as a resevoir of air to equalise the pressure between the middle ear and the atmosphere in the case of auditory dysfunction with the auditory tube.
If the air cells become infected (mastoiditis) this is a medical emergency.
Just posterior to the mastoid process is the mastoid foramen (mastoid branch of the occipital artery and the mastoid emmissary vein) that can also be seen on the medial view where the groove for the sigmoid sinus is located.
The petrous part can only be observed on the medial view. It contains the inner ear.
Foramina:
1) Internal acoustic meatus - located anterior to the internal jugular foramen - transmits the facial nerve, vestibulocochlear nerve, labyrinthine arteries and veins.
2) Hiatus for greater petrosal nerve - posterior to the hiatus for lesser petrosal nerve and lateral to the foramen lacerum.
3) Hiatus for the lesser petrosal nerve
The carotid canal also runs deep in the petrous temporal bone.
Muscle attachments of the temporal bone
Muscles involved?
Site of attachment?
Purpose?
1) Temporalis - originates from the lower part of the squamous temporal bone - muscle of mastication
2) Masseter - lateral zygomatic surface - muscle of mastication
3) Sternocleidomastoid - mastoid process - superficial muscle of the neck used for head rotation and flexion.
4) Posterior belly of digastric - mastoid process - suprahyoid muscle for swallowing
5) Spenius capitus - mastoid process - strap-like muscle in the back of the neck used for movements like shaking the head located posterior to the trapezius.
Clinical relevance: mastoiditis
Complications?
Treatment?
Middle ear infections (otitis media) can spread to the mastoid air cells and due to their porous nature, they are a suitable place for pathogen replication.
From the mastoid process, the infection can spread to the middle cranial fossa, and into the brain, causing meningitis.
If mastoiditis is expected, pus must be drained from the air cells but there is a risk of damaging the facial nerve.
