Normal tympanic membrane with landmarks labeled.
a. lateral process of malleus
b. tympanic annulus
c. chorda tympani
d. incudostapedial joint
e. handle of malleus
f. shadow of Eustachian tube
g. shadow of round window niche
h. promontory (floor of middle ear)
i. umbo
j. bulge of anterior EAC wall
k. hypotympanic air cells
1 Frontal crest
2 Foramen cecum
3 Crista galli
4 Cribriform plate of ethmoidal bone
5 Lesser wing of sphenoidal bone
6 Superior orbital fissure
7 Foramen rotundum
8 Carotid sulcus
9 Middle cranial fossa
10 Foramen ovale
11 Foramen spinosum
12 Clivus
13 Groove for superior petrosal sinus
14 Jugular foramen
15 Groove for sigmoid sinus
16 Internal occipital crest
17 Groove for transverse sinus
18 Internal occipital protuberance
19 Digitate impressions
20 Anterior cranial fossa
21 Chiasmatic sulcus
22 Anterior clinoid process
23 Optic canal
24 Sella turcica (hypophysial fossa)
25 Posterior clinoid process
26 Dorsum sellae
27 Foramen lacerum
28 Groove for greater petrosal nerve
29 Internal acoustic meatus
30 Hypoglossal canal
31 Foramen magnum
32 Posterior cranial fossa
33 Diploe
TM—tympanic membrane
M—malleus, I—incus
AA—anterior attic
MA—mastoid antrum area
DP—dural plate
SP—sinus plate
FN—facial nerve
LSCC—lateral semicircular canal, SSCC—superior semicircular canal,
PSCC—posterior semicircular canal, TP—tympanic plate
Right temporal bone showing labyrinthine (white arrow head), tympanic (black arrow head) and mastoid segment (white
arrow) of the facial nerve. Red dot indicates first genu or geniculate ganglion and blue dot indicates second genu.
EAC: External auditory canal (anterior wall); LSCC: Lateral semicircular canal; P:
Promontory; PC: Processus cochleariformis; PSCC: Posterior semicircular canal; RWN:
Round window niche; S: Stapes; ST: Stapedius tendon; TTC: Tensor tympani canal;
SSCC: Superior semicircular canal.