Osteology
|
| Bone |
Structure |
Description |
| temporal |
petrous part (N9, TG7-07) |
contains tympanic cavity & bony labyrinth (Greek, petra = rock) |
|
internal acoustic meatus (N8,N10, TG7-04, TG7-07) |
on posterior surface of petrous part; transmits facial nerve, vestibulocochlear nerve, & labyrinthine artery (Latin, meatus = a passage) |
|
facial canal (N94, TG7-68) |
through petrous part; transmits facial nerve to stylomastoid foramen |
|
carotid canal (N8, TG7-06) |
through petrous part; transmits internal carotid artery & internal
carotid plexus of sympathetic nerves |
|
mastoid process (N94, TG7-06, TG7-68) |
projects inferiorly from junction of petrous & squamous parts; contains
mastoid air cells
that open into tympanic cavity through mastoid
antrum |
|
tegmen tympani (N92, TG7-66) |
on anterior surface of petrous part superiorly; thin bony roof of tympanic cavity (Latin, tegman = a cover or roof; Greek, tympanum = a kettle drum) |
|
jugular fossa (N8, TG7-06) |
on posterior surface of petrous part; forms anterior margin of jugular
foramen |
|
tympanic part (N8, TG7-67A, TG7-67B) |
consists primarily of external acoustic meatus & tympanic ring (Greek, tympanum = a kettle drum) |
|
external acoustic meatus (N8,N10, TG7-04, TG7-07) |
opening which allows sound to reach tympanic membrane (Latin, meatus = a passage) |
|
tympanic ring (TG7-04) |
attachment of tympanic membrane |
| |
semicanal for tensor tympani m. (TG7-68A) |
consists of the superior surface of the cartilaginous part of the pharyngotympanic
tube, the greater wing of the sphenoid, and the petrous part of the temporal
bone |
| incus (N92,N93,N94, TG7-65, TG7-68, TG7-69A, TG7-69C) |
|
articulates with head of malleus and head of stapes (Latin, incus = anvil) |
| stapes (N92,N93,N94, TG7-65, TG7-68, TG7-69A, TG7-69D) |
|
articulates with long process of incus and base fills vestibular window (Latin, stapes = step or stirrup) |
| malleus (N92,N93,N94, TG7-65, TG7-68, TG7-69A, TG7-69B) |
|
manubrium is attached to inner aspect of tympanic membrane; head articulates with incus (Latin, malleus = hammer) |
| middle cranial fossa |
hiatus for greater petrosal nerve (N10, TG7-07) |
also houses petrosal branch of middle meningeal artery |
| pterygopalatine fossa (N4, TG7-32) |
pyramidal space inferior to apex of orbit |
lies between the pterygoid process of the sphenoid bone posteriorly and the posterior aspect of the maxilla anteriorly (Greek, pterygoid = wing-shaped) |
| sphenopalatine foramen (N4, TG7-32) |
|
communicates with the pterygopalatine fossa medially through the nasal cavity |
| vomer (N2,N6, TG7-03, TG7-41) |
|
thin, flat bone that forms the posteroinferior part of the nasal septum (Latin, vomer = a ploughshare, the latin word is said to have been derived from vomere, to vomit, because the plough "throws up" the earth) |
| maxilla (N2, TG7-03) |
upper jaw |
consitute the supporting bone for the maxillary teeth |
|
sinus (N48,N49, TG7-44A, TG7-44BC) |
the largest of the paranasal sinuses; occupy the bodies of the maxillae |
| ethmoid (N6, TG7-08 |
air cells N48,N49, TG7-44A, TG7-44BC) |
pneumatized spaces (3-18 in number) within the ethmoid bone; located between
the orbits; three groups may be identified: anterior (drain into the hiatus semilunaris
in the middle nasal meatus), middle (drain onto the apex of the bulla ethmoidalis
in the middle nasal meatus), posterior (drain into the superior nasal meatus) (Greek, ethmoid = resembles a sieve) |
|
perpendicular plate (N6, TG7-41) |
superior part of the nasal septum that descends from the cribiform plate; superior to the cribiform plate it is the crista galli |
|
cribriform plate (N6, TG7-41) |
perforated portion of ethmoid bone on either side of the crista galli; perforated for passage of the olfactory nerves |
|
superior nasal concha (N6,N37, N38, TG7-08, TG7-42) |
medial projection of the ethmoid bone from the superolateral wall of the
nasal cavity; forms the superior nasal meatus below it and the sphenoethmoidal recess
above it |
|
middle nasal concha (N6,N37, N38, TG7-08, TG7-42) |
portion of the ethmoid bone that projects inferomedially from the lateral
wall of the nasal cavity; forms the superior nasal meatus above it and the middle nasal meatus (which
overlies the bulla ethmoidalis and hiatus semilunaris) below it |
|
bulla ethmoidalis (N37,N38, TG7-42, TG7-43) |
rounded elevation on the lateral wall of the nasal cavity; located under cover of the middle nasal concha; middle ethmoidal air cells
drain at its apex |
| nasal septum (N2, N6, N39, TG7-03, TG7-41A, TG7-41B) |
|
divides the chamber of the nose into two nasal cavities, with three major components: perpendicular plate of the ethmoid, vomer, and septal cartilage |
| nasal conchae (N6,N37, N38, TG7-08, TG7-42) |
|
three curved bony plates on the lateral side of each nasal cavity; the superior and middle concha are part of the ethmoid bone, the inferior concha is a separate bone |
| sphenoid |
body (N6, TG7-07, TG7-08) |
central part, containing sinuses (Greek, sphenoid = wedge-shaped) |
|
medial pterygoid plate (N6,N8, TG7-06, TG7-08) |
projects posteriorly from pterygoid process; attachment of superior pharyngeal constrictor & pharyngobasilar fascia (Greek, pterygoid = wing-shaped) |
|
pterygoid hamulus (N6,N8, TG7-06, TG7-08) |
hook-like projection from the inferior end of the medial pterygoid plate; it acts as a pulley for the tendon of the tensor veli palatini m. (Greek, pterygoid = wing-shaped; Latin, hamus = hook) |
Muscles of Ear
|
| Muscle |
Origin |
Insertion |
Action |
Innervation |
Notes |
Image |
| stapedius (N93,N94, TG7-66, TG7-68) |
walls of pyramidal eminence |
neck of stapes |
dampens vibration of stapes |
facial nerve (VII) |
entirely enclosed in bone, except for its tendon |
 |
| tensor tympani (N93,N94, TG7-66, TG7-68) |
cartilagenous auditory tube & greater wing of sphenoid adjacent to it |
manubrium of malleus |
dampens vibrations of the tympanic membrane |
medial pterygoid branch of mandibular division of the trigeminal nerve (V) |
V3 innervates both tensor muscles (tympani and veli palatini) |
 |
| levator veli palatini (N64,N65,N68, TG7-20, TG7-24) |
apex of the petrous part of the temporal bone and the medial surface of the auditory tube cartilage |
muscles and fascia of the soft palate; palatine aponeurosis |
elevates the soft palate |
vagus nerve (X) via the pharyngeal plexus |
a derivative of the fourth pharyngeal arch (Latin, levator = to lift) |
 |
| tensor veli palatini (N64,N65,N68, TG7-20, TG7-24) |
scaphoid fossa, lateral wall of the auditory tube cartilage |
palatine aponeurosis |
opens the auditory tube; tenses the soft palate |
mandibular division of the trigeminal nerve (V) |
remember: V3 innervates both tensor muscles (tympani and veli palatini); ALL other palatal muscles are innervated by vagus |
 |
Nerves
|
| Nerve |
Source |
Branches |
Motor |
Sensory |
Notes |
| facial (N92, N94, N97,N104,N123, TG7-47, TG7-65, TG7-68, TG7-87) |
pons & medulla: nucleus solitarius of medulla via nervus intermedius (SVA sensory root) from geniculate ganglion; superior salivatory nucleus (GVE preganglionic parasympathetic) of pons via nervus intermedius, facial motor nucleus of pons via motor root |
greater petrosal (preganglionic parasympathetic to pterygopalatine ganglion, postganglionic parasympathetic travels with brs. of maxillary div. of V), chorda tympani (SVA taste from anterior 2/3rds of tongue; preganglionic parasympathetic to submandibular ganglion, postganglionic parasympathetic to submandibular & sublingual glands), n. to stapedius, posterior auricular, intraparotid plexus with temporal, zygomatic, buccal, marginal mandibular & cervical brs. |
stapedius, stylohyoid, posterior belly of digastric, muscles of facial expression; secretomotor to lacrimal, submandibular, sublingual, and mucous glands of nasal & oral cavities |
taste (SVA) from anterior 2/3rds of tongue; part of skin of external auditory meatus |
also known as: CN VII, 7th cranial nerve; passes into internal acoustic meatus, goes through facial canal, exits at stylomastoid foramen |
| ganglion, geniculate (N92, N94, N97, N123, TG7-67B, TG7-68B) |
chorda tympani, from facial n. (VII) |
nucleus solitarius of medulla via nervus intermedius (SVA sensory root of facial n.) |
|
taste (SVA) from ant. 2/3rds of tongue |
a sensory ganglion equivalent in structure and function to a dorsal root ganglion; some taste from palate travels through greater petrosal n. to geniculate ganglion; located in facial canal of petrous temporal bone (Latin, geniculate = to bend) |
| petrosal, greater (N104,N123, TG7-67B, TG7-68B) |
facial (VII) |
joins deep petrosal n. to form n. of pterygoid canal |
secretomotor (preganglionic parasympathetic) to lacrimal gland & mucous glands of lower nasal cavity, maxillary sinus, palate |
|
contains: preganglionic parasympathetic axons bound for the pterygopalatine ganglion where they will synapse; passes through hiatus of canal of greater petrosal n. in petrous part of temporal bone |
| chorda tympani (N94, N123, TG7-67B, TG7-68A) |
facial (VII) |
|
secretomotor to submandibular & sublingual glands (preganglionic parasympathetic to submandibular ganglion) |
taste to anterior 2/3rds of tongue |
joins lingual nerve in infratemporal fossa and continues with it to the tongue (Latin, chorda = a cord; Greek, tympanum = a kettle drum) |
| vestibulocochlear (N92, N97, N104,N124, TG7-65, TG7-67B, TG7-89C) |
pons & medulla: vestibular nuclei from vestibular ganglion of semicircular ducts; cochlear nuclei in inferior cerebellar peduncle from spiral ganglion of cochlea |
divides within the temporal bone into vestibular and cochlear parts |
|
vestibular: balance/proprioception (SSA); cochlear: hearing (SSA) |
also known as: CN VIII, 8th cranial nerve; auditory nerve; passes into internal auditory meatus |
| cochlear (N92, N97, TG7-89C) |
vestibulocochlear n., cochlear nuclei in inferior cerebellar peduncle from spiral ganglion of cochlea |
|
|
hearing (SSA) |
passes into internal acoustic meatus |
| vestibular (N92, TG7-89C) |
pons & medulla: vestibular nuclei from vestibular ganglion of semicircular ducts |
|
|
balance/proprioception (SSA) |
part of vestibulocochlear n., CN VIII; passes into internal auditory meatus |
| glossopharyngeal (N104, TG7-90C) |
medulla: spinal trigeminal nucleus from superior ganglion (GVA); nucleus solitarius from inferior ganglion (SVA); nucleus ambiguus (GVA); inferior salivatory nucleus (GVE preganglionic parasympathetic) |
tympanic nerve to tympanic plexus & lesser petrosal n., carotid sinus n., stylopharyngeus brs., pharyngeal brs. |
GSE: stylopharyngeus; GVE: secretomotor to parotid gland (preganglionic parasympathetic via tympanic n. to lesser petrosal n. to otic ganglion, postganglionic parasympathetic via auriculotemporal n.) |
GVA: carotid body & sinus, pharynx, middle ear; GSA: skin of external ear; SVA: taste from posterior 1/3rd of tongue |
also known as: CN IX, 9th cranial nerve; passes through jugular foramen; may penetrate the stylopharyngeus m. |
| tympanic (TG7-90C) |
glossopharyngeal |
tympanic plexus, which gives rise to lesser petrosal n. |
secretomotor (pregang. parasymp., synapsing in otic gang.) to parotid gland |
mucous lining of middle ear cavity |
passes from inferior ganglion of CN IX through tympanic canaliculus to middle ear (Greek, tympanum = a kettle drum) |
| ganglion, spiral |
fibers of cochlear hair cells |
cochlear n. of vestibulocochlear n. to cochlear nuclei in inferior cerebellar peduncle |
|
hearing (SSA) |
sensory ganglion of cochlear part of CN VIII |
| olfactory nn. (N42,N43, TG7-41 TG7-77AB TG7-77C) |
the filaments of the bipolar olfactory epithelial cells constitute the olfactory
nerves |
second order olfactory nerve cell bodies located in the olfactory bulb |
none |
smell (SVA) |
also known as CN I, 1st cranial n.; multiple olfactory filaments pass through
the cribriform plate to enter the anterior cranial fossa and synapse in the
olfactory bulb; the olfactory tract carries the signal from the bulb to olfactory
cortex of the forebrain |
Viscera/Fascia
|
| Organ |
Location/Description |
Notes |
| torus tubarius (TG7-23) |
mucosal fold covering the anteromedial end of the auditory
tube cartilage |
torus tubarius projects toward the midline from the lateral wall of the nasopharynx (Latin, torus = knot) |
| arcuate eminence (anterior semicircular canal) (TG7-67) |
communicate with the vestibule of the bony labyrinth |
the canals lie posterosuperior to the vestibule into which they open and at right angles to each other (Latin, arucuate = bowed) |
| auditory (pharyngotympanic) tube (TG7-65, TG7-67) |
joins the middle ear to the nasopharynx |
|
| epitympanic recess (TG7-68) |
space superior to the tympanic membrane in the middle ear |
|
| oval window (TG7-70) |
an oval opening on the medial wall of the tympanic cavity leading
to the vestibule of the internal ear (bony labyrinth) |
|
| promontory of the cochlea (TG7-70) |
bulging of the medial wall of the tympanic cavity produced
by the large basal turn of the cochlea |
|
| round window (TG7-70) |
an opening in the medial wall of the middle ear leading into
the cochlea |
|
| outer ear (N92, TG7-65) |
comprises the auricle, which collects sound, and the external
acoustic meatus |
|
| middle ear (N92, TG7-65) |
located in the temporal bone, it consists of the tympanic
cavity and the epitympanic recess |
|
| inner ear (N92, TG7-65) |
contains the vestibulocochlear organ and the sacs and ducts
of the membranous labyrinth |
|
| choanae (N37, N66, TG7-22, TG7-43) |
posterior opening of the nasal cavities into the nasopharynx |
(Latin/Greek, choanae = a funnel-shaped hollow in the brain) |
| soft palate (TG7-24, TG7-43) |
the movable posterior third of the palate, which is suspended from the posterior border of the hard palate |
|
| uvula (TG7-41) |
conical process that is the posteroinferior extension of the soft palate |
(Latin, uva/uvula = a grape) |
Clinical Terms
|
| Term |
Definition |
| otitis media |
infection or inflammation of the middle ear space and eardrum |
| myringotomy |
removal of fluid from the middle ear space by creating an incision in the eardrum. In chronic cases
of otitis media, a tube may be left in place to drain the fluid (tympanostomy tube). |
| otitis externa |
infection or inflammation of the external ear canal. |
| mastoiditis |
inflammation of any part of the mastoid process and the cells. |
| otosclerosis |
A pathological condition of the bony labyrinth of the ear, in which there is formation of spongy bone (otospongiosis), especially in front of and posterior to the footplate of the stapes, it may cause bony ankylosis of the stapes, resulting in conductive hearing loss. Cochlear otosclerosis may also develop, resulting in sensorineural hearing loss. |
| epistaxis |
nosebleed, hemorrhage from the nose. Usually from superficial vessels in the anterior
part of the nasal septum (cartilaginous portion). Bleeding from more posterior vessels
is more serious and can be life-threatening requiring prompt care and deep packing. |
| Kiesselbach's area |
an area on the anterior portion of the nasal septum where nosebleeds often occur |
| sinusitis |
inflammation of a sinus. The condition may be purulent or nonpurulent, acute or
chronic. Depending on the site of involvement it is known as ethmoid, frontal,
maxillary or sphenoid sinusitis. |
| deviated septum |
a common condition in which the nasal septum bows to one or the other side of the
nasal cavity rather than being in the midline |
| cleft palate |
a congenital fissure in the roof of the mouth forming a communication between the
nasal passages and the oral cavity. More common in males. Due to the failure
of the maxillary prominence to fuse with the medial nasal prominence (tongue
fails to move out of the groove between these two plates). Repair is usually done
in the second year of life. |
| tonsillitis |
inflammation of the palatine tonsil |
| tonsillectomy |
surgical removal of the palatine tonsils. Lingual tonsils are also taken. Indications include airway obstruction or
recurrent tonsillitis. Complete recovery is in two weeks. Adults have a significantly
longer period of recovery and a much higher complication rate than children. |
| adenoidectomy |
surgical removal of adenoids or inflamed pharyngeal tonsils. Indications include airway obstruction,
nasal obstruction, sleep apnea and chronic ear infections |
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