Head and Neck: Special Organs in the Head (Ear)

What are the three main anatomical divisions of the Ear?

Outer Ear, Middle Ear, and Inner Ear

What anatomical landmarks make up the outer visible structure of the Auricle (pinna)?

Helix, Scapha, Triangular fossa, Antihelix, Concha, and Auricular lobe (Earlobe)

Which ossicles are located within the Middle Ear?

Malleus, Incus, and Stapes

Which key structures are located in the Inner Ear?

Semicircular canals, Vestibule, Cochlea, Vestibular nerve, Cochlear (Auditory) nerve, and Oval window

What is the structural composition of the Auricle?

Elastic cartilage covered by skin

Which nerves supply sensory innervation to the Auricle?

Auricular branch of Vagus and Facial nerves, Greater auricular nerve, Auriculotemporal branch of Trigeminal nerve, and Lesser occipital nerve

What is the total length of the External Auditory Meatus (Ear Canal)?

2.5 cm long

What is the structural composition of the external 1/3 vs. internal 2/3 of the External Auditory Meatus?

External 1/3 is cartilaginous; internal 2/3 is bony

Which nerves supply sensory innervation to the External Auditory Meatus?

Auriculotemporal branch of the Trigeminal nerve, and auricular branches of the Facial, Vagus, and Glossopharyngeal nerves

Where is the Cone of Light located on the tympanic membrane?

Seen in the anteroinferior quadrant, originating from the umbo

What are the three layers composing the Tympanic Membrane?

Outer (cutaneous), intermediate (fibrous), and inner (mucous) layer

What is the covering and sensory innervation of the External / Lateral concave surface of the tympanic membrane?

Covered by skin; innervated by the auriculotemporal branch of the Trigeminal nerve and auricular branches of the Facial, Vagus, and Glossopharyngeal nerves

What is the covering and sensory innervation of the Internal / Medial surface of the tympanic membrane?

Covered by mucous membrane; innervated by the tympanic branch of the Glossopharyngeal nerve

Where is the Tympanic Cavity located, and what does it contain?

Contained within the petrous part of the temporal bone; contains the chorda tympani branch of CN VII and the tympanic plexus of CN IX

What are the components of the Auditory Ossicles?

Malleus, Incus, and Stapes

What is the innervation and function of the Stapedius Muscle?

Innervated by the Facial nerve; pulls on the stapes to prevent hyperacusis

What is the innervation of the Tensor Tympani Muscle?

Mandibular branch of the Trigeminal nerve (CN V3)

What is Otosclerosis?

Abnormal bone formation around the stapes and oval window, resulting in conduction deafness

What are the three main parts of the Bony Labyrinth, and what fluid does it contain?

Vestibule, three Semicircular canals, and Cochlea (upper scala vestibuli and lower scala tympani); contains perilymph

What are the sensory organs and fluid contents of the Membranous Labyrinth?

Contains maculae utricle and saccule (for linear acceleration), ampullae of semicircular ducts (for angular acceleration), and the cochlear duct/scala media (for hearing); filled with endolymph

What are the three channels of the cochlea arranged from superior to inferior, and what fluids do they contain?

1. Scala vestibuli (perilymph), separated by the vestibular membrane; 2. Scala media (endolymph), separated by the basilar membrane; 3. Scala tympani (perilymph)