SPECIAL ORGANS IN THE HEAD

Eyelids (palpebra)

folds of skin that cover and protect the eye

Lacrimal apparatus / Tear duct

consist of the lacrimal glands which produce tears and tear ducts which drain tears from the eyes into the nasal cavity

Tears

help lubricate the eyes, wash away debris, and prevent infection

Orbits

bilateral bony cavities in the facial skeleton that resemble hollow, quadrangular pyramids

Orbital axis

diverge at 45 degrees

Optical axis

axes of gaze, line of sight if the eyeballs are parallel

Primary position

Eyeballs looking straight ahead

Frontal bone

Superior orbital margin

Frontal and zygomatic processes

Lateral orbital margin

Zygomatic bone and maxilla

Inferior orbital margin

Maxillary and frontal processes

Medial orbital margin

Roof

Orbital plate of the frontal bone and lesser wing of sphenoid

Lateral Orbital Wall

Zygomatic bone and greater wing of sphenoid

Floor orbital wall

Orbital plate of the maxilla, zygomatic, and palatine bones

Medial Orbital wall

Frontal process of the maxilla, lacrimal bone, orbital plate of ethmoid, and the body of sphenoid

Oculomotor, Trochlear, Abducens nerves, Ophthalmic nerve, Superior ophthalmic vein

⭐️ Structures in the superior orbital fissure

Common tendinous ring

Fibrous ring that surrounds the optic canal and the medial part of the superior orbital fissure. Site of origin of the four rectus muscles of the eye.

Ophthalmic nerve (CNV1)

Optic Nerve (CN2)

Oculomotor nerve (CN3)

Trochlear nerve (CN4)

Abducens nerve (CN6)

Nerves in the eye

Oculomotor nucleus and nerve

ventral part of periaqueductal gray of the midbrain at the level of SUPERIOR colliculus

Abducens nucleus and nerve

⭐️ beneath the facial colliculus in the floor of the 4th ventricle in the caudal pons

Medial deviation or ESOTROPIA and paralysis of abduction of the ipsilateral eye

Injury in the abducens nucleus and nerve causes?

Trochlear nucleus and nerve

ventral border of periaqueductal gray of the midbrain at the level of INFERIOR COLLICULUS

Ophthalmic Artery

A branch of the ICA and enters the optic canal beneath the optic nerve

Central Artery of the Retina

Most important branch of blood vessel. And END artery.

Central retinal artery occlusion

CRAO

Superior ophthalmic vein

formed by the union of the supraorbital and supratrochlear, and angular veins

Inferior ophthalmic artery

begins by the union if SMALL VEINS in the of the FLOOR OF THE ORBIT

Lacrimal gland

lies in the upper lateral region of the orbit on the lateral rectus and the levator paloebrar superior muscles

Lacrimal canaliculi

are two curved canals that begin as a lacrimal punctum (or pore) in the margin of the eyelid and open into the lacrimal sac

Lacrimal sac

Upper dilated end of the nasolacrimal duct which opens into the inferior meatus of the nasal cavity

Crocodile tears syndrome (Bogorad syndrome)

Spontaneous lacrimation during eating caused by a lesion of the facial nerve proximal to the geniculate ganglion

Eyeball

Spherical structure containing the visual receptors (rods and cones) and other internal structures responsible for vision

Conjunctiva

thin, transparent membrane that lines the surface of the eyelids

Palpebral conjuctiva

Inner surface of the eyelids

Bulbar conjunctiva

Outer surface of the eyeball

Sclera

white, tough, outer layer of the eyeball and provides structural support and protection to the inner structures of the eye

Cornea

transparent dome shaped outermost layer of the eyeball that helps focus light rays onto the retina

Choroid

Consists of an outer pigmented layer and inner highly vascular layer. It nourishes the retina and darken the eye.

Ciliary processes

radiating pigmented ridges that encircle the margin of the lens

Ciliary muscle

consists of meridional and circular fibers of meridional and circular fibers of smooth muscle innervated by para sympathetic fibers

Ciliary body

ring shaped structure located behind iris.

Sphincter pupillae

Circular muscle fibers innervated by PARASYMPATHETIC fibers

Dilator pupillae

radial fibers innervated by SYMPATHETIC fibers

Pupillary light reflex

Constriction of the pupil in response to light stimulation (direct reflex), and the contrlateral pupil also constricts (consensual reflex)

Anisocoria

Unequal size of the pupil

Miosis

Constricted pupil caused by paralysis of the dilator pupillae resulting from a lesion of sympathetic nerve

Mydriasis

Dilated pupil caused by paralysis of the sphincter pupillae resulting from a lesion of the parasympathetic nerve

Argyll-Robertson pupil

Mitotic pupil that responds to accommodation but fails to respond to light. Seen in NUEROSYPHYLIS and DIABETES

Posterior part

PHOTOSENSITIVE internal nervous coat

Anterior part

Internal nervous coat that is not photosensitive

Optic disk (Blind spot)

consists of optic nerve fibers formed by axons of the ganglion cells

Physiologic cup

Depression in the center of the optic disk

Macula (Yellow spot/Macula Lutea)

Contains the FORVES CENTRALIS A yellowish stea near the center of the retina in the temporal side of the optic disk for the MOST DISTINCT VISION

Forvea centralis

Central depression (foveola) in the macula. It has cones only (no rods)

Rods

Contain RHODOSPIN. Most numerous from thr FORVEA CENTRALIS. Specialized for vision in dim light.

Cones

Most numerous in the FOVEAL REGION associated with VISUAL ACUITY and COLOR VISION

Cornea

Transparent structure forming the anterior one-sixth of the external coat responsible for the refraction of light entering the eye

Aqueous humor

Formed by the ciliary processes and provides nutrients for the avascular cornea and lens

Aqueous humor

Passes through the pupil from the POSTERIOR CHAMBER into the ANTERIOR CHAMBER and is drained into the scleral venous plexus through the canal of Schlemm at the iridocorneal angle

Lens

transparent AVASCULAR BICONVEX structure enclosed in an elastic capsule

zonal fibers

Suspensory ligament of the lens.

Vitreous Body/Vitreous humor

transparent gel which fills the eyeball posterior to the lens and hold the retina in place and provides support for the lens

Glaucoma

⭐️ Increased intra ocular pressure resulting from impaired drainage of aqueous humor into the venous system through scleral venous sinus

Cataract

clouding (opacity or milky white) of the crystalline eye lens or of its capsule

Nasal Dorsum

ridge of the nose extending from the nasal root to the tip

Alar cartilage

Paired cartilage structures that form the lateral walls of the nostrils

Columella

Fleshy tissue that separated the nostrils at the base of the nose

Philtrum

Vertical groove or depression in the midline of the upper lip

Alar sulcus

Crease or groove that extends from the nostrils to the sides of the nose

Nasolacrimal duct

Small tube thAt drains tears from the lacrimal sac into the nasal cavity. Opens into the inferior meatus of the nasal cavity.

Vestibule

Front part of the nasal cavity (just inside nostrils)

Vibrissae

Coarse hairs in the nasal cavity

Olfactory region

Located at the roof of the nasal cavity which is specialized for DETECTING ODORS.

Respiratory region

Located below the olfactory region and extends to the nasopharynx

Respiratory epithelium

Found in the respiratory region that helps humidify and filter the air and trap pathogens and particles

Medial wall (Nasal Septum)

Has osseous and cartilaginous parts of the PERPENDICULAR PLATE OF THE ETHMOID BONE (superior), THE VOMER (Inferior), and SEPTAL CARTILAGE (ANTERIOR)

Sphenoethmoidal recess

Opening if the SPHENOID SINUS

Superior Meatus

Opening of the POSTERIOR ETHMOIDAL AIR CELLS

Middle meatus

Opening of the frontal sinus into the infundibulum, openings of the middle ethmoidal air cells ont he E

Inferior Meatus

Opening of the nasolacrimal duct

Sphenopalatine foramen

Opening into the pterygopalatine fossa that transmits the sphenopalatine artery and nasopalatine nerve

Frontal, Ethmoid, sphenoid, and maxillary sinuses

Paranasal sinuses

Keisselbach area

Anastomotic plexus involving all five arteries at the anterior part of nasal septum

Anterior ethmoidal artery

Posterior ethmoidal artery

Sphenopalatine artery

Greater palatine artery

Septal branch of the superior labial artery

Blood supply in the nasal cavity

Epistaxis

Nosebleed resulting from the rupture of the sphenopalatine artery

Compression of nostrils and surgical packaging

Treatment for epistaxis

Special Visceral Afferent

Smell sensation. Supplied by the olfactory nerves CNI

Geniglossus

Protrude

Hyglossus

Depres

Styloglossus

Retract

Palatologlossus

Elevate

Hyoid Bone

Horseshoe shaped bone located in the neck that serves as attachment point of muscles involved in tongue movement and swallowing

CNXII Hypoglossal nerve

Innervation for tongue muscles

CNX Vagus Nerve via pharyngeal plexus

⭐️Innervation for pataloglossus

Lingual artery

Branch of the external carotid artery that supplies blood to the tongue

Parotid glands

Largest of the major salivary glands that produces serous saliva.