Other - Lacrimal Gland

Question 1

What type of gland is the lacrimal gland?

What does it secrete?

Where does it secrete it onto?

Answer 1

A serous type exocrine gland that secretes lacrimal fluid onto the surfaces of the conjunctiva and cornea of the eye.

It is a compound tubuloacinar gland, comprised of lobules - which are formed by multiple acini.

Question 2

What is the function of lacrimal fluid?

Answer 2

1) Nourishes the eye
2) Lubricate the eye
3) Cleans the eye

It forms tears in excess.

Question 3

Anatomical location of the lacrimal gland?

Answer 3

Superolateral aspect of the bony orbit, within the lacrimal fossa - a depression in the orbital plate of the frontal bone.

Anatomical relations:

Superior - zygomatic process of the frontal bone

Anterior - orbital septum

Posterior - orbital fat

Inferolateral - lateral rectus

Question 4

Anatomical structure of the lacrimal gland?

Answer 4

It can be divided into two parts, the orbital and palpebral parts.

Orbital - larger and sits on the lateral margin of the levator palpabrae superioris muscle.

Palpebral - smaller and located along the inner surface of the eyelid.

Question 5

From the lacrimal gland, where does the fluid go to?

Answer 5

1) Empties into the eye via the excretory ducts
2) The fluid moves medially by blinking and eventually reaches the lacrimal caruncle (pink fleshy nodule at the inner corner of the eye).
3) It then enters the lacrimal punta and enters the canaliculi.
4) The fluid then accumulates in the lacrimal sac.
5) Then empties into the nasolacrimal duct.
6) Then empties into the inferior meatus of the nasal cavity.

Question 6

Vasculature of the lacrimal gland

Answer 6

Arterial supply - lacrimal artery (a branch of the ophthalmic artery)

Venous drainage - superior ophthalmic (that drains into the cavernous sinus.

Lymphatic drainage - superficial parotid lymph nodes (empties into the deep cervical nodes).

Question 7

Innervation of the lacrimal gland

*Image depicts sensory innervation of lacrimal gland*

Answer 7

Receives sensory innervation from lacrimal nerve (a branch of the ophthalmic nerve - the ophthalmic nerve is a branch of the trigeminal nerve).

It also receives autonomic innervation:

Parasympathetic

• Preganglionic fibres are carried in the greater petrosal nerve (branch of the facial nerve), and then the nerve of the pterygoid canal, before synapsing at the pterygopalatine ganglion.
• Postganglionic fibres travel with the maxillary nerve, and finally the zygomatic nerve.
• Stimulates fluid secretion from the lacrimal gland.

Sympathetic

• Fibres originate from the superior cervical ganglion, and are carried by the internal carotid plexus and the deep petrosal nerve.
• They join the parasympathetic fibres in the nerve of pterygoid canal, and follow the same route to supply the gland.
• Inhibits fluid secretion of the lacrimal gland.

Question 8

Clinical innervation - dacryoadenitis?

Classifications?

Clinical features?

Treatment?

Answer 8

Refers to the inflammation of the lacrimal glands.

Presents acutely or chronically.

1) Acute dacryoadenitis - typically due to bacterial and viral infections, such as mumps, Epstein-Barr virus, staphyloccocus, and gonococcus.
2) Chronic dacryoadenitis - usually due to non-inflammatory condition, such as sarcoidosis (abnormal collection of inflammatory cells known as granulomas accumulate in lungs, skin, lymph nodes etc.), or thyroid eye disease associated with Grave’s disease.

Clinical features - swelling, pain, excess tear production that can lead to visual impairment, secondary to pressure on the eye.

Treatment - alleviate symptoms in viral cause or otherwise treating the underlying cause.