Lachrymal Apparatus

The lachrymal apparatus consists of:

Location and Function

Lachrymal gland: Located under the conjunctiva of the upper eyelid, near the caruncle. It secretes about 1.5 ml of lachrymal fluid per minute.
Lachrymal canaliculi: Located on the medial side of the eyelid, they connect the lachrymal gland to the lachrymal sac.
Lachrymal sac: Located under the conjunctiva of the medial side of the eye, it receives the lachrymal fluid from the canaliculi.
Nasolacrimal duct: Located in the medial canthus, it receives the lachrymal fluid from the lachrymal sac and drains it into the nasal cavity.
Puncta lacrimalia: Located on the medial side of the eyelid, they are the openings of the lachrymal canaliculi.

Applied Anatomy

The lachrymal apparatus helps to maintain the integrity of the eye by:

Lachrymal Apparatus Development

Step 1 →: Lachrymal gland and canaliculi develop from the ectoderm of the medial angle of the eye
Step 2 →: Lachrymal sac develops from the ectoderm of the medial angle of the eye
Step 3 →: Nasolacrimal duct develops from the endoderm of the nasal cavity

Lachrymal Apparatus Nerve Supply

Step 1 →: Lachrymal gland is supplied by the sympathetic nerves from the superior cervical ganglion
Step 2 →: Lachrymal gland is also supplied by the parasympathetic nerves from the facial nerve (CN VII)
Step 3 →: Other structures of the lachrymal apparatus receive sensory innervation from the trigeminal nerve (CN V)

Lachrymal Apparatus Blood Supply

Step 1 →: Lachrymal gland is supplied by the lacrimal artery (a branch of the ophthalmic artery)
Step 2 →: Lachrymal sac and canaliculi are supplied by the nasolacrimal duct
Step 3 →: Nasolacrimal duct is supplied by the sphenopalatine artery

Lachrymal Apparatus Lymph Drainage

Step 1 →: Lachrymal gland drains lymph into the submandibular lymph nodes
Step 2 →: Other structures of the lachrymal apparatus drain lymph into the submandibular and parotid lymph nodes

LACHRYMAL APPARATUS