Orbit and ocular adnexae



  • Superficial to deep: 
    • Skin (thinnest in the body)
    • Subcutaneous tissue
    • Orbicularis oculi fibres
    • Orbital septum/tarsal plates
    • Levator (in upper lid)
    • Conjunctiva

Hot Topic

Grey line sits between lashes and openings of the tarsal (meibomian) glands

  • Defines the anterior lamellae (skin/lashes, subcut tissue, orbicularis) from posterior lamellae (tarsal plate and conj)

  • Posterior to tarsal glands the conjunctiva meets the keratinised epithelium of the skin.
  • 25-35 Meibomian (tarsal) holocrine glands sit within the tarsal plates 
    • Secrete the lipid layer of the tear film
    • Drain into a central ductule opening at the mucocutaneous border
    • Secretion increases with age
    • Mixture of lipids with a melting point of 35 degrees
    • There are more glands in the upper than lower tarsus
  • Sebaceous glands of Zeis open into the ciliary follicles (holocrine glands):
    • There are also more sebaceous glands in the upper than lower lid (two glands per cilium)

    • Secrete via plasma membrane rupture which destroys the cells at time of secretion
  • Modified sweat glands of Moll (apocrine glands):
    • There are more in the lower than the upper lids

    • They secrete via pinched off membrane vesicles containing secretion
  • Note: glands of Zeis and Moll are located in the anterior lamellae of the lids, associated with the lash follicles

  • Caruncle medially with adjacent plica semilunaris

Arterial supply

  • Superior and inferior medial palpebral arteries are branches of ophthalmic artery
  • Superior and inferior lateral palpebral arteries are branches of lacrimal artery (branch of ophthalmic)

  • The two branches of each palpebral artery form marginal and peripheral arterial arches which anastomose across the lids

  • Further anastomoses between the circulations of the internal and external carotid occur in the lids: branches of the superficial temporal, transverse facial and infraorbital arteries

Hot Topic

The pre-tarsal portion of the eyelids is supplied by the superficial temporal and facial artery branches. The post-tarsal portion is supplied by branches of the ophthalmic as above

  • The arches run anterior to the tarsal plate and Muller’s muscle but behind orbicularis

  • The marginal arch runs 3mm from the lid margin
  • The peripheral arch is often absent inferiorly

Venous drainage

  • Ophthalmic and angular veins medially
  • Superficial temporal vein laterally

Lymphatic drainage

  • Lateral two-thirds: superficial parotid nodes and preauricular nodes
  • Medial third: submandibular nodes

Nerve supply

  • Upper lids’ skin supplied by branches of the ophthalmic nerve (V1) : supratrochlear, infratrochlear, supraorbital and lacrimal

  • Medial lower lids’ skin supplied by infratrochlear branch of ophthalmic
  • Lateral lower lids’ skin supplied by infraorbital nerve which is the terminal branch of the maxillary nerve (V2)

Orbital septum

  • Thickened continuation of the periosteum (connective tissue) both above and below
  • Defines the anterior limit of the orbit
  • Attached to orbital margins: arcus marginalis
  • Posterior to medial palpebral ligament which attaches tarsi to lacrimal crest and frontal process of maxilla

  • Anterior to lateral palpebral ligament which attaches tarsi to marginal tubercle of zygoma

  • Attached to levator aponeurosis just above where the levator inserts into orbicularis (ie just above the skin crease) and just above the superior border of the tarsus

  • The lower lid septum actually inserts directly onto the inferior tarsal border

Clinical Correlate

The orbital septum prevents the spread of pre-septal cellulitis into the orbit

Tarsal plates

  • Upper tarsus: 11mm
  • Lower tarsus: 4mm
  • 1mm thick
  • About 29mm wide
  • Embedded with meibomian glands
  • The bulbar conjunctiva adheres to the tarsus


  • Derived from the common tendinous ring at superolateral optic foramen
    • Attached to inferior surface of lesser wing of sphenoid
  • Passes above superior rectus
  • Fibres develop a fan-shaped aponeurosis: wider than the original muscle at the level of superior transverse ligament of Whitnall

  • Aponeurosis descends behind orbital septum and inserts into tarsal plate 

Hot Topic

Some fibres continue on and attach to skin, creating primary lid crease

  • The aponeurosis divides the lacrimal gland into orbital and palpebral portions
  • Lateral horn inserts into marginal tubercle of zygoma
  • Medial horn blends with the septum and medial palpebral ligament.
  • Note: the horns act as ‘checks’ on the action of levator with the eyelid
  • Function: raises lid by 15mm
  • Innervation: superior branch of oculomotor nerve which penetrates through superior rectus to reach the levator and then penetrates levator at the posterior ⅓-anterior ⅔

  • Smooth muscle of Muller (superior tarsal muscle) arises from inferior surface of levator and inserts into tarsal plate

Superior transverse ligament of Whitnall

  • Supports upper lid and acts as a check for the levator: prevents posterior displacement and provides a fulcrum so the direction of levator can turn from horizontal to vertical

  • Comprises a bundle of fascia beneath the superior orbital rim extending from the lacrimal gland to the trochlea

    • Medial insertion at the trochlea
    • Lateral insertion at the frontozygomatic suture
  • Weakening with age can lead to ptosis

Orbicularis oculi

  • Flat elliptical striated muscle
  • Orbital, palpebral (or ‘pretarsal’) and lacrimal portions
    • Orbital: arises from medial palpebral ligament
      • Forms circumferential fibres around orbital margin
      • Some fibres insert into the skin and soft tissue of eyebrow
      • Under voluntary control
    • Palpebral portion is ‘button-holed’ by palpebral fissure
      • Also arises from medial palpebral ligament
      • Fibres intertwine to form the lateral palpebral raphe
      • Sits anterior to orbital septum and tarsal plate
      • Provides reflex (involuntary) blinking and some voluntary function
    • Lacrimal portion attached to the posterior lacrimal crest
      • Passes deep to the medial palpebral ligament 
      • Attaches to posterior lacrimal crest behind the lacrimal sac
      • Pull the lids and papillae medially during blinking
  • Medial fibres surround the canaliculi
  • Nerve supply: temporal and zygomatic branches of the facial nerve

Clinical Correlate

Paralysis of orbicularis leads to ectropion and upper lid retraction

  • Contains Riolan’s muscle and Horner’s muscle
  • Riolan’s muscle
    • Striated muscle fibres next to anterior border of the tarsal plate
    • Represents the grey line
    • Extends the length of the eyelid and is the most posteriorly placed orbicularis portion
    • Together with pretarsal orbicularis, surrounds the canaliculus to shorten it during blinking and promote tear drainage

Preaponeurotic fat

  • Situated behind the orbital septum and in front of the muscular portion of the levator
  • Divided into medial and lateral pad (larger) by the trochlea
  • The medial pad is more fibrous giving it a whitish colour while the lateral pad is yellowish


  • 5 groups of muscles move the eyebrows
    • (Occipito)Frontalis elevates the eyebrows: supplied by the temporal branches of the facial nerve

      • Elevates the eyebrows and moves the scalp forward
      • Produces furrows in forehead
      • Extends from eyebrows to nuchal lines
    • The others all depress the eyebrows

      • Orbicularis oculi
      • Procerus
      • Depressor supericilii
      • Corrugator supercilii: produces vertical furrows in forehead
  • Procerus and corrugator also move the eyebrows medially
  • Frontalis: deficient laterally (only supports the medial 2/3rds hence lateral ptosis)
  • All are supplied by the facial nerve


  • Twice as many and longer on the upper lid
    • 150 in the upper compared to 75 in lower lid
  • Glands of Zeis and Moll open into the hair follicles
  • No erector pili muscles
  • Replaced every 100-150 days (3-5 months)

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