Midterm 1 Flashcards
The space that contains the eye, connective tissue, and fat
Orbit
The orbital roof is composed of:
The frontal bone and the lesser wing of the sphenoid bone
A raised area of bone on the anterior lateral wall of the orbit
Whitnall’s tubercle
The medial wall of the orbit is composed of:
The frontal process of the maxilla, lacrimal bone, ethmoid bone, and a small portion of the lesser wing of the sphenoid
The orbital floor is composed of:
Maxilla, zygomatic bone, orbital process of the palatine bone
Layers of connective tissue within the orbit
Orbital fascia
3 types of orbital fascia
Bulbar fascia, periosteum, and orbital septum
A thin, dense, fibrous membrane that extends over the eyeball - stretches from the optic nerve entrance posteriorly to the margin of the cornea
Fascia bulbi (tenon’s capsule)
The space between the episclera and Tenon’s capsule is called
Episcleral or tenon’s space or strands of loose connective tissue
Outer to tenon’s capsule is
Orbital fat
Posteriorly in the orbit, a muscle is ensheathed by its epimysium, but anteriorly it is ensheathed by the epimysium as well as by:
Tenon’s capsule
Superior rectus fascia sends extensions to unite with the fascial extension from the ___________________________ muscle
Levator palpebrae superioris muscle
The inferior rectus fascia becomes continuous with that of the
Inferior oblique
A collagen hammock that helps hold the eye and orbital contents in place
Suspensory ligament of Lockwood
All orbital striated muscles send off a __________ ligament that anchor them to the bones of the orbitals to other structures nearby
check ligament
The check ligament and sheath of the levator palpebrae superioris is a derivative of
Tenon’s capsule
The check ligament of the lateral rectus inserts to ________________ of the zygomatic bone
Whitnall’s tubercle
The connective tissue coating of the orbital bones that arises from the dura mater of the optic nerve - which follows the optic nerve to the orbital canal
Periorbita
At the orbital opening, some dura mater continues as the dura of intraorbital part of optic nerve. The rest of the dura mater splits away to become
Periorbita
Bone attachments at sutures leave a mark on the ______________ when it is removed from bone
Periorbita
Part of the connective tissue layer of eyelids formed when the Periorbita at the orbital margin runs vertically into the eyelids
Orbital septum
The orbital septum ends on the aponeurosis of the _________________________________ in the upper lid and the tarsal plate in the lower lid
Levator palpebrae superioris
Much of the tissue posterior to the orbital septum is
Orbital fat
_________________ is divided into fat compartments by the extraocular rectus muscles and thin connective tissue layers
Orbital(retrobulbar) fat
Fat within the muscle cone (intraconal) is around the ___________ part of the optic nerve
Intraorbital
Fat outer to muscle cone (extraconal) is limited by the ____________
Periosteum
In intraorbital fat, there are thin partitions of fibrous connective tissue that serve these 3 functions:
Connect muscles to periosteum
Divide fat into lobules
Support vessels and nerves
Bones of the face and orbit are derived from _________________________ cells that migrate and then change into __________________
Ectodermal neural crest cells
Mesenchyme
The size of the developing orbit is determined by the optic cup of the early eyeball, which is derived from
Neural tube ectoderm
The ______________________ of the orbit are the last part of the orbit to develop
Bony walls
The ________ develops first, then choroid, sclera, then muscles and finally orbital bony walls, in an in-to-out sequence
Retina
Bony parts of the orbit have __________________ development except for the endochondral parts (the sphenoid body, lesser wing and greater wing of the sphenoid bone and the ethmoidal plate
Intramembranous
A child does not develop all his cranial capacity until about _______ years old, so skull sutures close tightly around this time, as bone contacts bone
5-7
Abnormalities of cranial or facial bones are often due to premature closure of
Sutures
The most common type of premature closing of sutures - _____________, scaphocephaly causes no brain damage
Sagital suture
Supportive structures that surround the eye, but not the eye itself
Ocular adnexa
Of the six muscles that move the eye, four are __________ muscles and the other two are ___________ muscles
Rectus;oblique
Rectus muscles originate from the __________________________ at the apex of orbit, which surrounds the optic foramen and the wide part of the superior ophthalmic fissure
Annulus of Zinn
________________________ runs forwards underneath levator in the superior orbit - elevates and intorts
Superior rectus
____________________ runs forwards along the orbital floor - depresses and extorts the eye
Inferior rectus
___________________ runs forwards along the lateral orbital wall - acts to abduct the eye
Lateral rectus
The ________________________ is a boney protrusion of the greater wing of the sphenoid bone that often projects across the SOF - anchors the portion of the annulus of Zinn that gives rise to LR
Spina recti lateralis
_____________________ runs forward along the medial orbital wall -acts to adduct the wall, strongest extraocular muscle/shortest recti
Medial rectus
__________________ originates from the sphenoid bone just superomedially to the optic foramen - NOT PART OF THE ANNULUS OF ZINN
Superior oblique
The _____________ tendon is the longest tendon of all EOMs
SO
______________________ originates from the maxilla near the lacrimal sac and runs laterally between the inferior rectus and orbital floor/shortest tendon of insertion
Inferior oblique
Originates from the lesser wing of the sphenoid bone, superior to the annulus of zinn, runs forwards along the orbital roof until sending out its aponeuroses to insert in the dermis of the upper eyelid
Levator palpebrae superioris
Recti insert in the anterior hemisphere of the eye at an average of _______ mm from the corneal margin
6.65
The ___________________ is most anterior, inserting only 5.5 mm from the cornea
Medial rectus
Obliques insert in the _____________ hemisphere of the eye
Posterior
The SO inserts to the __________________ quadrant
Superolateral
The IO inserts to the __________________ quadrant, which is near the fovea centralis
Inferolateral
Both obliques insert near the two temporal _______ veins
Vortex
All 7 muscles receive muscular branches of _______________ artery
Ophthalmic
LR also receives a muscular branch of ___________ artery
Lacrimal
Muscular branches of infraorbital artery supply _______ and ________ and continue on to the lacrimal sac
IO and IR
From the tendons of recti muscles, muscular arteries emerge as _______________________ arteries
Anterior ciliary
Two arteries per muscle, except for LR(only has one) for a total of _______ anterior ciliary arteries
7
Bilateral condensation of mesodermal mesenchyme is the first sign of muscle development in each orbit. These cells become ___________
Myoblasts
Extraocular muscles arise form the paraxial, ________________________
Mesodermal somites