Test 198  (Ocular anatomy)

1. Muscles that depress the eyebrows include:

a. frontalis

b. orbicularis oculi

c. procerus

d. corrugator supercilii

e. depressor supercilii

 
Answera.F   b.T  c.T   d.T  e.T
Eyebrow movement is governed by five sets of muscles: the occipitofrontalis, procerus, corrugator supercilii, orbicularis oculi, and depressor supercilii. The occipitofrontalis muscle is the elevator of the 
eyebrow. The other four muscles are the depressors of
the eyebrow.

2. The temporal artery:

a. is a branch of the internal carotid artery

b. runs on the surface of the deep fascia

c. runs under the zygomatic arc on its way to the scalp

d. is in close relation to the auriculotemporal nerve in
    front of the ear

e. may provide significant blood supply to the intracranial 
    circulation

 

Answera.F  b.T  c.F  d.T  e.T
The temporal artery is a branch of the external carotid artery. It runs on the surface of the deep fascia. It 
crosses the root of the zygomatic arch just in front of the auriculotemporal nerve anterior to the ear on its way to the scalp. Biopsy of the artery anterior to the ear runs the risk of damaging this branch of the facial nerve. In patients with anastomoses between the internal and external carotid arteries in the forehead, the temporal artery may provide a significant amount of blood supply to the intracranial circulation. Ligation of the temporal artery has been reported to cause stroke.

 
 

3. True statements about the eyelashes include:
 

a. they are longer in the upper than the lower lid

b. they are usually darker than the hair of the scalp

c. they are renewed every six weeks

d. hyperpigmentation of the eyelashes is seen in 
    topical latanoprost use

e. excessive growth is seen in AIDS patients

 
Answer
a.T   b.T  c.T  d.F  e.T
The cilia are distributed in two or three irregularly placed rows. In the upper lid, the cilia are more numerous 
(100 to 150) and longer (8 to 12 mm). Fewer (50 to 75) and shorter (6 to 8 mm) cilia are found in the lower eyelid. The cilia are typically darker than the hair 
of the scalp and are more resistant to greying with age. The rate of growth is very slow, and they are renewed about every 3 to 5 months. Topical latanoprost causes increased pigmentation of the eyelashes. Excessive growth of eyelashes is seen in AIDS patients.

 

. 4. Whitnall's superior transverse ligament:

a. limits posterior displacement of the muscle with 
    contraction

b. acts as a sling for the levator muscle

c. when attenuated with age may contribute to ptosis

d. is important in the suspension of the levator muscle

e. joins the trochlear fascia medially

Answer
a.T  b.T  c.T  d.F  e.T
Whitnall's ligament acts as a fixed pulley for the levator 
and, thereby, support of the upper eyelid. Attenuation of the ligament with ageing may in part contribute to the development of ptosis. It acts as a check ligament to the levator, limiting posterior displacement of the levator with contraction. The ligament is unlikely to suspend the levator muscle due the fact the main medial and lateral attachments of Whitnall's ligament insert 
inferior to the culmination point of the levator muscle. It has facets of insertion laterally from inside the orbital rim near the maxillary-frontal suture along with the lacrimal gland capsular fibers and continues across the superior orbit to insert inside the rim on the frontal bone with the trochlear fascia medially.

5. With regard to the lacrimal gland:

a. the palpebral part is larger than the orbital part

b. both palpebral and orbital portions have ductules that 
    open separately into the conjunctiva

c. the ductules open into the conjunctiva at the upper 
    border of the upper tarsus

d. biopsy of the orbital part is more likely to impair tear 
    production than biopsy of the palpebral part

e. lacks a true capsule

 
Answer
a.F   b.F  c.F  d.F  e.T
The lacrimal gland is divided into a larger orbital lobe and a smaller palpebral lobe by the lateral horn of the levator and extensions of Müller's muscle. The palpebral lobe contains the secretory ducts from both the palpebral and the orbital lobes of the lacrimal 
gland. The ductules drain into the superotemporal 
conjunctival fornix a few millimeters above the tarsus. 
Thus, a biopsy of the more easily accessible palpebral 
lobe could impair ocular lubrication more significantly than a biopsy of the orbital lobe. The lacrimal gland lacks a true capsule but is surrounded by a connective tissue layer (pseudocapsule) that is continuous with the fascial network of the orbit

 

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