UMN Facial plasy

The UMN Facial pasly is the supranuclear palsy, charectaristically involves only the ipsilateral lower half of the face ( Upper half has bilateral supply)

It is of two types.

1. Mimetic Facial Palsy: Also called emotional facial paresis, characterized by clinically identifiable  facial palsy on mimetic movements like smiling, weeping e.t.c. There is no facial paresis with voluntary facial expression like showing teeth and closing eyes.

This is seen with lesions involving the contralateral frontal lobe anterior to the precentral gyrus, SMA, frontal lobe white matter, Mesial temporal lobe, insula, thalamus and subthalamus and post encephalitic parkinsonism.

2. Volitional Facial Palsy: The facial palsy is most marked on voluntary contraction of muscles and less so on mimetic movements.

This is seen with lesions interrupting the ipsilateral corticobulbar  fibers from the lower precentral gyrus, internalcapsule, cerebral peduncle, upper pons ( above facial nucleus)

Taylor-Haughton lines

In 1900 Taylor and Haughton described a technique to define a line on the scalp directly above the central (rolandic) fissure.

1. Draw a Nasion-Inoin line ( Nasion - Just below Glabella and Inion -External Occipital protruberanc)

2. Divide the Nasion-Inoin line in to 25%, 50% and 75%

3. Bregma is the point between the 25% and 50% points and Lambda is at 75% point

4. Sylvian fissure is drawn from the orbitotemporal angle (A point of depressin where eyebrow ends) to the 75% point on naso-inion line.

5. Draw a line perpendicular to the root of the zygoma starting at preauricular point 

6. Central sulcus is drawn from 54% point on naso-inoin line to the point where the sylvian line cuts the perpendicular line

Nucleus of Darkschewitsch and Cajal

Nucleus of Darkschewitsch: An ovoid cell group in the ventral central gray substance rostral to the oculomotor nucleus, receiving fibres from the vestibular nuclei by way of the medial longitudinal fasciculus; projections are not known, although some cross in the posterior commissure.

Nucleus of Cajal : A group of widely spaced, medium-sized neurones in the dorsomedial region of the upper mesencephalic tegmentum, immediately lateral to the nucleus of Darkschewitsch; together with the latter, the interstitial nucleus is closely associated with the medial longitudinal fasciculus, via which it receives fibres from the vestibular nuclei and projects crossed fibres via the posterior commissure to the oculomotor nucleus; also projects fibres to all spinal levels.

It is believed to be involved in the integration of head and eye movements, particularly eye movements of a vertical or oblique nature.

Structues passing in superior and inferior orbital fissures

Structures passing through Superior Orbital fissure

It is divided into 3 parts from lateral to medial

Lateral Part transmits: lacrimal nerve, frontal nerve, trochlear nerve, meningeal branch of lacrimal artery, anastomotic branch of middle meningeal artery which anastomoses with recurrent branch of the lacrimal artery

Middle Part transmits: Upper and lower divisions of the oculomotor nerve, nasociliary nerve between the two divisions of oculomotor nerve and abducent nerve

Medial Part transmits: Superior ophthalmic vein and sympathetic nerves from the plexus around internal carotid artery

Mnemonic for nerves in superior orbital fissure

Little FairyTold Sheena About New Ingrediants.

Lacrimal, Frontal, Trochlear, Superior Division of Oculomotor, Abducens, Nasociliary and Inferior Division of Oculomotor nerve.

Structures passing through Inferior Orbital fissure

It transmits the maxillary nerve and its zygomatic branch, and the ascending branches from the pterygopalatine ganglion.

The infraorbital vessels are not found in the inferior orbital fissure, but rather in the infraorbital foramen.

Short ciliary nerves

Branches of the ciliary ganglion.

6 to 10 in number, Arranged in 2 bundles at the superior and inferior angles of ciliary ganglion, Inferior bundle is large

Run forward with ciliary arteries ine above and one below the optic nerve.

Accompanied by long ciliary nerves.

They pierce the sclera at the back part of the bulb of the eye, pass forward in delicate grooves on the inner surface of the sclera, and are distributed to the Ciliaris muscle, iris, and cornea.

Contain both sympathetic and parasympathetic fibers.

Aqueduct of Sylvius

It is the cavity of diencephalon.

Also called the Mesencephalic duct or Cerebral Aqueduct.

It connects 3rd  ventricle to the 4th Ventricle.

The normal mean cross sectional area of the Aqueduct at birth is o.5 mm with a range from 0.2 to 1.8 mm.

In Aqueductal stenosis the size of the aqueduct is focally reduced either at the level of the superior colliculus or at the level of inferior colliculus.

In CT the Aqueduct is usually not visualized and this is attributed for the "Partial volume effect"

 

Nerve Fiber type and function

Erlanger and Gasser divided mammalian nerve fibers into A, B, and C groups.

 

Spurling's Maneuver

This is also called the foraminal compression test.

This test done in upper limbs is considered equivalent to SLR in lower limbs.

This is done to test cervical nerve root irritability in neck.

Standing behind the patient, head is bent backwards and flexed laterally to the symptomatic side.

This posture may elicit pain or paresthesia in the involved root.

If pain or paresthesia are not seen then a downward compression over the vertex is given to aggravate the foraminal compression so as to elicit the pain and paresthesia 

Hypoglossal Canal

Hypoglossal canal is the Bony canal which transmits the Hypoglossal nerve.

It is also called anterior condyloid foramen.

It is present in the Occipital Bone.

It lies in the epiphyseal junction between the basiocciput and the jugular process of the occipital bone.

This location corresponds to 10'O clock position on the left and 2'O clock position  in relation to the Foramen magnum.

The canal is superiorly surrounded by Jugular tubercle, Superio laterally by the Jugular foramen, laterally by the sigmoid sinus and inferiorly by the occipital condyle.