Physiology Lecture 6 PDF

Physiology Sympathetic NV to head & Neck LECTURE (6) DR. El-Sawy 0  Physiology Sympathetic NV...

Physiology Sympathetic NV to head & Neck LECTURE (6) DR. El-Sawy 0  Physiology Sympathetic NV to head & Neck Origin :  Lateral horn cells of 1st & 2nd thoracic segments of spinal cord. Relay (Ganglia) :  Superior cervical ganglia (SCG). Functions : 1. Mydriasis (pupil dilatation) : Due to contraction of dilator pupillae muscle (radial ms). 2. Elevation of upper eyelid : Due to contraction of superior tarsal muscle → widening of palpberal fissure. 3. Exophthalmos : Due to contraction of Muller's muscle (behind eye ball). 4. Accommodate far vision : Due to relaxation of ciliary muscle→ ↓ convexity of lens. 5. VC & trophic secretion of lacrimal glands. Eye DR. El-Sawy 1  Physiology Sympathetic NV to head & Neck 1. VC of salivary gland blood vessels. 2. Trophic secretions: Little. Salivary Viscous, concentrated secretion. Glands Poor in water & electrolytes. Rich in enzymes. 3. Contraction of myoepithelial cells Squeezing of salivary secretion to outside. 1. VC or VD of skin blood Vessels , but mainly VC. Skin 2. Erection of Hair due to contraction of pilo-erector muscle. 3. Sweat secretion. Cerebral Mild vasoconstriction (VC). vessels DR. El-Sawy 2  Physiology Sympathetic NV to head & Neck Def :  Group of signs which results from interruption of sympathetic to head and neck.  Occur at same side of the lesion. Causes: a) Lesion in Tl and T2 segments. b) Lesion in Superior cervical ganglion. Signs:  Dropping of upper eye lids due to paralysis of superior Ptosis tarsal muscles. Miosis  Constriction of pupils due to paralysis of dilator pupillae ms. Enophthalmos  Sinking of eye ball due to paralysis of Muller's muscles.  Absence of sweat secretion → dryness of affected side of Anhydrosis face.  of skin blood vessels, due to loss of sympathetic vasoconstrictor Vasodilatation tone so skin becomes Red & Warm. DR. El-Sawy 3