forHEALTHYlife

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Surgical applications of midcheek anatomy

Nov 30

Posted by for healthy life in Disease & Illness | No Comments

Similar to surgery of the forehead, there are divergent surgical philosophies regarding the best surgical plane; the decision being between the subperiosteal and com­posite sub-SMAS approaches. In subperiosteal surgery the benefit of repositioning the periosteum is mediated through the retaining ligaments to the superficial fascia. Ahhough the ligaments arc not visualized they are detached at their base from their skeletal attachments as an integral part of the subperiosteal surgery. By contrast, if the dissection plane is beneath the SMAS and the overlying tissue is repositioned, it then becomes necessary to identify and release those retaining liga­ments that are providing a resistance to tension-free advancement and redraping of the facelift flap.33 Con­siderable mobility may remain in the more superficial layers which is taken up by further advancing the SMAS.

In the midcheek, the main ligaments of importance requiring release are the orbicularis retaining ligament, the zygomatic ligaments and the masseteric ligaments.

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Innervation , Eyelid

Nov 30

Posted by for healthy life in Cosmetic | No Comments

The course of the facial nerve and its branches is of the utmost importance to facial rejuvenation surgery.In the midface, damage to a distal branch rarely results in a noticeable deformity because the major nerve divisions cross innervate approximately 70% of the time. However, the frontal and mandibular branches are much more susceptible to significant sur­gical injury as they are usually terminal branches with very few crossover communications.

The exact location of the frontal branch in relation to the SMAS is critical to a safe dissection in the peri­ocular and temporal regions. Pitanguy and Ramos30 first described the frontal branch of the facial nerve as crossing roughly a line from 5 mm below the tragus to 15 mm above the lateral end of the eyebrow. The ante­rior branch of the temporal artery is often said to accompany the nerve. More recent studies have shown this nerve to arborize into two to four branches that leave the superior pole of the parotid gland at the level of the zygomatic arch. The nerves then travel on the deep surface of the SMAS plane as they traverse the

zygomatic arch. Dissection of the SMAS layer off the arch can therefore damage these branches. For this reason, most authors recommend either converting to a subcutaneous dissection over the arch or when a sub-SMAS midface dissection is combined with a superior temporal or brow lift, a ‘meso-temporalis’ is left intact at the level of the arch.

The innervation of orbicularis is predominantly from zygomatic branches of the facial nerve that enter the pars orbicularis at or near its inferior-lateral periph­ery. The limited information available shows that this innervation consists of five or six branches that course over the body of the zygoma (Fig. 5-22). The branches that are at or near the intercanthal line ramify into smaller branches before they reach the orbicularis border, while branches nearer the upper and lower orbital rims cross under muscle for several millimeters before dividing into smaller branches. All branches enter the underside of the muscle and then ramify within the SOOF layer. The lower lid orbicularis receives an additional, inferior branch from the mid-cheek, which having passed deep to zygomaticus major ascends to cross the inferior border of the orbicularis some 10 mm medial to the zygomaticus major.31 An additional medial innervation is provided by superfi­cial buccal branches of the facial nerve, which course over levator labii superioris and ascend along the lateral border of levator labii superioris alaeque nasi to innervate the orbicularis on the way to innervating procerus and corrugator supercilii.

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Aging changes

Nov 29

Posted by for healthy life in Cosmetic | No Comments

The visible effects of facial aging are the summation of a complex interplay of factors that take place at all anatomical levels. In addition to these soft tissue changes, the support of the skin and soft tissue by retaining ligaments becomes attenuated, and the face loses volume from adipose, and possibly muscle mass, atrophy. In addition to these soft tissue changes, the facial skeleton undergoes resorption of areas of maxil­lary and  alveolar bone,  and parts of the skeleton.

In the upper midcheek, the caudal volume displace­ment of the soft tissue leads to a relative uncovering of the anatomy of the orbit.27 The lid-cheek junction also appears to descend from a position above the orbital rim in youth to a position below the orbital rim with aging (Fig. 5-19). However, it is a change to the underlying anatomy that defines the junction rather than actual stretching of the lower lid skin that takes place.

The youthful cheek has a high convex contour that overlies the septum orbitale as far up as the infratarsal crease. With aging, cheek soft tissue volume loss and descent, combined with septal laxity and orbital fat protrusion alter the contour of the lower lid to define a new lid—cheek junction with the appearance of the nasojugal groove medially and the palpcbromalar groove inferolaterally (Figs 5-17 & 5-19). The lid appears to lengthen creating a rounded eye and giving the impression that the lid—cheek junction descends with the soft tissue. The lid-cheek junction is therefore not a surface crease but is a surface contour that pas­sively reflects the contour change underlying the skin. The description ‘lid-cheek junction’ is still used regard­less of the fact that the location of the contour transi­tion has moved. Accordingly, due to these changes there is a transitional segment of skin, which was origi­nally in the area of the upper cheek and becomes incor­porated into the aged lower lid (and yet reverts to become cheek skin again following blepharoplasty). There has not been a specific name given to this tran­sitional segment of skin, which is here called the lid-cheek segment. It should be noted that in youth the lid—cheek segment extends above the orbital rim to the lid-cheek contour transition.

The displaced prezygomatic volume accumulates in the infrazygomatic part of the cheek medial to the midcheek furrow, most evident as increasing fullness of the nasolabial fold. This infrazygomatic soft tissue fullness is often termed the malar fat pad,2S and it should be distinguished from the malar mound, which overlies the prezygomatic space.

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Blood supply , Eyelid

Nov 29

Posted by for healthy life in Cosmetic | No Comments

A rich cutaneous vascular network exists in the face to function as part of the thermoregulatory and emo­tional response mechanism. In general, the anterior part of the face is perfused by numerous musculocuta­neous perforators, whereas the lateral face is supplied by relatively few large fasciocutaneous perforators in predictable locations. This network has been clearly defined in terms of vascular territories, however, in practical terms a medially based facelift flap, raised at whatever level, has a reliable blood supply.

In the midface, the blood supply is mainly from branches of the external carotid artery (Fig. 5-20) although as described above, multiple anastomoses exist with branches of the internal carotid artery around the eye. The facial artery supplies the superior and inferior labial arteries to the lips, and the lateral aspect of the dorsum of the nose. The internal maxil­lary artery gives rise to the infraorbital artery in the pterygopalatine fossa. The infraorbital artery passes through the infraorbital fissure into the orbit. It con­tinues anteriorly in the infraorbital groove and canal to emerge below the inferior orbital margin, where it supplies the lower eyelid and cheek. The infraorbital artery may be damaged during subperiosteal midface lifts as it exits its foramen. The superficial temporal artery is the terminal branch of the external carotid artery arising from within the parotid gland. It travels in the SMAS layer across the zygomatic arch and there­fore dissections deep to the SMAS layer protect the superficial temporal artery from injury. Before crossing the arch, it gives off the transverse facial artery, which supplies the lateral canthal area, by anastomosing with the lateral palpebral arteries.

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Soft tissues , Eyelid and Midcheek

Nov 28

Posted by for healthy life in Cosmetic | 2 Comments

In the midcheek, the prezygomatic space is a key space defined by structural ligamentous boundaries.It lies between the superficial and deep fascial layers overly­ing the zygoma (Fig. 5-16). It has a triangular shape with the apex medially and a broader base laterally reflecting the shape of the underlying body and maxillary process of the zygoma. It can be considered to b a transition zone between the mobile periorbital tissue of the lower lid, which contribute to the upper bounc ary, and the attachments of the more fixed tissues c the infrazygomatic region, which form the floor an> inferior boundary.

In the midcheek, the pars orbitalis of the orbiculari oculi lies flat across the cheek at a superficial level wit] a variable descent towards the lip. Accordingly, th superficial fascial layer in this area, which forms th roof of the prezygomatic space, consists of the par orbitalis of the orbicularis oculi, the orbicularis muscl fascia and a thin layer of suborbicularis oculi fa (SOOF).2^ This finely lobulated and distinctly yellov layer of fat can be repositioned in periorbital aesthete procedures, although it has no intrinsic structura ability and is more likely to be resuspended via fixatioi of the orbicularis fascia.

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Surface anatomy

Nov 28

Posted by for healthy life in Cosmetic | No Comments

In the midface, the area known as the midcheek is com­monly referred to, particularly in the context of aes­thetic surgery, although it does not conform to a classic anatomical region. By common usage, the midcheek is simply that part of the face visible front on (en face), between the lower lid above and the nasolabial fold below. It has a triangular shape, narrowing medially due to the upward inclination of the nasolabial fold. Its outer part merges imperceptibly around the convex­ity of the zygomatic substructure onto the lateral face without a defining landmark such as a visible skin crease.

The midcheek of a child is characteristically a soli­tary structure with a homogeneous, uniform rounded fullness of contour. This youthful smooth surface however conceals the structural components that lie within and further subdivide the midcheek. Aging changes result in a profound alteration of contour of the midcheek which progressively reveals three sepa­rate structural components. These separate structural components become defined from each other by the appearance of three interconnected grooves or furrows that trisect the original single midcheek mound. The three furrows interconnect much like the three limbs of the italic letter Y (for the right side of the face) (Fig. 5-17). The stem of the Y is formed by the midcheek groove, or furrow which is obliquely ori­ented and roughly parallel to the nasolabial groove. The upward continuation of that straight stem devel­ops into the nasojugal groove. The side arm of the Y attached to the stem near the top of the midcheek develops into the palpebromalar groove.

The names given to the three segments are usually only ascribed to their established form when defined by the grooves, but for explanation this terminology can also be applied to the areas of the three potential segments within the uniform youthful midcheek. Lat­erally, over the prominence of the zygoma, lies the prezygomatic or malar segment which may develop into the malar mound,23 also termed by some authors the malar bag or malar crescent.24 The area medial and inferior to the midcheek furrow is the infrazygomatic area of the midcheek, also termed the nasolabial fold segment (as distinct from the nasolabial groove which is the concavity separating the midcheek from the lip). Between the two upper limbs within the V area is the lid cheek segment.

Functionally, the midcheek being part of the ante­rior face is significant for its intrinsic movements, par­ticularly when compared to the lateral face which has only limited passive movement secondary to move­ments of either the anterior face or the jaw. Of the three segments, the most mobile is the nasolabial, as it overlies the vestibule of the oral cavity. The lid—cheek junction segment above also has significant movement, more so its upper part to do with contraction of the lower lid. The malar mound segment may have the least active displacement of the midcheek soft tissues, but it eventually develops within its surface the lower crow’s foot and zygomatic smile lines.

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