Figures 1 and 2 show the bony anatomy of the face. Many anthropological landmarks, bony and soft tissue, are illustrated in Figures 3 and 4. External link, please review our disclaimer. Anatomy of the Face and Cranium Head shape and upper face shape are closely related to the shape of the bony skull.
Figure 1 Figure 2 Figure 3 Figure 4 The anatomy of the various structures is described in more detail below. Cranium: The upper part of the skull consists of paired frontal and parietal bones and a single posterior occipital bone Figures 1 and 2. In early life these bones are separated by five major sutures Figures 1 and 2. Three, the coronal, lambdoidal and squamosal, are paired, and two, the sagittal and metopic, are single. Cranial growth normally occurs perpendicular to each of these major sutures.
Forehead: The part of the face above the eyebrows, below the hairline and between the temples. The paired frontalis muscles join in the midline and adhere to the superficial fascia over the frontal bone.
These muscles effect forehead wrinkling or furrowing. They have no bony attachments, but inferiorly the fibres blend with the muscles encircling the eyelids.
From these attachments the fibers are directed upward, and join the galea aponeurotica below the coronal suture. The galea aponeurotica is a layer of dense fibrous tissue which covers the upper part of the cranium and attaches posteriorly to the occipital bone. It is closely connected to the integument by the firm, dense, fibro-fatty layer which forms the superficial fascia of the scalp.
It cannot be wrinkled or furrowed because it does not contain muscle fibres. The anterior hairline is typically situated at the junction of frontalis muscle and galea aponeurotica. Glabella: The most prominent point on the frontal bone above the root of the nose.
Supra-orbital Ridge: The supraorbital portion of the frontal bones. The maxillary portion of the bucco-maxillary ligaments divide these two compartments [45]. Nasolabial fat NLF Figure 2 : this has an oblong form, lies lateral to the nasal pyramid and cranial to the nasolabial fold.
The orbicularis retaining ligament represents the superior border of this compartment [33]. Its supero-lateral boundary is the medial cheek fat and its infero-medial boundary is the nasolabial fold. Its inferior part borders and overlaps the SJF [33]. Middle cheek fat MCF Figure 2 : this is located lateral to the medial cheek fat and it is bordered above by the zygomatic ligament [29]. Above this compartment, the ligament is thick and constitutes the McGregor patch [43]. The middle cheek fat does not extend above the inferior margin of the zygomatic arch.
Its anterior boundary is the masseter ligament that starts inferior to the McGregor patch and descends vertically along the anterior margin of masseter muscle. This ligament arises from the fascia of the masseter muscle and inserts into the SMAS and overlying dermis of the cheek [29].
The middle cheek fat medially borders the lateral temporal-cheek fat. The subcutaneum parotideomassetericum septum, originating from the SMAS in the region of the parotid gland and running in an anterior and lateral direction into the dermis of the cheek, divides these two compartments [46]. Caudal to the middle cheek fat lies the inferior jowl fat. There is also the Lateral temporal-cheek fat LTCF : this is the most lateral compartment of the cheek.
It lies in direct contact with the parotid gland and connects the temporal fat to the cervical subcutaneous fat [33]. The cheek part of this compartment is firmly adherent to the parotid fascia.
At the level of preauricular region the platysma-auricular ligaments forms the posterior border of the lateral temporal cheek fat [45]. A true vertical septal barrier is located anterior to this compartment. This septum was named the lateral cheek septum by Rorich and Pessa [33] as or the subcutaneum parotideomassetericum septum by Pils and Anderhuber [46]. Superior Jowl fat SJF Figure 2 : this is lateral to the modiolus, clinically it appears as the most inferior extension of the nasolabial fold and of the nasolabial fat.
Its lateral borders lies against the middle cheek fat and its inferior border against the inferior jowl fat. Then there is the Inferior Jowl fat IJF Figure 2 : this is located below the middle cheek fat and inferior to the superior jowl fat.
Its medial boundary is the mandibular ligament and its lateral boundary is the lateral temporal-cheek fat. The inferior boundary is made up by the mandibular septum [24,38].
The first three superficial fat compartments infraorbital fat, superficial medial cheek fat and nasolabial fat are often described as a single anatomical structure: the malar fat pad.
It has a triangular shape with the base parallel to the nasolabial fold and with the apex near the malar projection Figure 3. The malar fat pad is loosely adherent to the deep plane SMAS , but it is firmly adherent to the skin The malar fat pad is supported in its location during youth by multiple fibroelastic fascial septa that extend through the fatty cheek mass originating from the underlying superficial fascia that invests the facial expression muscles to insert into the overlying dermis [11].
Figure 3. Deep cheek fat compartments: A Medial sub-orbicularis oculi fat. The sub-orbicularis oculi fat compartments are located below the orbicularis oculi muscle. In this anatomic dissection, the SOOFs are visible thanks to the separation of the muscular fibers of orbicularis oculi muscle. The upper part of DMCF is below the orbicularis oculi muscle. It lies laterally to the zygomaticus major muscle. It extends from the medial limbus to the outer cantum.
Figure 4. In this anatomical dissection the middle cheek fat has been removed and the buccal extension of buccal fat is clearly visible. Lateral Suborbicularis Oculi Fat L-SOOF Figure 4 : this is located at the lateral orbital rim above the prominence of the zygoma but does not reach above the superior margin of the zygomatic arch and it does not extended above the lateral canthus and the lateral orbital thickening represents the upper limit of L-SOOF. Its medial half is covered by the orbicularis oculi muscle.
L-SOOF lies above another more deeply situated fat compartment, therefore it is not in direct contact with the periosteum [30]. Its superior boundary is the zygomatic-cutaneous ligament that divides it from M-SOOF and it medially borders the buccal fat and with the zygomaticus major muscle. The medial boundary is the pyriform ligament surrounding the nasal base and the inferior boundary is the sub—orbicularis orris fat.
This fat compartment lies on the periosteum of the maxilla. Pils et al. Other authors [13] describe this compartment as divided into two different parts. One, the medial part, located beneath the nasolabial fat, does not lie immediately on the periosteum of the maxilla but it is bordered posteriorly by another small, triangular compartment. The lateral part is located under the superficial medial cheek fat and lies directly on the maxilla. Buccal fat BF : this is located below the zygoma and anteriorly to the ramus of the mandible surrounding the medial pterygoid and masseter muscles.
This fat compartment has a buccal extension Figure 3 that abuts the medial cheek fat, the deep medial cheek fat, the middle cheek fat, the sub—orbicularis oculi fat, the jowl fat, and the fat of the pre-masseter space. Gierloff et al. They have hypothesized that the buccal extension can be regarded as a distinct fat compartment. Other authors share this opinion [27]. The fat compartments undergo specific changes due to the aging process [20,21].
In some compartments the main changes are volume augmentation; in other the volume reduction or ptotis. The capability to understand these changes is essential in order to make a correct assessment of facial aging. The main age-related modifications, as indicated by our cadaver dissections and clinical experience, are different in superficial fat compartments compared to the deep ones. This evaluation is confirmed in recent scientific literature concerning the aging process of the face.
In the superficial medial cheek fat, the aging process causes a global volume increase with an inferior volume shift within the fat compartment. The volume increases in the lower two thirds and remains stable in the upper one [13].
Similar changes are observed in nasolabial fat that shows an inferior volume shift of fat tissue. In aged patients, the sagittal diameter of the upper third is smaller and the sagittal diameter of the lower third is higher [13]. These modifications create an overall volume augmentation of lower part of malar fat pad due to the ptosis and caudal migration of fat tissue.
The ptosis and the volume augmentation of these fat compartments contribute to the increase of the depth of the nasolabial fold [11,18]. The middle cheek fat, is loosely adherent to SMAS plane just like the malar fat pad, and its aging is characterized by ptosis, by caudal migration of fat and by a whole volume augmentation [13]. These modifications produce an increasing of convexity in the central portion of the cheek.
Finally the lateral temporal-cheek fat lies upon and is adherent to the parotid fascia without any deep fat compartment between them. Aging results in a hypotrophic involution of this compartment that does not usually have any tendency to caudal migration, showing a different aging process than the other superficial fat compartments previously described.
In deep fat compartments we find different aging related modifications. The medial and lateral SOOF both lie on periosteum and have an aging characterized by deflation with low tendency to ptosis. This is due to the fact that the reduced weight and the stronger attachment to underlying tissue makes it less likely to ptosis under the effects of gravity.
The deflation of medial SOOF produces the formation of the hollow in the infraorbital region. Reduction of the medial SOOF has been noted to increase the orbit cheek crease and the V deformity of the lower lid described by Mendelson et al. The medial SOOF supports the palpebral tissues of the inferior eyelid, so its reduction in volume increases the relaxation of the tissue of inferior eyelid and of the intraorbital fat.
The volume reduction of the lateral SOOF decreases the forward protrusion of the malar area and of the cheekbone, facilitating the ptosis of superficial fat compartments of the cheek. The deep medial cheek fat undergoes a gradual and global decrease of volume [15,23] and a caudal migration [13].
The volume reduction is greater in the upper two thirds and minor in the lower third where the caudal migration of fat compensates the volume loss [13]. The part of buccal fat that influences the aesthetic of the cheek is its buccal extension.
It seems to be mainly characterized by a hypotrophic ageing response. Several authors have observed a lower volume of the buccal extension in older cadaver specimens [13,48]. The deflation of this fat compartment leads consequently to a lack of support for the medial cheek and middle cheek fat, aggravating the descent of these compartments. Other authors [49,50] have observed an antero-inferior protrusion of buccal fat that increases the convexity of cheek and the ptosis of jowl.
Clinical and anatomical observations suggest that, with age, fat compartments could tend to deflation, specifically in the deep compartments, and to volume augmentation and ptosis, especially in the superficial fat compartments [19,51].
Some scientific support for this hypothesis is observed in literature. These authors introduced in this study the concept of an inferior volume shift within the compartments observed especially in nasolabial and superficial medial cheek fat. A similar hypothesis is proposed by Gosain et al.
They sustain that the facial expression muscle movements related to smiling result in the shrinkage of the base of superficial fat compartments of the malar fat pad and a consequent protrusion of the fat tissue especially in their inferior portion. The continued stress and lengthening of fibrotic septa of the SMAS results in their progressive loosening and the reduction of their retentive capability.
With aging the inferior migration of fat tissue becomes permanent and produces a volume augmentation in the lower part of malar fat pad and a consequent increase of depth of the nasolabial fold. The pattern of facial aging is probably produced by the combination of the different volumetric and morphologic modifications of the various fat compartments.
These changes can vary in different patients and can manifest themselves in different ways. The volumetric reduction of deep fat compartments causes the formation of hollows and flattening especially of infraorbital and zygomatic areas; contemporaneously it causes the ptosis of superficial fat compartments due to the loss of support determined by hypotrophy of deep adipose tissue.
The compartmental changes secondary to gravity are also influenced by compartmental changes secondary to deflation. These synergistic effects may influence the shape and position of adjacent compartments [22,28]. If, instead, the hypertrophy and ptosis of the superficial fat compartments are prevalent, the aging is characterized by volume augmentation especially at inferior part of the malar fat pad.
This aspect is combined with the volumetric reduction of infraorbital and zygomatic areas that are mainly caused by the volume reduction of the deep fat compartments infraorbital fat, deep medial cheek fat and lateral SOOF.
The volumetric modifications of superficial and deep fat compartments appear to be confirmed from the histologic point of view, in a recent study [53] that demonstrated in old cadaveric specimens 47— years, mean 71 years a smaller adipocyte size in the deep medial cheek fat compared to the nasolabial fat; unfortunately in this study these findings were not compared to a younger group and nor was whether these size differences of superficial and deep adipocytes are present in younger subjects when the volumetric compartments change have not yet developed.
For a truly controlled study of fat pads age-related changes, it is mandatory to have a younger cohort with which compare the histologic findings in cadavers of elderly people. Such a cohort may come from those having fat removed during reconstructive and cosmetic surgery.
Weight modification and weight differences can influence the volume of fat compartments but it is not well-know to date how this occurs. The clinical observation of submental fat hypertrophy concomitant with deep cheek fat atrophy in overweight patients suggests that weight gain may affect mainly the superficial compartments [30]. Meanwhile, a histologic study on cadavers showed the adipocyte size is increased in both the superficial and deep cheek compartments with higher weight [53].
Wan et al. This is due to the different anatomical location of the two fat layers: superficial fat compartments are located adjacent to the muscles of facial expression, while the deep fat pads lies directly on the periosteum. The continuous compression of the deep fat pads against bone during facial muscle movements and mastication may explain their tendency to selectively hypotrophy [54,55].
The same authors suggest that the proximity of superficial fat pads to the facial muscles may render them more metabolically active, thus requiring a more extensive and vascularized fascial network compared to the deep fat compartments as shown in histologic studies [16,17,25]. The anatomic modifications of the fat compartment of the face are one of the most important causes of facial aging. The causes of such changes are actually only partially understood, and their clinical implications are yet to be completely clarified.
The introduction of the compartmentalization concept of adipose tissue of the face has resulted in an important improvement in our capability to assess the aging of the face and the injection technique based on the compartment-specific volume augmentation has improved our ability to treat the aging of midface [31,32]. Further anatomical, physiological, metabolic and histological studies are necessary to continue to better understand the behavior of fat compartments.
All authors disclose any potential sources of conflict of interest. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
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