The intercarotid or alar fascia, other cervical fascias, and their adjacent spaces - a plea for clarification of cervical fascia and spaces terminology

Abstract

Due to varying descriptions and terminology of fascias of the neck, medical advice relying on this basic knowledge is insufficient. Our goal was to provide a precise anatomical description of cervical fascias and spaces with special focus on the intercarotid fascia, or the alar fascia. One hundred bodies donated to science embalmed with Thiel's method were investigated, cervical fascias were dissected layer by layer, and the results were documented by photography, with a focus on the intercarotid fascia. In addition, we performed a review of recent literature concerning cervical surgical interventions, radiological diagnostic pathways, and basic anatomical works focusing on core information on anatomical relations of cervical fascias and spaces. In another 10 bodies donated to science, the spaces of the neck were injected with coloured latex under ultrasound guidance, dissected, and documented by photography. The intercarotid fascia was a constantly developed connective tissue interconnecting the carotid sheath of both sides. In 52 of 100 specimens (52%) it crossed to the opposite side without any fusion to the ventrally situated visceral fascia. Fusion with the visceral fascia was found in 48%, either at the lateral border of the pharynx or on its dorsal side. The results of our dissections strengthen the precise description of the cervical fascias provided by Grodinsky and Holyoke in 1938. Spaces can be confirmed as described by Hafferl in 1969. The international anatomical and ENT societies should codify a unified anatomical terminology of the cervical spaces and fascias to prevent varying interpretations in the future.

Keywords: alar fascia; cervical abscess; cervical fascia; fascia alaris; fascia cervicalis; fascia intercarotica; head and neck; intercarotid fascia; neck anatomy.

Figure 1

Drawings of a median (mediosagittal) and transverse cross‐section with the cervical fascias exposed: fascia cervicalis superficialis (light green), fascia cervicalis media (blue), fascia buccopharyngea (green), fascia intercarotica (orange), fascia prevertebralis (pink), and fascia alaris (turquoise). The fascia alaris is marked by arrows as well

Figure 2

Fascia cervicalis superficialis dissected in the anterior, lateral, and posterior regions of the neck including the sensory nerves of the cervical plexus piercing this fascia at different levels. The fascia is visible as the light green structure in the drawings

Figure 3

Dissection of an entire fascia cervicalis media between the two omohyoid muscles: a blue probe is positioned underneath the fascia in the pretracheal space. Fascia is marked blue in the graphic scheme

Figure 4

Fascia buccopharyngea/visceralis covering the organs: larynx, trachea, thyroid gland, pharynx, oesophagus

Figure 5

The fascia intercarotica is easily identifiable and connects the two common carotid arteries; the tweezers are positioned behind (‘danger space’) the fascia which is marked orange in the graphic scheme

Figure 6

The vagina carotica (Vc) is marked at the border to the fascia intercarotica (FI) which crosses dorsally to the pharynx to the contralatral side. The fusion of the FI with the fascia buccopharyngea is visible in the median plane

Figure 7

The fascia prevertebralis covering the deep cervical muscle layer and the brachial plexus entering the lateral cervical triangle/region via the posterior interscalene gap

Figure 8

The turquoise fascia alaris, marked with an arrow, is shown as a sagittally oriented fascial layer between the vagina carotica (purple) and fascia prevertebralis (pink) (a). The dissection photos show the fascia as the lateral border of the medially located ‘Danger space’ (b,c). The tweezers are inserted in the ‘Danger space’ cranially (c)

Figure 9

View from the ventral right side: green latex is visible in the suprasternal space underneath the intact fascia cervicalis superficialis. The platysma muscle is retracted laterally (a). (b) The elevated latex mass and the exposed fascia cervicalis media (FCM). SCM, sternocleidomastoid muscle

Figure 10

View from the ventral right side: the left image (a) shows the fascia cervicalis media (FCM) with its lateral extention to the lateral margin of the omohyoid muscle (OHM). The blue latex injected into the pretracheal space is visible. (b) The latex; the FCM is resected. Retraction of the infrahyoid muscle group exposed the blue latex in the pretracheal space surrounding the thyroid gland (TG) in (c)

Figure 11

View from the ventral right side: the blue latex in the pretracheal space is elevated ventrally and the fascia intercarotica (FI) and the vagina carotica (VC) are exposed (a). (b) Partial resection of the VC shows the red latex in the ‘danger space’. Dorsally, the green latex is visible underneath the fascia prevertebralis (FPV) in the prevertebral space