Boundaries of the temporal region
The temporal region is bounded anteriorly by the zygomatic process of the frontal bone and the frontal process of the zygomatic bone. The inferior boundary is the zygomatic arch, while the superior and posterior boundary is the contour of the upper edge of the temporalis muscle. To easily remember the anterior boundary, simply swap the bone names: the frontal and zygomatic bones give rise to their respective processes.
Layer-by-layer Structure
- Skin is thin and mobile; hair is present only in the posterior part.
- Subcutaneous adipose tissue (SAT) is loose, thin, and not divided by connective tissue septa. It contains the superficial temporal artery.
- Superficial fascia is thin and represents a continuation of the epicranial aponeurosis.
- Proper (temporal) fascia is dense; 3–4 cm above the zygomatic arch, it splits into superficial and deep layers. The superficial layer attaches to the outer margin, and the deep layer to the inner margin of the zygomatic arch.
- Interaponeurotic space is located between the layers of the fascia and contains the middle temporal artery.
- Subaponeurotic space lies between the temporal fascia and the temporalis muscle, communicates with the masseteric-mandibular space, and contains the temporal extension of the buccal fat pad (fat body of the cheek), which emerges between the anterior margin of the temporalis muscle and the outer wall of the orbit.
- Temporalis muscle is a muscle of mastication, originating from the periosteum of the temporal bone and the deep surface of the temporal fascia, and inserting into the coronoid process and the anterior margin of the ramus of the mandible.
- Osteomuscular space between the muscle and the periosteum communicates with the temporopterygoid space.
- Periosteum is tightly fused to the bone in the lower part and loosely above.
- Temporal bone lacks diploë, consists only of compact bone, and is fragile. It is adjacent to the middle meningeal artery, injury to which leads to epi- and subdural hematomas.
Purulent processes of the temporal region
Three levels of phlegmon are distinguished:
- Superficial — located in the subcutaneous adipose tissue; extensive due to the absence of septa.
- Middle — located in the interaponeurotic space; rare, typically secondary to osteomyelitis of the zygomatic arch.
- Deep subaponeurotic — spread into the buccal region via the buccal fat pad, as well as into the temporopterygoid and interpterygoid spaces, the pterygopalatine fossa, and the masseteric-mandibular space.
The deepest processes between the muscle and the periosteum communicate with the infratemporal fossa and the pterygoid spaces.
Neurovascular bundle and lymphatic drainage
Main bundle: a. temporalis superficialis, accompanying vein, and n. auriculotemporalis. Projection: a vertical line 1 cm anterior to the tragus of the ear, where the pulsation of the artery can be palpated. Lymphatic drainage goes to the nodes embedded within the parenchyma of the parotid gland.
Mastoid region
Boundaries correspond to the outlines of the mastoid process; the superior boundary is the line continuing the zygomatic arch. Layers: thin mobile skin, loose subcutaneous tissue with vessels and nerves, superficial fascia (continuation of the epicranial aponeurosis), proper fascia (continuation of the fascia of the m. sternocleidomastoideus), muscles (m. sternocleidomastoideus, m. splenius capitis, m. digastricus), thick periosteum tightly fused to the bone (except at Chipault's triangle). The bone contains air cells, the largest being the mastoid antrum (antrum mastoideum), which communicates with the middle ear, providing a mutual pathway for the spread of pus.
Intraosseous structures and Chipault's triangle
To project the intraosseous structures, two perpendicular lines are drawn across the mastoid process, dividing it into four quadrants:
- Anterosuperior — mastoid antrum.
- Anteroinferior — bony canal of the facial nerve.
- Posterosuperior — posterior cranial fossa containing the sigmoid sinus.
- Posteroinferior — sigmoid sinus of the dura mater.
Chipault's triangle is bounded: anteriorly by the posterior margin of the external acoustic meatus, posteriorly by the crista mastoidea, and superiorly by a horizontal line continuing the zygomatic arch. Dangerous structures are located around its perimeter: superiorly — middle cranial fossa, posteriorly — sigmoid sinus, anteriorly — facial nerve canal. It is precisely within this triangle that antrotomy — trepanation of the mastoid process to evacuate pus from the air cells — is safely performed.
Key points
- The temporal region has 10 layer-by-layer structures, including the split temporal fascia.
- The buccal fat pad (fat body of the cheek) serves as a pathway for the spread of subaponeurotic phlegmon into the buccal region.
- The temporal bone lacks diploë and is fragile; its fracture frequently damages the middle meningeal artery.
- The superficial temporal artery is projected 1 cm anterior to the tragus of the ear.
- Lymph drains into the parotid lymph nodes.
- The mastoid antrum communicates with the middle ear, facilitating the spread of mastoiditis.
- Chipault's triangle is the only safe zone for antrotomy.
- The quadrants of the mastoid process project the antrum, the facial nerve canal, the sigmoid sinus, and the posterior cranial fossa.