🥇 HUESO TEMPORAL, Anatomía. Fácil, Rápido y Sencillo

Introduction to the Temporal Bone

Overview of the Temporal Bone

• The video introduces the temporal bone, described as anatomically complex and significant in anatomy studies.

• The name "temporal" has two theories: it resembles a sundial or is associated with aging, as gray hair often appears in that area.

Anatomy of the Skull

• The skull consists of 8 cranial vault bones, including paired parietal and temporal bones, along with four unpaired bones: frontal, sphenoid, occipital, and ethmoid.

• At fetal development (7-8 weeks), the temporal bone comprises three separate portions: petrous portion, tympanic portion (incomplete ring), and fetal scale.

Development and Structure of the Temporal Bone

Adult vs. Fetal Temporal Bone

• Post-birth development leads to fusion of these portions into what is recognized as an adult temporal bone.

• The adult structure includes a scaly portion resembling fish scales, a mastoid portion formed from outer fetal structures, and a petrous portion from inner fetal structures.

Study Approach

• To simplify learning about the temporal bone, it can be divided into three main portions; some texts may mention five but three is more common.

Detailed Examination of Portions

Flaky Portion Characteristics

• The flaky (scaly) portion features two faces: external (exocranium-facing) and internal (endocranium-facing).

• A notable groove for the middle temporal artery runs along its external face; also present is the zygomatic process forming part of the zygomatic arch.

Zygomatic Process Details

• The zygomatic process has two faces—external covered by skin and internal facing temporalis muscle—and connects to various anatomical structures.

• It features an upper edge for temporal aponeurosis insertion and a lower edge related to masseter muscle attachment near temporomaxillary joint.

Complexities of Zygomatic Process

Structural Components

• The zygomatic process base consists of transverse and longitudinal roots; transverse root forms an elevation known as articular tubercle.

• This tubercle marks anterior limits for fossa where mandible head articulates to form temporomandibular joint.

Temporal Bone Anatomy Overview

Supramastoid Crest and Joint Structures

• The supramastoid crest is located above the mastoid portion of the temporal bone, serving as a landmark for anatomical orientation.

• The anterior tubercle marks the anterior limit of the temporomandibular joint cavity, crucial for understanding jaw mechanics.

Internal Face of Temporal Bone

• The internal face features a groove for the middle meningeal artery, paralleling an external groove found on the outer surface.

• Articulations with adjacent bones include an anterior edge connecting to the greater wing of the sphenoid and a superior edge articulating with the parietal bone.

Mastoid Portion Characteristics

• Named for its breast-like shape, the mastoid portion consists of two faces: an external face housing neck muscle attachments and an internal endocranial face.

• The digastric groove on this portion is significant as it serves as an origin point for muscles like the posterior belly of the digastric muscle.

Internal Features and Venous Structures

• The internal face contacts the cerebellum in the posterior cranial fossa, featuring important structures such as mastoid orifices and grooves related to venous sinuses (transverse sinus).

• A notch at the junction between squamous and mastoid portions facilitates articulation with parietal bones, highlighting complex inter-bone relationships in cranial anatomy.

Petrous Portion Complexity

Anatomy of the Petrous Portion of the Temporal Bone

Overview of the Petrous Portion

• The petrous portion resembles a laid-down Egyptian pyramid with four faces, edges, a base, and a vertex. It is crucial for understanding its anatomy.

Base Structure

• The base is the most external and posterior part of the petrous portion, containing the opening to the external auditory canal. This hole is formed by tympanic bone in three parts: anterior, lower, and posterior.

• Above this opening lies the supra meatic spine and fossa, which contains a sinus above it. This anatomical detail is significant for understanding surrounding structures.

Vertex Location

• The vertex or tip is located anteromedially where the body of the sphenoid joins its greater wing; mastering adjacent bones like occipital and sphenoid is essential before studying temporal bone anatomy.

• A recommended study order for skull bones starts with frontal, then ethmoid, sphenoid, occipital, parietal, concluding with temporal to avoid confusion.

Carotid Orifice Details

• The carotid orifice serves as a channel piercing through the petrous portion; it has both internal and inferior orifices where the internal carotid artery enters and makes an elbow inside before exiting.

Edges of Petrous Portion

• There are four edges: upper (with groove for superior petrosal sinus), posterior (articulating with occipital bone), anterior (joining squamous portion), and lower edge details will be discussed later.

• The upper edge features a groove for superior petrosal sinus while the posterior edge has grooves related to inferior petrosal sinus along with other important structures like jugular process and facets associated with jugular foramen.

Jugular Foramen Insights

• The internal jugular vein enters at this region where sigmoid sinus transitions into internal jugular vein; this area marks critical anatomical relationships relevant to cranial nerves 9, 10, and 11 descending through specific foramina.

Additional Anatomical Features

• Notable structures include petrotympanic fissure leading to tubal muscle duct allowing communication between middle ear and pharynx via eustachian tube; these connections are vital for ear function.

Understanding the Temporal Bone Anatomy

Overview of Internal Anatomy

• The internal anatomy of the temporal bone is crucial for understanding hearing, as discussed in the inner ear video. This aspect is often overlooked in general studies of bone anatomy.

Faces of the Temporal Bone

• The temporal bone has four faces resembling a pyramid: antero-superior, postero-superior, and two lower faces. The antero-superior surface features a depression known as the Gasser fossa, which houses the Gasser ganglion (trigeminal ganglion).

Important Structures on Antero-Superior Surface

• The fallopian hiatus serves as a conduit for the greater superficial petrosal nerve. Additionally, the arcuate eminence is formed by semicircular canals and contributes to the roof of the middle ear (tegmen tympani).

Posterior Superior Aspect Details

• On this aspect, there is an internal auditory canal that connects to both the eighth cranial nerve (vestibulo-cochlear) and facial nerve. The vestibule aqueduct allows passage from inner ear structures. A notable feature here is the fossa subacquata, more pronounced in fetuses than adults.

Lower Edge and Its Zones

• The lower edge consists of two additional faces: postero-inferior and antero-inferior. The postero-inferior face divides into three zones: external (styloid process), middle (jugular fossa), and medial/internal zone (inferior orifice of carotid duct). Each area has significant anatomical relevance including where cranial nerves emerge.

Summary of Key Features

• External zone includes important attachments for neck ligaments/muscles; mastoid orifice where facial nerve exits skull.

• Middle zone contains jugular fossa associated with venous drainage.

• Medial zone features entry point for internal carotid artery.

• Anteroinferior aspect relates to external auditory canal part of tympanic bone structure.