head and neck anatomy

Landmarks on the Bones of the Skull

Frontal Bone

  • Supraorbital Foramen: Located on the upper rim of the orbit. This foramen provides blood and nerve supply to the forehead, which is essential for sensory innervation.

  • Zygomatic Process: This is the superior and lateral portion of the orbit, contributing to the structure and shape of the frontal bone.

  • Frontal Sinus: An air-filled space within the frontal bone that is involved in reducing the weight of the skull and producing mucus.

  • Anterior Cranial Fossa: This structue houses the frontal lobe of the brain, providing protective support.

Sphenoid Bone

  • Body of Sphenoid: Central portion of the sphenoid bone involved in forming the base of the skull.

  • Lesser Wing of Sphenoid: This structure makes up the posterior medial portion of the orbit, providing a base for further structures.

  • Greater Wing of Sphenoid: Constitutes the posterior lateral portion of the orbit, contributing to the skull's depth.

  • Medial Pterygoid Process (Plate): Features a medial component that supports muscles of mastication.

  • Lateral Pterygoid Process (Plate): Features a lateral component that also supports mastication muscles.

Sphenoid Bone - Anterior View

  • Hypophyseal Fossa (also known as Sella Turcica or Turkish seat): This fossa houses the pituitary gland, a critical endocrine organ.

  • Sphenoidal Sinuses: These air-filled cavities located within the sphenoid bone help to lighten the skull and are involved in nasal drainage.

Greater and Lesser Wings of Sphenoid

  • Optical Foramen and Canal: Located on the lesser wing of the sphenoid, this passage allows the optic nerve and ophthalmic artery to pass through, essential for vision functions.

  • Superior Orbital Fissure: Situated between the greater and lesser wings of the sphenoid, it accommodates cranial nerves (III, IV, VI) and the ophthalmic branch of the trigeminal nerve (V).

  • Inferior Orbital Fissure: This fissure is located between the greater wing of the sphenoid, zygoma, and maxilla; it allows the passage of the infraorbital and zygomatic nerves, the infraorbital artery, and ophthalmic vein.

Greater Wing of Sphenoid

  • Foramen Rotundum: This foramen houses the maxillary nerve, which is a division of the fifth cranial nerve ensuring sensory function.

  • Foramen Ovale: Contains the mandibular nerve, another division of the fifth cranial nerve; critical for both sensory and motor functions.

  • Foramen Spinosum: This foramen is the passage of the middle meningeal artery, which is vital for the blood supply to the brain's protective coverings.

  • Foramen Lacerum: Bordered by the sphenoid, temporal, and occipital bones, this foramen has multiple surrounding structures and functions for various nerves and arteries.

Pterygoid Process of Sphenoid

  • The Pterygoid Process comprises the most inferior section of the sphenoid and includes the medial and lateral pterygoid plates as well as the pterygoid fossa located between them.

  • Pterygopalatine Fossa: This opening leads to the area behind and below the eye, located between the maxilla and pterygoid process, extending medially to the palatine bone. It serves as a critical junction for major nerves and vessels to the oral and nasal cavities and midface.

Ethmoid Bone

  • Crista Galli: An important attachment point for the Falx Cerebri, one of the main folds of dura mater that separates the left and right hemispheres of the brain.

  • Cribriform Plate: This plate provides pathways for the olfactory nerve fibers leading to the nasal cavity, crucial for the sense of smell.

  • Superior and Middle Nasal Conchae & Meatuses: These structures contribute to the architecture of the nasal cavity, enhancing airflow.

  • Ethmoid Sinus: Air cells located within the ethmoid bone that help reduce skull weight and contribute to nasal drainage.

Occipital Bone

  • Occipital Condyles: These structures articulate with the first vertebra of the spine, providing nodding movement and support for the skull.

  • Foramen Magnum: This large opening houses the spinal cord, vertebral arteries, and the 11th cranial nerve, crucial for the central nervous system transmission.

  • Posterior Cranial Fossa: This fossa houses the brain stem and cerebellum, providing relevant support and protection to these vital areas.

  • Hypoglossal Canals: These canals accommodate the hypoglossal nerve and vessels responsible for tongue movements.

Temporal Bone

  • Three Main Parts:

    • Mastoid Process: Contributes to muscle attachment and sound conduction.

    • Squamous Portion: Forms the side of the skull and contributes to cranial shape.

    • Zygomatic Process: Connective structure forming the zygomatic arch, providing facial contour.

  • Styloid Process: Acts as an attachment point for muscles and ligaments in the head and neck region.

  • External Acoustic Meatus: Passageway for sound waves towards the inner ear.

  • Internal Acoustic Meatus: Carries auditory and vestibular nerves to the inner ear.

  • Petrous Temporal Bone: Houses the components of the inner ear, vital for hearing and balance.

  • Middle Cranial Fossa: This fossa supports the temporal lobe of the brain.

Temporal Bone - Carotid Canals

  • Carotid Canals: Pathway for the internal carotid artery and nerve plexus leading into the cranial cavity through the foramen lacerum.

  • Jugular Fossa and Foramen: Located at the border of the temporal and occipital bones, these structures provide a passage for significant cranial nerves and veins.

  • Stylomastoid Foramen: This foramen is crucial as it allows the seventh cranial nerve to exit, innervating muscles of facial expression.

Temporal Fossa

  • The temporal fossa is not just composed of the temporal bone but includes four additional bones: the frontal, parietal, sphenoid, and temporal bones, contributing to this anatomical region's structural complexity.

Temporal Bone - TMJ

  • Articular Eminence: Located just anterior to the point of articulation, providing a surface for jaw movement.

  • Mandibular Fossa: This structure articulates with the mandibular condyle, forming the temporomandibular joint (TMJ).

  • Postglenoid Process: Situated just posterior to the articulation point, playing a supportive role for the joint.

Mandible

  • Body: The horizontal portion of the mandible that supports the lower teeth.

  • Ramus: The vertical portion of the mandible extending from the body.

  • Alveolar Process: Contains the sockets for the teeth; critical for dental support.

  • Growth in the mandible takes place in the alveolar process and body, which increases in width and height. Bone is added to the posterior border of the ramus while being taken away from the anterior border, contributing to lengthening.

Mandible – Buccal View

  • Mental Foramen: Located apical and interproximal to the premolars, this foramen allows passage for the mental nerve and vessels, supplying the chin, lower lip, and anterior facial gingiva of the mandible.

  • Mental Protuberance: Represents the tip of the chin, a defining feature of facial structure.

Mandible- Buccal View

  • Angle of Mandible: This angle divides the body from the ramus at the most inferior point, providing structure to the mandible's shape.

  • External Oblique Line (ridge): Runs from the anterior border of the ramus to where it meets the body, marking the outer contour of the ramus and bordering the alveolar process.

Mandible – Lingual View

  • Mandibular Foramen: This foramen allows the inferior alveolar nerve and vessels to enter and supply the lower teeth and lip, crucial for oral sensation and function.

  • Lingula: A bony process that partially covers the mandibular foramen, serving as an attachment point for a ligament.

Mandible- Lingual View

  • Mylohyoid Groove: Located beneath the mandibular foramen, this groove serves as a passage for the mylohyoid nerve and vessels, essential for muscular innervation.

  • Mylohyoid Line: This line runs forward and down from the mandibular foramen and acts as the attachment for the mylohyoid muscle, which contributes to oral function.

Mandible- Lingual View

  • Sublingual and Submandibular Fossae: These fossae house the sublingual and submandibular salivary glands, which are imperative for digestion.

  • Retromolar Triangle: This triangular area is located behind the third molar and is essential for dental considerations.

Mandible- Lingual View

  • Mental Spines (genial tubercles): Attachment points for muscles located lingually at midline, providing structural support to the floor of the mouth.

  • Digastric Fossa: This fossa serves as another attachment point for muscles, located lingually at the inferior border near the midline.

Mandible

  • Mandibular Notch: This depression in the ramus is located anterior to the temporomandibular joint and provides landmarks for muscular attachments.

  • Coronoid Process: Situated anterior to the mandibular notch, this process serves as an attachment point for one of the muscles of mastication.

Mandible- TMJ

  • Condyloid Process: The most posterior superior extension of the mandible that participates in joint formation with the temporal bone.

  • Head of Condyle: Articulates with the mandibular fossa of the temporal bone, forming the temporomandibular joint, which is vital for jaw movement.

  • Condylar Neck: A slightly narrowed area just inferior to the condyle, which supports the condyloid process during mastication and articulation.

Mandible TMJ - Structures

  • Subordinate Structures: Understanding the temporal bone and mandible structures is essential in the anatomy of the temporomandibular joint (TMJ).

Nasal Bone

  • Piriform Aperture: The pear-shaped opening in the skull located just inferior to the nasal bones, contributing to the facial structure and nasal cavity.

Zygomatic Bone

  • Inferior Orbital Fissure: Located at the junction where the zygomatic bone meets the sphenoid bone and maxilla.

  • Temporal Process: Forms the zygomatic arch in conjunction with the zygomatic process of the temporal bone, essential for aesthetic and functional surveys of the skull.

  • Frontal Process: This process helps form the anterior lateral orbital wall, a critical aspect of the eye's support.

  • Maxillary Process: Contributes to the infraorbital rim and part of the anterior lateral orbital wall, facilitating the structural integrity of the skull.

Palatine Bone

  • Greater Palatine Foramen: This foramen transmits the greater palatine nerve and vessels, important for sensation and vascular supply.

  • Lesser Palatine Foramen: This foramen allows the passage for lesser palatine nerve and vessels, located just posterior to the greater palatine foramen and contributing to the oral cavity's innervation.

Maxillae

  • Frontal Process: This process plays a role in the facial skeleton and extends toward the frontal bone.

  • Zygomatic Process: A projection forming part of the zygomatic arch in conjunction with the zygomatic bone, which is important for facial aesthetics.

  • Alveolar Process: This process contains the sockets for the upper teeth and is essential for dental structure.

  • Palatine Process (Horizontal): This part forms most of the hard palate, critical for oral cavity structure and function.

Maxillae

  • Maxillary Tuberosity: Located posterior to the terminal molar; this area is where blood vessels and nerves enter to supply posterior teeth and part of the maxillary sinus, ensuring dental health and sensation.

Maxillae

  • Alveolar Eminences: These are facial surfaces on the alveolar process, important for dental aesthetics.

  • Canine Eminence: Specific to the canine teeth and important for dental landmarks.

  • Canine Fossae: Areas surrounding the canine eminences that contribute to the dentition layout.

Maxillae

  • Anterior Nasal Spine: Part of the inferior portion of the nasal cavity, playing a key role in nasal structure.

  • Lacrimal Groove: Extends from the lacrimal bone to the maxilla and into the nose, important for tear drainage.

  • Infraorbital Foramen: This foramen allows vessels and nerves to pass through, supplying the upper lip, some facial gingiva, the lower eyelid, and the side of the nose.

Maxillae - Final Structures

  • Incisive Foramen: This foramen, positioned at the most anterior and medial aspect of the palate, is where nerves and arteries enter to supply the anterior region of the palate.

  • Maxillary Sinus: An air-filled space that helps to lighten the weight of the skull and features drainage pathways to the nasal cavity, impacting dental sensations and sinus health.