the eyebrows are superficial to what bone and bony feature
Inductive and lateral views of the skull
The man skull consists of nigh 22 to 30 single bones which are mostly connected together by ossified joints, so called sutures. The skull is divided into the braincase (cerebral cranium) and the face (visceral cranium).
The master task of the skull is the protection of the near important organ in the human body: the brain. The encephalon is virtually entirely enclosed by the cerebral attic with the exception of the foramen magnum and other foramina at the skull base which serve as entry and exit point for blood vessels and cranial fretfulness. In this article we will see the bones of the skull as seen from an anterior and lateral view.
| Frontal os | Forms the forehead and part of the orbital socket (orbital surface) |
| Greater wing of sphenoid bone | Foramen rotundum (CNV/2), foramen ovale (CNV/III), foramen spinosum (middle meningeal artery), foramen petrosum ocasionally (lesser petrosal nervus) |
| Bottom wing of sphenoid bone | Forms the anterior edge of the middle cranial fossa |
| Bony Orbit | Orbital surface of frontal bone, orbital surface of the sphenoid bone, orbital procedure of the palatine bone, orbital surface of zygomatic os, orbital surface of ethmoid bone |
| Mandible | Condyle, ramus, coronoid process |
| Maxilla | Articulates with nasal bones, alveolar processes, frontal process |
| Zygomatic bone | Forms part of the lateral orbital rim and the lateral role of the orbital socket |
| Nasal skeleton | Ethmoid os (cribriform plate, crista galli), frontal bone, nasal bones |
| Ethmoid bone | Orbital function of the ethmoid bone forms the is office of the medial portion of the eye socket |
| Parietal bone | Articulations with the frontal, occipital, and parietal bones |
| Temporal os | Squamous function, mastoid procedure, petrous part |
Contents
- Sphenoid os
- Facial skeleton and sensory nerves
- Mandible
- Maxilla and zygomatic arches
- Nasal skeleton
- Parietal bone
- Temporal os
- Summary
- Sources
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Sphenoid bone
The greater wing of the sphenoid is a construction that extends from the side of the body of the bone to curve backwards and laterally. The most posterior part of this projection is a triangular process that fits neatly into the ridge betwixt the petrous and squamous portion of the temporal os.
The greater fly of the sphenoid contains the foramina for many structures. These include:
- The foramen rotundum for the maxillary branch (CNV/Ii) of the trigeminal nerve,
- The foramen ovale which is an oval shaped foramen that allows the mandibular branch (CNV/Three) of the trigeminal to pass through together with the accessory meningeal avenue.
- The foramen spinosum. If the foramen ovale represents the direct line of an exclamation point, the foramen spinosum represents the dot. The middle meningeal artery (co-operative of the maxillary avenue) enters the cranial cavity through here (foramen spinosum).
- An occasional opening in the greater wing is the foramen petrosum which is a minor opening between the spinosum and ovale for the lesser petrosal nerve to exit through.
The lesser wings of the sphenoid are paired wings that extend from the anterior clinoid process laterally to form the inductive border of the middle cranial fossa.
The optic canal travels through the medial portion of the wings, and the sella turcica which contains the pituitary gland sits just behind the clinoid processes. Together with the posterior clinoid process (which arise from the trunk of the pituitary itself) they make a structure that resembles a 'iv poster bed' in which the pituitary sits. The origin of the words clinoid and clinical are both 'klinikē' which is Greek for 'bedside'.
Facial skeleton and sensory nerves
The orbital surface of Frontal bone is the anteroinferior most section and gives rise to the roof of the orbital socket. The bone articulates with the zygomatic os laterally the sphenoid os deep in the eye socket likewise as the ethmoid bone at the deep medial section of the eye socket.
The orbital surface of the Zygomatic bone is the lateral rim and border of the orbital socket. The bone articulates medially with the maxilla, superiorly with the orbital process of the frontal bone, and with the sphenoid bone deep in the eye socket.
The infraorbital foramina are paired openings that can be located on the malar surface of the maxillary os and transmits the infraorbital nerve. This nerve is a branch of the maxillary partitioning (CNV/II) of the trigeminal nerve and provides sensory innervation to the lower eyelid and cheek.
The mental foramina are paired openings that are located on the anterior well-nigh aspect of the mandible and transmit the mental nervus. This provides sensory innervation to the chin surface area and is a branch of the mandibular division (CNV/Three) of the trigeminal nerve.
In humans the Glabella is the region plant between both eyebrows and refers to both the overlying skin and the underlying os which is likewise indented. The bone is the orbital process of the frontal bone in the midline as it articulates with both paired nasal bones. The supraorbital notch transmits the supraorbital nervus which provides sensory innervation to the eyebrow and upper eyelid.
The orbital plate of the ethmoid is a thin plate of bone and forms part of the medial office of the eye socket. Information technology is part of the ethmoid os which is a small unpaired os which separates the nasal crenel from the brain.
The Zygomatic bone forms role of the lateral orbital rim as well every bit the lateral part of the orbital socket. The bone articulates with the maxilla inferiorly, the frontal bone superiorly and the sphenoid bone within the eye socket.
Mandible
The mandible is the os that forms the lower jaw. It consists of various parts including the condyle, which articulates with the temporal bone at the temporomandibular joint, the ramus which forms the posterior edge, the torso which contains the tooth sockets, and the coronoid process to which the temporalis muscle gains its insertion.
The os contains the mandibular foramen at the inner surface of the ramus of the mandible which allows the inferior alveolar nervus; a branch of the mandibular nervus which is a branch of the trigeminal nerve. Information technology allows the nerve to enter the os and innervate the lower teeth. The trunk of the mandible can be described as the chief bulk of its structure. Information technology is the horizontal section of the bone which gives rise to the row of junior teeth. The orbital surface of maxilla is the superior aspect of the bone which gives rising to the medial part of the floor of the orbital socket.
The ramus of the Mandible is a ridge of os that connects the body of the bone to the condyle. The condyle articulates at the TMJ or Temporomandibular joint. The articulation is complex and allows for not only pivot movement for opening and closing, but besides some anterior translation. Ligament control the range of the move in this joint.
Maxilla and zygomatic arches
The maxilla is the os that forms the upper jaw. The zygomatic process articulates with the zygomatic os laterally, the frontal process articulates with the nasal bones in the anterior midline, the alveolar process gives zipper to the superior teeth and the palatine process which forms the anterior ii-thirds of the difficult palate.
The Alveolar process is a thickened ridge of bone that contains the teeth sockets that give rise to the teeth which attach past immovable joints known equally gomphosis.
The frontal process of maxilla is the portion of the bone that ascends lateral to the nasal bones. Along with the lacrimal bone and the ethmoid bone, the bone articulates with the orbital surface of the frontal bone superiorly. The frontal process of Zygomatic is the part of the os that articulates with the frontal bone. The os extends superiorly and forms the lateral office of the eye socket.
Nasal skeleton
The Ethmoid os is a small unpaired bone that separates the encephalon from the nasopharynx. The cribriform plate of the ethmoid bone transmits the fibres of the olfactory nerve. The crista galli is an upward facing ridge of bone that divides the two halves of the plate.
The Frontal os overlies the frontal lobe of the brain anteriorly and forms the forehead and part of the orbital socket. The bone articulates with the parietal cones posteriorly and the greater fly of the sphenoid bone laterally.
The Nasal bones are 2 small-scale paired structures that form the bony part of the external nose. They clear with anteroinferior portion of the frontal bone superiorly and the nasal process of the maxillary bone laterally. This is in addition to the opposing nasal os and the ethmoid os inside the orbit. The bones give zipper to the quadrangular cartilage of the nasal septum and the lateral cartilages that form the lateral part of the nasal bridge.
Parietal bone
The Parietal bone articulates with the frontal bone anteriorly and overlies the parietal lobe of the brain. It articulates with the occipital bone posteriorly too as the temporal os laterally.
Temporal bone
The Temporal bone is a complex structure with numerous sections. These include the squamous portion which is similar in structure to other bones of the skull and forms the anterosuperior role of the bone. The outer surface of this portion is convex to allow for the attachment of the temporalis musculus. The mastoid is a significant pyramidal protrusion from the underside of the os and gives rise to the sternocleidomastoid and splenius capitis and the longissimus capitis.
The petrous portion of the bone is a hard pyramidal shaped department of the bone that has a complex structure simply essentially contains the organs of hearing. The proper name 'petrous' comes from the latin word 'petrosus' which ways 'stone-like', the tympanic section of the bone surrounds the external auditory meatus and the styloid process.
Summary
The bones of the skull that are visible from an inductive and a lateral view are the following:
- the sphenoid bone (with the greater and the bottom wings)
- the frontal bone (specially the orbital surface)
- the zygomatic bone
- the maxilla
- the mandible
- the nasal bones
- the ethmoid bones
- the parietal os and
- the temporal bone
All these bones have several openings (foramina) through which the various nerves and vessels laissez passer.
Anterior and lateral views of the skull: want to learn more about it?
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