Osteology: Skeleton Anatomy PDF

Ok, here is the information from the images in a markdown format. ## Overview - General Information * Most complicated bony structure in the human body * The complete bony framework of the head; includes the mandible * 28 individual bones make up the skull: * 11 are paired * 6 ar...

Ok, here is the information from the images in a markdown format. ## Overview - General Information * Most complicated bony structure in the human body * The complete bony framework of the head; includes the mandible * 28 individual bones make up the skull: * 11 are paired * 6 are single * Wormian bones, or sutural bones, are irregularly shaped small bones found along sutures that occur naturally ### Functions * Most important function: to protect the brain * Also protects the 5 organs of special sense: * Olfaction * Vision * Taste * Vestibular function * Auditory function ### Divisions * 2 major ways to divide the bones of the skull: * Regional * Developmental * Regionally, the skull is divided into the mandible (lower jaw) and cranium (skull without the mandible) * Cranium is further divided into: * Cranial vault-upper portion of the skull * Cranial base-inferior portion of the skull * Cranial cavity-interior of the skull * Facial skeleton-bones that make up the face * Acoustic skeleton-ear ossicles * Developmentally, the skull is divided into: * Viscerocranium-the portion of the skull related to the digestive and respiratory systems * Neurocranium-the portion of the skull that protects the brain and the 5 organs of special sense * Cranial cavity divisions: * Anterior cranial fossa-contains the frontal lobe of the brain * Middle cranial fossa-contains the temporal lobe of the brain * Posterior cranial fossa-contains the cerebellum * Skull is depicted by observing it from 5 views: * Norma frontalis-the anterior view * Norma lateralis-the lateral view * Norma occipitalis-the posterior view * Norma basalis-the inferior view * Norma verticalis-the superior view ## Bones of the Skull - Frontal Bone | Characteristics | Parts | Ossification | Comments | | :----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | :------------- | :------------------------------------------- | :----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | Contains the frontal paranasal sinuses | Squamous portion | Intramembranous (for all 3 parts) | The largest part of the frontal bone. Forms the majority of the forehead. Forms the supraorbital margin and the superciliary arch. The zygomatic process of the frontal bone extends from the posterior part of the supraorbital margin. Arachnoid foveae-depressions caused by arachnoid granulations | | Has 2 primary centers that ossify along the frontal suture (metopic) in the 2nd year Helps form the foramen cecum, which allows passage of an emissary vein that connects to the superior sagittal sinus There is 1 frontal bone | Orbital portion | | Forms the roof of the orbit and the floor of the anterior cranial fossa The trochlea of the orbit articulates with the orbital portion | | | Nasal portion | | Articulates with the nasal bones and the frontal process of the maxilla to form the root of the nose | ## Bones of the Skull - Parietal Bone | Characteristics | Parts | Ossification | Comments | | :---------------------------------------------------------------------------------------------------- | :--------------------------------------------------------------------------------------------------------------- | :--------------- | :---------------------------------------------------------------------------------------------------------- | | Forms the majority of the cranial vault Provides for the attachment of the temporalis muscle | The 4 corners: Frontal-located at bregma Sphenoid-located at pterion Occipital-located at lambda Mastoid-located at asterion | Intramembranous | Relatively square, forming the roof and sides of the cranial vault. Endocranial surface is filled with grooves made by branches of the middle meningeal a. Sigmoid sulcus is a groove | | The 4 corners of the parietal are not ossified at birth and give rise to the fontanelles | | | | | There are 2 parietal bones | | | | ## Bones of the Skull - Occipital Bone | Characteristics | Parts | Ossification | Comments | | :--------------------------------------------------------------------------------------------------------------------------------------------------- | :---------------- | :------------ | :---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | Forms the posterior part of the cranial vault Articulates with the atlas | Squamous portion | Intramembranous | Articulates with the temporal and parietal bones. The largest portion of the occipital bone Located posterior and superior to the foramen magnum Has the external occipital protuberance (more pronounced in males) Has the superior and the inferior nuchal lines. Has grooves on the internal surface for 3 of the sinuses forming the confluence of the sinuses (the superior sagittal and the right and left transverse sinuses|) | | The squamous and lateral portions normally ossify together by year 4 The basilar portion unites to this section at year 6 There is 1 occipital bone | Lateral portion | Endochondral | Articulates with the temporal bone. Is the portion lateral to the foramen magnum. Has the occipital condyles that articulate with the atlas Contains the hypoglossal canal Forms a portion of the jugular foramen | | | Basilar portion | Endochondral | Articulates with the petrous part of the temporal and the sphenoid bones. Is the portion immediately anterior to the foramen magnum. Pharyngeal tubercle is part of the basilar portion that provides attachment for the superior constrictor Internal surface of the basilar portion is called the clivus, and part of the brainstem lies against it | ## Bones of the Skull - Temporal Bone | Characteristics | Parts | Ossification | Comments | | :------------------------------------------------------------------------------------- | :----------- | :------------------------ | :---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | The paired temporal bones: | Squamous part | Intramembranous | The largest portion of the bone. 3 portions to the squamous part: Temporal, Zygomatic process, Glenoid fossa. Temporal portion is the thin large area on the squamous part of the temporal On the internal surface of the temporal portion lies a groove for the middle meningeal a. | | Help form the base and the lateral walls of the skull | | Endochondral | The zygomatic process extends laterally and anteriorly from the squamous portion; it articulates with the temporal process of the zygomatic bone to make the zygomatic arch | | House the auditory and vestibular apparatuses Contain mastoid air cells | | | Glenoid fossa is inferior and medial to the zygomatic process; it articulates with the mandibular condyle, forming the temporomandibular joint | | Each bone has 8 centers of ossification that give rise to the 3 major centers | Petrous part | | Forms the solid portion of bone. The auditory and vestibular apparatuses are located within the petrous part. Helps separate the temporal and the occipital lobes of the brain; it extends anteriorly and medially. | | observed before birth There are 2 temporal bones | | | The medial part articulates with the sphenoid bone to form the foramen lacerum. Internal acoustic meatus is observed on the medial side of the petrous part. | | | | | Carotid canal lies on the inferior part of the petrous part Petrotympanic fissure lies between the petrous part of the temporal bone and the tympanic part of the temporal bone On the medial portion of the petrous part lie grooves for the superior and inferior petrosal sinuses | | | Tympanic part| Intramembranous |On the posterior inferior surface of the petrous part lies the jugular fossa Between the jugular fossa and the carotid canal is the tympanic canaliculus The mastoid process extends posteriorly and has large mastoid air cells | | | Styloid | Endochondral | A plate of bone forming the anterior, posterior, and inferior portions of the external acoustic meatus | | | process | A projection from the temporal bone |Anterior part forms the posterior portion of the glenoid fossa The stylomastoid foramen lies posterior to this process | ## Bones of the Skull - Sphenoid Bone | Characteristics | Parts | Ossification | Comments | | :-------------------------------------------------------------------------------- | :----------- | :--------------------------------- | :---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | Forms the majority of the middle portion of the cranial base | Body | Endochondral | The center of the sphenoid Anterior portion of the body helps form part of the nasal cavity Superior part of the body, known as the sella turcica, is saddle-shaped and possesses the anterior and posterior clinoid processes Hypophyseal fossa, the deepest part of the sella turcica, houses the pituitary gland | | Forms the majority of the middle cranial fossa Contains the sphenoid paranasal sinus | | | Dorsum sellae is a square-shaped part of the bone that les posterior to the sella turcica Clivus is the portion that slopes posterior to the body Body contains the sphenoid paranasal sinuses Lateral portion of the body is covered by the cavernous sinus Optic canal is found in the body of the sphenoid | | There is 1 sphenoid bone | Greater wing | Endochondral and intramembranous | Extends laterally and anteriorly from the posterior portion of the body of the sphenoid Endocranial portion helps form a large part of the middle cranial fossa | | | Leser wing | Extends laterally and anteriorly from the superior portion of the sphenoid body Separated from the greater wing by the superior orbital fissure | | Pterygoid | A small orbital process helps form part of | Lateral portion is the infratemporal surface Anterior portion lies in the orbit Contains 3 foramina: Foramen spinosum Foramen rotundum Foramen ovale Process | | intramembranous| the orbit ## Bones of the Skull - Lacrimal Bone | Characteristics | Parts | Ossification | Comments | | :------------------------------------------------------------------------------ | :---- | :-------------- | :------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | Lacrimal bone is small and rectangular in shape and very thin and fragile | | Intramembranous | Forms a small portion of the medial wall of the orbit. Articulates with the frontal process of the maxilla, orbital plate of the ethmoid bone, the frontal bone, and the inferior nasal concha | | There are 2 lacrimal bones | | The inferior part of the lacrimal forms a small portion of the lateral wall of the nasal cavity | | | | | ## Bones of the Skull - Nasal Bone | Characteristics | Parts | Ossification | Comments | | :---------------------------------------------------------------------------------------------------------------- | :---- | :-------------- | :------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | Inferior portion forms the superior margin of the nasal aperture Forms the bridge of the nose | | Intramembranous | Articulates with the nasal bone of the opposite side, the nasal portion of the frontal bone, the frontal process of the maxilla. Forms the root of the nose | | There are 2 nasal bones | | The inferior part of the lacrimal forms a small portion of the lateral wall of the nasal cavity | ## Bones of the Skull - Zygomatic Bone (Zygoma) | Characteristics | Parts | Ossification | Comments | | :---------------------------------------------------------------------------------------------------------------- | :---- | :-------------- | :----------------------------------------------------| | Forms the majority of the skeleton of the cheek Process | | Intramembranous | Articulates of the frontal bone There are 2 zygomatic bones | | | To help from the orbit Provides for attachment of the masseter | ## Bones of the Skull - Ethmoid Bone | Characteristics | Parts | Ossification | Comments | | :------------------------------------------------------------------------------------------------------------------------------------------- | :---------------- | :----------- | :---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | A porous bone that forms the major portion of the middle part of the face between the orbits | Perpendicular plate | Endochondral | A flat plate that descends from the cribriform plate to form part of the nasal septum, forming the superior part of the septal bone - articulates with the vomer inferiorly. | | Helps form the orbit, nasal cavity, nasal septum, and anterior cranial fossa There is 1 ethmoid bone | Cribriform plate | | A horizontal bone that forms the superior surface of the ethmoid | | | Ethmoid labyrinth | |Descends inferiorly from the cribriform plateEthmoid paranasal sinuses are located within the ethmoid labyrinth Lies within a curve in the lateral wall of the articulates which forms the orbit | nasal cavity ## Bones of the Skull - Vomer | Characteristics | Parts | Ossification | Comments | | :------------------------------------------------------------ | :---- | :-------------- | :--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | Shaped like a plow Forms the posterior inferior part of\ the nasal septum | | Intramembranous | Articulates with the perpendicular plate of the ethmoid, maxilla, palatine, and sphenoid bones and septal cartilage Posterior border does not articulate with any other bone | | There is 1 vomer bone | | |Lies within a curve in the lateral wall of the nasal cavity ## Bones of the Skull - Inferior Nasal Concha | Characteristics | Parts | Ossification | Comments | | :----------------------------------------------------------------------------------- | :---- | :----------- | :------------------------------------------------------------------------------------------------- | | Is described as a curved bone that forms part of the lateral wall of the nasal cavity | | Endochondral | Lies within a curve in the lateral wall of the nasal cavity | | There are 2 inferior nasal conchae | | Articulates with which forms the superior ## Bones of the Skull - Palatine Bone | Characteristics | Parts | Ossification | Comments | | :------------------------------------------------------------------------------------------------------------------------- | :---------------- | :-------------- | :--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | Forms part of the nasal cavity and the hard palate Is L-shaped There are 2 palatine bones | Perpendicular plate | Intramembranous | Is in the shape of a vertical rectangle. On the superior border is a notch that articulates with the sphenoid bone, forming the sphenopalatine foramen A small orbital process helps form part of the orbit | | | Horizontal plate | | Forms part of the wall of the pterygopalatine fossa and the lateral wall of the nasal cavity Lateral wall articulates with the maxilla to form the palatine canal Forms the posterior portion of the hard\ palate. | | | Pyramidal process | | Extends posteriorly and inferiorly from the junction of the perpendicular and horizontal plates of the palatine | | Greater palatine foramen is on this plate ## Bones of the Skull - Maxilla | Characteristics | Parts | Ossification | Comments | | :------------------------------------------------------------ | :---- | :-------------- | :---------------------------------------------------------------------| Forms the majority of the skeleton of the face and the upper . | Body| Intramembranous Forms shaped like a Pyramid Contains the maxillary Contains the sinus Is in the shape of a vertical | Contains the Sinus Forms with upper bone Extends and lacrimal ## Bones of the Skull -Mandible | Characteristics | Parts | Ossification | Comments | | :------------------------------------------------------------------------------------------------------------- | :------ | :------------ | :---------------------------------- | | Forms the lower jaw | Body | Intramembranous | Mental foramen lies on the anterior part of the lateral surface of the body Lateral part of the bone Provides insertion and thick parts of the mandibular | Described as horseshoe-shaped | | Extenal foramen All muscles of mastication attach to the mandible There is 1 mandible ## Major Foramina and Fissures - Anterior View | Foramen/Fissure/Opening | Located in or Formed by | Vessels Passing Through | Nerves Passing Through | | :------------------------ | :---------------------------------------------- | :---------------------- | :----------------------- | | Supraorbital foramen | Frontal | Supraorbital a. & v. | Supraorbital n. | | Optic canal | Sphenoid | Ophthalmic a. | Optic n. | | Superior orbital fissure | Between the: Greater wing of the sphenoid and Lesser wing of the sphenoid | Superior ophthalmic v. Inferior ophthalmic v. | Nasociliary, frontal, and lacrimal Oculomotor n. Trochlear n. | | Anterior ethmoid foramen| | | Posterior ethmoid foramen |Between the pterygoid| |Between the Maxillary ## Cervical Vertebrae- General Information * 7 cervical vertebrae (CI to C7) * The smallest vertebrae in the body * The 1st, 2nd, and 7th cervical vertebrae are unique in their shape; the 3rd to the 6th are similarly shaped | Vertebra | Characteristics | | :---------- | :---------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | Atlas (C1) | Supports the skullNo bodyNo spinous processHas an anterior arch and a posterior arch Large lateral masses support the occipital condyles of the skull superiorly and articulate with the axis inferiorly | | Axis (C2) | Dens (odontoid process) located on the body's superior surface Spinous process is large and bifid | | C3-C6 | Cervical vertebrae have small bodies Pedicles project posteriorly and laterally Spinous processes are short and bifid | | C7 | Also called "vertebra prominens" because its long spinous process makes it visible under the skin Long spinous process is not bifid | ## Cervical Vertebrae - Major External Ligaments | Ligament(s)/Membrane(s) | Comments | | :--------------------------------- | :------------------------------------------------------------------------------------------------------------------------------------------------------------- | | Anterior longitudinal ligament | Attached to the anterior surfaces of the vertebral bodies, extending from the axis to the sacrum Superior to the axis | | Ligamenta flavaAttached | Ligamentum nuchae |Extends from of | ## Comments DEEP LIGAMENTS/MEMBRANES Ligaments/Membrane |Comments Ligaments | extends