Skullnotes 110929075222-phpapp01
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The skull is composed of 22 bones that form the cranium and face. It protects the brain and houses various structures. The bones include the frontal, occipital, temporal, parietal, sphenoid, ethmoid, zygomatic, nasal, lacrimal, maxilla, palatine, and vomer. Key features include the orbits, nasal cavity, foramina, and sutures where bones interconnect. The skull has anterior, posterior, superior, inferior and lateral views defined by its component bones and landmarks important for clinical evaluation.
Skullnotes 110929075222-phpapp01
- 1. The Skull Areas of Anatomy 1) Gross anatomy: part listing of the human body; studied by region or by system 2) Microscopic anatomy: histology 3) Developmental anatomy: embryology 4) Functional anatomy: physiology 5) Radiographic anatomy: study of the human body using x-rays - Anatomical position: body upright, with palms and hands facing forward, and feet close together - Body defining planes: 1) Coronal plane: passes from one side to another dividing the body into anterior and posterior parts 2) Sagittal plane: passes from front to back dividing the body into right and left parts. Mid-Sagittal is when the right and left parts are exactly equal, the dividing line passing in the middle 3) Transverse plane: passes from side to side and front to back horizontally dividing the body into superior and inferior parts - Relative anatomical terms: o Anterior = ventral = front o Posterior = dorsal = back o Superior = cephalic = upper o Inferior = caudal = lower o Proximal = closer to origin o Distal = away from origin o Superficial = close to surface o Deep = away from surface - Movement of body parts : o Extension = returning part to normal position o Flexion = bending body part ( forward movement of body part) o Abduction = moving part away from position; laterally o Adduction = moving part closer to body; medially o Rotation = along 1 axis, its either external (lateral) or internal (medial) o Circumduction = combined complex movement o Protrusion = forward movement of the mandible o Retraction = moving mandible back to its place - Basic body tissues and parts:
- 2. o Tendons: fibrous connective tissue band which originates from the skeletal muscle and inserts into the bone. o Aponeurosis; fibrous connective tissue that forms a flat sheet. it lies between parts of the body o Fascia: a covering structure which surrounds and divides large spaces in the body to smaller compartments o Borsa: synovial structure that is found between, tendon-tendon, tendon-bone, it produces synovial fluid for lubrication Body Systems: Note: nerves are either sensory or motor or both 1) Nervous system: a. Central nervous system: brain and spinal cord b. Peripheral nervous system: cranial nerves (12 pairs arise from the brain), spinal nerves (31 pairs arise from spinal cord) and autonomic nervous system. Nervous and endocrine systems are responsible Spinal cord: for body function. o Contains dorsal horn, which is located at the dorsal aspect. It is completely sensory o Contains ventral horn, located at the ventral aspect. It is completely motor o Dorsal root arises from dorsal horn while ventral root arises from ventral horn o Dorsal root passes through dorsal root ganglion, ventral root passes through ventral root ganglion o After passing through ganglia they form together spinal nerves o They then divide into ventral and dorsal rami both being mixed Sensation (Sensory and motor) General Special Pain Vision 2) Mucoskeletal system : has 3 main components a. Joints: where 2 or more bones come together Touch Taste i. Bony joints: immovable (pelvis, sutures) Temprature Hearing ii. Relatively movable: fibrocartilage iii. Freely movable: synovial Pressure Smelling b. Muscles: smooth, skeletal, cardiac i. Skeletal: it is for movement, it is named based on 1. Function: extensor, abductor, etc 2. Shape: deltoid 3. Size: maximus, minimus 4. Attachment: temporalis 5. Length: short, long c. Bones: 2 types i. Axial skeleton: lies in the center (ex: pelvis) ii. Appendicular: has similar right and left parts
- 3. Bone is classified according to being: Short Long (ex: arm & forearm) Flat (ex: skull) Irregular (vertebrae) Pneumatic: contains air cavities Sesamoid: bone that lie in the tendon (ex: patella) Synovial Joints Synovium is the membrane that produces the synovial fluid, it is important for lubrication and reduction of friction. It is a weak structure, thus surrounded by fibrous joint capsule to prevent it’s separation during movement. Joint stability is achieved by: It is not necessary 1) Joint capsule to have all the 2) Shape of the bone forming the joint structures to 3) Ligaments achieve stability 4) Muscles around the joint The skull is part of the axial skeleton It is composed of 22 bones: - 21 firmly joined together by sutures - Mandible: a single movable bone which articulates with the skull at the TMJ (a synovial joint) The 22 bones are either single or paired (one on each side) Note: 6 Single Bones 8 Paired Bones Mandible Maxillary The hard palate is formed by Frontal Nasal the Maxillary bones (anterior Occipital Zygomatic 1/3) and the palatine bones Sphenoid Inferior Nasal conchae (posterior 2/3) Ethmoid Parietal Vomer Temporal Lacrimal Palatine Bones are either facial or cranial
- 4. Views of the Skull Outside views Superior Inferior = Basal Posterior = occipital Anterior = Frontal Lateral = Temporal 1) Anterior View: frontal Bones present in this view are: frontal, nasal, lacrimal, maxillary, mandibular, zygomatic, vomer, inferior conchae a. Frontal bone: convex in shape, forms forehead b. Orbit: opening of the eyes. Has 4 orbital margins i. Supraorbital margin: formed by frontal bone ii. Medial orbital margin: formed by fontal (superiorly), maxilla (inferiorly) iii. Infraorbital: formed by zygoma, and maxilla iv. Lateral orbital margin: frontal (superiorly), zygomatic (inferiorly) Landmarks of the orbit: 1) Supraorbital notch/foramen: in the superior orbital margin for transmission of vessels and nerves. Painful if pressed on 2) Superciliary arch: a bony elevation lying above the supraorbital margin. (eyebrows lie exactly above the margin) 3) Glabella: hairless region between the supraciliary arches. Clinical significance: 1- skin turgidity can be measured in patients suspected of dehydration. 2- glabellar reflex, in which a person’s forehead is taped several time and the subject blinks, if the blinking persists, which is called Myerson’s sign, being an early symptom of Parkinson’s disease, dementia and neurological disorders 4) Nasion: root of the nose, depressed area between the 2 orbits
- 5. 5) Infra-orbital foramen: located in the anterior surface of the maxilla on the same line vertically with the supra-orbital foramen 6) Anterior nasal apertures: (nasal openings), their boundaries are the 2 nasal bones superiorly, maxillary bone laterally, maxillary bone inferiorly 7) Zygoma: 2 bones below the orbit 8) Inferior and middle nasal conchae (superior are hidden and not seen in frontal view) Superior and middle nasal conchae are part of the ethmoid but the inferior nasal concha is a separate bone 9) Alveolar processes a. Of the maxilla, have sockets that carry the maxillary teeth b. Of the mandible, containing sockets for the mandibular teeth
- 6. 2) Lateral View: also called the temporal view Landmarks of the lateral view: a. Anterior nasal spine: union of 2 maxillary bones at the lower border or the anterior nasal apertures b. Nasal septum: divides nasal cavity vertically into 2 cavities nasal septum is divided into 3 parts: anteriorly nasal cartilage, inferiorly vomer, superiorly perpendicular plate of the ethmoid. c. Lateral orbital margin d. Temporal lines: they are either superior and inferior or one single line e. Zygomatic arch: formed by the zygomatic process of temporal bone and the temporal process of the zygomatic bone f. Temporal fossa: i. Region limited by temporal lines superiorly and zygomatic arch inferiorly ii. Formed by: frontal, parietal, greater wing of sphenoid and temporal bones
- 7. iii. Gives rise to temporalis muscle iv. Pterion: 1. H-shaped region 2. Lies above anterior branch of middle meningeal artery 3. Very thin bone, easily fractured leading to injury of underlying artery which will result in intercranial, epidural or extradural hematoma. May compress the brain tissue g. External acoustic meatus: auditory tube, posterior to the TMJ h. Mastoid process: i. Conical bony projection behind ear, pulpable area ii. Contain air filled cells, function in????? iii. Provides attachment to muscles and ligaments??????? i. Styloid process: deep, not pulpable, attaches muscles and ligaments (styloid apparatus) j. Paranasal air sinuses: air filled cavities which open into the nose i. Frontal ii. Maxillary iii. Sphenoid iv. Ethmoid 3) Superior View: calvaria Bones present are: frontal bone, right and left parietal bones, occipital bone Landmarks: a. Coronal suture: between frontal bone and the 2 parietal bones b. Sagittal suture: between the 2 parietal bones c. Lambdoid suture: between the 2 parietal and the occipital bones d. Bregma : meeting point of coronal and sagittal sutures e. Lambda: meeting point of lambdoid and sagittal sutures f. Parietal foramen: in the parietal bones, for transmission of emissary veins (veins which connect venous blood from the outside to the inside) Neonatal skull: - Sutures are not well joined together Sagittal suture looks like an arrow Metopic suture: lies between the 2 frontal bones and ossifies by the age of 5 Anterior fontanelle: unossified “bregma”, ossifies by the age of 18 month to form bregma Posterior fontanelle: unossified “lambda”, ossifies by the age of 9 month to form lambda They function to assess the intercranial pressure by palpation (bulge if high and depress if low pressure)
- 8. 4) Posterior view: - Landmarks of the posterior view: Sagittal Suture Lambdoid Suture External Occipital protuberance: a projection in the squamous part of the occipital bone Nuchal lines: superior and inferior extending from the lateral part of the external occipital protuberance Temporal Bone Parietal Bone Occipital Bone Maxillary Bone Mandibular Bone
- 9. 5) Inferior view: 12 pairs of cranial nerves which pass through the openings in the inferior view I. Olfactory II. Optic III. Occulomotor IV. Trochlear V. Abducent VI. Trigeminal Muscles of mastication: i. V1 ophthalmic ii. V2 Maxillary 1) Temporalis iii. V3 Mandibular 2) Masseter VII. Facial 3) Medial pterygoid VIII. Vestibulochoclear 4) Lateral pterygoid IX. Glossopharyngeal X. Vagus XI. Accessory XII. Hypoglossal Landmarks of the inferior view: 1) U-Shaped maxilla
- 10. 2) Hard palate: separates oral from nasal cavity, anterior 2/3 formed by maxilla, posterior 1/3 formed by the horizontal plate of the palatine bone 3) Palatine process of the maxilla 4) Sphenoid bone a) Greater wing b) Lesser wing c) Medial and lateral pterygoid processes d) Body of the sphenoid 5) Pterygoid fossa: lies between the medial and lateral pterygoid processes and gives attachment to pterygoid muscles 6) Infratemporal fossa: exposed by removal of the zygomatic arch and the mandible, it’s boundaries are: a) Anteriorly: maxilla b) Posteriorly: styloid process c) Laterally: zygomatic arch or ramus of the mandible d) Medially: lateral pterygoid plate 7) Posterior nasal openings: nasal choanae, communicates the nasal cavity to the oropharynx it’s boundaries are: a) Superiorly: body of the sphenoid b) Inferiorly: horizontal plates of the palatine bone c) Medially: vomer d) Laterally: medial pterygoid processes 8) Temporal bone: a) Zygomatic process b) Squamous part c) Petrous part d) Styloid process e) Mastoid process f) Tympanic plate
- 11. 6) Cranial base of the skull: - Contains several openings and foramina through which the nerves and blood vessels pass - Occipital condyle: bony mass on each side of foramen magnum and articulates with atlas (C1) to form atlantooccipital joint Opening position Structures passing through Cribriform plate Part of the Ethmoid bone Olfactory bulb/fibers (from olfactory nerve I) Optic canal At root of lesser wing Optic nerve II Ophthalmic artery Supraorbital Communicates the orbital canal and middle Oculomotor nerve III fissure cranial fossa, between lesser and greater Trochlear nerve IV wings of sphenoid Ophthalmic nerve V1 Abducent VI
- 12. Superior and inferior ophthalmic veins Foramen In greater wing of sphenoid, communicates Maxillary nerve V2 Rotundum middle cranial fossa with pterygopalatine fossa Foramen Ovale In greater wing of sphenoid , communicates Mandibular nerve V3 middle cranial to Infratemporal fossa Foramen Between body of the sphenoid and Petrous Greater Petrosal nerve lacerum part of temporal bone (a branch of the facial nerve VII, which then leaves through the stylomastoid foramen) Foramen In greater wing of the sphenoid, Anterior branch of the middle spinosum communicates middle cranial fossa to meningeal artery Infratemporal fossa Carotid canal In Petrosal part of temporal bone, opens Internal carotid artery into posterior wall of foramen lacerum Sympathetic nerve plexus Internal acoustic Intracranially, in the posterior surface of the Facial nerve VII meatus Petrous part of the temporal bone Vestibulocochlear nerve VIII Stylomastoid Between styloid and mastoid processes of Facial nerve VII (pure motor branch) foramen the temporal bone Jugular foramen Between occipital bone and Petrous part of Glossopharyngeal IX temporal bone Vagus nerve X Accessory nerve XI Internal jugular veins Sigmoid sinus Posterior meningeal artery Inferior Petrosal venous sinus Condylar canal Anterior to occipital condyle Emissary veins Hypoglossal Posterior to condyle Hypoglossal nerve XII canal Foramen Occipital bone Spinal root and its covering meninges magnum Spinal root accessories Vertebral artery The spinal root arises from the spinal cord Vertebral then enters the skull through foramen arteries supply magnum to join with the cranial root and posterior part of leave jugular foramen as accessory nerve the brain
- 13. Cranial Fossae 1) Anterior cranial fossa: Boundaries: from Squamous part of the frontal bone to the lesser wing of the sphenoid Contents: frontal lobes of brain Floor is formed by: Cribriform plate of the Ethmoid bone , it lies between the nasal cavity and the anterior cranial fossa (part of floor of ACF and roof or nasal cavity) Crista galli: upward bony projection (from cribriform plate) which attaches to falx cerebri Orbital plate of frontal bone 2) Middle cranial fossa: Boundaries: lesser wing of sphenoid anteriorly to petrous part of temporal bone posteriorly It is composed of 2 lateral portions, a central portion formed by superior surface of the body of the sphenoid
- 14. The central portion includes sella turcica (also called the hypophyseal fossa or pituitary fossa). Tuberculum sellae: anterior limit of sella turcice. Dorsum sellae: posterior limit of sella turcica Floor: Greater wing and body of sphenoid Squamous part of temporal bone Part of Petrous part of temporal bone 3) Posterior cranial fossa: - Boundaries: upper border of Petrous part of temporal bone anteriorly and Squamous part of occipital bone Posteriorly - Contains: the cerebellum - Landmarks: Internal occipital protuberance: projection in the inner surface opposite to the external occipital protuberance Sigmoid sulcus: S-shaped sulcus, contains the sigmoid venous sinus Sulcus for Transverse Sinus: contains the transverse venous sinus Before the facial nerve enters the internal acoustic meatus, it gives a branch to the greater petrosal nerve, which then leaves through foramen lacerum. The facial nerve leaves the Stylomastoid foramen as pure motor Facial nerve Great petrosal Stylomastoid IAM Foramen lacerum Facial foramen Meninges They are 3 membranes which surround the brain and spinal cord. I. Pia mater: delicate layer directly attached to the brain and spinal cord a. Subarachnoid space: space that lies between the Arachnoid mater and the Pia mater. Contains CSF (cerebrospinal fluid) which act as a cushion to protect the brain and spinal cord II. Arachnoid mater: transparent layer, which lies over the Pia mater. It shows trabeculations (arachnoid granulation villi), which function in the drainage of the CSF and the venous blood in the venous sinuses a. Subdural Space: contains blood vessels III. Dura mater: tough layer which lies over the Arachnoid mater Cranial dura: consists of periosteal layer (endosteal layer) which is the lining of the skull bone, and the real dura mater, which is the tough fibrous layer a. Epidural Space: lies between dura mater and bone. Contains blood vessels
- 15. Dura Mater The Dura mater is separated into 2 layers called the dural folds or projections, they separate different brain hemispheres. I. Falx Cerebri: a. separates the 2 cerebral hemispheres b. Double layer of dura which separate the 2 cerebral hemispheres c. Attached anteriorly to crista galli d. It has 2 borders: i. Upper: superior Sagittal sinus lies in it ii. Lower border: inferior Sagittal sinus lies in it II. Falx Cerebelli: a. separates the 2 cerebellar hamispheres III. Tentorium Cerebelli: a. separates the cerebellum from the occipital lobes of the cerebrum b. Forms a tent over the posterior cranial fossa
- 16. IV. Diaphragm Selli: a. Very small dural projection that form the roof of sella turcica b. Has an opening in the middle for the stalk of the pituitary gland Dural Venous Sinuses Venous channels which lie between the 2 layers of the Dura mater. They lack valves and smooth muscles in their walls, as blood flows with gravity. Single Sinuses Paired Sinuses Superior Sagittal Venous Sinus Transverse Venous Sinus Inferior Sagittal Venous Sinus Sigmoid Venous Sinus Straight Sinus Cavernous Venous Sinus Superior Petrosal Sinus Inferior Petrosal Venous Sinus Single Sinuses I. Superior Sagittal venous sinus: a. In the upper border of the falx cerebri b. Runs upwards and backwards ending at the internal occipital protuberance II. Inferior sagittal venous sinus: a. In the lower border of the falx cerebri b. Joins with the great cerebral vein to form the straight sinus, which runs upwards and medially III. Straight Sinus: a. Formed by the union of the great cerebral vein and the inferior petrosal venous sinus b. Runs at the meeting point of the tentorium cerebella and falx cerebri c. Ends at the internal occipital protuberance Paired Sinuses I. Transverse Sinus: a. Right transverse sinus: continuation of the superior Sagittal sinus b. Left transverse sinus: continuation of the straight sinus c. Passes lateral to the internal occipital protuberance on both sides II. Sigmoid Sinus:
- 17. a. Continuation of the transverse sinus b. Ends at the jugular foramen forming the jugular bulb which then continues as internal jugular vein III. Cavernous Sinus: a. Cave like, lies in body of the sphenoid b. It has a special importance as some important structures pass through it i. Vessels: internal carotid artery ii. Nerves: Occulomotor III, Trochlear IV, Abducens VI, V1 & V2 of trigeminal V c. Infection in the dangerous zone (angle between mouth and eye) can easily transmit it into the brain by the following pathway: Facial Vein pterygoid venous plexus inferior ophthalmic vein cavernous sinus Any problem in the cavernous sinus affects movement of eyeball, sensation of the face, blood supply to the brain Cavernous sinus receives blood from superior and inferior ophthalmic vein. Before entering the sinus, the inferior ophthalmic vein communicates with the pterygoid plexus
- 18. IV. Superior petrosal sinus: a. Arises from the upper posterior part of the cavernous sinus b. Runs in the upper border of the petrous part of the temporal bone, to joining the sigmoid venous sinus V. Inferior petrosal sinus a. Arises from lower part of cavernous sinus b. Joins internal jugular vein, from outside the skull after passing through the jugular foramen c. It’s the only venous sinus that leaves the skull with the venous blood Individual Bones of the Skull 1) Maxilla: a paired bone which has 4 processes and 4 surfaces - 4 surfaces :
- 19. Superior: it separates the orbital cavity from the maxillary air sinuses Anterior: facial Posterior: forms anterior limit of infratemporal fossa Medial (nasal): forms lateral wall of the nasal cavity - 4 processes: Frontal: joins the frontal bone to form the medial orbital margin Zygomatic: joins the zygoma to form the infra orbital margin Alveolar: Contains sockets for upper teeth Palatine: joins palatine bone to form the hard palate - Articulations of the maxilla: frontal, nasal, zygomatic, inferior nasal concha, palatine bone, ethmoid, maxilla - Maxillary nasal sinuses are located in the medial (nasal) process. It is one of the biggest sinuses and functions in resonance of voice and lightening of weight of skull 2) Mandible: A single bone, horseshoe shaped, which is composed of a body and 2 rami - The body: composed of 2 surfaces (inner and outer) and 2 borders (superior and inferior) Outer surface: Mental protuberance: lies in the midline Mental tubercle: lies on both sides of the protuberance
- 20. Mental foramina: located below the apices of the premolar-molar. Can be used to determine the age of a person as it is closer to the inferior border in infants and closer to the superior border in elderly people, in adults it lies in the middle. (the change in position is relative as the bone is not completely grown in infants and is resorbed in elderly) Oblique line: also called the external oblique ridge, extends from mental foramen to the anterior border of the ramus Inner surface: Superior and inferior mental spines (genial tubercles): 4 projections which lie in the midline which give attachment to: Superior: genioglossus muscle Inferior: geniohyoid muscle Mylohyoid line: gives attachment to mylohyoid muscles which are 2 muscles join to form the floor of the mouth
- 21. Sublingual fossa: a depression which lies above the mylohyoid line. Contains the sublingual salivary glands Submandibular fossa: a depression which lies below the mylohyoid line. Contains the submandibular salivary gland Digastric fossa: located below the genial tubercle - The Ramus: each has 2 surfaces(medial and lateral),2 processes (anterior/coronoid and posterior/condylar) and 2 borders (anterior and posterior) - Ramus meets the body to form the angle of the ramus Surfaces: Lateral: smooth except where it gives attachment to the massetter muscle Medial surface: Mandibular foramen: opens to the mandibular canal which ends at the mental foramen, transmitting the inferior alveolar nerve and blood vessels. Mental nerve is the continuation of the inferior The ramus is sandwiched by the massetter muscle from outside and medial pterygoid from the inside
- 22. alveolar nerve, supplies lower teeth and lip, thus anesthesia is given in it. Lingula: bony projection, lies anterior to mandibular foramen. Provides attachment to ligaments. Rough region in the lower part of inner surface, gives attachment to the medial pterygoid muscle. Processes: Coronoid/anterior: gives attachment to temporalis Condyle/posterior: Head: articulates with mandibular fossa of temporal bone forming TMJ Neck : provides attachment to capsule of TMJ 3) Sphenoid Bone: a single bone has the shape of a butterfly. It is composed of: - Body - 2 greater wings - 2 lesser wings - 2 pterygoid processes Body: o Has 2 surfaces: Superior: forms sella turcica/pituitary fossa/ Inferior: forms upper margin of coanae and upper border of pharynx o Sphenoid air sinuses: Upper border: sella turcica Lower border: roof of pharynx Visible in the anterior view Greater wing of sphenoid: o Has 4 surfaces: Cranial surface Lateral surface: temporal Inferior : infratemporal , roof of infratemporal fossa orbital Between the lesser and greater wings lies the superior orbital fissure Pterygoid plates/processes: Medial and lateral processes/plates in between them lies the pterygoid fossa The pterygoid fossa provides attachment to the medial and lateral pterygoid muscles The pterygoid fossa can be seen only in the posterior view
- 23. Optical canal is located at the roof of lesser wing and above superior orbital fissure, while rotundum is below superior orbital fissure Above the pterygoid plate lies the pterygoid canal (transmits the pterygoid nerve) Ovale, rotundum and spinosum are present on the greater wing but are not visible in the anterior or posterior view. Articulations of the sphenoid bone: o Palatine bone, ethmoid, nasal bone, temporal , vomer, frontal, parietal, occipital, zygoma, maxilla 4) Ethmoid: single bone, lies between the 2 orbits - it is also located in:
- 24. o upper part of nasal cavity To differentiate between medial and lateral views of o roof of nasal cavity the nasal cavity: in the medial o perpendicular plate of the ethmoid, forms part of the nasal septum o lateral wall of ethmoid forms the medial wall of the orbit view the septum is present o medial wall of the ethmoid forms the lateral wall of the nasal cavity - the labyrinth contains air filled cavities (ethmoidal air cells), each has o medial/ nasal plate has 2 projections: superior and middle nasal conchae o lateral/orbital plate - cribriform plate separates the nasal cavity from the anterior cranial fossa
- 25. 5) Frontal Bone: single bone, developed from 2 halves, which are separated by the metopic suture (ossifies at the age of 5 years) - It is composed of 2 processes: o Maxillary: articulates with the maxilla to form medial orbital margin o Zygomatic: articulates with the zygoma to form lateral orbital margin - In the upper orbital margin lies the supraorbital foramen/notch - Supraciliary arch: lies above the supraorbital margin (below the eyebrow) - Glabella: hairless area between the supraciliary arches - Frontal nasal sinuses: 2, which drain the nasal cavity o They are lined by the same epithelium of the nasal cavity o They function in: Weight reduction Sound resonance - Squamous part: o Forms the vault and forehead o Forms the floor of the anterior cranial fossa o Forms the roof of the orbital cavity - Foramen cecum: lies anterior to crista galli, for transmission of emissary veins 6) Temporal Bone: paired bone, on the lateral sides of the skull, composed of 5 parts Squamous, petrous, mastoid, styloid, tympanic - Squamous: o Vertical flat part o Forms part of the floor of the temporal fossa o Has the zygomatic process which articulates with the zygoma to form the zygomatic arch o Mandibular fossa: inferior to zygomatic process. Site of articulation with the condyle - Tympanic plate: o Anterior limit of external acoustic meatus Chorda tympani - Mastoid process: exits between the tegmen tympani o Conical, palpable bony projection, lies behind the ear and anterior edge o Contains air filled cavities (mastoid air cells) of tympanic plate o For resonance of sound o Gives attachment to sternocleidomastoid muscle and posterior belly of Digastric muscle o Gives attachment to ligaments - Styloid process: o Deeply seated, non-palpable o This downwardly projected bony process o Gives attachment to:
- 26. Stylohyoid muscle Stylopharyngeal muscle Styloglossus muscle Stylohyoid ligament o Stylomastoid foramen lies between the styloid and mastoid processes - Petrous part: o Sometimes called petromastoid (closely related to mastoid) o Hard rock like bony part containing important structures Ear cavity (through internal acoustic meatus) Carotid canal (transmits internal carotid artery and sympathetic plexus) Facial nerve Vestibulocochlear nerve 7) Occipital bone: single flat bone, forms posterior part of the skull and part of the base of the skull - Squamous part: The curved, expanded plate behind the foramen magnum o Superior and inferior nuchal lines which project laterally from the external occipital protuberance o Internal occipital crest: projection which lies posterior to the foramen magnum (internally) o Internal occipital protuberance (internally) o Has transverse groove for transverse sinus (internally) - Basilar part: the thick part in front of the foramen magnum,
- 27. o Projects anteriorly, forming part of the roof of the pharynx (pharyngeal tubercle) - Articulates with part of the sphenoid 8) Nasal bone: a paired bone - Join in the midline forming part of the roof of the nasal cavity 9) Zygomatic bone: paired bone, forms the prominence of the cheek
- 28. - Articulates with frontal, maxillary, greater wings of sphenoid and temporal bone 10) Lacrimal bone: paired bone - Forms part of the medial wall of the orbit - Nasolacrimal duct: a canal that connects the orbit to the nasal cavity (for the drainage of tears) 11) Palatine bone: paired bone, L-shaped
- 29. - 2 plates: o Horizontal: forms the posterior third of the hard palate and the projecting nasal crest forms part of the nasal septum o Perpendicular plate: forms lateral wall of the nasal cavity 12) Inferior nasal conchae: paired bones - Attached to lateral wall of the nasal cavity - A fragile bone - Increases surface area of nasal cavity - Lined by mucous membrane 13) Vomer: single bone, a thin deep plate - Articulates with o Maxilla Nasal septum: vomer, o Ethmoid septal cartilage, o Sphenoid perpendicular plate of o Septal cartilage the ethmoid (inferiorly) Face
- 30. The face extends from the hair to the lower border of the mandible and from the ear to the ear Contents of the face: - Skin: includes hair follicles, sweat glands and sebaceous glands - Connective tissue: has superficial fascia only, no deep fascia - Muscles: mastication and facial expression muscles - Blood Vessels: arteries and veins - Glands: parotid and submandibular glands - Nerves: trigeminal and facial nerves Muscles of facial expression: - Responsible for expression - Control size of facial openings (each has sphincter/closes o Mouth o Nose o eyes - Arise from facial skeleton and are inserted into skin - Arise from 2nd branchial arch - Supplied by facial nerve Muscles of the Eyes: Name of Muscle Sphincter/Dilator Function Whole muscle: helps move tears towards midline of Orbicularis oculi face Peripheral/orbital part sphincter Orbital part: forceful closure Central/palpebral part Palpebral part:gentle closure Elevates eyebrows, and wrinkles forehead, opens the Frontalis Dilator eye Levator palpebrae Elevates upper eyelid, only muscle supplied by the Dilator superioris occulomotor nerve Muscles of the nostrils: Name of Muscle Sphincter/dilator Function Dilator naris Dilator Dilates opening of nose Compressor naris Sphincter Closes opening of nose
- 31. Muscles of the Mouth: Name of muscle Sphincter/dilator function Orbicularis oris Sphincter Arises from the maxilla and mandible, brings the 2 lips together (whistling action) Zygomaticus major and minor Dilator Elevates the angel of the mouth Levator labii superioris Dilator Elevates the upper lip upwards Levator anguli oris Dilator Lies between the zygomaticus major and minor, elevates angel of mouth Depressor labii inferioris Dilator Moves lip downwards Depressor anguli oris Dilator Moves angel of mouth downwards Mentalis Dilator Depressing of chin Resorius Dilator Moves angle of mouth horizontally Platysma Dilator Depression of lower lip, tightening of the skin of the neck Muscles of the Cheek:
- 32. Buccinator Muscle: lie between massetter and angel of mouth - Anterior fibers mix with orbicularis oris muscle - Pierced by the duct of the parotid gland - Function o Blowing o Pushing food out of the vestibule into the oral cavity proper Blood Supply of the Face 1) Arterial blood supply: Common Carotid Artery External Carotid Artery Internal Carotid Ophthalmic Superficial Facial Artery Maxillary Artery Temporal Artery Artery Supraorbital Supratrochlear Infraorbital Mental Artery Artery Artery Artery 2) Venous drainage: Facial Vein Superficial Retromandibular Temporal Vein Vein External and Internal Jugular Veins Nerve Supply of the face Sensory for the skin Motor for the muscles
- 33. Sensory Supply: Trigeminal Nerve V Ophthalmic Maxillary Division Mandibular division V1 V2 Division V3 From angle of the eye to the Angle of the mouth Skin of the face from the angle of the mouth. Lower downwards. Parotid angle of the eye upwards. eyelid, skin of cheeks, upper region, lower lip, chin, Upper eyelid skin, anterior lip lateral side of the scalp and lateral parts of the nose, forehead Motor Supply: All muscles of facial expression are supplied by the facial nerve (VII) except the levator palpebrae superioris muscle which is supplied by the occulomotor nerve (III) Facial Nerve gives 5 motor branches: - Temporal - Zygomatic - Buccal - Mandibular - cervical Facial Palsy: damage to the facial nerve It leads to: paralysis to ½ of the face inability to whistle inability to close eyes leading To dry and ulcerated cornea inability to blow angle of mouth droops causing saliva to come out face will shift towards normal side
- 34. Parotid Region It is the area in the side of the face inferior and anterior to the ear salivary glands in the parotid region are: o parotid: the largest salivary gland o submandibular o sublingual o scattered small salivary glands in the submucosa of the cheeks saliva is either o serous (water like) o mucous (thicker) o it helps in digestion, turning food into a bolus thus making swallowing easier and also helps in speech 1) parotid salivary glands: - 1 on each side: wedge shaped, exocrine gland - It has 3 surfaces: o Anteromedial surface: faces the massetter muscle, medial pterygoid muscle and ramus of mandible o Posteromedial surface: faces the mastoid process and sternocleidomastoid muscle o Lateral surface: faces the skin and great auricular nerve - Surrounded by parotid capsule which is a continuation of the investing layer of the deep fascia - Stansen’s duct: the opening of the parotid gland. Starts from the anterior border of the gland and then passes through the massetter and turns medially to pierce the buccinator muscle then pens into the vestibule opposite to the upper second molar - Structures that pass within the parotid gland: o Facial nerve o Retromandibular vein o External carotid artery o Auriculotemporal nerve Facial Nerve: enters the parotid gland without supplying it from the posteromedial surface, dividing it into a deep lobe and a superficial lobe. It ends within the parotid gland giving five terminal motor
- 35. branches (temporal, zygomatic, Buccal mandibular, cervical) Structures passing into the parotid gland: 1) Veins - Superficial vein and maxillary vein join into the gland to form the retromandibular vein. - The retromandibular vein then divides into anterior and posterior divisions - The anterior division joins the facial vein to form the common facial vein which extends as the internal jugular vein - The posterior division joins the great auricular vein to form the external jugular Superficial vein Facial Common temporal Retromandibular Facial Parotid gland Ant. division Internal jugular Maxillary Posterior External jugular division Great auricular 2) Arteries: - External carotid enters the gland and ends in it by giving superficial temporal artery and maxillary artery Nerve Supply of the gland 1) Sensory: a. by auriculotemporal nerve which is branch of V3 b. carries pain sensation from the capsule of the parotid gland 2) Autonomic: a. Sympathetic: i. By sympathetic plexus surrounding external carotid artery ii. Decreases salivation and secretions (dry mouth) b. Parasympathetic i. By glossopharyngeal carried by the lesser petrosal nerve ii. The salivary nuclei located in the brain is responsible for the production of saliva iii. The preganglionic parasympathetic, stops to relay in otic ganglia, located in the infratemporal fossa iv. Post ganglionic fibers runs to the parotid gland with the auriculotemporal nerve Lesser Petrosal Auriculotemporal
- 36. Damage to the gland can lead to damage to the Pre ganglionicfacial nerve Blood Supply of the gland: Parasympathetic Post ganglionic Secretomotor Fibers Parasympathetic Otic Ganglia - Arterial blood supply: through external carotidartery and terminal branches of Secretomotor Fibers superficial temporal artery and maxillary artery - Venous drainage: through maxillary vein and superficial temporal vein of the retromandibular Lymph nodes: - Drainage is by the parotid lymph nodes and the deep cervical lymph nodes Mumps: viral infection of the parotid gland Parotitis: bacterial infection of the parotid gland
- 37. The Orbit 2 cavities, pyramidal in shape, located in the anterior view of the skull Each orbit has: - Base: directed forwards - Apex: directed backwards - 4 orbital margins - 4 walls I. Roof: separates the orbital cavity from the anterior cranial fossa. Formed from lesser wing of sphenoid and orbital plate of frontal bone II. Floor: separates orbit from maxillary air sinuses. Formed from maxilla and zygoma III. Lateral wall: separates orbit from temporal fossa, formed from zygomatic bone and greater wing of the sphenoid IV. Medial wall: separates orbital and nasal cavities, formed from lacrimal, labyrinth of ethmoid bone and part of palatine bone - Openinings in the orbit: 1. Superior orbital fissure: communicates with the middle cranial fossa 2. Optic canal: communicates with the anterior cranial fossa/middle cranial fossa 3. Infra-orbital fissure: communicates with the pterygopalatine fossa 4. Supraorbital notch: communicates with the anterior surface of forehead 5. Infraorbital notch: communicates with the face
- 38. 6. Nasolacrimal duct: connects the nasal cavity to the orbit - Contents of the orbit I. Eyeball II. Muscles III. Nerves IV. Blood vessels V. Fat VI. Lacrimal apparatus VII. Ciliary ganglion I. Eyeball: spherical in shape, camera of the body, consists of 3 layers a. Outer layer: a fibrous coat that protects the eye. Formed from sclera and cornea i. Sclera: 1. provides attachment to the muscles 2. white in color 3. protects the eyeball ii. cornea: 1. transparent part b. Middle layer: also called the vascular coat. i. Choroid: becomes enlarged anteriorly to form the Ciliary body ii. iris: a forward extension of the Ciliary body which gives the color of the eye (pigmented coat) iii. pupil: an opening in the middle iv. 2 muscles of the eye for visual adaptation (affected by the amount of light) 1. Constrictor pupilae: is stimulated by high light intensity and is under parasympathetic control 2. Dilator pupilae: is stimulated by absence of light, under sympathetic control v. Lens: connected to Ciliary body by suspensory ligaments vi. Ciliary muscles: group of involuntary muscles in Ciliary body 1. Change thickness of lens by changing length of suspensory ligaments 2. Allows for visual accommodation (ability to see far and near) c. Inner layer: nervous coat called the retina i. Has many photsensory receptors (rods and cons) 1. Rods: for dark light 2. Cons: for daylight, colors and moving objects ii. Optic nerve: originates from the retina from the rods and cons iii. Fibers travel posteriorly from the rods and cons to form the optic nerve iv. Fundus: site of attachment of the optic nerve to the eyeball. It has no rod and cons, thus it’s a blind spot - Chambers of the eyeball: divided because of presence of lens d. Anterior chamber: contains aqueous humor (an aqueous watery fluid) e. Posterior chamber: contains vitreous humor (jelly like fluid) it gives the round shape of the eyes
- 39. - Eyelids: f. Conjunctiva: i. the lining of the eyelids ii. a transparent membrane inner surface which turns to line the eyeball iii. inflammation can occur leading to red itchy eyes (conjunctivitis) II. Fat: a. Allows eye to move freely within the bony orbit b. Supports the eyeball III. Muscles There are 2 groups of muscles in the eye 1. Intraocular: muscles inside the eyeball a. Constrictor b. Dilator c. Ciliary muscles 2. Extraocular: muscles inside the orbit (outside the eyeball) a. Recti (meaning straight) i. Superior rectus ii. Inferior rectus Nerve iii. Medial rectus Supply: iv. Lateral rectus b. Oblique LR6 SO4 3
- 40. i. Superior oblique ii. Inferior oblique c. Levator palpebrae superioris Movements of the Eyes Right eye Left eye Movement Superior Rectus3 Superior rectus3 Inferior Rectus3 Inferior Rectus3 Lateral Rectus6 Medial Rectus3 Medial Rectus3 Lateral Rectus6 Inferior Oblique3 Superior Rectus3 Superior Rectus3 Inferior Oblique3 Superior Oblique4 Inferior Rectus3 Inferior Rectus3 Superior Oblique4 Testing the function of the nerves through eye movements: - Abducens VI: look lateral by left eye - Trochlear IV: look down and lateral by right eye - Occulomotor III: look at any other direction Problems With the eye: - Convergent Squint/diplopia/strabismus: double vision created when both eyes move medially - Divergent Squint; when one eye moves normally and the other eye moves laterally IV. Nerves: a. Optic nerve II: i. pure sensory nerve for vision The remaining ii. arises from the retina and goes into the brain cranial nerves arise iii. Nasal part of retina views pictures coming from lateral/ temporal side from the brain stem iv. Lateral part of retina views vision from medial side, these are called visual field
- 41. v. The two fibers join to form the optic nerve Decussation: vi. Nasal fibers of the optic nerves cross the midline forming the optic chiasma, it crossing of fibers to contains nasal fibers of both eyes the opposite side vii. Optic tract: the continuation of the nasal fibers of the opposite side eye and the temporal fibers of the eye on the same side viii. The optic tract ends in the visual cortex of the occipital lobe of the brain If someone Optic chiasma is receives a hit in the closely related to back of the brain, it the pituitary gland, can affect vision thus any damage to (visual cortex) the pituitary gland affects the chiasma Damage to the optic nerve: one eye is blind Damage to chiasma: bitemporal hemianopia (blindness of the fields from the lateral side) Damage to optic tract: contralateral hemianopia (blindness of the temporal of one eye and nasal of the other eye)
- 42. Damage to the occulomotor causes: 3D Diplopia Nerves passing through the optic cavity: Drooping of upper eyelid= ptosis 1. V1 of the trigeminal Dilated pupil a. Pure sensory nerve b. Enters the orbit through superior orbital fissure c. Branches: i. Lacrimal: sensory, supplies lacrimal gland, conjunctive and the skin of the upper eyelid ii. Frontal: ends by giving 2 terminal branches 1. Supraorbital : supply upper eyelid, scalp, skin of the forehead, and frontal air sinuses 2. Supratrochlear : supply upper eyelid, scalp, skin of the forehead, and frontal air sinuses iii. Nasociliary:has 2 parts: a. Visceral secretomotor: receives post ganglionic parasympathetic fibers from ciliay ganglia to supply the Ciliary body (muscles of the iris=constrictor pupilae) and lacrimal gland b. Sensory: supplies nasal cavity, skin of the nose, skin of upper eyelid and ethmoidal air cells 2. Occulomotor nerve: arises from the brain stem and enters the orbit through the superior orbital fissure. Has 2 components: 1. Motor: to all muscles of the orbit except the superior oblique and the lateral rectus 2. Parasympathetic: preganglionic fibers which pass through the ciliary ganglia to supply the ciliary muscles (constrictor pupilae). It’s also responsible for visual accommodation a. To test the function of the Trochlear: ii. Defect in eyeball movement iii. Drooping iv. Light reflex 3. Trochlear: arises from the brain stem. a. Enters orbit through superior orbital fissure b. Pure motor nerve c. Supplies only superior oblique 4. Abducens arises from the brain stem. a. Enters orbit through superior orbital fissure b. Pure motor nerve c. Supplies only lateral rectus 5. V2 of the trigeminal: pure sensory a. Leaves skull through foramen Rotundum, to go to pterygopalatine fossa b. Enters the orbit and become Infraorbital nerve, which runs in the floor of the orbit and leaves the orbit through the Infraorbital foramen c. Supplies The pterygopalatine I. the skin of the face form angle of the eye to the angle of the mouth ganglia is suspended II. nasal cavity III. maxillary air sinus by V2, but is IV. upper teeth functionally related V. part of the pharynx to the facial nerve d. Branches: I. Posterior superior alveolar nerve. II. Middle superior alveolar nerve
- 43. III. Anterior superior alveolar nerve V. Ciliary Ganglia: small pin head sizes parasympathetic ganglia a. Functionally related to occulomotor nerve b. Receives preganglionic fibers c. Postganglionic fibers pass through the nasociliary nerve VI. Blood Vessels a. Arteries: ophthalmic artery, i. a branch of internal carotid artery ii. enters the orbit through optic canal, and ends by giving terminal branches 1. supraorbital 2. Supratrochlear iii. Before entering the orbit it gives central retinal artery which runs in the center of the optic nerve iv. Damage can result in blindness, as it supplies the retina b. Vein: i. Superior ophthalmic vein: formed by union of supra orbital, Supratrochlear and angular veins ii. Inferior ophthalmic vein: forms by small veins in the orbit joined together and drain into the cavernous sinus iii. Both leave the obit VII. Lacrimal Apparatus: contains a. Lacrimal gland b. Canaliculi c. Lacrimal sac d. Nasolacrimal duct - Lacrimal gland: I. an exocrine gland, II. produces and secretes tears III. located in upper lateral side of the orbit IV. has 2 parts large orbital part small palpebral part V. receives its parasympathetic fibers from facial nerve, carried by greater petrosal nerve VI. tears flow on the anterior surface of the eyeball VII. blinking distributes the tears to moisten the eyeball VIII. All tears will accumulate in the medial angle IX. Superior and inferior punctums: openings in the medial surface of the eye (corner) which pass the tears on to the canaliculi - Canaliculi: small ducts which drain the tears to the lacrimal sac, closely related to the medial wall of the orbit - Nasolacrimal duct: connects the lacrimal sac to the wall of the nasal cavity, thus making a pathway for draining the tears (passes through lacrimal bone)
- 44. - Tears are then absorbed by the nasal mucosa - Nasal mucosa inflammation: blocked opening = teary eyes - Crying: excessive tear production, therefore inability of mucosa to absorb it all, leading to runny nose The end