LAB 6: The Head Flashcards
1
Q
bones of neurocranium
A
- frontal
- parietal
- occipital
- temporal
- sphenoid
2
Q
bones of neurocranium: frontal
A
- scoop shaped
- forms the forehead and rood of the orbit (eye socket)
- articulates posteriorly along the coronal suture with 2 parietal bones
- at birth there are 2 frontals separated by a median sagittal suture -> region where the four incompletely ossified frontal and parietal bones will eventually meet is not yet ossified
- in this region ^ the brain is covered only by membranous tissue
- soft spot is the bregmatic fontanelle
- there are other fontanelle
- fontanelles are obliterated by bone growth by 2 years
- frontal contains a paranasal sinus of variable size just above the nose
3
Q
bones of neurocranium: parietal
A
- paired parietals are quadrilateral bones
- top and side of cranium
- articulate with one another along the midline sagittal suture
- articulates posterior with occipital bone along the lambdoid suture
- articulates inferiorly with the temporal bones along the squamosal suture
- internally, there is a gutter along the sagittal suture that is created by the superior sagittal sinus
4
Q
bones of neurocranium: occipital
A
- scoop shaped
- back of the skull
- contains the large foramen magnum -> passes the medulla oblongata of the brain stem and the vertebral arteries
- on both sides of the foramen magnum lie the convex occipital condyles where the skull articulates with the atlas
- exiting anteriorly between each condyle and the foramen magnum is the hypoglossal canal -> transmits the hypoglossal nerve (CN XII)
- neck muscles attach to the nuchal lines along the back of the bone
- internally, there is a n inverted t-shaped sulcus formed by the superior sagittal sinus and the left and right transverse sinuses
- occipital articulates anteriorly with the sphenoid bone by a synchondrosis
5
Q
bones of neurocranium: temporal
A
- 3 parts: squamous, petrous, tympanic
- SQUAMOUS:
- flat squamous portion forms part of the lateral wall of the braincase
- anterolateral process constitutes the back of the zygomatic arch
- at the base the glenoid fossa forms a jaw (temporomandibular) joint with the condyle of the mandible
- the mastoid process, which contains numerous air cells, projects inferiorly from the back of the squamous temporal
- PETROUS:
- pyramid-shaped
- houses the middle and inner ear cavities
- endocranially it separates the middle and posterior cranial fossae
- there is a deep s-shaped sulcus along its border with the occipital that is formed by the sigmoid sinus -> becomes the internal jugular vein as it drains through the jugular foramen
- this foramen also transmits the glossopharyngeal (CN IX), vagus (CN X), and accessory (CN XI) nerves
- endocranially, the internal auditory (acoustic) meatus pierces the back wall of the bone -> transmits the facial (CN VII) and vestibulocochlear (CN VIII) nerves into the inner and middle ear cavities
- underside of the bone has the carotid foramen through which the internal carotid artery enters the carotid canal to merge endocranially where the petrous temporal meets the body of the sphenoid bone
- foramen lacerum is located at this junction
- foramen is plugged by cartilage in vivo and transmits only the thin, greater petrosal nerve (branch of CN VII)
- styloid process projects inferiorly just medial to the mastoid process, and next to it is the stylomastoid foramen -> where terminal branch of the facial nerve (CN VII) exits the skull
- TYMPANIC:
- bridges the gap between the glenoid fossa and mastoid process -> creating the auditory canal and the external auditory (acoustic) meatus
6
Q
bones of neurocranium: sphenoid
A
- complex
- boxlike body of the sphenoid articulates posterior with the occipital and anteriorly with the ethmoid and vomer -> forms the back roof of the nasal cavity
- body has a large sinus
- endocranial aspect resembles a saddle (sella turcica) -> seat of which houses the pituitary gland (hypophyseal fossa)
- in front of the hypophyseal fossa are the optic canals -> transmit the optic nerves (CN II)
- lesser wings splay laterally to form the back part of the floor of the anterior cranial fossa
- lesser wing is separated from the greater wing by the superior orbital fissure-> transmits the oculomotor (CN III), the trochlear (CN IV), the abducent (CN VI), and the ophthalmic division of the trigeminal nerve (CN VI)
- inferior to the medial end of the superior orbital fissure is the foramen rotundum -> transmits the maxillary division of the trigeminal nerve (CN V3)
- lateral to the foramen ovale is the small foramen spinosum -> middle meningeal artery enters the cranial cavity
- greater wing splays out laterally from the body to form part of the lateral wall of the braincase and the back wall of the orbit
- medial and lateral pterygoid plates project from the bottom of the greater wing where it joins the body
7
Q
bones of the face
A
- maxilla
- nasal
- lacrimal
- zygomatic
- ethmoid
- inferior nasal concha
- vomer
- palatine
- mandible
8
Q
bones of the face: maxilla
A
- maxillae are paired bones that constitute most of the hard palate and the face below the orbits
- form the floors of the orbits, and each has a very large sinus
- articulate with one another along the median palatine suture, which is interrupted anteriorly by the incisive foramen
- alveolar process houses the roots of the teeth around the front and the side of the palate
- maxilla articulates laterally with the zygomatic bone
- immediately below the inferior margin of the orbit is the infraorbital foramen
- maxillae form the inferior and lateral margins of the nasal (pyriform) aperture and the anterior nasal spine -> attached to the septal cartilage of the nose
- perpendicular plate of the vomer articulates along the length of the maxillae in the midline
- partly divides the nasal cavity into left and right halves
- maxilla articulates with the frontal, lacrimal, nasal bones
- nasolacrimal duct transverses the maxilla from the orbit to drain into the nasal cavity below the inferior nasal concha -> causes nose to run while crying
9
Q
bones of face: nasal
A
- nasals are paired small bones that articulates superiorly with the frontal and lateral with the maxillae
- their free inferior margins form the superior border of the pyriform aperture
10
Q
bones of face: lacrimal
A
- lacrimals are paired little bones that articulate with the maxillae
- each forms a lacrimal duct along the medial side of the orbit that is continuous with the nasolacrimal duct in the maxilla
11
Q
bones of face: zygomatic
A
- zygomatics are paired bones that form the prominence of the cheeks
- thin plate extends posteriorly to contract the finger-like projection from the temporal, forming the zygomatic arch
12
Q
bones of face: ethmoid
A
- unpaired
- box shaped
- top side and lateral sides, and the interior of the box contains several thin bony sheets and some air sinuses
- its top -> fills a small midline gap in the frontal bone in the anterior cranial fossa -> perforated by numerous hole -> cribriform plate
- cribriform plate- transmits the olfactory nerves (CN1) from the nasal cavity
- crista galli- perpendicular crest, rises between the 2 olfactory bulbs to anchor a fold of dura mater
- sides of the box which form the medial wall of the orbit; balloon inward to form the superior nasal concha
- inferior to nasal concha another thin bony plate, the middle nasal concha, extends downward into the nasal cavity
- midline -> thin perpendicular plate of the ethmoid articulates with the vomer to form the bony part of the nasal septum
13
Q
bones of face: inferior nasal concha
A
- paired small bones that extend along the lateral walls of the nasal cavity just below the middle nasal conchae
- articulates with the maxillae
14
Q
bones of face: vomer
A
- thin
- unpaired
- forms part of the midline nasal septum
- articulates inferiorly with the maxillae and superiorly with the ethmoid and sphenoid
15
Q
bones of face: palatine
A
- paired
- L-shaped small bones
- vertical and horizontal plates
- horizontal plates articulate with the maxillae forming the back of the palate and with the pterygoid plates of the sphenoid
- horizontal plate is perforated by a greater palatine foramen
- vertical plate extends upward forming a tiny part of the lateral wall of the nasal cavity and the sphenopalatine foramen
16
Q
bones of the face: mandible
A
- constitutes the lower jaw
- has a body that contains the roots of the teeth within its alveolar process
- body projects forward in the midline as the mental protuberance (chin)
- posterior surface has small genial spines for attachement of tongue muscles
- lateral surface of the body is pierced by the mental foramen -> transmits one of th terminal branches (mental nerve) of the mandibular division of trigeminal (CN V)
- vertical ramus has 2 processes that extend superiorly
- anterior is the coronoid process
- posterior has a condyle that articulates with the temporal
- internal aspect of the ramus is pierced by the mandibular foramen ->where inferior alveolar nerve enter the mandible
17
Q
dentition
A
- two sets of teeth in life
- childhood teeth- deciduous dentition
- second set- permanent dentition
18
Q
permanent dentition
A
- 32 (16 maxillary and 16 mandibular)
- adult teeth
- each maxilla has 8 teeth and each side of the mandible has 8 teeth
- each of the 4 quadrants contains 4 types of teeth that differ morphologically:
- Incisors (1=two teeths)
- Canine (C=one tooth)
- Premolars (P=two teeth)
- Molars (M=three teeth)
- maxillary canine is sometimes called the eye tooth -> bc long root that extends upward toward the orbit
- premolars may be referred to as bicuspids bc they have 2 cusps
- last (third) molars are wisdom teeth bc they generally erupt between 18 and 21 years (age of wisdom)
19
Q
deciduous dentition
A
- 20 teeth
- 5 in each quadrant
- divided into 3 types according to their morphology
- Incisors (two teeth)
- Canine (one tooth)
- Premolars (two teeth)
- deciduous premolars are commonly referred to as deciduous molars bc they more closely resemble permanent molars than premolars in morphology, but they occupy premolar positions
20
Q
dental development and eruption
A
- teeth calcify within jawbones before erupting into the oral cavity
- timing of tooth calcification and eruption is reasonably well correlated with ontogenetic age
- useful for forensics
- Birth -> no teeth erupted
- six months -> deciduous central incisor
- three years -> deciduous dentition fully erupted
- six years -> permanent first molars and/or central incisors
- ten years -> permanent premolars and/or canines
- twelve years -> permanent second molars
- nineteen years -> permanent dentition fully erupted
21
Q
dental anatomy
A
- 2 parts to tooth: crown and root
- crown- part enclosed by the white, shiny enamel cap
- crown projects above gingiva into the oral cavity
- deep to the enamel cap is the dentine -> forms the bulk of the tooth root
- root is embedded in alveolar bone
- external surface of the root has thin layer of bonelike cementum -> serves to anchor the root in the alveolar bone by numerous short periodontal ligaments
- the dentine surrounds the pulp chamber -> nutritive portion of the tooth, containing blood vessels and nerves
- these are branches of the alveolar nerves and vessels -> make their way into the pump chamber by means of canals in the roots
22
Q
muscles of facial expression
A
-25
-small and overlapping
-originate on bone > insert on skin/superficial fascia
-move the skin, lips, nostril, eyelids
-all are innervated by facial nerve (CN VII) -> somatic motor innervation
-exits skull via stylomastoid foramen
-
-platysma
-frontalis
-orbicularis oculi
-zygomaticus major
-buccinator
-orbicularis oris
23
Q
muscles of facial expression: frontalis
A
- arises superiorly from a flat tendon (the epicranial aponeurosis) that stretches across the parietals to the occipital bone
- inserts into the skin of the eyebrows and draws them upward
- wrinkles the skin of the forehead
- elevates eyebrows
24
Q
muscles of facial expression: orbicularis oculi
A
- encircles the orbit
- consists of 3 portions, each with a different function
- palpebral portion- runs in the eyelids, lowering them during blinking and voluntary closing of the eyes -> blink, wink
- the orbital portion- runs around the periphery of the eyelids and acts during forceful closure of the eyes
- lacrimal portion runs from the crest of the lacrimal bone to the medial part of the eyelids -> compresses the lacrimal sac
25
Q
muscles of facial expression: zygomaticus major
A
- arises from the front of the zygomatic bone and inserts into the corners of the mouth
- draws the corners of the mouth upward, as in smiling
- if it bifid, the result is dimples
26
Q
muscles of facial expression: buccinator
A
- arises from the lateral surfaces of the alveolar processes of the maxilla and mandible opposite the molar teeth
- inserts into the corners of the mouth
- increases the rigidity of the cheek, which helps to position food on the premolars and molars during mastication
- it is pierced by the parotid duct from the parotid (salivary) gland, which opens into the oral cavity opposite the second molar
- keeps cheeks taught keeps food positioned during chewing
27
Q
muscles of facial expression: orbicularis oris
A
- encircles the mouth within the lips
- closes the lips, compresses them against the front teeth, and purses them, as in pouting or kissing
28
Q
muscles of mastication
A
- 5
- move the mandible during chewing
- innervated by CN V3 (except posterior belly of digastric -> CN V2)
- *digastric opens the mouth
- other 4 elevate, protrude, retract, and/or laterally translate the mandible
- masseter
- temporalis
- medial pterygoid
- lateral pterygoid
29
Q
muscles of mastication: masseter
A
- arises from the inferior edge of the zygomatic arch
- inserts on the lateral surface of the ramus and angle of the mandible
- elevates the mandible, and can also pull it forward (protraction)
- innervated by CN V3
30
Q
muscles of mastication: temporalis
A
- fan-shaped
- arises from the lateral surface of the cranial vault along a curved line that runs from behind the orbit on the frontal bone, across the parietal bone, and onto the temporal bone just above the mastoid process
- passes deep to the zygomatic arch (in the temporal fossa)
- inserts onto the tip of the coronoid process of the mandible
- elevates the mandible
- innervated by CN V3
31
Q
muscles of mastication: medial pterygoid
A
- runs from the medial surface of the lateral pterygoid plate of the sphenoid
- inserts onto the medial surface of the angle of the mandible
- elevates and protrudes the mandible
- innervated by CN V3
32
Q
muscles of mastication: lateral pterygoid
A
- arises from the lateral surface of the lateral pterygoid plate and base of the sphenoid
- has 2 parts: superior head and inferior head
- superior head- inserts onto the articular disc that sits between the glenoid fossa and the mandibular condyle
- inferior head- inserts onto the front of the neck of the mandibular condyle -> pulls the condyle of the mandible downward and forward -> causes the mandible to protrude and move from side to side
- inferior head of the lateral pterygoid is the most important for opening the mouth
- innervated by CN V3
33
Q
muscles that move the soft palate
A
- 2 muscles move the soft palate
- soft- palate- back of the roof of the mouth
- move for swallowing and breathing
- covered with mucosa (fold)
- tensor palatini- tightens it
- levator palatini- elevates it during swallowing
- working in conjunction of superior pharyngeal constrictor -> close off the nasopharynx from the oropharynx -> prevents food and drink from passing upward into the nasopharynx and nasal cavity
- tensor palatini and levator palatini arise from the auditory (eustachian) tube -> they also open the pharyngeal end of the tube during swallowing and this equalizes pressure in the middle ear and pharynx
- tensor (veli) palatini
- levator (veli) palatini
- innervated by the vagus nerve (except tensor veli palatini -> V3
34
Q
muscles that move the soft plate: tensor (veli) palatini
A
- arises from the hollow (scaphoid fossa) between the medial and lateral pterygoid plates and from the edge of the auditory tube
- curves medially around the little hook at the inferior edge of the medial pterygoid plate (pterygoid hamulus)
- insert into the soft palate
- tightens/tenses the soft palate
- opens auditory tube
- hooks around pterygoid hamulus
- innervated by mandibular division of trigeminal nerve (CN V3)
35
Q
muscles that move the soft plate: levator (Veli) palatini
A
- arises from the petrous portion of the temporal bone just anterior to the carotid foramen and from the edge of the auditory tube
- runs along the tube
- inserts into the upper surface of the soft palate
- elevates the soft palate
- innervated by pharyngeal branch of vagus nerve (CN X)
36
Q
muscles that move the tongue
A
- 6
- two groups: intrinsic muscles and extrinsic muscles
- intrinsic muscles: alter the shape of the tongue, they are confined to the tongue
- extrinsic muscles- protrude, retract, elevate, and depress the tongue, they attach the tongue to the bones of the skull and hyoid
- body of tongue is wholly muscular
- divided into left and right halves by a fibrous median septum
- upper part of the tongue is made up of intrinsic muscle fibers that attach to the septum
- lower part is comprised mostly by an extrinsic muscle (genioglossus)
37
Q
intrinsic tongue muscles: transverse and longitudinal fibers
A
- transverse and longitudinal fibers
- attach to the fibrous median septum and to the mucous membrane of the tongue
- supplied by hypoglossal nerve (CN XII)
38
Q
extrinsic tongue muscles
A
- 4
- attach the tongue to the bones of the skull, the hyoid, and the soft palate
- motor innervation: all CN XII except for palatoglossus -> CN X
- general sensory: anterior 2/3 -> CN V3; posterior 1/3 -> CN IX
- taste sensation: anterior 2/3 chorda tympani -> CN VII posterior 1/3 -> CN IX
- one is innervated by vagus nerves (CN X)
- the others are innervated by hypoglossal nerve (CN XII)
- genioglossus
- hypoglossus
- styloglossus
- palatoglossus
39
Q
extrinsic tongue muscles: genioglossus
A
- forms the greater part of the bulk of the tongue
- arises from the genial spines on the back of the mandibular symphysis
- fibers fan posteriorly into the substance of the tongue along the median septum from its base to the tip
- some fibers reach the hyoid bone
- protrudes the tongue and prevents it form being sucked into the oropharynx during inspiration
- supplied by hypoglossal nerve (CN XII)
40
Q
extrinsic tongue muscles: hypoglossus
A
- arises from the hyoid bone and inserts into the fibrous tissue of the tongue near its dorsum
- flattens (depresses) the tongue
- supplied by hypoglossal nerve (CN XII)
41
Q
extrinsic tongue muscles: styloglossus
A
- arises from the styloid process
- insert into the edge of the tongue as far as its tip
- retract the tongue upward and backward -> important for swallowing
