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How many bones make up the head?
What are the two parts of the head?
Cranium and the mandible
What are the two parts of the cranium?
Calvaria and the viscerocranium (facial bones)
What bones meet at the coronal suture?
Frontal and 2 parietal bones
What bones meet at the sagittal suture?
2 parietal bones
What bones meet at the lambdoid suture?
Occipital and parietal bones
What bones meet at the squamous suture?
Temporal and parietal bones
What bones meet at the sphenoparietal and sphenosquamous sutures?
- Sphenoparietal: Greater wing of sphenoid and parietal bone
- Sphenosquamous: Greater wing of sphenoid and temporal bone
What bones meet at the Parietomastoid and Occipitomastoid sutures?
- Parietomastoid suture: Parietal and mastoid process
- Occipitomastoid suture: Occipital and mastoid process
What are the bregma and lambda?
- Bregma: intersection of coronal and sagittal sutures
- Lambda: intersection of sagittal and lambdoid sutures
What are the asterion and nasion?
- Asterion: Posterior part of Parietomastoid suture
- Nasion: Nasal and frontal bones meet
What is the Pterion and what is important about it?
Pterion: weakest point of skull; where frontal, parietal, temporal, and sphenoid meet; right on top of the middle meningeal artery
What can be injured with a Pterion fracture?
Damage of middle meningeal artery can cause extradural hematoma
What are fontanels and where are they located?
- Posterior fontanel: Where occipital and parietals meet (Sagittal and Lambdoid sutures)
- Anterior fontanel: Where parietals and frontal meet (bregma)
What are the main features of the frontal bone?
- Supercilliary arches
- Supraorbital foramina or notch
What are supercilliary arches and where do they meet?
Arches just superior to orbits; meet at glabella
What are the two regions of the temporal bone?
Squamous and petrous
What is the squamous part of the temporal bone?
Flat, superior portion. Articulates anteriorly with greater wing of sphenoid and posteriorly with the parietal bone and occiptal bone
What is the petrous part of the temporal bone?
inferior aspect of temporal bones
What are the main features of the temporal bone?
- Mastoid process
- Mastoid notch
- Zygomatic process
- External acoustic meatus
- Inner and Middle ear
- Styloid process
What are the main parts of the sphenoid bone?
- 2 greater wings
- 2 lesser wings inside skull
- 2 pterygoid process that point inferiorly
- Body is between 2 pterygoid processes
- Sella turcica
- Temporal lobe sits on depression just lateral of the body
What are the pterygoid processes?
- Two inferiorly pointing processes of the sphenoid bone
- Each process has a medial and lateral plate
What is the hamulus?
The hook on the medial plate of a pterygoid process of the sphenoid bone
What is the sella turcica?
- in depression in body of sphenoid bone
- seat of saddle is the hypophyseal fossa which holds pituitary gland
- Tuberculum sellae: Anterior to hypophyseal fossa
- Dorsum sellae: posterior wall of hypophyseal fossa
Where is the ethmoid bone located?
Just anterior to the lesser wings of the sphenoid bone
What are the main features of the ethmoid bone?
- Crista galli
- Cribriform plates
What are cribriform plates?
Holes where parts of olfactory nerve penetrate ethmoid bone
What are the parts of the occipital bone?
- Squamous: posterior skull
- 2 lateral parts: either side of foramen magnum
- Basilar part: anterior to foramen magnum
What are the key features of the occipital bone?
- External occipital protuberance
- Superior and inferior nuchal lines
- External occipital crest just inferior to EOP
- Occipital condyles
What is the mnemonic for the facial bones (viscerocranium)?
- Virgil Can Not Make My Pet Zebra Laugh
What are the 2 nasal bones?
- Joins frontal bone at nasion
- Articulates with frontal and maxilla bones
What are the main features of the maxilla?
- Makes medial part of orbit
- Frontal process: articulates with frontal bone
- Zygomatic process articulates with zygomatic bone
- Alveolar process articulates with teeth
- Infraorbital foramina
- Piriform aperture: where the nose sits
Which of the nasal conchae are part of the maxilla?
Inferior nasal conchae
What is the piriform aperture and what can be seen through it?
- Perpendicular plate of the ethmoid bone
- Middle Nasal Conchae (part of ethmoid)
- Inferior Nasal Conchae (part of maxilla)
What is the zygomatic bone?
- “cheek bone”
- articulates with temporal, frontal, and maxilla
- Makes up lower lateral orbit
- Looks like a diagonal sling shot
Where are the lacrimal bones?
Posterior to maxilla
What is the vomer?
- Posterior to piriform aperture
- On top of palatine bones, extends superiorly and posteriorly
- Separates 2 posterior nasal apertures or choanae
- leads to opening of nasopharynx
What are the palatine bones?
- Top of oral cavity, “hard palate” “underside of maxilla”
- 2 bones
- Anterior part is part of maxilla
- Posterior part of palate are 2 palatine bones
What are the different parts of the mandible?
- Body (anterior part)
- Angle of the mandible (between body and ramus)
- Ramus (posterior/vertical part)
What are the two parts of the body of the mandible?
- Alveolar part (upper): Where teeth insert into lower jaw
- Base of mandible:
- Mental protuberance: Midline where 2 parts of body meet
- Mental tubercles: Just lateral to mental protuberance
- Mental foramina
What are the two parts of the ramus of the mandible?
- Coronoid process
- Condylar process
What are the coronoid and condylar processes of the mandible?
- Coronoid process: Anterior; Insertion for temporalis muscle (mastication)
- Condylar process: Posterior; Articulates with temporal bone
Where do cranial nerves emerge from?
Directly from the brain, most from brain stem: midbrain, pons, and medulla
What types of function do cranial nerves have?
Has both somatic and visceral (autonomic) components as well as special sensory and motor functions
Where do the first 2 cranial nerves emerge from?
First 2 cranial nerves emerge from telencephalon (I) and diencephalon (II)
Where do cranial nerves (III-XII) emerge from?
Brain stem: midbrain, pons, and medulla
Which nervous system do the cranial nerves belong to?
Peripheral nervous system except for cranial nerve II: optic nerve
How many pairs of cranial nerves are there and what is the mnemonic?
- 12 pairs
- Oh, Oh, Oh, To Touch And Feel Very Good Velvet, Ah Heaven
What are the names of the 12 cranial nerve pairs?
- I: Olfactory
- II: Optic
- III: Oculomotor
- IV: Trochlear
- V: Trigeminal
- VI: Abducens
- VII: Facial
- VIII: Vestibulocochlear
- IX: Glossopharyngeal
- X: Vagus
- XI: Spinal Accessory
- XII: Hypoglossal
What is the mnemonic for function of cranial nerves?
Some Say Marry Money, But My Brother Says Big Boobs Matter More
S= sensory M= motor B= both
Cranial nerve I: Olfactory
Olfaction (sense of smell), receptors in nose, nerves pass through nasal cavity, up through cribriform plates of ethmoid bone and synapse on olfactory bulb (runs along foramina in cribriform plates)
Cranial Nerve II: Optic
Vision; From retina to brain; Cross at optic chiasm
Cranial nerve III: Oculomotor
- Originates anteriorly in midbrain in floor interpeduncular fossa near pillars called cerebral peduncles
- Responsible for innervating muscles that move the eye (extraocular muscles) and pupillary sphincter
Cranial Nerve IV: Trochlear
Originate on dorsal surface of the midbrain, winds around sides of cerebral peduncles Movements of eyes by innervating one muscle (superior oblique muscles)
Cranial nerve V: Trigeminal
- Originates off lateral sides of pons on middle cerebellar peduncle (connects pons to cerebellum) and goes to trigeminal ganglion (group of cell bodies of sensory neurons) and splits into three parts:
- Opthalmic (V1)
- Maxillary (V2)
- Mandibular (V3)
- Responsible for sensation of the face and innervating muscles of mastication
What are the 3 branches of the trigeminal nerve (V)?
- V1: Opthalmic
- V2: Maxillary
- V3: Mandibular
Cranial nerve VI: Abducens
- Originates at border between pons and medulla
- Innervates one of the extraocular muscles (lateral rectus muscles)
Cranial nerve VII: Facial
- Originates at the cerebellopontine angle above the olive of the medulla
- Responsible for muscles of facial expression, receives taste from anterior ⅔ of tongue and secretomotor function to salivary glands and lacrimal glands
Cranial nerve VIII: Vestibulocochlear
- Originates just lateral to facial nerve at cerebellopontine angle
- Responsible for hearing and balance
- 2 branches
- Vestibular part: for balance
- Cochlear part: for hearing
Cranial nerve IX: Glossopharyngeal
- Originates just inferior to facial (VII) and vestibulocochlear (VIII); just dorsal to olive on lateral margin of medulla
- Responsible for taste on posterior ⅓ of tongue, secretomotor function for parotid gland (salivary), innervating muscles in throat, and carrying sensation from areas in throat
Cranial nerve X: Vagus
- Originates in postero-lateral sulcus of the medulla just behind olive and below glossopharyngeal (IX)
- Innervates lots of laryngeal and pharyngeal muscles and almost all abdominal and thoracic viscera
Cranial nerve XI: Spinal Accessory
- Cranial and spinal root
- Innervates sternocleidomastoid and trapezius muscles
Cranial nerve XII: Hypoglossal
- Originates between medullary pyramids and olive of medulla
- Innervates muscles of the tongue
In general, what passes through foramina in the skull?
Nerves and blood vessels that carry blood and information to and from the brain
What are the externally visible foramina on the orbits?
- Optic canals (most medial)
- Superior orbital fissures (larger than foramen)
- Inferior orbital fissures
What is the externally visible foramen on the Maxilla?
What is the externally visible foramen on the Frontal bone?
Supraorbital formina or notch
What is the externally visible foramen on the zygomatic bone?
Zygomatico facial foramen: zygomatic facial nerve passes through
What is the externally visible foramen on the mandible?
What are the 3 cranial fossae?
- Anterior cranial fossa
- Middle cranial fossa
- Posterior cranial fossa
Anterior Cranial Fossa
- Frontal and ethmoid bone
- Crista galli and cribriform plates (Olfactory nerve)
- Frontal lobes of brain housed in lateral portion
Middle Cranial fossa
- Temporal and sphenoid bones
- Dorsum sellae and hypophyseal fossa (Sella turcica)
- Temporal lobes of brain
Posterior Cranial fossa
- Occipital bone
- Brain stem and cerebellum
What are the internal foramina visible in the anterior cranial fossa?
- Optic canals
- Superior orbital fissures
What are the internal foramina visible in the middle cranial fossa?
- Foramen spinosum (most lateral and posterior in middle cranial fossa)
- Foramen ovale
- Foramen rotundum (anterior to foramen ovale)
- Foramen lacerum (filled with cartilage, nothing passes through)
What are the internal foramina visible in the posterior cranial fossa?
- Internal auditory meatus
- Jugular foramen
- Hypoglossal canal
- Foramen magnum
What nerve innervates the muscles of facial expression?
Cranial nerve VII: Facial nerve
How do you test the facial nerve (VII) clinically?
- Wrinkle forehead
- Close eyes tightly
- Puff out cheeks
What are the muscles of facial expression around the orbits?
- Occipitofrontalis muscle
- Orbicularis oculi
- Corrugator supercilii
- 2 bellies: frontal and occipital
- Bellies connected by the epicranial neurosis 3rd layer of scalp under skin and connective tissue
- On top of loose connective tissue and periosteum
- Circular around eyes “like sphincter of the eye”
- Outer and inner part
- Outer (orbital part): Closes eyes forcefully
- Inner (palpable part): Closes eyes gently
- Just deep to obicularis oculi
- Draws eyebrows medially and downward
What are the muscles of facial expression around the nasal region?
- Depressor septi nasi
- O: Nasal bone
- I: Skin of forehead
- When frowning
- Transverse part: Compresses nares
- Alar part: Flares nares
Depressor septi nasi
Depresses nasal septum and draws nose down inferiorly
What are the muscles of facial expression around the mouth?
- Orbicularis oris
- Zygomaticus major
- Zygomaticus minor
- Levator labii superioris
- Levator angulii oris
- Levator superioris alaeque nasi
- Depressor anguli oris
- Depressor labii inferioris
- Circular around oral cavity
- Closes mouth and purses lips (Like whistling)
- Muscular component of cheek
- Puffing up cheek, blowing air out
Inserts corner of mouth, retracts mouth laterally
Inserts corner of mouth, draws mouth upward and laterally
Inserts corner of mouth, draws lip upwards
Levator labii superiorus
Lifter of upper lip
Levator anguli oris
Lifter of corner of mouth, just deep to levator labii superiorus
Levator superioris alaeque nasi
Lifter of upper lip and alar cartilage of nose
Depressor anguli oris
- Depresses corner of mouth
- Most superficial of lower group
Depressor labii inferioris
Depresses lower lip and moves laterally
Helps position lip like when drinking from a cup
What are the auricular muscles?
- Auricularis posterior: Pulls ear posteriorly
- Auricularis superior: Elevates ear
- Auricularis anterior: Pulls ear upwards and forward
What are the 3 parts of the brain stem?
- 1. Midbrain (top)
- 2. Pons
- 3. Medulla oblongota (bottom)
2 thick stalks on posterior aspect of pons that connect cerebellum to pons and midbrain
- Between midbrain and medulla oblongata, anterior to cerebellum
- Tracts that send signals from brain to cerebellum to medulla oblongata and tracts that send sensory signals to thalamus
- Pneumotaxic center: regulates change from inhalation to exhalation
- Most inferior part of brain stem, between pons and spinal cord
- Autonomic functions (cardiac, respiratory, vomiting, and vasomotor)
What are the main parts of the midbrain (mesencephalon)?
- Cerebral peduncles (anterior)
- Corpora quadrigemina (posterior)
- Tectum (roof of midbrain)
Corpora quadrigemina of midbrain
- Posterior portion
- Formed by Quadruplet bodies (hills): Superior colliculi and Inferior colliculi
Tectum of midbrain
- Roof of midbrain (dorsal aspect)
- Auditory and visual reflexes
Function of Midbrain
- Loads of nuclei (collections of cell bodies in CNS)
- Important for controlling HR, BP, respiration, wakefulness, arousal
- Just posterior to brain stem (means little brain)
- 2 lobes
- Motor control, coordination, balance, muscle tone, etc
- Sits on top of the brain stem
- Pineal gland
- Round, oval structures on top of midbrain
- 2 thalami make up the thalamus
- Joined by interthalamic adhesion
- Switchboard to cerebral cortex of cerebral hemisphere, relays info
- Contains lots of nuclei
- Sends and receives fibers from the cortex
- Thalamo-cortical loops and lots of reciprocal connections
- Just anterior and inferior to thalamus
- Links nervous system to endocrine system via pituitary gland
- Just posterior and inferior to interthalamic adhesion
- Melatonin- sleep/wake cycles
Cerebral Hemispheres (Right and Left)
Higher thinking (thinking, memory, emotions, consciousness, movement, language, sensory perception)
What are the 2 main layers of the cerebral hemispheres?
- Neocortex: 6 layers of gray matter; Evolutionarily newer portion; Higher functions like language and conscious thought
- Allocortex (2 parts): Less than 6 layersarchicortex and paleocortex
What are gyri and sulci of the cerebral hemispheres?
- Ridges are called gyri
- Grooves are called sulci
- Main one: Central sulcus and lateral sulcus; Separate lobes of brain
What are the 4 main lobes of the brain?
- Frontal lobe (anterior to central sulcus): Decision making, problem solving and planning
- Parietal lobe (posterior to central sulcus): Integrator of sensory information
- Temporal lobe (inferior to lateral sulcus): Memory, language, emotion, and hearing
- Occipital lobe: Vision
Where are the basal ganglia found?
Inside of the cerebral hemispheres
What are the 3 structures that make up the basal ganglia?
- Caudate nucleus: Head, Body, Tail
- Putamen (outside caudate nucleus)
- Globus pallidus (just medial and inferior to putamen) (lateral to thalmi) External/lateral,Internal/medial
What structures make up the lenticular nucleus?
What structures make up the neostratium?
Limbic system (Hippo wearing a HAT)
- Not anatomically distinct
- Involved in emotion, behaviour, memory, and motivation
- Hippocampus (memory) (medial aspect of temporal lobe)
- Amygdala end of caudate nucleus tail
What is the function of the hippocampus?
- Converts short term memories into long term memories
- If destroyed, can not form new long term memories, but previous memories still intact
What is the function of the amygdala?
Stimulates anger, violence, fear, and anxiety
What is Kluver-Bucy syndrome?
- Bilateral destruction of amygdalas
- Sx: hyperorality, hypersexuality, disinhibited behavior
- Kind of like being permanently drunk
Ventricles of the CNS
- Developed from neural tube
- Filled with CSF (protects and nourishes neural system)
- Lateral ventricles
- Third ventricle (connected to lateral ventricles via interventricular foramina): Form Walls of thalmus
- Fourth ventricle (in pons): Cerebral aquaduct runs within midbrain to connect 3rd and 4th ventricles
What passes through the optic canal?
- Optic nerve after crossing at optic chiasm (Cranial nerve II)
- Ophthalmic artery
What passes through the supraorbital fissure?
- Oculomotor nerve (III)
- Trochlear nerve (IV)
- Ophthalmic branch of trigeminal nerve (V1): Sensation around eye region
- Abducens (VI): muscles for abducting eye
- Ophthalmic veins
What passes through the Foramen rotundum?
- Maxillary branch of trigeminal nerve (V2)
- (Max is rotund)
What passes through the Foramen ovale?
- Mandibular branch of trigeminal (V3)
- (Mandy is oval)
What passes through the Foramen spinosum?
Middle meningeal artery (lies behind pterion)
What passes through the carotid canal?
Internal carotid artery (joins circle of willis at base of brain)
Internal auditory meatus
- Vestibulocochlear (VIII) and Facial (VII) nerves
- Labyrinthine artery
What passes through the Jugular foramen?
- Internal jugular vein
- Glossopharyngeal (IX), Vagus (X), and Spinal Accessory (XI) nerves
- Spinal accessory also passes through foramen magnum
What passes through the Hypoglossal canal?
Hypoglossal nerve (XII)
What passes through the Foramen magnum?
- Spinal cord and brainstem meet
- Vertebral arteries
- Spinal root of Accessory Nerve (XI)
Where are the common carotid and internal jugular veins found?
- Common carotid and Internal Jugular vein run parallel to each other (Carotid more medial)
- Common carotid bifurcates into internal and external carotid arteries
- Carotid system supplies blood to all structures in the head and neck
How many branches of the external carotid and internal carotid are found in the neck?
- Internal carotid artery has no branches in neck
- External carotid artery has 8 branches in the neck
What are the 8 branches of the external carotid artery in the neck?
- Superior thyroid: First branch after bifurcation, comes off anteriorly; Descends onto superior pole of thyroid gland
- Ascending pharyngeal: Comes off medioposteriorly
- Lingual: Comes off Anteriorly to tongue
- Facial (external maxillary): Comes off anteriorly, Windy, comes over edge of inferior aspect of mandibular angle and to anterior aspect of masseter muscle; Palpable on mandible
- Occipital: Comes off posteriorly at same level as facial artery; Extends to posterior side of scalp
- Posterior auricular: Comes off posteriorly, runs behind ear
- Maxillary (internal maxillary): Terminal branch; Runs behind neck of mandible to infratemporal fossa and ultimately into pterygopalatine fossa
- Superficial temporal artery: Runs anteriorly to ear and up superficially on scalp and branches into anterior and posterior branches; Terminal branch
- Mnemonic: Some Ancient Lovers Find Old Positions More Stimulating
Circle of Willis
- Supplies blood to brain by connecting 2 arterial sources: Internal carotid arteries and vertebral arteries
- Anastomose at base of brain to form circle of willis around optic chiasm and hypothalamus
The internal carotid arteries bifurcate into what two arteries in the Circle of Willis?
Medial cerebral artery and anterior cerebral artery
Middle cerebral artery
- Branch of internal carotid artery in Circle of Willis
- Runs in lateral sulcus
- Gives off striate arteries to supply basal ganglia
Anterior cerebral artery
- Branch of internal carotid artery in Circle of Willis
- Runs from front to back in interhemispheric fissure (aka medial longitudinal fissure) between hemispheres
What is the very short artery that connects 2 anterior cerebellar arteries?
Anterior communicating artery
Posterior communicating arteries
- Connects internal carotid artery to posterior cerebral artery
- Connects anterior circulation provided by internal carotids to posterior circulation provided by vertebro-basilar system
Comes off internal carotid, anteriorly, just after internal carotid passes through the cavernous sinus into the cranial cavity
- Come in posteriorly to Circle of Willis
- From first part of subclavian artery, run up transverse foramen of cervical vertebrae
The vertebral arteries branch off into what arteries?
- Posterior inferior cerebellar arteries
- Anterior spinal artery: Comes off vertebral arteries, unite and runs inferiorly down anterior spinal fissure
- Posterior spinal artery: Runs down posterior aspect of spinal cord
- Formed by union of two vertebral arteries at level of inferior aspect of pons
- Runs superiorly in midline of anterior aspect of the pons
Where does the basilar artery split?
- Splits at midbrain into posterior cerebral arteries
- Posterior cerebral arteries from bifurcation of basilar artery at midbrain
- Just before the bifurcation, basilar artery has 2 branches that come off called superior cerebellar arteries.
Small; come off as many branches off basilar artery in front of pons
- Provides posterior circulation
- Supplies cerebellum, brainstem, and posterior parts of cerebral hemispheres
Blood supply for different regions of the brain
- Anterior cerebral artery: Supplies medial and superior aspects of the cerebral hemisphere
- Middle cerebral artery: Supplies lateral aspect of cerebral hemisphere
- Posterior cerebral artery: Supplies posterior and inferior aspects of cerebral hemisphere
What nerve innervates the muscles of mastication?
Innervated by: Mandibular Branch of Trigeminal (V3)
What are the 4 muscles of mastication?
- Medial Pterygoid
- Lateral Pterygoid
- Sits in temporal fossa of skull
- Inserts on Coronoid process of mandible
- Causes mandible to elevate and retract
- 2 parts: superficial and deep parts
- Deep part: Originates more posteriorly on zygomatic arch
- Superficial: Originates more anteriorly on zygomatic arch
- Insert onto lateral aspect of ramus of mandible
- Elevates mandible
Medial Pterygoid muscle
- deep to mandible
- Originate on medial aspect of lateral pterygoid plate of sphenoid bone
- Insert on medial surface of ramus of mandible
- Elevation and side to side movements of mandible
Lateral Pterygoid muscle
- deep to mandible
- Originates on lateral aspect of lateral pterygoid plate of sphenoid bone
- 2 parts: superior and inferior
- Superior originates on infratemporal surface of greater wing of sphenoid and inserts superiorly on condylar process of mandible
- Inferior lateral pterygoid originates on lateral surface of lateral pterygoid plate inserts on neck of condyle of mandible
- Depression, Protrusion and side to side movements of mandible
4 movements of the mandible
- Retraction: movement posteriorly
- Protrusion: movement anteriorly
- Elevation: movement superiorly
- Depression: movement inferiorly
- Thin muscles on anterior aspect of neck
- In superficial fascia
- Origin: Manubrium and medial portion of the clavicles
- Insertion: Mastoid processes
- Action: Unilateral rotation to opposite side, cervical lateral flexion, and lifts sternum for forced inspiration
Anterior triangle boundaries (neck)
- Superior border: inferior border of mandible
- Medial border: midline
- Lateral border: anterior aspect of sternocleidomastoid muscle
Major Structures in anterior triangle of neck
- Hyoid bone
- Suprahyoid and Infrahyoid (strap) muscles
- Thyroid gland
- Larynx and Trachea
- Parathyroid glands
- Common carotid and it’s branches
- Internal jugular vein
- Vagus and recurrent laryngeal nerves
Posterior triangle boundaries (neck)
- Inferior border: 2nd third of clavicle
- Posterior border: anterior aspect of trapezius muscles
- Anterior border: posterior aspect of sternocleidomastoid muscle
Major Structures in posterior triangle of neck
- Levator scapulae
- Scalene muscles (ribs to transverse processes of c-spine; accessory muscles for respiration)
- Subclavian vein
- External jugular
- Vertebral veins
- Brachial plexus
- Accessory nerve
What are the 2 types of fascia in the neck?
- Superficial fascia: Platysma muscles
- Deep Fascia: Investing layer, Carotid sheath, Pretracheal, and Prevertebral
Investing layer (neck fascia)
- Surrounds entire neck
- Splits to encapsulate trapezius and sternocleidomastoids
Common carotid, internal jugular vein, deep cervical lymph nodes, and vagus nerve
Encloses trachea, larynx, pharynx, thyroid gland, and esophagus
- Prevertebral muscles
- Anterior, middle, and posterior scalene muscles
- Deep muscles of back
What are the 4 suprahyoid muscles?
- Attaches to hyoid bone and digastric fossa on inside surface of mandible
- Originates on medial surface of mastoid process
- Two bellies: anterior (O: digastric fossa on mandible I: hyoid bone) and posterior (O: medial of mastoid I: hyoid bone)
- If hyoid is fixed, anterior belly of digastric opens mouth by pulling mandible down
- If mandible is fixed, both bellies contract and elevate hyoid
- Originates on Styloid process of temporal bone to lateral surface of hyoid
- Elevates tongue and hyoid (during swallowing)
- Floor of mouth, on top of digastric (anterior belly), fan shaped
- O: Mylohyoid line of mandible
- I: Hyoid bone
- Elevates hyoid bone
- Superior to mylohyoid
- O: inferior mental spine of mandible
- I: Hyoid bone
- If hyoid fixed, opens jaw
- If mandible is fixed, elevates hyoid
- Genio = chin
What are the 4 infrahyoid or strap muscles?
- Opposite action to suprahyoid, so they depress the hyoid bone
- O: Sternum
- I: Hyoid
- Depresses hyoid bone after swallowing
- Lateral to sternohyoid
- O: Superior border of scapula
- I: Hyoid bone
- Through posterior and anterior triangles of neck
- 2 bellies: superior and inferior
- Intermediate tendon separates two bellies and attaches to clavicle
- Depresses and fixes hyoid
- O: Oblique line on thyroid cartilage
- I: Hyoid bone
- If larynx is fixed, depresses hyoid
- If hyoid is fixed, elevates larynx
- Continuous with thyrohyoid, but is the inferior portion
- O: sternum
- I: thyroid
- Draws larynx downwards
What are the muscles found in the posterior triangle of the neck?
- Scalene muscles
- Splenius capitis
- Levator scapulae
- Prevertebral muscles
- Lateral vertebral muscles
- O: Transverse processes of cervical vertebrae
- I: 1st and 2nd ribs on superior surface
- Anterior (1st rib), middle (1st rib) and posterior (2nd rib) scalene muscles
- Elevate ribs, accessory muscles for respiration
- O: Spinous processes of vertebrae (C7-T4)
- I: Mastoid process
- Draws head backwards if both contracting
- If one contracts, rotates head
- O: Upper surface, medial border of scapula
- I: transverse processes of C1-C4
- Elevates scapula
- Anterior to vertebral bodies
- Flex the neck and head
- 1. Longus capitis
- 2. Longus colli
- 3 parts: superior oblique, inferior oblique, and vertical
- Attaches to anterior parts of vertebral bodies and transverse processes of cervical vertebrae
- Flexes neck anteriorly and laterally; slight rotation to opposite side
- O: transverse processes of C3-C6
- I: inferior surfaces of occipital bone (basilar part, anterior to foramen magnum)
- Flexes head downwards
- Flex head muscles
- Rectus capitis: anterior and lateralis
Rectus capitis anterior
- O: upper surface of atlas
- I: basilar part of occipital bone
- Flexes head at atlanto-occipito joint
Rectus capitis lateralis
- O: Superior surface of transverse process of atlas
- I: occipital bone
- Flexes head laterally
- Between larynx and mandible
- Connects floor of oral cavity to pharynx and larynx
- 3 parts: Body, Greater horns (posteriorly), lesser horns (superior)
What are the 4 extrinsic muscles of the tongue?
- O: superior mental tubercles on inside of mandible
- I: entire length of tongue and hyoid
- Depresses center of tongue and protrudes tongue
- O: Greater horn of hyoid
- I: Lateral surface of tongue
- Depresses tongue
- O: Styloid process of temporal
- I: Entire lateral surface of tongue
- Blends with upper border of hyoglossus muscle
- Elevates tongue and retracts tongue
- O: inferior surface of palatine aponeurosis
- I: Lateral margin of tongue
- Depresses palate and elevates back of tongue