OSU Anatomy 2300 Unit 4

Overview of the skull

-part of the axial skeleton

-composed of 22 bones total

-8 bones form cranium

-14 associated w/ face

-7 additional bones associated w/ skull

What are the bones of the cranium?

-frontal bone (1)

-occipital bone (1)

-sphenoid bone (1)

-ethmoid bone (1)

-parietal bones (2)

-temporal bones (2)

Frontal bone of skull

forehead bone; protects cranium (yellow on fig.)

-supra-orbital notch (foramen)

-supra-orbital nerve travels through notch

Parietal bones of skull

Bones that form the sides and top of the cranium

Temporal bones of skull

-contains external acoustic meatus

-mastoid process

-styloid process

-zygomatic process

carotid canal of temporal bone

for internal carotid artery

stylomastoid foramen of temporal bone

contains facial nerve

mandibular fossa of temporal bone

articulates with the mandible

internal acoustic meatus of temporal bone

Facial n. (CN VII)

Vestibulocochlear n. (CN VIII)

jugular foramen of temporal bone

foramen for internal jugular vein and cranial nerves IX, X, and XI

occipital condyles of occipital bone

rounded processes that articulate with the atlas (C1)

foramen magnum of occipital bone

-spinal cord exist via foramen magnum

-vertebral arteries enter via foramen magnum

external occipital protuberance of occipital bone

projection at base of skull posterior to foramen magnum

hypoglossal canal of occipital bone

contains hypoglossal nerve (CN XII)

What are the main structures of sphenoid bone (8)

(1) lesser wing

(2) greater wing

(3) sella turcica

(4) foramen lacerum

(5) optic canal

(6) foramen rotundum

(7) foramen ovale

(8) foramen spinosum

Sella Turcica ("Turkish Saddle") of the Sphenoid Bone

(inferior view)

foramen lacerum of sphenoid bone

-opening for the internal carotid artery

-lateral to Sella Turcica

optic canal of sphenoid bone

contains optic nerve (CN II)

foramen rotundum of sphenoid bone

First part of Cowboy Ros, transmits maxillary branch CN V2 (part of trigem)

Foramen ovale

foramen spinosum of sphenoid bone

(red circle); inferior to foramen rotundum; lateral to foramen ovale

Greater wing of sphenoid bone

posterior & inferior to lesser wing on the interior of the skull; also visible in the posterior orbit and lateral side of the skull

Lesser wing of sphenoid bone

anterior & superior to greater wing on the interior of the skull

Cowboy Ross Mnemonic

Cowboy: sits in the saddle (Sella turcica)

R: foramen rotundum

O: foramen ovale

S: foramen spinosum

ROS: medial --> lateral

What nerve runs through foramen rotundum?

Maxillary nerve (CN V2)

-second division of trigeminal

What nerve runs through foramen ovale?

Mandibular nerve (CN V3)

-third division of trigeminal

What runs through foramen spinosum?

middle meningeal artery

What runs through foramen lacerum?

Nothing; it is covered w/ cartilage

Sphenoid bone (anterior view): optic canal

Identify this structure:

Sphenoid bone (anterior view): superior orbital fissure

Identify this structure:

What travels through the superior orbital fissure?

CN III, IV, V (1st part), VI and the superior ophthalmic vein

Medial pterygoid plate

Lateral pterygoid plate

Crista galli of ethmoid bone

Cribriform plate & cribriform foramina of ethmoid bone

innervated by CN1 / olfactory nerve

Perpendicular plate of ethmoid bone

forms superior part of nasal septum

middle nasal concha of ethmoid bone

Bone between the superior and inferior conchae

Describe characteristics of suture joints?

Fibrous joints

-very short fibers connect the interlocking edges of articulating bones

-joints between bones of skull

4 major sutures of the skull

(1) coronal suture

(2) squamous suture

(3) lambdoidal suture

(4) sagittal suture

coronal suture of the skull

separates frontal and parietal bones

squamous suture of skull

separates parietal from temporal

lambdoidal suture of skull

between parietal and occipital bones

sagittal suture of the skull

between parietal bones

Identify the bones of the face (14)

-maxillae (2)

-nasal (2)

-zygomatic (2)

-lacrimal (2)

-palatine (2)

-inferior nasal conchae (2)

-vomer (1)

-mandible (1)

Infra-orbital foramen of maxilla

What goes through the infra-orbital foramen?

Infra-orbital nerve (V2) and Infra-orbital artery (maxillary artery, pterygopalatine segment)

Alveolar process of maxilla

curved, inferior margin of the maxilla that supports & anchors the upper teeth

Palatine processes of maxillary bone

Identify the paranasal sinuses (4)

(1) frontal sinus

(2) sphenoid sinus

(3) ethmoid sinus

(4) maxillary sinus

What is the function of paranasal sinuses?

lighten the skull, act as a resonance chamber for speech, produce mucus, help to moisten the air

Horizontal plate of palatine bone

form the posterior part of the hard palate of the mouth & the floor of the nose

What 2 structures form the hard palate?

(1) palatine processes of the maxillae

(2) horizontal plates of the palatine bones

Zygomatic bone

the arch of bone beneath the eye that forms the prominence of the cheek

Temporal process of zygomatic bone

Name this part of the zygomatic bone.

What 2 structures form the zygomatic arch?

temporal process of zygomatic bone + zygomatic process of temporal bone

lacrimal bones

paired bones at the corner of each eye that cradle the tear ducts

What 7 bones make up the orbit of the eye?

(1) frontal bone

(2) zygomatic bone

(3) maxillary bone

(4) sphenoid bone

(5) ethmoid bone

(6) lacrimal bone

(7) palatine bone

Inferior nasal conchae

-most inferior within nasal cavity

-help to warm/clean air before it enters lungs

What 3 structures form the nasal septum?

(1) perpendicular plate of ethmoid bone

(2) vomer bone

(3) septal cartilage

What is a deviated septum?

-occurs when nasal septum is displaced to one side

-often present at birth / can occur due to injury

Symptoms: nosebleeds, congested nostril, noisy breathing during sleep

Angle of the mandible

Name this bony landmark.

Ramus of the mandible

vertical portion of the mandible

Condylar process of mandible

articulates with temporal bone forming the temporomandibular joint at mandibular fossa

Coronoid process of mandible

Mental foramen of mandible

one of two holes located on the anterior surface of the mandible

-permits passage of the mental nerve and vessels

Mandibular foramen of mandible

Located on the medial surface of each ramus; passageway for the nerve involved in tooth sensation

(Dentists inject anesthetic into this foramen before working on the lower teeth)

Genoid tubercle of mandible

attachment point for muscles of tongue

What are fontanelles?

-soft fibrous areas where several sutures unite

-allow for molding & remodeling

Hyoid bone

U-shaped bone at the base of the tongue that supports the tongue and its muscles

What are the 4 lobes of the cerebral hemispheres?

(1) frontal

(2) parietal

(3) temporal

(4) occipital

Gyrus

elevated fold of the brain

Sulcus

shallow groove between gyri

Fissure

deep groove between gyri

Longitudinal fissure of brain

deep groove down the brain; separates left & right hemispheres

Sylvian/lateral fissure of brain

separates frontal & parietal from temporal lobes

Central sulcus of brain

separates frontal & parietal lobes

Transverse fissure of brain

separates cerebrum from cerebellum

What is located in the anterior cranial fossa?

frontal lobe

What is located in the middle cranial fossa?

temporal lobe

What is located in the posterior cranial fossa?

cerebellum

What are the 3 basic regions of each hemisphere?

(1) cerebral cortex

(2) internal white matter

(3) basal nuclei

What comprises grey matter of the brain?

cell bodies, dendrites & unmyelinated axons

What comprises white matter of the brain?

myelinated axons

What are the 3 main functions of the cortex?

(1) motor areas: initiation of movement

(2) sensory areas: sensory info. reception/ perception

(3) association areas: complex integrative functions

Prefrontal cortex

Location:

Function:

Location: frontal lobe

Function: personality & character traits

Primary motor cortex

Location:

Function:

Location: precentral gyrus (frontal lobe)

Function: fine motor control

Broca's area

Location:

Function:

Location: frontal lobe (dominant hemisphere only)

Function: speech production

Primary sensory cortex

Location:

Function:

Location: postcentral gyrus (parietal lobe)

Function: sensory

Primary auditory cortex

Location:

Function:

Location: temporal lobe

Function: hearing

Primary visual cortex

Location:

Function:

Location: occipital lobe

Function: vision

What are commissural fibers?

fibers connecting grey area matter between the two hemispheres

Ex. corpus callosum

What are association fibers?

fibers connecting parts of the same hemisphere

Ex. general cerebral white matter

What are projection fibers?

fibers connecting the cerebral cortex to other parts of the CNS

Ex. spinal tracts

What are basal nuclei?

collection of nerve cell bodies deep in the cerebellum

What is the function of basal nuclei?

Influence motor function by regulating the initiation and termination of movement. Inhibits extraneous muscle contraction and helps to maintain motor control

*damage can lead to muscle rigidity and/or resting tremors

Thalamus

major relay center for all sensation entering the cerebral cortex except olfaction; aids in motor activity

Hypothalamus

major regulator of the body's internal environment, through the autonomic, limbic, and endocrine systems

Epithalamus

regulates sleep/wake cycle w/ hypothalamus

-main projection called pineal body secretes melatonin hormone

Identify the 3 parts of the brain stem:

midbrain, pons, medulla oblongata

Function of brain stem:

(1) produces autonomic behaviors vital to survival

(heart rate, respiration)

(2) pathway for descending & ascending axons

(3) contains nuclei for CN3-12