SPHENOID Bone

Question 1

Sphenoid bone

Answer 1

Forms the ROSTRAL part of the base of the skull

1. OS PRESPHENOIDALE (rostral)
2. OS BASISPHENIODALE (caudal)
   - At birth the two parts united by synchondrosis intersphenoidalis, which becomes ossified during the 1st years of life

Both parts comprise:

1. Median body (Corpus)
2. Wings
3. Processus pterygoideus

Question 2

Os PRESPHENOIDALE

Answer 2

In the body of presphenoid Extends towards the cranium as the ROSTRUM SPHENOIDALE

The rostrum sphenoidale continues into the CRISTA GALLI of the ethmoid bone

CORPUS OSSIS PRESPHENOIDALIS
1 Fossa crani rostralis
- forms with the wings

2. SINUS Sphenoidalis
   Paired
   Septum sinuum sphenoidalium
3. SULCUS CHIASMATIS
   - in the caudal part of the presphenoid
   - houses the Chiasma opticum
   - marked by the CRISTA orbitosphenoidalis

ALA Ossis PRESPHENOIDALIS

• the outer surface participate in the formation of the orbit and optic canal
• the inner surface forms the Cranial cavity

Question 3

Os PRESPHENOIDALE

ALA OSSIS PRESPHENOIDALE

Answer 3

1. CANALIS opticus
   - at the root of the wings
   - leads to the orbit
   - houses the optic nerve
2. FISSURA orbitalis
   - in ca, eq
   - lies below and behind the optic canal
3. FORAMEN rotundum (round foramen)
   - lies below the fissura orbitalis
   - within the wing
   - in ca, eq it opens rostraly into the Canalis alaris
4. FORAMEN orbitorotundum
   - in BO
   - the round foramen and the orbital fissure unite

Question 4

Os PRESPHENOIDALE

CORPUS OSSIS PRESPHENOIDALE

Answer 4

1. Fossa crani media
   - formed by the body and the wings of basisphenoid
2. SELLA TURCICA
   - in the floor of the cranial cavity
   - houses FOSSA HYPOPHYSIALIS
   - Projects as the DORSUM SELLAE - Exept in EQ
3. SULCUS CAROTICUS
   - in ca & eq

Question 5

OS SPHENOIDALE

ALA OSSIS BASISPHENOIDALE

Answer 5

1. SULCUS Nervi Opthalmici et maxillaris
   - in bo
   - situated on the cerebral surface
   - connects the foramen orbitorotundum with the orbit
2. SULCUS NERVI OPTHALMICI
   - in car, eq
   - medial one
   - communicates with the orbital fissure
3. SULCUS NERVI MAXILLARIS
   - in eq, car
   - Lateral one
   - leads to the round foramen
4. FOSSA PIRIFORMIS
   - houses the piriform lobe of the brain
   - lateral From the sulcus n. Maxillaris
   - “paired”
5. FORAMEN LACERUM
   - in EQ, the caudal border of each wing demarcates the rostral margin
   - There are 3 notches in the border:

A. Incisura CAROTICA
- medial 
- doubled
B. Incisura OVALIS
- lateral 

C. Incisura SPINOSA

ABSENT in car + ru = replaced by 3 foramina

A. Foramen OVALE

• in the wing of the basisphenoid
• in car & bo

B. Foramen CaROTICUM

• formed by the TYMPANIC part of the temporal bone
• in car

C. Foramen SPINOSUM
- in car

Question 6

OS SPHENOIDALE

Processus Pterygoideus

Answer 6

PROCESSUS PTERYGOIDEUS

• arises laterally from the rostral end of the basisphenoid
• projects downwards, forwards
• unites with the perpendicular plate of the palatine bone
• Make up margin of Choanae

HAMULUS PTERYGOIDEUS
- hook - like process at the rostroventral end of the pterygoid process

1. CANALIS ALARIS
   - in ca, eq
   - on its root
   In CA:
   - exit = FORAMEN ALARE rostrale (orale)
   - entrance = FORAMEN ALARE Caudale (aboral)

In EQ:
- exit = FORAMEN ALARE ROSTRALE
- entrance = FORAMEN ALARE caudale
+ FORAMEN ALARE PARVUM

2. CRISTA PTERYGOIDEA
   - absent in ca
   - crest continuing the proc. Pterygoideus dors
   - border of the FOSSA PTERYGOPALATINA
3. CANALIS PTERYGOIDEUS
   - longitudinal canal
   - through the base of the proc. Pterygoideus
4. SULCUS NERVI CANALIS PTERYGOIDEUS
   - caudal continuation of the Canalis Pterygoideus

Question 7

INTERSPECIAL DIFF

Os basisphenoidale

Answer 7

CORPUS:
1. DORSUM SELLAE: Ø in EQ

2. SULCUS CAROTICUS
   In EQ and CA
   Ø in BO and SUS

ALA:

1. Foramen Rotundum
   In EQ and CA
   - ORBITOROTUNDUM in BO and SUS
2. Foramen LACERUM
   In EQ and SUS
   Ø in ca and bo

A. INCISURA CAROTICA
Eq: doubled
Ca: foramen
SUS: has it 
Ø in bo

B. INCISURA OVALIS
In Eq and SUS
FORAMEN in Bo and ca

C. Incisura SPINOSA
In Eq and SUS
In bo: foramen, fused ovale
In ca: FORAMEN

3. SULCUS N. OPTHALMICI
   In Eq and Ca
   In BO and SUS:
   Sulcus nn Opthalmici et maxillaris
4. SULCUS N. MAXILLARIS
   In EQ and Ca
   In BO and SUS:
   Sulcus nn Opthalmici et maxillaris

Question 8

INTERSPECIAL differences

ALA Ossis basisphenoidale

Answer 8

OPENINGS 
1. Foramen ROTUNDUM
= passage for N.Maxillaris (v2)
In Car, Eq
Ru: For. ORBITOROTUNDUM 

2. Foramen OVALE
   = passage for N.Mandibularis (V3)
   In car, ru
   In eq, su= inc OVALIS
3. Foramen SPINOSUM
   = passage for a.meningea media
   In car
   In EQ, Su: INC. CAROTICA