Anatomy

Review Notes on Anatomy

ANTERIOR VIEW OF THE SKULL, MANDABLE AND HYOID

1. Bones of Skull

A.          FRONTAL: 

Frontal eminence, superciliary arch with supraorbital notch of foramen, glabella, and zygomatic process, nasal part

B.          NASAL

C.          NASAL SEPTUM

D.          MAXILLA

Facial surface, incisive and canine fossae, infraorbital foramen , anterior nasal spine, nasal notch, alveolar process

E.          ZYGOMATIC

Frontal process, temporal process

2. Sutures of Skull

A.     FRONTON

Frontal and two nasal bones, nasion is the midpoint of the suture

B.          ZYGOMATICOMAXILLARY

Zygomatic and maxillary bones

F.           Frontozygomatic

Zygomatic  and frontal bones

G.          INTERMAXILLARY

Between maxillary bones

3. HYOID

(MAKE UP OF 5 PARTS BODY,2 GREATER AND 2 LESS CORNUA)

A.     BODY: 

Quadrangular , convex ventrally

B.     GREATER CORNUA

Long ,  projecting backward from body;  joined in a synostosis

C.     LESSER CORUA

Short and conical processes projecting upward and backward from body; base attached at line of union of body and greater cornu by fibrous tissue (syndesmosis).

4.    MANIBLE     

H.          BODY – (Convex anteriorly)

1.           Externally: mental protuberance with mental tubercles on either side ; mental  foramen ; oblique line ; groove for facial artery

2.           Internally : mental spine ; mylohyoid line ; alveolar border ; submandibular and sublingual fossae

I.            RAMI

Which form  angles with the body

1)   Condyloid process ,  with rounded head for articulation

2)   Constricted neck

3)   Coronoid process : thin separated from condyloid process  by a wide mandibular notch and pointed at superior end

4)   On inner (medial) surface :  mandibular foramen, the lingula and the mylohyoid groove

II.       CLINICAL CONSIDERATIONS

Fractures take many forms and occur in many places

Open type : bone fragments break the mucous membrane in the mouth

Closed type : vertical breaks between ramus and body of mandible. The ramus fragment is pulled upward by the temporalis  and masseter muscles and medially by the medial Pterygoid muscle ; the body fragment is pulled downward by gravity and the geniohyoid muscle  and backward by the digastric  and mylohyoid muscles.

LATERAL VIEW OF THE SKULL

I.    BONES

A. Parietal: part of roof and sides of cranium. Note superior and inferior temporal lines, and the parietal foramen (inconstant)

B. Frontal (squamous part ): anterior and anterolateral part of cranium. Note superciliary arch ,the  glabella (uniting the arches over the nose ), zygomatic process, and  temporal line.

C. Lacrimal , antermedial wall of orbit : lacrimal sulcus and crest

D. Great wing of sphenoid and lateral pterygoid plate

E. TEMPORAL

1.      Squama, flat, forming part of side of cranium : note zygomatic process, articular tubercle , mandibular  fossa , and suprameatal crest

2.         Mastoid , large potion behind ear: mastoid process and foramen

3.       Tympanic,  surrounding external meatus

4.         Styloid  process with its vaginal sheath

F:       ZYGOMATIC: cheek bone : zygomaticofacial foramen

G.       MAXILLA: anterior nasal spine and alveolar border

H.       OCCIPITAL: squamous portion: external protuberance and superior nuchal line 

II.     SUTURES OF SKULL

A.   CORONAL: frontal and parietal bones

B.   SPHENOFRONTAL: great wing of sphenoid  and frontal bones

C.   SPHENOPARIETAL: great wing of sphenoid and parietal bones (pterion is the end  of the suture )

D.   SQUAMOSAL: Squama of temporal and parietal bones

E.   PARIETOMASTOID :  parietal and mastoid of temporal bone

F.    LAMBOIDAL: parietal and occipital bones

G.   OCCIPITOMASTOID:  occipital and mastoid of temporal bone: asterion is the point at which the lambdoidal and  occipitomastoid sutures meet

H.   SPHENOSQUAMOSAL: great wing of sphenoid and squamous temporal bones

I.     TEMPOROZYGOMATIC: process of zygomatic and temporal bones

J.    FRONTOZYGOMATIC: zygomatic and frontal bones

III.   SPECIAL FEATURES

1.   TEMPORAL FOSSA . Bounded above and behind by temporal lines, in front by frontal and zygomatic bones, laterally by zygomatic arch, below by infratemporal crest.

2.   INFRATEMPORAL FOSSA. Bounded in front by maxilla, behind by articular tubercle    of infratemporal crest and alveolar  border of maxilla,medially by lateral pterygoid plate.

3.   PTERYGOPALATINE FOSSA.  Bounded above by body of sphenoid, in front by maxilla , behind by pterygoid process and great wing of sphenoid , and medially by palatine bone. Five foramina open into fossa: rotundum , pterygoid canal , pharyngel canal sphenopalatine, and pterygopalatine canal.

SKULL FROM BEHIND

1. BONES

A. FRONTAL: usually smooth and convex in adult. In infancy, 2 frontal bones  are joined as frontal (metopic) suture. Lower end of this suture, above nose, sometimes seen in adults.

B. PARIETAL: forms most of superior and lateral cranium; shows parietal foramen and tuberosity

C. OCCIPITAL: forming dorsal part of cranium, shows external Occipital crest running caudally and the supreme and superior nuchal lines arching laterally from it; the planum occipitale lies above highest line ; the  inferior nuchal lines run laterally from midpoint of the median crest ; and planum nuchale is that part of bone below superior nuchal lines.