Fish Skull

plus anatomical directions

Lateral

Medial

proximal

Anterior/rostral

dorsal

posterior/caudal

distal

ventral

Chondrocranium

bone derived from embryonic cartilage

Dermatocranium

bone that evolved from scales and dermal armor

Branchiocranium

• includes jaws and respiratory apparatus

• contains cartilage and dermal derived bones

Ethmoid

ethmoid region

antermost skull bone

Vomer

ethmoid region

can be dentigerous (toothbearing)

Frontals

orbital region

paired, largest bone on the skull

Circumorbitals

orbital region

large bones surrounding the eye in early diverging bony fishes

Sclerotic

orbital region

these bones/cartilages are found in fishes and non-fish vertebrates

Epiotics

otic region

one of the attachment sites for the posttemporal bone, creates the head joint

Intercalars

otic region

the other attachment site for the posttemporal bone, creates the head joint

-iotics

enclose semicircular canals

Exoccipital

basicranial region

surrounds foramen magnum

Basioccipital

basicranial region

connects to first vertebra

Supraoccipital

basicranial region

often has medial crest

Parasphenoid

basicranial region

bar-shaped, occurs between eyes

Premaxilla (pmx)

branchiocranium: mandibular arch

tooth-bearing, L-shaped in species with upper jaw protrusion

Maxillae (mx)

branchiocranium: mandibular arch

moves independently of premaxilla in most modern fishes

Dentary (d)

branchiocranium: mandibular arch

tooth-bearing

Angular-articular (ang-ar)

branchiocranium: mandibular arch

inserts into the back of the dentary, rotates around the quadrate at lower jaw base

Retroarticular (rar)

branchiocranium: mandibular arch

at the posterior corner of the lower jaw, fused with articular in many bony fishes

Hyomandibula (h)

spensorium

connects to skull

Quadrate (q)

spensorium

fan-shaped bone, connects to lower jaw

Palatines (pal)

palatine arch

sometimes tooth bearing, inserts onto dorsal head of maxilla

Opercle (op)

opercular apparatus

largest opercule element

Subopercle (sop)

opercular apparatus

most posterior element

Preopercle (pop)

opercular apparatus

anterior, lies on top of other elements

Interopercle (iop)

opercular apparatus

most ventral element

Hyoid Complex

sits medial to jaws and operculum

Branchiostegal rays

hyoid complex

riblike in appearance and function in respiration

Hyoid Depression

Involved in feeding, expands to create a vacuum

Branchial Complex

involved in respiration and feeding, contains gill arched and rakers