Lab 1-Cranial Anatomy-Bio168 CSUS

1. Detailed anatomy of the mammalian skull

Use accompanying diagrams and series of opossum, cat, coyote and rat skulls to learn labeled structures. Concentrate on the major bones of the skull, not the details. By the end to today, you should be able to identify any of the major bones visible on the outside of the skull.

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Skull and mandible of the common opossum (Marsupialia: Didelphidae; Didelphis)

lateral view (A), lateral view of cranium with zygomatic arch cut away (B), ventral view (C), medial view of right side of skull (D)

Taken from Jollie, M. 1962. Chordate Morphology

1. Detailed anatomy of the mammalian skull (continued)

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skull of domestic cat (Carnivora: Felidae; Felis sylvestris)

lateral view (A), lateral view with zygomatic arch cut away (B), medial view of right side of skull (C), ventral view (D)

from Jollie, M. 1962. Chordate Morphology.

1. Detailed anatomy of the mammalian skull (continued)

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Skull of coyote (Carnivora: Canidae; Canis latrans)

Terminology al – alisphenoid an – angle of mandible bo – basioccipital bsp – basisphenoid c – canine cl – condyle of mandible cp – coronoid process eam – external auditory meatus eo – exoccipital fm – foramen magnum fo – foramen ovale i1 – first upper/lower incisor i2 – second upper/lower incisor i3 – third upper/lower incisor inc – incisive foramen inf – infraorbital foramen ip – interparietal j – jugal l – lacrimal mp – mastoid process mx – maxillary m1 – first upper/lower molar m2 – second upper/lower molar m3 – third lower molar n – nasal oc – occipital condyle or – orbit pa – parietal pl – palatine pm1 – first upper/lower premolar pm2 – second upper/lower premolar pm3 – third upper/lower premolar pm4 – fourth upper/lower premolar pmx – premaxillary pop – postorbital process pt – pterytgoid r – rostrum of skull sg – sagittal crest so – supraoccipital sq – squamosal tb – tympanic bulla v – vomer zma – zygomatic arch

From Grinnell and Linsdale. Fur-bearing mammals of California.

1. Detailed anatomy of the mammalian skull (continued)

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Skull of the murid rodent Rheomys thomasi (Rodentia: Muridae; Sigmodontinae)

dorsal (upper left), ventral (upper right), and lateral views (below)

terminology: aaf = anterior alar fissure; als = alisphenoid; bmf = buccinator-masticatory foramen; boc = basioccipital; bsp = basisphenoid; cc = carotic canal; eam = external auditory meatus; ect = ectotympanic part of auditory bulla; ef = ethmoid foramen; exo = exoccipital; foa = foramen ovale accessories; fm = foramen magnum; fr = frontal; glf = glenoid fossa; gp = gnathic process; hyp = hypoglossal foramen; if = incisive foramen; ip = interparietal; izr = inferior zygomatic root; jug = jugal; lr = lambdoidal ridge; mal = malleus max = maxillary; mpf = mesopterygoid fossa; mrz = macillary root of zygomatic arch; mt = masseteric tubercle; nas = nasal; nlf = nasolacrimal foramen; occ = occipital condyle; of = optic foramen; pal = palatines; par = parietal; per = periotic capsule of mastoid; pet = petrosal part of auditory bulla; pgf = postglenoid foramen; ppf = parapterygoid fossa; pre = premacillary; sf = stapedial foramen; soc = supraoccipital; sof = supraorbital foramina; spv = sphenopalatine vacuities; sqm = squamosal; srz = squamosal root of zygomatic arch; sty = stylomastoid foramen; tc = transverse canal.

Drawings by Karen Klitz. From Voss, R.S. 1988. Bull. AMNH 188.

Foramina of the skull

Name	Bone(s) penetrated	Traversing structures
Infraorbital	Maxilla, ventromedial to orbit	Trigeminal and infraorbital nerves and blood vessels
Lacrimal	Lacrimal	Tear duct from orbit to pharynx
Mental	Lateral body of mandible (usually 2)	Mental nerves and blood vessels
Mandibular	Medial surface of mandible	Inferior alveolar nerve and vessels
Optic	Center of orbitosphenoid	Optic nerve (cranial nerve II)
Orbital fissure	Orbitosphenoid-alisphenoid junction	Oculomotor (III), trochlear (IV), abducens (VI), ophthalmic branch of trigeminal (V1)
Incisive	Premaxilla-maxilla, between canines	Palatine vessels, trigeminal and nasopalatine nerves
Palatine	Maxilla-palatine junction	Palatine vessels and trigeminal nerve
Sphenopalatine	Palatine, vertical wing	Sphenopalatine nerves and vessels
Rotundum	Alisphenoid	Maxillary branch of trigeminal (V2)
Ovale	Alisphenoid	Mandibular branch of trigeminal (V3)
Hypoglossal	Occipital, lateral to end of condyle	Hypoglossal nerve
Stylomastoid	between mastoid and styloid processes	Facial nerve
Magnum	Occipital, center	Spinal cord
Eustacian tube	Tympanic bulla	From middle ear
Olfactory	Ethmoid, cribiform plate	Olfactory nerves

2. Compare the skulls from the four mammalian taxa above to those of a kangaroo, elk, anteater, and porpoise. Look for:

a. changes in the shape and position of specific elements

b. changes in general cranial proportions

c. think about what these changes might mean functionally

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Skull of a bottle-nosed dolphin, Tursiops (Cetacea: Delphinidae)

ventral view

lateral view