Frog Dissection: Skeletal and Muscular Systems

Frog Skeletal System Skull, Lower Jaw Part

Position

Cranium

Suture Olfactory capsule

(see above)

Function Encloses brain

Protect brain from trauma Houses scent organs

Otic capsule

Lodges inner ear

Orbit

Houses eyeball

Premaxillary processes

Adjoins maxillary arch

Foramen magnum (in occipital region)

Hole through which spinal cord passes

Occipital condyles

Articulate with first vertebra

Maxillary arch

Borders orbit, bears teeth

Vertebrae

Atlas

Part

Position

Function Articulates with occipital condyles; one cervical vertebra

Centrum

Body of vertebra

Neural arch

Inner lining of neural spine

Neural canal

Neural spine

Passageway through which spinal cord passes to and from brain and body Dorsal side of spine

Transverse processes

Extend laterally to support body

Zygapophyses

Articulate successive vertebrae

Sacral

Ninth vertebra

Urostyle

Tenth vertebra

Pectoral Girdle, Sternum, Forelimb

Suprascapula

Part

Function Flat trapezoid, cartilaginous

Scapula

Articulates with suprascapula

Glenoid fossa

Where upper arm bone fits; Smooth concavity on proximal end of scapula

Fenestra

Gap between clavicle, coracoid, and spatula

Clavicle

Anterior to fenestra; thin; Articulates with scapula

Coracoid

Posterior to fenestra; Articulates with scapula; Directly attached to epicoracoid cartilage

Epicoracoid cartilage

Joins left and right coracoids

Sternum

Position

(see above)

Lies on mid-ventral axis

Episternum

Flat, rounded

Omosternum

Inverted y-shaped bone; Two arms rest on clavicle

Mesosternum

Anterior end wedged between coracoids; articulates with xiphisternum at posterior end

Xiphisternum

Posterior to mesosternum

Humerus

Most proximal to body; Attaches to glenoid fossa

Radio-ulna

Comprises forearm region

Pelvic Girdle, Hindlimb Part Os innominatum

Position

Function Half of pelvic girdle

Acetabulum

Cup-shaped depression; Where femur fits

Ilium

Articulates with sacral; U-shaped; forms anterior border of acetabulum

Ischium

Fan-shaped; forms posterior border of acetabulum

Pubis

Triangle bone beneath ischium; Apex contributes to acetabulum

Femur

Most proximal bone in hindlimb; Attaches to acetabulum

Tibio-fibula/ shank

More distal to main body

Frog Muscular System Head Part

Position

Function Raises lower jaw (yellow)

(see green pin above)

Lowers lower jaw Raises floor of mouth

Temporalis

Depressor mandibulae Mylohyoid

Trunk Part Longissimus dorsi

Coccygeosacralis

Position

Function Elevates head; straightens back

Keeps coccyx region in line with ilium

Coccygeoiliacus

Keeps coccyx region in line with ilium

External oblique

Compresses abdomen

Rectus abdominis

Compresses abdomen

Linea alba

Connective tissue acting as septum; divides rectus abdominis into two symmetrical parts

Inscriptiones tendinae

Connective tissue acting as septum; run perpendicular

Forelimb Part Sterno-radialis

Position

Function Draws arm towards chest

Pectoralis

Draws arm towards chest

Latissimus dorsi

Draws arm away from body

Deltoid

Draws arm towards chest

Triceps brachi

Straightens forearm

Hindlimb Part Triceps extensor femoris

Position

Function Straightens shank; bends thigh

Semimebranosus

Draws thigh medially; bends shank

Biceps femoris

Draws thigh medially; bends shank

Sartorius

Bends the leg

Gracilis major

Draws thigh medially

Adductor magnus

Adducts leg and thigh; Draws thigh ventrally

Gastrocnemius

Bends shank; extends foot

Peroneus

Straightens shank; bends foot

Tibialis anticus

Bends foot

Tibialis posticus

Extends foot