The Axial Skeletal System

Skeletal System 206 Bones in body

Table 07.01

The Axial Skeleton Forms the longitudinal axis of the body Divided into three parts Skull Vertebral column Bony thorax

The Axial Skeleton Figure 5.6a

The Axial Skeleton Figure 5.6b

The Skull Two sets of bones Cranium Facial bones Bones are joined by sutures

Cranial Bones Frontal Bone- makes up forehead Supraorbital Forament- holes above eyes Occipital Bone- back of head Occipital chondyles- connect head to cervical vertebrae Foramen Magnum- hole for brain stem Parietal Bones Bones on each side of the head

Human Skull, Anterior View Figure 5.11

Human Skull, Inferior View Figure 5.9

Human Skull, Lateral View Figure 5.7

Cranial Bones Temporal Bone Skull bone by ears Mastoid process- bump below ear Mastoiditis- inflammation of air spaces of mastoid process External Auditory (or Acoustic) Meatus- ear Zygomatic Process- connects cheek bone to temporal bone Styloid Process- projection inferior to external auditory meatus Carotid Canal- where carotid artery runs

Human Skull, Lateral View Figure 5.7

Cranial Bones Sphenoid Bone Bat or butterfly Acts as a brace for the skull Greater Wing Lesser Wing Sella turcica- where pituitary gland sits Foramen Ovale- hole for cranial nerve 5 to pass to chewing muscle of the lower jaw Optical Canal- allows optic nerve to pass to eye

Sphenoid Bone Superior Orbital Fissure- cranial nerve controlling eye movements to pass through

Sphenoid Bone

Human Skull, Superior View Figure 5.8

Human Skull, Inferior View Figure 5.9

Cranial Bones Ethmoid Bone- makes up eye and nose Cristi gali- hook of ethmoid that holds the menenges in place Cribiform plate- separates nasal and oral cavity Holes for nerves to reach the brain Makes up part of superior and middle conchae (nasal walls) Perpendicular plate Divides nose into right and left Deviated septum

Human Skull, Anterior View Figure 5.11

Human Skull, Lateral View Figure 5.7

Facial Bones Only mandible and vomer are single bones Lacrimal bone- just inside eye Has tear ducts Mandible-jaw Largest and strongest bone in face Only moveable joint in face Alveolar Processes-hold teeth in Chondyloid or Chondyler process- posterior part of jaw that connects to temporal bone

Facial Bones Mandible Coronoid Process- anterior part of jaw that connects to temporal bone Mental foramen- for nerves that carry info from lips and chin Mandibular Foramen- nerves for lower teeth

Facial Bones Maxillary or Maxilla Fuse to form upper jaw Alveolar processes- bones for teeth Infraorbital foramen- holes below eyes Palatine process- forms the anterior portion of the hard palate Nasal Bones- forms bridge of nose Palatine bones- make up the palate Vomer- makes up bottom part of septum

Facial Bones Zygomatic Bones- cheek bones Hyoid Bone- Only bone that doesn’t articulate with another bone Serves as a base for the tongue

The Hyoid Bone Figure 5.12

Sutures Immoveable joints between skull bones Saggital suture- connects two parietals Coronal- connects frontal and two parietals Lambdoidal- connects parietals to occipital Squamous- connects temporal to parietal

Sutures

Paranasal Sinuses Hollow portions of bones surrounding the nasal cavity Functions of paranasal sinuses Lighten the skull Give resonance and amplification to voice Four bones with sinuses Frontal Maxillary Sphenoid Ethmoid

Paranasal Sinuses Figure 5.10a

Paranasal Sinuses Figure 5.10b

The Fetal Skull The fetal skull is large compared to the infant’s total body length Fontanels—fibrous membranes connecting the cranial bones Allow the brain to grow Convert to bone within 24 months after birth

The Fetal Skull Figure 5.13a

The Fetal Skull Figure 5.13b