Axial Division (CH. 6) Flashcards
Number of bones
206 in body
80 in axial
126 in appendicular
Axial skeletal system bone numbers
80 in total
- 29 in skull
- 25 in thoracic cage
- 26 in vertebral column
Functions of the axial skeleton
- support and protective framework
- supports and protects organs in body cavities - Houses and protects special sensory organs
- taste, smell, hearing, balance, vision - Provide extensive muscle attachments sites
- vertebral column and ribs (head/neck/trunk posture)
- thoracic cage (respiration movements)
- stabilizes the appendicular skeleton
Skull
divided into 2 major sections:
Cranial division (neurocranium)
- 8 bones
Facial division (viscerocranium)
- 14 bones
Orbital complex
7 Bones:
Zygomatic bone, Maxillary bone, Frontal bone, Lacrimal bone, Sphenoid, Ethmoid, Palatine bone (medial wall).
Optical canal, Superior orbital fissure
Superior orbital fissure
INNERVATED BY CN III, IV, VI
Optic canal
INNERVATED BY CN II: special sensory nerve
Artery: ophthalmic artery
Sphenoid
Floor of cranium
- connects all cranium bones
- Sella turcica
Sella turcica
Part of Sphenoid where pituitary gland sits
Temporal bones
Only articulation with the mandible (temporomandibular joint - TMJ)
Protects sensory organs in internal ears
Mandible
Lower jaw
- TMJ – head of mandible articulates with the mandibular fossa on temporal bone
- Coronoid prosses and Condylar process
Paranasal Sinuses
Air-filled chambers that open to the nasal cavity
- contained within the nasal complex
- Frontal sinus, Ethmoidal sinus, Sphenoindal sinus, Maxillary sinus
Cranial Fossae
Anterior cranial fossa
Middle cranial fossa
Posterior cranial fossa
Anterior cranial fossa
- frontal, ethmoid, sphenoid (lesser wings)
- cradles frontal lobe
Middle cranial fossa
Sphenoid, temporal, parietal bones
- cradles frontal lobe, diencephalon, mesencephalon
Posterior cranial fossa
Occipital bone, frontal, parietal bones
- occipital lobes, cerebellum, posterior brain stem
Infant skull features
- 4 major fontanelle areas:
- anterior fontanelle (baby’s soft spot)
- sphenoidal fontanelle
- mastoidal fontanelle
- posterior fontanelle
- membranous areas where sutures will form
- allow for distortions of the skull during childbirth
Sutures of the skull
Suture: dense fibrous connective tissue
Lambdoid, sagittal, coronal, squamous
Lambdoid suture
between occipital bone and 2 parietal bones
Sagittal suture
between 2 parietal bones
Coronal suture
Between frontal bone and 2 parietal bones
Squamous suture
Between temporal and parietal bone
Bones of the cranium
Occipital, frontal, parietal, temporal, sphenoid, ethmoid
Bones of the face
Maxillae, Palatine, Nasal, Lacrimal, Zygomatic, Mandible, Vomer
Maxillae
Largest bone in the face
- maxillary sinuses - largest sinuses
- articulates with all facial bones except mandible
Palatine bones
2 small bones making up part of the roof of the mouth
- posterior to the palatine process in the maxilla
- articulates with: maxillae, sphenoid, ethmoid, and inferior nasal concha
Nasal bones
articulate with the frontal bone
Zygomatic bones
Articulate the zygomatic process in the temporal bone – form zygomatic arch
- zygomaticofacial foramen
Lacrimal bones
Medial portion of the orbit of the eye
- lacrimal groove leads to the nasolacrimal canal
Vomer
Forms the inferior portion of the nasal septum
Vertebral Column Bones
26 bones:
24 vertebrae
- 7 cervical vertebrae
- 12 thoracic vertebrae
- 5 lumbar vertebrae
1 sacrum (5 fused vertebrae)
1 coccyx (3-5 fused vertebrae)
Vertebral Anatomy
- Vertebral body
- Pedicle
- Transverse Process
- Articular process
- Vertebral foramen
Vertebral Body
Anterior structure
Separated by adjacent vertebral bodies via intervertebral disc
Pedicle
Connect the vertebral arch to the body
Articular process
Joint surfaces:
Superior articular process
Inferior articular process
(2 on either side of the spinous process)
Vertebral foramen
- formed by the vertebral/neural arch
- spinal cord and meninges
Vertebral canal
Formed by adjacent vertebral foramen
Zygapophysial Joints
Adjacent vertebrae articulate at their superior and inferior articular processes
- allow flexion, extension, lateral flexion, and rotation
Intervertebral Joints
Intervertebral discs are pads of fibrous cartilage between adjacent vertebral bodies
- symphysis joints
- Anulus fibrosus - inner
- Nucleus pulposus - outer
Cervical Vertebrae
- support weight of the head, provide flexibility
- bifid except for C7
- c7 has a long spinous process (vertebral prominens
- Transverse foramina
- C1, C2, C7 are atypical
Atlas
C1
- articulates with occipital condyles of the skull
- allow yes nodding
- NO BODY
- largest vertebral foramen
Axis
C2
- has a dens
- transverse ligament connects dens to the atlas
- allow head to nod no
Antlanto-occipital Joint
1 of 2 atlas/axis joints
- synovial joint between occipital condyles and C1
- flexion of head
Atlanto-axial Joint
synovial joint between atlas and axis
- allow head to turn side to side
Thoracic vertebrae
12
- rib articulation points
- joint surfaces: costovertebral joints
- heart shaped body
- most spinous process point inferiorly
Lumbar vertebrae
5
- Large vertebral bodies and oval shaped
- support weight of torso
Sacrum
- 5 fused vertebrae
- protects reproductive, digestive, and excretory organs
- attaches pelvis girdle of the appendicular skeleton
Coccyx
3-5 fused vertebrae
- adult male = points anteriorly
- adult female = points inferiorly
Thoracic cage
2 functions:
- protects heart, lungs, thymus, and other structures
- attachment site for muscles involved in respiration, positioning the vertebral column, movements of the pectoral girdle
Composed of:
the ribs, costal cartilages, sternum
Sternum
Flat bone
Manubrium -> jugular notch
Body
Xiphoid process
Ribs
12 pairs
- vertebrosternal rib- ribs 1-7
- vertebrochondral ribs- Ribs 8-10
- Vertebral ribs - Ribs 11-12
- each rib articulates with a thoracic vertebra
Vertebrosternal ribs
1-7
- connects to the sternum via costal cartilages -> “true ribs”
Vertebral ribs
11-12
- floating ribs
- “false ribs’
- no anterior cartilage
