Chapter 6

Thoracic cage

Made of sternum, 12 pairs of ribs and 12 thoracic vertebrae

cranial cavity

The cranial cavity is a fluid-filled chamber that supports and protects the brain.

•Major features of the infant skull

4 major fontanel areas •Membranous areas where sutures will eventually form •Anterior fontanel (baby's "soft spot") •Posterior fontanel •Sphenoidal fontanels •Mastoid fontanels

kyphosis

Exaggerated posterior curvature of the thoracic region

Paranasal sinuses

are the interconnected hollow spaces inside the frontal, ethmoid, sphenoid, and maxillary bones. §These spaces reduce the weight of the skull, produce mucus, and allow air to resonate for voice production. §These paranasal sinuses are called the frontal sinus, maxillary sinus, sphenoidal sinus, and the ethmoidal air cells.

12 pairs of ribs

§1-7 are true ribs: attach to the sternum by separate cartilaginous extensions. §8-10 are false ribs: attach to the sternum by one shared cartilaginous extension. §11-12 are floating ribs: not attached to the sternum.

Thoracic Vertebrae

§12 total thoracic vertebrae make up the posterior of the rib cage. §The bodies of the thoracic vertebrae have a heart shape. §The spinous process is long and slender and points on a posterocaudal angle. §The transverse processes point dorsolateral. §The thoracic vertebrae articulate with ribs and therefore contain extra facets.

Lumbar Vertebrae

§5 total lumbar vertebrae are the largest vertebrae, and they make up the lower back region. §The body of lumbar vertebrae is very thick and oval shaped. §The relatively small vertebral foramen is triangular. §The transverse processes point more laterally than the thoracic vertebrae. §The spinous process resembles a tail fin of a fish, stumpy and flattened.

Function of thoracic cage

§Function: §It protects the heart, lungs, thymus, and other structures within the cavity. §It serves as the attachment site for muscles involved in §Respiration §Positioning the vertebral column §Movements of the pectoral girdle and upper limb

Sternum is made of

§Manubrium §Body §Xiphoid process

cranial cavity is made of

§Occipital: foramen magnum, hypoglossal canal, occipital condyle. §Parietal (2): coronal, lambdoid and sagittal surures. §Frontal: supraorbital foramen, supraorbital arch, glabella, frontal sinus. §Temporal (2): squamous portion, petrose portion, mastoid process, styloid process, external acoustic meatus. §Sphenoid: sella turcica, clinoid process, optic groove, dorsum sellae, pterigoid process. §Ethmoid: perforating panel, crista galli, perpendicular plate, ethmoid sinuses, superior portion of nasal septum.

Primary curves

§Primary curves/accommodation curves are the posteriorly sweeping curves of the thoracic and sacral regions. §These curves develop before birth to allow the abdominopelvic viscera more room

§Secondary curves

§Secondary curves/compensation curves develop in the infant and toddler as anteriorly sweeping curves of the cervical and lumbar regions. §These curves develop as the infant learns to hold up his or her head (cervical) and begins to walk (lumbar)

the axis (C2)

§The Axis (C2) §The body of the atlas fuses with the body of the axis during development to form the dens (odontoid process). §Because of the dens, there is no intervertebral disc. §The articulation between the atlas and axis allows one to shake his or her head "no."

atlas C1

§The atlas has no body and articulates cranially with the occipital condyles. §The articulations with the occipital condyles allow one to shake his or her head "yes." §The atlas has two arches—the anterior and posterior vertebral arches.

§Vertebra Prominens (C7)

§The last cervical vertebrae, and therefore resembles the thoracic vertebra in structure §This vertebra has a long, slender spinous process, and enlarged transverse processes that may or may not contain a transverse foramen. §An elastic ligament called the ligamentum nuchae extends from the spinous process cranially to the occipital crest.

•Associated bones

•Auditory ossicles - 6 •Hyoid bone - 1

• The axial skeleton

•Composed of bones along the central axis of the body •Divided into three regions: •Skull •Vertebral column •Thoracic cage

•Functional anatomy of the vertebral column

•Encloses and protects the spinal cord •Supports the skull •Supports the weight of the head, neck, and trunk •Transfers weight to the lower limbs •Helps maintain the upright position of the body

lordosis

•Exaggerated anterior curvature of the lumbar region

Functional anatomy of the axial skeleton

•Framework that supports and protects organs in the dorsal and ventral body cavities •Protects special sense organs for taste, smell, hearing, balance, and vision •Attachment sites for muscles that: •Adjust the posture of the head, neck, and trunk •Move the thoracic cage for respiration •Stabilize the appendicular skeleton •The connection between axial and appendicular skeleton in the upper body is sternum-clavicle.

scoliosis

•Scoliosis •Abnormal lateral curvature

•The adult vertebral column is made up of how many bones

•The adult vertebral column is made up of 26 bones: •24 vertebrae •7 cervical vertebrae •12 thoracic vertebrae •5 lumbar vertebrae •1 sacrum (5 fused vertebrae) •1 coccyx (3 to 5 fused vertebrae)