Ch 8 Axial Skeleton Notes PDF

Preview

Summary

Download Ch 8 Axial Skeleton Notes PDF

Description

Chapter 8 Class Notes and Study Guide - Bone Terminology and Axial Skeleton Bone Terminology Holes/Spaces 1. Foramen (plural is foramina) - round hole all the way through a bone 2. Canal - tunnel-shaped passageway 3. Sinus - cavity/hollow space 4. Fissure - narrow, slit-like opening Articular Surfaces (areas of attachment with muscles/ligaments; forms joints) 1. Condyle - ‘knuckle’; large & smooth rounded area 2. Head - prominent rounded epiphysis of long bone 3. Facet - small, flat, shallow surface Depressions/dents in bone (muscles or tendons sit in rounded out depressions of bones) 1. Fossa - shallow ‘scooped out’ area of bone 2. Sulcus - narrow groove Sites of attachment 1. Process - ANY marked bony prominence 2. Epicondyle - projection adjacent to/on either side of condyle 3. Spine - slender, long, pointed area 4. Ramus - branched/angular extension of bone 5. Tubercle - small round projection 6. Tuberosity - large roughened projection 7. Line - raised, thin, long ridge across bone

Axial Skeleton •

Skull, vertebral column, sacrum, coccyx, ribs, and sternum

•

Contains most red marrow in adults

Skull - 22 bones Bones are knitted together by sutures (joints of the skull; dense regular connective tissue ‘sews’ bones of skull together) Cranial Bones - 8 bones Paired cranial bones - parietal, temporal Unpaired cranial bones - sphenoid, ethmoid, frontal, occipital Facial Bones - 14 bones Paired facial bones - zygomatic, nasal, lacrimal, palatine, maxilla, inferior nasal concha Unpaired facial bones - mandible, vomer Frontal Bone(s) - Supraorbital notch/foramen (passageway for arteries & nerves), superciliary arches (point of attachment of muscles that elevate the eyebrows) Parietal Bone(s) - Superior middle and posterior portions of the skull; knitted to the other skull bones via the main sutures Coronal suture links parietal to frontal Sagittal suture links parietal to parietal Lambdoid suture links parietal to occipital Squamous suture links parietal to temporal Temporal Bone(s) - Holds the organs of hearing & maintain balance in the middle and inner ear • The external acoustic/auditory meatus enables sound waves to travel through the bone into the structures that process sound • Major muscles that flex the head (move it forward) attach to the mastoid process and styloid process • The mandible joins the temporal bone at the mandibular fossa and forms temporomandibular joint/TMJ (enables mouth/jaw movement)

• The zygomatic process joins the temporal process of the zygomatic bone and forms the zygomatic arch (cheekbones) Sphenoid Bone - plays a critical role holding the skull together from the inside • Greater wings form the posterior of the orbit and part of the lateral surface of the skull ⚬ Contains superior orbital fissure and the optic foramen/canal for optic and cranial nerves • Lesser wings are smaller and superior to the greater wings • Sella turcica holds the pituitary gland in a central brain location

Ethmoid Bone - rectangular structure that forms part of the medial orbit and the superior part of the nasal cavity • Cribriform plate is a perforated structure on either side of the crista galli (ridged structure where the dura mater that covers the brain attaches) • Holds the olfactory bulbs; projections of the olfactory nerves go through perforations, allow sense of smell • Perpendicular plate forms the superior part of the nasal septum (along with the vomer); the superior and middle nasal conchae help form the nasal cavity

Occipital Bone - forms the posterior and inferior portions of the skull • Vertebral column attaches here where the atlas (C1) joins to the occipital condyles • Spinal cord goes through the foramen magnum • Hypoglossal canal is the passageway for cranial nerves that innervate the face and structures in the mouth • Atlanto-occipital joint between the skull and vertebral column enables head movement

Cranial Fossae are in the interior skull. They are hollow areas where the brain structures sit in the skull. Anterior Cranial Fossa contains the frontal lobes Middle Cranial Fossa contains the temporal lobes and pituitary gland Posterior Cranial Fossa contains the brainstem and cerebellum Cavities of the skull: Cranial cavity - formed by the cranial bones; contains and protects the brain Oral cavity - the mouth • Formed by the palatine bone and the palatine process of the maxilla • Hard palate - forms the superior portion of the oral cavity (roof of the mouth) and inferior portion of the nasal cavity Nasal cavity - lined with nasal mucosa • Nasal complex - all superior, middle nasal conchae, perpendicular plate of ethmoid, inferior nasal conchae, vomer, cribriform plate, sphenoid bone, maxilla, lacrimal bone Orbit - eye sockets; protects the eyes and associated structures • Orbital complex (bones that form each orbit) - frontal bone, zygomatic bone, greater wing of sphenoid bone, maxilla, lacrimal bone, ethmoid bone Paranasal Sinuses - Air pockets inside bones that makes voice louder, increase surface area for the

mucous membrane, & reduce weight of the skull Bones with sinuses: 1. Frontal 2. Maxillary 3. Sphenoid 4. Ethmoid Mandible - strongest and largest bone of the skull; only movable skull bone

• •

Forms the temporomandibular joint where the temporal bone articulates with the mandibular fossa Comprised of a body, ramus, and angle

Hyoid Bone - only bone in the body that does not articulate with another bone • Serves as a site of attachment for the muscles in the neck that lower the jaw and moves the tongue

Vertebral Column •

Made of 24 vertebrae, plus 5 fused vertebrae that form the sacrum and 4 fused vertebrae that form the coccyx (26 bones total)

•

4 curvatures - one at each level of vertebrae (cervical, thoracic, lumbar, sacral) o Thoracic and sacral curves present at birth o Cervical and lumbar curves develop as the body begins to move vertically rather than horizontally; cervical from holding head up, lumbar from walking

Abnormal curvatures: •

Kyphosis - exaggerated thoracic curvature and is often associated with osteoporosis as the bodies of vertebrae collapse on each other

•

Lordosis - exaggerated lumbar curvature and is often associated with android (apple shaped) obesity or pregnancy

•

Scoliosis - lateral curvature anywhere in the column (often thoracic)

Distinguish among the 3 levels of vertebrae, including their major “parts”: vertebral arch, vertebral foramen, lamina, pedicle, spinous process, body, transverse process.

Vertebral Anatomy

Vertebra location

Body

Cervical

Smaller than others Heart shaped Bifid spinous process Transverse processes have Kidney bean shaped - forked at the end holes in them (foramen for blood vessels)

Thoracic Heart shaped

Lumbar

Vertebral Foramen

Oval shaped

Thick & oval shaped Triangular

Vertebral Joints There are two joints between each adjacent vertebrae:

Special Vertebrae:

Spinous Process

Long, pointy, points downward (when looked at from side)

Other Unique Feature

Body and transverse processes have facets for rib attachments

Short, thick, & dense Transverse processes don’t extend far (similar to spinous process)

•

C7 - Vertebra Prominens - transition vertebra between cervical and thoracic ○ Has a long, sometimes bifid spinous process; can be easily palpated between the scapulae at the base of the neck • C1 - Atlas - no body, no spinous process; most superior vertebra ○ Articulates with the condyles of the occipital bone; attaches head to the body ○ Lack of body allows it to rotate on the dens of theaxis • C2 - Axis - has a dens (aka odontoid process) ○ Forms a pivot joint with the Atlas; allows head rotation (acts as an axis for the head to rotate around) Sacrum and coccyx in adults are made of fused vertebrae that form one bone. In the elderly these two bones may fuse. Bone

# of Special note Vertebrae 5 Site of pelvic girdle connection to the axial Sacrum skeleton 4 Points more posteriorly in females to open birth Coccyx canal.

Typical Age of Fusion ~20 Begins in mid-20s

Ribs • 12 pairs • Originate on thoracic vertebrae True ribs - ribs 1-7 • Connect individually to the sternum by costal cartilages False ribs - ribs 8-12 • Ribs 8-10 indirectly attached to sternum; costal cartilage is fused to costal cartilage of true ribs • Ribs 11-12 have no connection to sternum (floating ribs)

Thoracic Cage ● Consists of thoracic vertebrae, ribs, and sternum ● Attachment sites for many muscles allowing torso movement ● Protects the hearts and lungs...