Human Anatomy Bio 11

Axial Skeleton “chapter 7” Axial Skeleton = skull + vertebrae + ribs Skeleton = bones & associated structures

Typically, there are 206 named bones in the adult skeleton. These bones are divided into one of two categories: Axial skeleton – skull, vertebral column and thoracic cage (80 named bones) Appendicular skeleton – shoulder and hip girdles and bones of the upper and lower extremities (126 named bones) bones of the skull cranium + facial bones coronal section

Note color coding is consistent within a text frontal view Note sutures Sutures • Immovable joints between skull bones • There are four major sutures: 1. Coronal – between frontal and parietal bones 2. Lambdoid – between parietal and occipital bones (inverted v-shape like the Greek letter lambda) 3. Sagittal – shared by the two parietal bones and runs along the mid-sagittal plane from the frontal bone to the occipital bone 4. Squamous – between the temporal and parietal bones • There are many other sutures Selected Bone Landmark & Structure Terms

• process(es) • foramen / foramina • spine(s) • fossa(e) • condyle(s) • fissure(s) • epicondyle(s) • groove(s) • plate(s) • cavity/cavities • protuberance(s) • tuberosity(--ies) • canal(s) • line(s) • sinus(es) • facet(s) • arch(es) lateral view sagittal section inferior view floor of the cranial cavity 8 cranial bones

• Frontal (1) • Parietal (2) • Temporal (2) • Occipital (1) • Sphenoid (1) • Ethmoid (1) frontal bone parietal bone temporal bone occipital bone sphenoid sphenoid sphenoid “the keystone” ethmoid The cranium – the “braincase” 3 cranial fossae

A fossa is a depression [found in or among bones] 1. Anterior cranial fossa 2. Middle cranial fossa 3. Posterior cranial fossa 14 facial bones

• Zygomatic (2) • Lacrimal (2) • Nasal (2) • Inferior nasal conchae (2) • Palatine bones (2) • Maxillae (2) • Vomer (1) • Mandible (1) zygomatic bone vomer: plowshare (plow blade) palatine bone maxilla(e) cleft palate with cleft lip

• The left and right palatine plates of the maxillae fail to fuse • Sometimes the palatine bones are also involved (particularly severe) • cleft lip is when only the soft tissue fails to fuse mandibile nasal concha(e)

and nasal complex “nasal complex”

Consists of bones and cartilage that enclose and define the boundaries of the nasal cavities and the sinuses surrounding the nasal cavities paranasal sinuses paranasal sinuses

• Hollow, air-filled chambers within skull bones surrounding the nasal cavity • Have a mucous lining that helps to humidify and warm inhaled air • There are four major sinuses: – frontal sinus – ethmoid sinus – sphenoid sinus – maxillary sinus orbital complex Other Bones of the Skull: auditory ossicles Auditory ossicles are tiny bones within the temporal bone and are associated with hearing (see Chapter 19). There are three within each temporal bone: 1. Malleus 2. Incus 3. Stapes hyoid bone fontanelle – fontanel vertebral column not “spinal column” not “spine” vertebral column •not “spinal column” •not “spine” Regions of the Vertebral Column

• Cervical vertebrae – 7 (C1 – C7)

• Thoracic vertebrae – 12 (T1 – T12)

• Lumbar vertebrae – 5 (L1 – L5) • Sacrum – 1 (a fusion of 5 vertebrae) • Coccyx – 1 (a fusion of 4 vertebrae) • TOTAL – 26 vertebrae Four curvatures in the adult vertebral column

1. cervical curvature -- anterior curve 2. thoracic curvature – posterior curve 3. lumbar curvature – anterior curve 4. sacral curvature – posterior curve Vertebral Curvatures

A vertebra and its parts A vertebra and its neighbors - and how they interact atlas & axis

Two Special Vertebrae sacrum sternum: manubrium body xiphoid process Common Vertebral Column Distortions: kyphosis – lordosis - scoliosis “rib cage” ribs:

• True (#1-7) False (#8-12) Floating (#11-12) Ribs

Each rib has the following major structures: 1. Head – with superior and inferior articular facets 2. Tubercle 3. Angle 4. Shaft 5. Costal groove Development of the Skeletal System Development of the Rib Cage Development: Vertebrae from Somites and the Notochord