C HAPTER 5: S PECIAL C HARACTERISTICS OF A XIAL S KELETON B ONES

Axial Skeleton  bones of the skull, vertebral column, and thorax Skull  formed of the cranial and facial bones (interlocked, non moving) Sutures  bind together the skull bones *not sealed off in babies and infants

B ONES OF THE C RANIUM 8 Total Bones protect the brain: Frontal Bone Pareital Bones (2) Temporal Bones (2) Occipital Bone Sphenoid Bone Ethmoid Bone

C RANIAL B ONES Frontal bone —forms the forehead, eyebrows and the superior eye orbit Pareital bones —forms the superior and lateral walls of the cranium Occipital bone —most posterior part of the cranium Foramen Magnum —hole where the brain attaches to the spinal column Sphenoid bone —butterfly shaped bone & forms part of the cranial cavity Sella Turcica —region of the sphenoid that holds the pituitary gland in place

C RANIAL B ONES Temporal bones —lie inferior to the parietal bones External Auditory Meatus —canal leading to the middle ear Styloid Process —Sharp projection where muscles attach Zygomatic Process —thin bridge of bone that joins with Zygomatic bone Mastoid Process —attachment site for many muscles Jugular Foramen / Carotid Canal —allow for passage of vessels

CRANIAL BONES Sphenoid bone —butterfly shaped bone & forms part of the cranial cavity Sella Turcica —region of the sphenoid that holds the pituitary gland in place Ethmoid bone —lies anterior to the sphenoid Crista Galli —part of the ethmoid where the brain’s covering attaches Cribiform Plates —small holes in the Crista Galli allowing for communication between olfactory receptors and the brain

FACIAL BONES 14 Bones composing the “face”: 6 Pairs and 2 Singular Bones Maxillary Bones Palatine Bones Zygomatic Bones Lacrimal Bones Nasal Bones Conchae Bones Vomer Bone Mandible Bone

FACIAL BONES Maxillary bones —contain the Palatine process (forms part of the hard palate of the mouth) Paranasal Sinuses —contained w/in the maxilla & drain into the nasal passage Palatine bones —form the posterior part of the hard palate Zygomatic bones —called the “Cheekbones” Lacrimal bones —helps to form the eye orbit Nasal bones —form the bridge of the nose

FACIAL BONES Conchae —thin curved bones projecting from the lat. walls of the nasal cavity Vomer bone —forms most of the nasal septum Mandible —lower jaw Body —forms the chin Rami —upright bars from the body connect with the temporal bones (TMJ)

HYOID BONE Hydoid Bone —does not articulate with any other bone, 1-2 cm above the larynx  Moveable base for the tongue  Attachment for muscles that move the larynx (swallow and speak)

FETAL SKULL Fetal Skulls —1/4 of the baby’s length and is “unfinished” Fontanels —fibrous membranes connecting the cranial bones that allow for birth

VERTEBRAL COLUMN Spine  26 irregular bones that are connected by ligaments forming a curved structure  Spinal Column—runs through the central column of the vertebral cavity  Spinal Cord—part of the Central Nervous System contained within the vertebrae

VERTEBRAL COLUMN Cervical —7 bones (concave) Thoracic —12 bones (convex) Lumbar —5 bones (concave) Sacrum —5 fused bones (convex) Coccyx —4 fused bones

VERTEBRAL CURVATURES Curvatures —help to prevent shock to the head when we walk/run/move Primary Curves —Thoracic & Sacral are present when we are born Secondary Curves —Lumbar & Cervical occur as we get older

ABNORMAL SPINAL CURVES Scoliosis —lateral curve Kyphosis —abnormal thoracic curve (hunchback) Lordosis —abnormal lumbar curve (beerbelly syndrome)

SCOLIOSIS

KYPHOSIS Normal Kyphosis

LORDOSIS

ANATOMY OF A VERTEBRA

7 CERVICAL VERTEBRA Cervical Vertebra —smallest & lightest  Vertebral Foramen—allow for passage of arteries to the brain  Spinous Process is divided into two branches

12 THORACIC VERTEBRA Thoracic Vertebra —larger than cervical  Heart shaped body  Two costal facets (for articulation with Ribs)  Spinous Process is long and down hooking

5 LUMBAR VERTEBRA Lumbar Vertebra —large bodies  Spinous process is hatchet shaped and short  Supports the weight of the upper body

FUSED VERTEBRA Sacrum —5 fused Vertebra Articulates with the hip bones Coccyx —3-5 fused bones Called the “Tailbone”

BONES OF THE THORAX Sternum —composed of Manubrium, body, and Xiphoid Process  Attached to the first 7 pair of ribs

B ONES OF THE T HORAX Ribs —forms the walls of the Thoracic Cage 12 pair of ribs True Ribs —first 7 pair that attach to the sternum by Costal Cartilage False Ribs —next 3 pair that do not directly attach to the sternum Floating Ribs —Last two pair of ribs that do not attach to the sternum

   True False Floating