The Skeleton

Skeleton The word skeleton comes from a Greek work meaning “dried up” Infants are born with about 350 bones which fuse resulting in 206 bones that provide the framework for our structure 177/206 is for voluntary movement

Functions Protection: Blood Production: Storage: Movement: Soft tissues and vital organs i.e. brain, heart lungs, and spinal cord Blood Production: Red blood cells (manufactured by red marrow) Storage: - Calcium and phosphorous Movement: Act as levers for muscle activity

Skeleton Organization Two Divisions: Axial Skeleton: protection of internal organs Appendicular Skeleton: movement

Axial Skeleton 80 bones Forms the vertical axis of the body: Skull Vertebral Column Thoracic Cage: Ribs Sternum

Appendicular Skeleton 126 bones Forms the appendages and their attachments to the appendicular skeleton: Upper Limbs Lower Limbs Shoulder Girdle Pelvic Girdle

Skull Bones that support the head, neck, and trunk, and protects the brain and spinal cord: - Cranial bones, facial bones, auditory ossicles, and hyoid bone Cranial Bones: enclose and protect the brain Facial Bones: forms the framework of the face

Skull Hyoid bone: Only bone that does not articulate with any other bone Suspended above the larynx (voice box) where it is anchored by ligaments to the styloid process of the temporal bone Helps to support the tongue Serves as an attachment point for muscles to help elevate the larynx during swallowing

Skull Auditory Ossicles: Stapes (stirrup), Incus (anvil), Malleus (hammer) Named for their shape Three smallest bones in the human body Located in the middle ear Transmit sound

Thoracic Cage 25 bones (page 4): Sternum and 24 Ribs Ribs: Encases heart, lungs, and organs Attached posteriorly to T1-T12 Ribs 1-7 are True Ribs and attach anteriorly to manubrium and body of sternum Ribs 8-10 are False Ribs, their cartilage joins the 7th rib anteriorly Ribs 11 and 12 are Floating Ribs and do not attach to the sternum

Coccyx: Tailbone 26 Bones (pg. 3) 7 cervical vertebrae Vertebral Column 26 Bones (pg. 3) 7 cervical vertebrae 12 Thoracic Vertebrae 5 Lumbar Vertebrae Sacrum 5 fused vertebrae Coccyx: Tailbone

Cervical Vertebrae Begins at the base of the skull Seven cervical vertebrae-C1-C7 Smaller in size than rest of vertebrae Most moveable vertebrae Protect the spinal cord, support the skull, and provide movement (i.e., rotation) Eight pairs of cervical nerves which control breathing and upper body muscles (C3 controls diaphragm) C1 is called the Atlas (ring shaped; no body and spinous process) C2 is called the Axis (has a body, spinous process, and dens)

Thoracic Vertebrae 12 Thoracic Vertebrae-T1-T12 Located in the chest Very little movement due to attachment to Ribs and Sternum Protect internal organs 1 Vertebral Body 2 Spinous Process 3 Transverse Process 4 Pedicle 5 Foramen 6 Lamina 7 Superior Facet

Lumbar Vertebrae 5 Lumbar Vertebrae-L1-L5 Designed to carry most of the body’s weight Largest vertebrae More range of motion than thoracic vertebrae, but less than cervical vertebrae

Sacrum Located behind the pelvis Connects the spine to the pelvis Five fused bones-S1-S5 Below the sacrum are five additional fused bones which form the coccyx (tailbone)

Curvature of the Spine Acts like a spring to absorb shock, maintain balance, and allow range of motion Cervical Spine: Curves slightly inward Inward curve of the spine is called Lordosis Thoracic Spine: Curves outward Outward curve of the spine is called Kyphosis Lumbar Spine: Curves slightly inward-Lordosis

Intervertebral Disks In between the vertebrae are intervertebral discs made of fibrous cartilage that act as shock absorbers and allow the back to move. As a person ages, these discs compress and shrink, resulting in a distinct loss of height (generally between 0.5 and 2.0cm) between the ages of 50 and 55.

Axial Skeleton Summary Vertebral column 7 cervical vertebrae 12 thoracic vertebrae 5 lumbar vertebrae Sacrum Coccyx Skull Cranial bones Facial bones Auditory ossicles Hyoid bone Thoracic Cage 24 ribs Sternum

Shoulder Girdle (pages 4-5) Pectoral or Shoulder Girdle Clavicle (2): collarbone Scapula (2): shoulder blade

Upper Extremities (pages 5-7) Humerus (2): arm bone Radius (2): forearm (thumb side) Ulna (2): forearm (pinky side) Carpals (16): wrist bones 8 in each wrist Metacarpals (10): hand bones Phalanges (28): Fingers 2 in each thumb and 3 in each finger

Pelvic Girdle (pg. 80) Attaches the lower limbs and transmits the weight of the upper body to the lower limbs Ilium: upper portion of the pelvis Ischium: what we sit on (butt bones) Pubis: Lower most anterior part of pelvis

Lower Extremities (pages 81-83) Femur (2): largest, longest and strongest bone (Thigh bone) Patella (2): Kneecap Tibia (2): Large shin bone Fibula (2): Thin shin bone Tarsals (14): ankle bones Metatarsals (10): foot bones Phalanges (28): Toes 2 in big toe and 3 in all other toes

Appendicular Skeleton Summary Shoulder Girdle Clavicle Scapula Upper Extremities Humerus Radius Ulna Metacarpals Carpals Phalanges Pelvic Girdle Ilium Ischium Pubis Lower Extremities Femur Patella Tibia Fibula Tarsals Metatarsals Phalanges

Bone Markings Passageways, joint formations, and attachment points for muscles, tendons, and ligaments Foramen: rounded hole or opening Foramen Magnum is the large hole in the skull

Bone Markings Process: projection Spinous Process of Vertebrae Fossa: shallow or hollow surface Iliac Fossa of Pelvis Crest: a prominent ridge Iliac Crest of Pelvis

Bone Markings Condyle: smooth or rounded projection Lateral and Medial Condyles of the Femur Epicondyle: projection located above a condyle Medial and Lateral Epicondyles of the Humerus

Bone Markings Trochanter: a large rough projection Greater Trochanter of Femur Tuberosity: a small rounded projection Tibial Tuberosity