ch. 5 | the skeletal system

functions of skeletal system:

1. support- provides framework to support soft tissues
2. protection- protects internal organs from injury
3. movement- muscles provide force while bones serve as levers 
4. mineral homeostasis- bone tissue stores calcium & phosphorus 
5. blood cell protection- red bone marrow goes through hemopoiesis (blood cell production)
6. triglyceride storage- yellow bone marrow is made of adipose cells which stores triglycerides

• the adult skeletal system is made of 206 different bones

4 types of bones:

1. long- longer than they are wide, knobby ends, curved structure (arms, legs, fingers, toes)
2. short- equal in width & length (wrists, ankles)
3. flat- thin, provide protection & surfaces for muscle attachments (skull, sternum, ribs)
4. irregular- complex shapes (face, vertebral column)

parts of a long bone:

• diaphysis: middle of long bone, hollow

has a hollow chamber called medullary cavity 

contains yellow marrow which stores fat 

• epiphysis: end of long bone, solid

contains red marrow which produces red blood cells

covered by articular cartilage

• periosteum: tough membrane covering the bone 

• osteoblasts: build extracellular matrix; when entrapped in matrix--> becomes osteocytes
• osteoclasts: digest & reabsorb proteins & minerals from matrix

axial skeleton: 80 bones

• foramen: holes in a bone for passage of vessels or nerves

cranial bones:

• suture: immovable joint that joins most of the skull bones
• fontanels: soft spots on a baby's head- allow the bones of skull to compress as baby is born & provide room for brain to grow 

• hyoid bone: located in the neck, suspended from styloid process; supports tongue, stabilizes airways, provides attachment points for tongue/neck/pharyngeal muscles 

vertebral column: 26 vertebrae

• types of vertebrae:

-cervical: (7) has 3 openings, neck region

-thoracic: (12) posterior to chest, attachment points for ribs

-lumbar: (5) form lower back

-sacrum: (5 fused into 1) posterior wall of pelvis

-coccyx: (4 fused into 1) tailbone 

• parts of a vertebrae:

thorax:

appendicular skeleton: 126 bones

• clavicle & scapula:

• humerus:

• radius & ulna:

• hand:

• pelvic girdle:

• femur:

• knee:

• fibula & tibia:

• foot:

types of joints:

• hinge joint:

• pivot joint:

• plane joint:

•  ball-and-socket:

movements:

• dorsiflexion: instep of foot moved toward shin
• plantar flexion: toes pointed downward

•  flexion: decreases angle btwn bones
• extension: increases angle btwn bones

• elevation: upward
• depression: downward

• lateral rotation: turn away from midline (horizontally)
• medial rotation: turn towards midline (horizontally)

• abduction: move away from midline (vertically)
• adduction: move towards midline (vertically)

joints classified structurally:

• fibrous: no movement

• cartilaginous: 

• synovial: freely movable