Anatomy Reviewer - Skeletal System PDF

**ANAPHY REVIEWER** **MODULE 6: SKELETAL SYSTEM** - **HUMAN SKELETON** -is the **internal framework** of the human -is constructed of **two** of the most **supportive tissues** found in the human body--- **cartilage** and **bone.** - **LIGAMENTS** -**fibrous cords** that **...

**ANAPHY REVIEWER** **MODULE 6: SKELETAL SYSTEM** - **HUMAN SKELETON** -is the **internal framework** of the human -is constructed of **two** of the most **supportive tissues** found in the human body--- **cartilage** and **bone.** - **LIGAMENTS** -**fibrous cords** that **bind the bones** together **at joints**. (bones-bones) - **JOINTS** -give **flexibility** and **allow movement** to occur. *(where bone meets another bone)* **THE SKELETON IS DIVIDED INTO 2 PARTS:** 1. **AXIAL SKELETON** -the **bones** that form the **longitudinal axis** of the body 2. **APPENDICULAR SKELETON** \- the **bones** of the **limbs and girdles** that **attach** them to the **axial** skeleton. **FUNCTIONS OF THE SKELETAL SYSTEM (SSPBM)** 1. **SUPPORT** -**Rigid, strong bone** is **well suited** for **bearing weight** and is the major **supporting** tissue of the **body.** - **Cartilage** provides a **firm yet flexible** **support** within certain structures. - **LIGAMENTS** \- are strong **bands** of **fibrous** connective tissue that **attach** to **bones** and **hold them together**. 2. **PROTECTION** - **BONE** -is **hard** and **protects the organs** it surrounds. -For example, the **skull encloses and protects the brain**, and the **vertebrae** surround the **spinal cord**. -**rib cage** protects the **heart, lungs**, and other organs of the thorax. 3. **MOVEMENT** -**skeletal muscles attach to bones** by **tendons**- which are **strong bands** of connective tissue. -**Contraction of the skeletal muscles** **moves** the **bones**, producing body movements. - **JOINTS** -which are formed where two or more **bones come together**, allow movement between bones. - **SMOOTH CARTILAGE** -**covers the ends of bones** within some joints, allowing the bones to move freely. - **LIGAMENTS allow some movement** between bones but **prevent excessive movements.** 4. **STORAGE** -Some **minerals in the blood** are **taken** into **bone** and **stored**. -are **calcium** and **phosphorus (minerals)**. -**If blood levels** of these minerals **decrease**, the minerals are released **from bone into the blood.** -Fat (adipose tissue) is also stored within bone cavities: as a **source of energy.** 5. **BLOOD CELL PRODUCTION** -Many bones **contain** **cavities** **filled with red bone marrow** -gives rise to **blood cells** and **platelets** - **BONE MATRIX** -**contains extracellular materials** of the bone -**bone, cartilage, tendons, and ligaments** of the skeletal system are all connective tissues. - **MATURE BONE** -**35% organic (collagen and proteoglycans)** and **65% inorganic** **(calcium phosphate)** material. - **ORGANIC MATERIAL** - **collagen** and **proteoglycans.** - **INORGANIC MATERIAL** - **calcium phosphate** **EXTRACELLULAR MATRIX** - **COLLAGEN** -is a **tough**, **ropelike** protein. - **PROTEOGLYCANS** -are **large molecules** consisting of **polysaccharides** *attached* to **core proteins** -similar to the **way needles of a pine tree** are **attached to the tree's branches**. -attract and **retain** **large amounts of water** between their polysaccharide "needles." - **TENDONS and LIGAMENTS** -**contains** large amounts of **collagen fibers,** making these structures very tough, like **ropes or cables.** - **CARTILAGE** -contains **collagen** and **proteoglycans**. -**Collagen** makes **cartilage** **tough**, whereas the **water-filled proteoglycans** make it **smooth and resilient.** -As a result: **rigid**, but it **springs back** to its **original shape** **after** being **bent** or slightly compressed -**Excellent shock absorber** - **BONE** -contains **collagen** and minerals, including **calcium** and **phosphate**. -**ropelike collagen fibers**, like the reinforcing **steel bars** in concrete, lend flexible strength to the bone. -mineral component, like the concrete itself, gives the bone compression (weight-bearing) strength. -**mineral in bone** is in the **form** of **calcium phosphate crystals** called **HYDROXYAPATITE** **GENERAL FEATURES OF BONE** **"4 CATEGORIES OF BONE: based on SHAPE"** 1. **LONG BONES** -are **longer than they are wide**. -Most of the bones of the **upper and lower limbs** are long bones. 2. **SHORT BONES** -are **approximately as wide** as **they are long** -examples are the bones of the **wrist** and **ankle**. 3. **FLAT BONES** -have a relatively **thin, flattened shape**. -Examples of flat bones are certain **skull bones**, the **ribs**, the **scapulae** (shoulder blades), and the **sternum**. 4. **IRREGULAR BONES** -include the **vertebrae** and **facial bones** -which have **shapes that do not fit readily** into the **other** three **categories** **STRUCTURE OF A LONG BONE** - **DIAPHYSIS** -(**growing between**) **central** **shaft** of long bone - **EPIPHYSIS** -(**growing upon**) the **two end** - **ARTICULAR CARTILAGE** \- A **thin layer of cartilage**, **covers** the **ends** of the **epiphyses** where the **bone** **articulates** (joins) with **other bones.** - **EPIPHYSEAL PLATE** -composed of cartilage, **between** each **epiphysis** and the **diaphysis** -is **where** the **bone grows in length.** -for **female**: closes around **14-15 y/o** -for **male**: closes around **21 y/o** - **EPIPHYSEAL LINE** -When bone **growth stops**, the cartilage of each epiphyseal plate **is replaced by bone** - **MEDULLARY CAVITY** -**cavities in the bone**, such as the **large cavity** in the **diaphysis**, as well as **smaller** **cavities** in the **epiphyses** of long bones. - **MARROW** -**soft tissue** **in the medullary cavities** of the bone **"MARROW"** 1. **YELLOW MARROW** -consists mostly of **adipose tissue.** -more in **old bones** 2. **RED MARROW** -consists of **blood-forming cells** and is the **only site of blood formation** in **adults** -***Children's bones** have proportionately **more red marrow** than do adult bones* - **PERIOSTEUM** -**outer surface of bone** is **covered** by dense **connective tissue**; consists of two layers and contains **blood vessels and nerves** - **ENDOSTEUM** -**surface** of the **medullary cavity** is **lined** with a **thinner connective** **tissue** membrane **"BONE CELLS"** 1. **OSTEOBLASTS (IMMATURE)** **-(bone-forming cells)**, which function in the **formation of bone**, as well as in the **repair** and **remodeling** of bone. -produce **collagen** and **proteoglycans**, which are packaged into vesicles by the Golgi apparatus -released from the cell **by exocytosis**. - **OSSIFICATION (OSTEOGENESIS)** **-**is the **formation of bone** by **osteoblasts.** - **OSTEOCHONDRAL PROGENITOR CELLS (from this to osteoblasts)** -are **stem cells** that can **become osteoblasts** -are located in the **inner layer of the periosteum**, and the **endosteum.** 2. **OSTEOCYTES (MATURE)** -**osteoblasts** become **surrounded by matrix** (**bone cells**). -it is a **mature bone cell** -**spaces occupied** by the **osteocyte cell** **bodies** are called **LACUNAE** -**spaces occupied** by the **osteocyte cell processes** are called **CANALICULI** 3. **OSTEOCLAST** -(**bone-eating** cells) are also present and contribute to bone **repair** and **remodeling** by **removing existing bone** **BONE TISSUE FOUND THROUGHOUT THE SKELETON IS DIVIDED INTO 2 MAJOR TYPES:** 1. **COMPACT BONE** -is mostly **solid matrix** and **cells**. 2. **SPONGY BONE (CANCELLOUS BONE)** -consists of a **lacy network of bone** with many **small**, **marrow-filled spaces**. *\]\]* **HISTOLOGY OF BONE: COMPACT BONE** 1. **COMPACT BONE or Cortical Bone** -Forms the **perimeter** of the **diaphysis** of a long bone -**Thinner surface** of all other bone -More **matrix** and is **denser**, with **fewer pores** - **OSTEONS** -Compose of **predictable pattern** of **repeating units** -the whole system - **LAMELLAE** -osteon consists of **concentric rings** -the layers or rings - **HARVESIAN or CANTRAL CANAL** **-running parallel** to the surface of the bone; **small canals** containing **blood vessels (capillaries/arterioles/venules)** - **LACUNAE** -**tiny cavities** between **two lamellae** - **CANALUCULI** -**give osteon** the **appearance** of having **tiny cracks** **within the lamellae** - **VOLKMANN'S OR PERFORATING CANALS** **-canals running horizontally** to harvesian canal, and also contain **blood vessels** -Nutrients leave the blood vessels of the central canals and diffuse to the osteocytes through the canaliculi. -Waste products diffuse in the opposite direction. -blood vessels in the central canals, in turn, are connected to blood vessels in the periosteum and endosteum. 2. **SPONGY BONE** -spongy bone, so called because of its appearance -Very **porous** -Located in the **epiphyses** of the long bone -**Less bone matrix** -More **open space** -It **forms the interior** of all other **bones**. - **TRABECULAE** -delicate **interconnecting rods** or **plates** of bone -which resemble the **beams or scaffolding** of a building -Add **strength to the bone** (scaffolding) -**Spaces filled with marrow**. -**no blood vessels - no central canals.** -Nutrients exit vessels in the marrow and pass by diffusion **(canaliculi to the osteocytes of the trabeculae)**  **BONE OSSIFICATION** - **OSSIFICATION** is the **formation of bone by osteoblasts**. -After an **osteoblast** becomes **completely** **surrounded** by **bone matrix**, it becomes a **mature bone cell**, or **osteocyte**. -fetus begins at 3rd month of fetal age - **INTRAMEMBRANOUS OSSIFICATION** -**bone formation** that **occurs within connective tissue membranes** - **ENDOCHONDRAL OSSIFICATION** -**bone formation** that occurs inside **cartilage** -Both types of bone formation result in compact and spongy bone. - **INTRAMEMBRANOUS OSSIFICATION** -occurs when **osteoblasts begin** to **produce** bone in **connective tissue membranes.** -primarily in the bones of the **skull**. -**Osteoblasts** **line up** on the surface of connective tissue fibers and begin **depositing bone matrix** to **form** **trabeculae.** -process begins in areas called **ossification centers**, and the trabeculae radiate out from the centers. -**trabeculae are constantly remodeled** after their initial formation \> compact bone - **ENDOCHONDRAL OSSIFICATION** -**bones at the base of the skull** and most of the remaining skeletal system develop through the process of endochondral ossification from cartilage models. -**cartilage models** have the general shape of the **mature bone** -**chondrocytes**, **increase** in number, **enlarge**, and **die** -Then the **cartilage matrix** becomes **calcified** -occurring in the center of the cartilage model, **blood vessels accumulate** in the **perichondrium.** -**presence of blood vessels in the outer surface of future bone** causes some of the unspecified connective tissue cells on the surface to **become osteoblasts**. -**osteoblasts then produce a collar of bone** around part of the outer surface of the **diaphysis**, and the **perichondrium becomes periosteum** in that area. -**Blood vessels also grow into the center of the diaphyses**, bringing in osteoblasts and **stimulating ossification**. -**center part of the diaphysis**, where **bone first begins to appear**, is called the **PRIMARY OSSIFICATION CENTER** -Osteoblasts invade spaces in the center of the bone left by the dying cartilage cells. **-calcified cartilage matrix is removed by osteoclasts**, and the **osteoblasts line up** on the remaining calcified matrix and begin to form **bone trabeculae.** -**medullary cavity forms** in the **center** of the **diaphysis** as **osteoclasts remove bone** -**calcified cartilage -- replace by bone marrow**. -**SECONDARY OSSIFICATION** centers **form in the epiphyses**  **BONE GROWTH** -process is called **APPOSITIONAL GROWTH**- **osteoblasts deposit new bone matrix** on the **surface of bones** between the **periosteum** and the **existing bone matrix**, the **bone increases in width, or diameter.** ▪ **Growth in the length of a bone**, which is the major source of **increased height** in an individual, **occurs in the epiphyseal plate**-occurs through **endochondral ossification** ▪ **Bone elongation occurs at the epiphyseal plate** as chondrocytes proliferate, enlarge, die, and are replaced by bone. **FACTORS AFFECTING BONE GROWTH** - **NUTRITION** - **VITAMIN D - [necessary]** for the **normal absorption** of **calcium** from the **intestines** - The body can **either synthesize** or **ingest vitamin D** - Insufficient vitamin D in children causes rickets - **RICKETS** -a disease in CHILDREN resulting from **reduced mineralization** of the **bone matrix.** (insufficient VIT D) - Low vitamin D levels can be one cause of **"adult rickets,"** - **OSTEOMALACIA** -a **softening of the bones** in ADULTS due to **calcium depletion.** - **VITAMIN C** -is necessary for osteoblasts to **synthesize collagen.** -old collagen breaks down, new collagen is synthesized to replace it. -deficiency results in bones and cartilage with fewer collagen fibers - collagen synthesis is impaired. -In children, deficiency can retard growth. -In **both children and adults**, **deficiency in VIT C** can result in **SCURVY,** which is marked by **ulceration and hemorrhage** in almost any area of the body. - **GROWTH HORMONE** -from **the anterior pituitary increases** general **tissue growth**, including overall bone growth - **GIGANTISM** -**Excessive growth hormone** secretion - **DWARFISM** **Insufficient growth hormone** secretion - **THYROID HORMONE** -**required for normal growth** of all tissues, including **cartilage** -decrease in this hormone can result in a **smaller individual** - **ESTROGEN AND TESTOSTERONE** -**cause increased bone growth** and closure of the **epiphyseal plate.** -**During puberty**, the **levels** of these **hormones** **increase** dramatically - **BONE REMODELLING** -Involves the **removal of existing bone** by **osteoclasts** and the **deposition of new bone by osteoblasts.** -Bones are remodeled continually in response to **changes in two factors**: ▪ calcium ion level in the blood ▪ pull of gravity and muscles on the skeleton. -Bone remodeling is **essential, to retain normal proportions and strength** during long-bone growth as the **body increases in size and weight.** -bones **become thicker and form large projection**s to increase their strength in areas where bulky muscles are attached **STAGES OF BONE REMODELLING** 1. **RESORPTION** -**Osteoclast remove bone mineral** and matrix, creating **erosion cavity** (3-4 weeks) 2. **REVERSAL** **-Mononuclear cells** **prepare bone surface** for **new osteoblasts** to **begin building bone** 3. **FORMATION** -**Osteoblasts synthesize a matrix** to **replace resorbed bone** with **new** bone (3 -- 4 months) 4. **RESTING** -A **prolonged resting period follows** until a new remodeling begins. **BONE REPAIR** ▪ Sometimes a bone is broken and needs to be repaired. ▪ When this occurs, **blood vessels** in the bone are also **damaged** ▪ vessels bleed, and a clot (**HEMATOMA**) **forms** in the **damaged area** ▪ 2 - 3 days after the injury, **blood vessels** and cells from surrounding tissues **begin to invade the clot.** ▪ Some of these cells produce a fibrous network of connective tissue between the broken bones, which holds the bone fragments together and fills the gap between them. ▪ Other cells produce **islets of cartilage** in the fibrous network. ▪ **CALLUS** -**network of fibers** and **islets of cartilage** between the **two bone fragments**  ▪ Osteoblasts enter the callus and **begin forming spongy bone** ▪ Spongy bone formation in the callus is usually **complete 4--6 weeks after the injury.** **▪ Immobilization of the bone** is **critical** up to this time ▪ Spongy bone is slowly remodeled to form compact and spongy bone, and the repair is complete **BONE FRACTURE CLASSIFICATION** 1\. mechanism of fracture 2\. soft-tissue damage 3\. displacement vs. non -- displacement 4\. fracture pattern 5\. number of fragments in the fractured bone 1. **MECHANISM OF FRACTURE** The first criterion for bone fracture type falls under the category of the mechanism by which the fracture occurred. 1. through a **trauma to the bone** **(TRAUMATIC)** 2. through **a pathology (disease) of the bone** **(PATHOLOGIC)** 2. **SOFT TISSUE DAMAGE** The next criterion by which bone fractures are classified is by the amount of soft-tissue damage. 1. **CLOSED (STABLE OR SIMPLE)** \- **no visible damage to the skin** at the injury site 2. **OPEN (COMPOUND)** -there is **visible damage to the skin** at the trauma site, possibly including a fragment of the **fracture bone protruding from the skin.** **3. DISPLACED VS. NON -- DISPLACED** Two possibilities exist for the position of the fractured bone ends after the fracture has occurred: 1. **DISPLACED** -where the **ends of the bones** are o**ffset from each other** and are **not aligned** anatomically 2. **NON -- DISPLACED** -where the ends of the bone **remain in anatomical alignment.** **4.FRACTURE PATTERN** This classification is based on the pattern of the fracture on the bone. These include: **1. LINEAR FRACTURE** - **runs parallel** to the **length** of the bone **2. SPIRAL FRACTURE** - results from **twisting** of **one part of the bone** **3. AVULSION FRACTURE** - **separation** of a bone **fragment** from the rest of the bone **4. STRESS (HAIRLINE) FRACTURE** **- incomplete fracture** resulting from **overuse of the bone** **5. COMPRESSION FRACTURE** - the **bone collapses**; common in **spongy bone**, often due to **weakening of the bone** such as in osteoporosis 5.  **NUMBER AND ARRANGEMENT OF BONE FRAGMENTS** Fractures are categorized by the completeness of the break 1. **INCOMPLETE FRACTURE** -a fracture that **only traverses' part of the bone** 2. **COMPLETE FRACTURE** -a fracture that **completely separates the bone** into at least **two fragments** 3. **COMMINUTED FRACTURE** -a fracture where the bone **breaks into multiple fragments** **CALCIUM HOMEOSTASIS** ▪ Bone is the major **storage site for calcium** in the body ▪ movement of calcium into and out of bone helps determine blood calcium levels ▪ Calcium (Ca2+) moves into bone as OSTEOBLASTS BUILD new bone and out of bone as OSTEOCLASTS BREAK down bone ▪ When osteoblast and osteoclast activity is balanced, the movements of calcium into and out of a bone are equal 1\. **Decreased blood Ca2**+ **stimulates PTH** (parathyroid hormone) secretion from parathyroid glands. 2\. **PTH stimulates osteoclasts** to **break down bone** and **release Ca2+** into **the blood.** 3\. In the **kidneys**, **PTH increases Ca2+** **reabsorption** from the **urine**. 4\. **PTH** **also stimulates active Vitamin D** formation**. Vitamin** **D promotes Ca2+ absorption** from the **small intestine** into the blood ▪ Increased blood **Ca2+ stimulates calcitonin secretion from the thyroid gland.** (5) ▪ **Calcitonin inhibits osteoclasts**, which allows for **enhanced osteoblast uptake of Ca2**+ from the blood to deposit into bone.(6) **CARTILAGES OF THE SKELETON** - **HYALINE CARTILAGE** -provides **sturdy support** with some **flexibility.** -Most skeletal cartilages are composed of **hyaline cartilage** - **ELASTIC CARTILAGE** -is much **more flexible than hyaline** cartilage, and it tolerates **repeated bending.** -**external ear and the epiglottis** (which **flops** over and covers the larynx when we swallow) - **FIBROCARTILAGE** **-**has great **tensile strength** and can **withstand heavy compression** ▪ intervertebral discs and knee joint **THE MOST IMPORTANT OF THE ADULT SKELETAL CARTILAGES** 1. **ARTICULAR CARTILAGES** -which cover the **bone ends** at **movable joints** 2. **COSTAL CARTILAGES** -which **connect the ribs** to the **sternum (breastbone)** 3. **NASAL CARTILAGES** -which support the **external nose** 4. **INTERVERTEBRAL DISCS** -which **separate** and **cushion** the **vertebrae** ▪ **Newborn** human has **350** bones ▪ **Adult** human has **206** bones - **AXIAL SKELETON** -can be divided into **three parts**: the **SKULL**, the **VERTEBRAL COLUMN**, and the **THORACIC CAGE**. -This division of the skeleton forms the longitudinal axis of the body and PROTECTS: the brain, spinal cord, heart, and lungs. 1. **SKULL** \- Sits on **top of the vertebral column** ▪ Two sets of bones ▪ Cranium (**8** bones) ▪ Facial bones (**14** bones) ▪ **Bones** are **joined** by **sutures** ▪ Only the **mandible** is **attached by a freely movable joint** - **CRANIUM** **-Eight Osseous Parts Forms The Skull** **-T & P is paired** **CRANIUM DIVIDED INTO 2 MAJOR AREAS** **1. CRANIAL VAULT OR CALVARIA -** forming the **superior**, **lateral**, and **posterior** walls of the **skull** **2. CRANIAL BASE -** forming the **skull bottom.** - **FRONTAL BONE** -Forms the **forehead**, superior part of the orbit, and the floor of the **anterior cranial fossa** **CRANIUM** - **PARIETAL BONE -- 2** -Form the **superior** and **lateral** aspects of the **skull**. - **TEMPORAL BONES -- 2** -Form **the inferolateral** aspects of the **skull** **sides** of the head, **close to ears.** -Commonly called the **temples** -Includes the **external auditory meatus** -**Opening** for the **ear** -Includes the **zygomatic process** -Part of the **cheekbone** ***-"Process" like zygomatic means nagdudugtong sa bones*** - **OCCIPITAL BONE** -Forms the **posterior** aspect and most of the **base of the skull.** -**back and base** of the **cranium** - **FORAMEN MAGNUM** -**Large opening** in the **base** of the **bone**, which allows the **spinal cord to join** with the **brain stem.** - **SPHENOID BONE** (1) **-Bat-shaped bone** that is described as the **keystone bone** of the cranium because it articulates with **all other cranial bones.** **-**parts of orbits of the eyes - Includes **SELLA TURCICA** -where **pituitary gland** sits **▪ OPTIC CANALS** - **cranial nerve II** (**optic** nerve) passes through to **serve the eye.** **▪ FORAMEN ROTUNDUM** - a branch of **cranial nerve V** (**maxillary division**) passes through. **▪ FORAMEN OVALE** - a branch of **cranial nerve V** (**mandibular division**) passes through. **▪ FORAMEN SPINOSUM** - provides **passageway** for the **middle meningeal artery** - **ETHMOID (1)** -**Contributes** to the **anterior cranial fossa** -forms **part of the nasal septum** and the **nasal cavity** -contributes to the **medial wall** of the **orbit**.  **4 MAJOR SUTURES** 1. **SAGITTAL SUTURE** -Occurs where the **left and right parietal bones meet superiorly** in the **midline of the cranium** 2. **LAMBDOID SUTURE** -Occurs where the **parietal bones meet the occipital bone posteriorly** 3. **SQUAMOUS SUTURE** -Occurs where each **parietal bone meets the temporal bone**, on each **lateral aspect of the skull** 4. **CORONAL SUTURE** -**Running** in the **frontal plane**, occurs **anteriorly** where the **parietal bones meet the frontal bone**  - **CRANIAL BASE** -has **3** **distinct depressions**: the **ANTERIOR, MIDDLE**, AND **POSTERIOR cranial fossae** ▪ The **BRAIN sits in these fossae**, completely enclosed by the **cranial vault.** **FACIAL BONE** - **NASAL (2) --** -Small **rectangular** bones **forming the bridge** of the **nose**. - **LACRIMAL (2)** -Each forms part of the **medial orbit** in between the **maxilla and ethmoid bone.** - **ZYGOMATIC (2)** -Commonly called the **cheekbones**; each forms part of the **lateral orbit** - **INFERIOR NASAL CONCHA (2)** -each forms part of the lateral walls of the **nasal cavities** -improves the **airflow** through the **nasal cavity** - **MAXILLA (2)** -**Keystone facial bones** because they **articulate** with **all other facial bones** **except** the **mandible** -form the **upper jaw** and parts of the hard palate, orbits, and nasal cavity. - **PALATINE (2)** -Forms the **posterior hard palate**, a small part of the **nasal cavity**, and part of the orbit. - **VOMER (1)** -**Thin, blade-shaped** bone that forms the inferior **nasal septum**  - **MANDIBLE (1)** -**lower jawbone**, which articulates with the **temporal bone** -carries the **lower teeth** -anterior portion forms the **chin** -Only freely movable joint in the skull - **CLEFT PALATE** -**Failure of the palatine** and/or **maxillary** bones **to fuse.** **OTHER PARTS** - **PARANASAL SINUSES** -the **sinuses found in the frontal bone**, the **ethmoid bone**, **the sphenoid bone**, and the **maxilla bone** -sinuses are **openings** within particular bones that **open into the nasal cavity**. sinuses have two major functions: ▪ they **decrease the weight of the skull** ▪ they **act as a resonating chamber** when **speaking.** - **HYOID BONE** **-U shaped** -Found in the **upper neck** -The **only bone** that does **not articulate with another bone** -It serves as a **point of attachment for many** **tongue** and **neck muscles.** **THE FETAL SKULL** - **FONTANELLES -**are the spaces or opening where the skull bones join - **ANTERIOR FONTANELLE** -- located at the **junction of two parietal bones**. It is a **diamond** in **shape**. normally closes at **12** to **18th** months of age - **POSTERIOR FONTANEL** --located at the **junction of parietal bones and occipital bone**. It is a **triangular** in **shape**. Closes by the end of the **2nd month** **"3 TINY BONES"** - transmit vibrations ▪ All derived from Latin words 1. **MALLEUS (HAMMER),** 2. **INCUS (ANVIL)** 3. **STAPES (STIRRUP)-** **Smallest** **bone** in the body **THE VERTEBRAL COLUMN** - **VERTEBRAL COLUMN** -extending from the **skull** to the **pelvis** -**forms** the **body's major axial support**. -it surrounds and protects the delicate **spinal cord** -column consists of **24** **single bones** called **VERTEBRAE** and **2 composite, or fused, bones** (the **SACRUM AND COCCYX**) **VERTEBRAL COLUMN** **▪ CERVICAL VERTEBRAE** -**7** bones of the neck are called ▪ **THORACIC VERTEBRAE** -the next **12** **▪ LUMBAR VERTEBRAE** -**5** supporting the lower back are **NOTE:** Remembering common mealtimes for breakfast, lunch, and dinner (7 a.m., 12 noon, and 5 p.m.)  - **INTERVERTEBRAL DISC** -**separate** the **vertebrae** -**pads** of **fibrocartilage** that **cushion** the vertebrae and **absorb shocks.** **-2 MAJOR REGIONS:** **1. NUCLEUS PULPOSUS** -a **central gelatinous** that behaves like **a rubber ball** **2. ANULUS FIBROSUS** - an **outer ring** of **encircling collagen fibers** that **stabilizes the disc** **STRUCTURE OF A TYPICAL VERTEBRA** **▪ TRANSVERSE PROCESSES** -**Two lateral projections** from the vertebral arch. **▪ SPINOUS PROCESS** -**Single medial** and **posterior projection** from the vertebral arch. **▪ SUPERIOR AND INFERIOR ARTICULAR PROCESSES** -**Paired projections lateral** to the vertebral foramen that **enable articulation with adjacent vertebrae.** **▪ INTERVERTEBRAL FORAMINA** -**openings**, for **spinal nerves** to **leave the spinal cord** between adjacent vertebrae. **CERVICAL VERTEBRAE** **▪ 7 cervical vertebrae (referred to as C1 through C7)** form the **neck portion** of the vertebral column. **▪ first 2 cervical vertebrae (atlas and axis)** are **highly modified** to perform special functions - **ATLAS (C1)** -**lacks a body** -its **lateral processes** contain **large concave** **depressions** on their superior surfaces that receive the occipital condyles of the skull. -this joint **enables you to nod**  **▪ OCCIPITAL CONDYLES** --rests on **the first vertebra** of the **vertebral column** - **AXIS (C2)** -acts as **a pivot** for the **rotation of the atlas** (and skull) above. -It bears a **large vertical process**, the **dens**, that serves as the **pivot point**. -**articulation between C1 and C2** allows you to **rotate** your **head** from **side to side** - **The more typical cervical vertebrae (C3 through C7)** -are **distinguished** from the **thoracic** and **lumbar verteb**rae by several features \- are the **smallest, lightest vertebrae** -vertebral foramen is **triangular**. -**SPINOUS PROCESS** is **short and often bifurcated (**divided into two branches). - **SPINOUS process of C7** -is not branched -substantially longer than that of the other cervical vertebrae. -spinous process of C7 is **visible through the skin at the base of the neck** -it is called the **VERTEBRA PROMINENS** and is **used** as **a landmark for** **counting** the **vertebrae**. - **TRANSVERSE PROCESSES OF THE CERVICAL VERTEBRAE** -are wide -**contain foramina** through which the vertebral arteries pass **superiorly on their way to the brain.**  **THORACIC VERTEBRAE** **▪ 12 THORACIC VERTEBRAE (REFERRED TO AS T1 THROUGH T12)** -have a larger body than the cervical vertebrae -body is somewhat **heart shaped** -**vertebral foramen is oval or round**, and the spinous process is long, with a sharp **downward hook.** -forming the thoracic part of the spine -form the posterior aspect of the thoracic cage -only vertebrae that articulate with the ribs. - **ARTICULAR FACETS** on the transverse **processes articulate** with the **tubercles of the ribs.**  **LUMBAR VERTEBRAE** **▪ 5 LUMBAR VERTEBRAE (L1 THROUGH L5)** -support the **majority of the body's weight** -they have massive bodies and heavy, rectangular transverse and spinous processes. **-SUPERIOR ARTICULAR FACETS** face **posteromedially;** the **inferior ones** are directed **ANTEROLATERALLY**. -adds strength to the inferior portion of the vertebral column and **limits rotation** of the **lumbar vertebrae** **THE SACRUM** -is a **composite bone** formed from the **fusion of five vertebrae** -**Superiorly** - **articulates with L5** -**Inferiorly** - **connects with the coccyx**. -located between the **two hip bones** -It **articulates with each hip bone** by way of the auricular surfaces, forming the sacroiliac joint -As part of the pelvic girdle, it **provides stable support for our lower limbs.** **THE COCCYX** -is **formed from the fusion** of **3-5 small** irregularly **shaped vertebrae.** -literally **the human tailbone** \- coccyx is **attached to the sacrum** by ligaments. **THE THORACIC CAGE** -consists of the **bony thorax**, which is composed of the **sternum, ribs, and thoracic vertebrae**, plus the **costal cartilages** -Its **cone-shaped**, **cagelike** structure **protects** the **organs** of the thoracic cavity, including the critically important **heart and lungs**. - **STERNUM (BREASTBONE)** -a **typical flat bone** -is a result of the **fusion** of **3 bones**---the **manubrium, body,** and **xiphoid process.** -It is attached to the **first 7 pairs of ribs.** 1. **MANUBRIUM** (**"sword handle")** -**superior most**; looks like the **knot of a tie**; it **articulates** with the **clavicle** (collarbone) **laterally**. 2. **BODY or GLADIOLUS ("blade")** -forms the **bulk of the sternum.** 3. **XIPHOID PROCESS** **("sword tip")** -constructs **the inferior end of the sternum** and lies at the level of the **5^th^ intercostal** **space**. -made **of hyaline cartilage** in **children**, it is usually **ossified** in **adults** over the age of **40** **THE RIBS** -**12 pairs of ribs** form the walls of the thoracic cage -**articulate posteriorly** with the **vertebral** **column** via their **heads and tubercles** - **VERTEBROSTERNAL (TRUE RIBS)** **-First 7 pairs**, called the **true**, ribs, **attach directly to the sternum** by their "**own**" costal cartilages. -All **the 12 ribs articulate posteriorly with the vertebrae** of the spine. Each rib forms **2 joints:** ▪ **COSTOTRANSVERSE JOINT** -**Between the tubercle of the rib**, and the transverse costal facet of the corresponding vertebrae. ▪ **COSTOVERTEBRAL JOINT** -**Between the head of the rib**, superior costal facet of the corresponding vertebrae, and the inferior costal facet of the vertebrae above. - **FALSE RIBS** -next 5 pairs are called; they attach indirectly to the sternum or entirely lack a sternal attachment. - **VERTEBROCHONDRAL RIBS** -**8--10**, have **indirect cartilage** **attachments** to the **sternum** via the costal cartilage **of rib 7.** - **FLOATING/ VERTEBRAL RIBS** -**11 - 12,** have **no sternal attachment**. - **APPENDICULAR SKELETON** \- composed of the **126 BONES** -**appendages** and the **pectoral** and **pelvic** **girdles**, which **attach the limbs to the axial skeleton.** - **PECTORAL GIRDLE** -Also called the **SHOULDER GIRDLE** -consists of **2 pairs** of bones, **4 bones**; **2 scapulae + 2 clavicles** -**attach the upper limbs** to the **axial skeleton** and provide attachment points for many trunk and neck muscles. -is **exceptionally ligh**t and allows the upper limb a degree of mobility - **SCAPULA** -commonly known as the **SHOULDER BLADE** -is **a flat, triangular bone** that can **easily** be **seen** and **felt** in a living person - **ACROMION PROCESS** -**form the point of the shoulder**; **attachment** **points** for some of the **shoulder muscles.** - **GLENOID CAVITY** -located in the **superior lateral portion** of the bone, **articulates** with the **head** of the **humerus**. - **CLAVICLE** -commonly known as **THE COLLARBONE** -is a **long bone** with a **slight sigmoid** (S-shaped) **curve**. -It articulates with the **scapula** and the **sternum**. -lateral end it **articulates** with the **acromion process**. -**medial end** it articulates with the **manubrium of the sternum**. -**clavicle** **holds** the **upper limb** **away** from the **body**, it facilitates the limb's mobility - **ARM/BRACHIUM** -contains a **single bone** - **HUMERUS**. -Proximally its **rounded head** **fits** into the shallow **glenoid cavity of the scapula**. -**head is separated from the shaft** by the **anatomical neck** and the more constricted **surgical neck** - which is a **common site of fracture.** - **CAPITULUM** -**rounded lateral condyle** that **articulates** with the **radius** - **TROCHLEA** -**flared medial condyle** that articulates with the **ulna** - **FOREARM/ANTEBRACHIUM** \- The forearm has **2 bones**: ▪**ulna and radius** - **ULNA** -is **medial**, the **same side** as the **little finger** **▪ TROCHLEAR NOTCH** **-C-shaped portion of the ulna** that articulates with the **humerus** is the -**rotates** over the **trochlea** of the **humerus** when **bending the elbow.** - **RADIUS** -is **lateral**, the **same side** as the **thumb**. **▪HEAD** **-portion of the radius** that articulates with the **humerus** **-rotates** over the **capitulum** of the **humerus** when **bending the elbow**. ▪ulna and radius articulate with the humerus at the **elbow joint.**  **HAND/ MANUS:** - **WRIST** -wrist is a **relatively short region** between the **forearm** and the **hand** -composed of **8 carpal bones** arranged into two rows of four each - **proximal row of carpal bones,** lateral to medial 1. **SCAPHOID** **-boat-shaped** 2. **LUNATE** **-moon-shaped** 3. **TRIQUETRUM** **-three-cornered** 4. **PISIFORM** **-pea-shaped** - **distal row of carpal bones,** from medial to lateral 1. **HAMATE** -has a **hooked process** on its palmar side 2. **CAPITATE** **-head-shaped** 3. **TRAPEZOID** -named for its **resemblance to a 4-sided** **geometric** form **two parallel sides** 4. **TRAPEZIUM** **-**named after **a 4-sided geometric** form **with no two sides parallel.** - **METACARPALS -- PALM** **-5 metacarpal bones** - attached to the carpal bones -**central portion** of the hand -in the **resting position**, the palm of the hand is **concave**. -**distal ends** of the metacarpal bones help **form the knuckles** of the hand - **PHALANGES** **-5 digits of each hand** include one **thumb** **(pollex)** and **four fingers**. -digit consists of **small long bones** called PHALANGES -**thumb** has **2 phalanges**, called **proximal** and distal. -**Each finger has three phalanges**, designated **proximal, middle, and distal.** - **PELVIC GIRDLE** -formed by the **2 hip bones** and the **sacrum**. -are **heavy and massive**, and they **attach** securely to the **axial skeleton.** **1. ILIUM** -- most **superior** **2. ISCHIUM** -- **inferior and posterior**; sit **down bone** **3. PUBIS** -- **inferior** and **anterior** - **PUBIC SYMPHYSIS** **-**where coxal bones join anteriorly - **SACROILIAC JOINTS** -joins the sacrum posteriorly - **ACETABULUM** -socket of the hip joint - **OBTURATOR FORAMEN** -large hole in each coxal bone ▪Male pelvis: larger and massive; Female pelvis; broader **LOWER LIMBS** - **THIGH** - **FEMUR** -**thigh** bone -**heaviest**, **strongest** **bone** in the body. **▪HEAD OF THE FEMUR** -- articulates with the **acetabulum** of the **coxal** bone **▪CONDYLES** -- articulates with the **tibia** **▪EPIDONDYLES** -- points of **ligaments** **attachments** - **PATELLA** -**knee** **cap** -**Triangular** bone **located** within a **tendon** that **passes over the knee.**  - **LEGS** \- **2 bones**, the **TIBIA** and the **FIBULA**, form the skeleton of the leg - **TIBIA (SHINBONE)** -is the **larger, medial**, **weight-bearing** bone of the leg. **▪ MEDIAL CONDYLE** -**Slightly concave** surface that **articulates** with the **medial condyle** of the **femur** - **FIBULA** -**thin and sticklike** that forms the lateral -**lies parallel to the tibia**, takes **no part** in forming the knee joint. -proximal head **articulates** with the **lateral condyle** of the **tibia**. - **ANKLE** -consists of the **distal ends of the tibia** and **fibula** **forming** a **partial socket** that **articulates** with a **bone of the foot** (the **talus**) -A **PROMINENCE** can be **seen** on **each side of the ankle** -These are the **medial malleolus** of the distal **tibia** and the **lateral malleolus** of the distal **fibula**. - **FOOT** **❖ Tarsal (7)** -- ankle **❖ Metatarsals (5)** -- sole **❖ Phalanges (14)** -- toes **7 TARSAL BONES** include**:** **1. Calcaneus** **2. Talus** **3. Cuboid** **4. Navicular** **5. Media cuneiforms** **6. Intermediate cuneiforms** **7. Lateral cuneiforms** ▪**Body weight is concentrated** on the **2 largest tarsals,** which form the posterior aspect of the foot**. larger calcaneus** (**heel** bone) and the **talus** ▪**metatarsals** are numbered **I through V**, medial to lateral. ▪ **toe** has **3 phalanges** except the **great toe, which has 2 phalanges.** ▪ bones in the foot are arranged to produce **3 strong arches** ▪ **2 longitudinal arches** (medial and lateral) and one transverse arch 2 main functions of the foot: 1\. to **support the body in its upright position** both while standing and in forward movement during walking 2\. to push the body forward during walking and to **absorb shock** when the foot contacts the ground. - **ARTICULATIONS/JOINTS** **-2 FUNCTIONS FOR THE BODY:** 1\. **hold the bones** together 2\. **allow the rigid skeletal** system some **flexibility** so that gross body movements can occur. -Ways **joints are classified** ▪ By their **function** ▪ By their **structure** **"FUNCTIONAL CLASSIFICATION OF JOINTS"** **▪ SYNARTHROSES -- immovable** joints **▪ AMPHIARTHROSES -- slightly moveable** joints **▪ DIARTHROSES** -- **freely** **moveable** joints **"STRUCTURAL CLASSIFICATION OF JOINTS"** **▪ FIBROUS JOINTS - Generally** **immovable** **▪ CARTILAGINOUS JOINTS - Immovable or slightly** moveable **▪ SYNOVIAL JOINTS** - **Freely** moveable - **FIBROUS JOINTS** **-2 bones** that are united **by fibrous tissue** -Exhibit little or **no movement** **1. SUTURES** -- **bet**. the **bones** of the **skull**; **squamous**, **lambdoid**, **coronal** 2. **SYNDESMOSES** -- **bones** are separated by some **distance** and **held together by** **ligaments**; **radius** and **ulna** 3. **GOMPHOSES** -- consists of **pegs fitted** into **sockets** and held in place by ligaments; joint bet. a **tooth and its socket** - **CARTILAGINOUS JOINTS** -**Unites 2 bones** by means of **cartilage** -**Slight** **movement** can occur **1. SYNCHONDROSIS (HYALINE CARTILAGE**) -costal cartilage of **rib 1** and the **sternum** -epiphyseal plate in growing long bones ▪ **Synarthrosis** (**immovable**) **2. SYMPHYSIS (FIBROCARTILAGE)** **-Intervertebral discs** between adjacent vertebrae -anterior **connection** between the **pubic bones** ▪ **Amphiarthrosis** (**slightly movable**) - **SYNOVIAL JOINTS** -**Freely movable joints** -Contains **fluid in a cavity** surrounding the ends of articulating bones -Reinforced by **ligaments** **Synovial joints typically have the following structural characteristics**: - **JOINT (ARTICULAR) CAVITY** -A **space** **between** the articulating bones. The **cavity is filled** with **synovial fluid.** - **ARTICULAR CARTILAGE** -**Hyaline cartilage** that **covers** the **surfaces** of the **bones** forming the joint. - **ARTICULAR CAPSULE** -**2 layers** that **enclose the joint cavity.** 1\. **external layer** is **the fibrous layer** composed of **dense irregular** connective tissue 2**. inner layer** is the **synovial membrane** composed of **loose connective** tissue. - **SYNOVIAL FLUID** -A **viscous fluid**, the **consistency of egg** **whites**, located in the joint cavity - fluid **acts as a lubricant** - **REINFORCING LIGAMENTS** -Synovial joints are **reinforced by ligaments** outside and inside the articular capsule - **NERVES AND BLOOD VESSELS** **-Sensory nerve fibers detect** **pain** and joint stretching. -Most of the **blood vessels** **supply** the **synovial membrane.** **6 TYPES OF SYNOVIAL JOINTS** 1. **HINGE JOINT** -permit **movement** in **one plane only** -**elbow** and **knee** joints 2. **BALL AND SOCKET JOINTS** -consist of a **ball (head**) and a **socket** -Bones can **move in many directions** -**shoulder** and **hip** joints 3. **PIVOT JOINTS** -**restrict movement** to **rotation** around a **single axis** -**rotation** that occurs bet. the **axis** and **atlas** -**articulation** bet. the **ulna** and **radius** 4. **PLANE/GLIDING JOINTS** -**2 opposed flat surfaces** that **glide** over **each other** -**Limited but complex** movement -Between **tarsal bone** 5. **SADDLE JOINTS** -**2 saddle shaped** articulating surfaces oriented **at right angles** -joint bet. the **metacarpal** bone and the **carpal** bone of the thumb 6. **ELLIPSOD/CONDYLOID JOINTS** **-elongated ball** and **socket joints** -joint bet. the **occipital condyles** (skull) and the **atlas** (vertebral column) -joints bet. the **metacarpals** and **phalanges** **TYPES OF BODY MOVEMENT** - **FLEXION** -is a movement, generally in the **sagittal plane**, that **decrease the angle** of the joint and brings two bones closer together - **EXTENSION** -the **opposite of flexion**, so it is a movement that **increases the angle**, or the distance, between two bones or parts of the body.  - **ROTATION** **-**is movement of a bone **around** a **longitudinal axis**; it is a common movement of **ball-and-socket joints.** - **ABDUCTION** -is moving the **limb away from the midline**, or median plane, of the body. - **ADDUCTION** -is the opposite of abduction, so it is the **movement of a limb toward the body midline.**  - **CIRCUMDUCTION** \- is a **combination of flexion, extension, abduction, and adduction** commonly seen in ball-and-socket joints; the proximal end is stationary, and its distal end **moves in a circle.** - **SUPINATION** -occurs when the **forearm rotates laterally** so that the **palm faces anteriorly** and the **radius and ulna are parallel** - **PRONATION** -occurs when the **forearm rotates medially** so that the **palm faces posteriorly**. - **OPPOSITION** **-**In the palm of the hand, the saddle joint between **metacarpal 1 and the carpals allows opposition of the thumb.** - **INVERSION AND EVERSION.** -To **invert the foot**, turn the **sole medially** **(INVERSION)**; to **evert** the **foot**, turn the **sole laterally** **(EVERSION).** - **DORSIFLEXION AND PLANTAR FLEXION.** **-DORSIFLEXION** **Lifting the foot** so that its superior surface **approaches the shin** **-PLANTAR FLEXION.** whereas **depressing the foot**