The Appendicular Skeleton PDF

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Includes notes and pictures about the skeleton and the entire chapter...

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The Appendicular Skeleton An Introduction to the Appendicular Skeleton (PG 242) 

Axial Skeleton = 80 bones

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Appendicular Skeleton - Includes bones of the limbs and the supporting bone (Pectoral and Pelvic) girdles that connect them to the trunk. o It is dominated by the long bones that support the limbs o One epiphysis is usually called the Head, The diaphysis is called the Shaf  A Neck separates the Head and Shaf

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The Axial Skeleton protects and supports internal organs and takes part in vital functions, such as breathing

The Pectoral Girdles - The Clavicles and Scapulae - Attach the Limbs to the Axial Skeleton (PG 242)   

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Articulates = Forms A Joint Each arm articulates with the trunk at a Pectoral Girdle (or Shoulder Girdle) The Pectoral Girdle consists of 2 S-Shaped Clavicles and 2 broad, flat Scapulae o The medial, anterior end of each clavicle articulates with the manubrium of the sternum o These articulations are the ONLY direct connections between the pectoral girdles and the axial skeleton o Scapulae has no direct bony or ligamentous connections to the thoracic cage, this is why shoulders are extremely mobile, but not very strong o Movements of the clavicles and scapulae positions the shoulder joints and provide a base for arm movement Bone markings such as Sulci or Foramina indicate the positions of nerves that control the muscles or the passage of blood vessels that nourish the muscles and bones

The Clavicles (PG 244) 

Clavicles - Are S-Shaped bones that articulate (forms a joint) at the superior, lateral border of the manubrium of the sternum, lateral to the jugular notch o The jugular notch is the depression just superior to the manubrium o Clavicles are small and fragile  Acromial End of the clavicle is broader than the sternal end  Sternoclavicular Joints are located where the sternum articulates with the clavicles o These are the ONLY articulations between the pectoral girdles and the axial skeleton

The Scapula (PG 244) 

The anterior surface of the body of each scapula forms a broad triangle o The three sides of the triangle are the Superior Border, the Medial Border (or Vertebral Border), and the Lateral Border (or Axillary Border (Axilla, Armpit)  Muscles that position the scapula attach along these edges  The corners of the triangle are called the Superior Angle, the Inferior Angle, and the Lateral Angel  The Lateral Angel (or Head of the Scapula) forms a broad process that supports the cup-shaped Glenoid Cavity  At the glenoid cavity, the scapula articulates with the humerus. This articulation is the Shoulder Joint, also known as the Glenohumeral Joint  The depression in the anterior surface is called the Subscapular Fossa

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Two large scapular processes extend beyond the margin of the glenoid cavity superior to the head of the humerus. o The smaller, anterior projection is the Coracoid Process o The larger, posterior is the Acromion  The acromion articulates with the clavicle at the acromioclavicular joint  It is continuous with the Scapular Spine, a ridge that crosses the posterior surface of the scapular body before ending at the medial border  The Scapular Spine divides the convex posterior surface of the body into two regions  The area superior to this spine is the Supraspinous Fossa  The region inferior to the spine is the Infraspinous Fossa o Both of these are attached to ligaments and tendons associated with the shoulder joint

The Upper Limbs Are Adapted For Free Movement (PG 245) 

The term arm refers only to the proximal portion of the upper limb (from shoulder to elbow)  The distal portion of the upper limb (from elbow to wrist) is he forearm

The Humerus (PG 254) 

The arm (or Brachium) contains only one bone, the Humerus, which extends from the scapula to the elbow  At the proximal end of the humerus, the round head articulates with the scapula 

Greater Tubercle is a rounded projection on the lateral surface of the epiphysis near the margin of the humeral head o It establishes the lateral contour of the shoulder

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Lesser Tubercle is a smaller projection that lies on the anterior, medial surface of the epiphysis, separated from the greater tubercle by the Intertubercular Groove (or Intertubercular Sulcus)  Both are important sites for muscle attachments

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Anatomical Neck lies between the tubercles and the articular surface of the head. o It marks the extent of the joint capsule

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Surgical Neck corresponds to the metaphysis of the growing bone o Fractures typically occur at this site

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Deltoid Tuberosity is a large, rough elevation on the lateral surface of the shaf, approximately halfway along its length o It is named afer the deltoid muscle which attaches to it

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On the posterior surface, the deltoid tuberosity ends at the Radial Groove o The depression marks the path of the Radial Nerve, a long nerve that provides both sensory information from the posterior surface of the limb and motor control over the large muscles that straighten the elbow

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Near the distal articulation with the bones of the forearm, the shaf expands to either side at the Medial and Lateral Epicondyles o Epicondyles are processes that develop proximal to an articulation o They provide additional surface area for muscle attachment

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The Ulna nerve crosses the posterior surface of the medial epicondyle. At the condyle, the humerus articulates with the radius and the ulna, the bones of the forearm o The condyle is divided into two articular regions: The Trochlea and the Capitulum  Trochlea: Is the spool-shaped medial portion of the condyle  Extends from the base of the coronoid fossa on the anterior surface to the olecranon fossa on the posterior surface  Capitulum: Forms the lateral surface of the condyle  The Radial Fossa accommodates a portion of the radial head as the forearm approaches the humerus  Projections from the ulnar surface fit into the coronoid fossa and the olecranon fossa as the elbow approaches the limits of its range of motion

The Ulna (PG 247) 

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The ulna and radius are parallel bones that support the forearm, or antebrachium o The ulna is medial to the radius in the anatomical position o Olecranon is the proximal end of the ulna, it is the point of the elbow o Anterior surface of the proximal epiphysis, the Trochlear Notch of the ulna articulates with the trochlea of the humerus at the elbow joint The olecranon forms the superior lip of the trochlear notch Coronoid Process forms its inferior lip o At the limit of Extension, movement that straightens the forearm and arm, the olecranon swings into the olecranon fossa on the posterior surface of the humerus o At the limit of Flexion, a movement that decreases the angle between the articulating bones, the arm and forearm form a tight V, and the coronoid process projects into the coronoid fossa on the anterior humeral surface. o Lateral to the coronoid process, a smooth Radial Notch accommodates the head of the radius at the proximal radioulnar joint

Interosseous Membrane, a fibrous sheet, connects the lateral margin of the ulna to the radius  Near the wrist the shaf of the ulna narrows before ending at a disc-shaped Ulnar Head (or head of the ulna)  Styloid Process, the posterior, lateral surface of the ulnar head o A triangular cartilage, the articular disc, attaches to the styloid process. It separates the ulnar head from the bones of the wrist

The Radius (PG 247)  

Radius is the lateral bone of the forearm Radial Head (or Head of the Radius), articulates with the capitulum of the humerus o It swings into the radial fossa of the humerus during flexion  Radial Tuberosity marks the attachment site of the biceps brachii muscle, a large muscle on the anterior surface of the arm  Ulnar Notch on the medial surface of the distal end of the radius marks the site of articulation with the head of the ulna  Styloid Process - on the lateral surface of the radius, helps stabilize the joint (wrist)

Carpal Bones (PG 247)

Carpal Bones: Some Loves Try Positions That They Can't Handle = Scaphoid, Lunate, Trapezium, Pisiform, Trapezoid Triquetrum, Capitate, Hamate

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The Carpus (or Wrist) contains 8 Carpal Bones o These bones form 2 rows, one with 4 Proximal Carpal Bones and the other with four Distal Carpal Bones  The carpal bones are the:

o Scaphoid (Skaphe, boat): is the proximal carpal bone on the lateral border of the wrist  It is the carpal bone closet to the styloid process of the radius  Lunate (Luna, moon): is comma-shaped. It lies medial to the scaphoid, and it articulates with the radius  Triquetrum (three cornered). It is a small, pyramid-shaped bone medial to the lunate.  It articulates with the articular disc that separates the ulnar head from the wrist  Pisiform: Pea-shaped. Sits anterior to the triquetrum  

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The distal carpal bones are the: Trapezium (4 sided with no parallel sides). It is the lateral bone of the distal row.  Its proximal surface articulates with the scaphoid Trapezoid (Wedge Shaped). Lies medial to the trapezium.  It has a proximal articulation with the scaphoid Capitate (head) is the largest carpal bone.  It sits between the trapezoid and the hamate Hamate (Hooked) is the medial distal carpal bone

The Metacarpal Bones and Phalanges (PG 248)

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5 metacarpal bones articulate with the distal carpal bones and support the hand

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Roman numerals I-V articulate with the trapezium Distally, metacarpal bones articulate with the proximal finger bones.

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Each hand has 14 finger bones (or Phalanges) The first finger is known as the Pollex (or thumb), has 2 phalanges (proximal and distal)  Each of the other 4 fingers has three phalanges (proximal, middle and distal)

The Pelvic Girdle - Two Hip Bones - Attaches The Lower Limbs To The Axial Skeleton (PG 250) 

Pelvic Girdle, the bones are massive because they are weight bearing  Consists of 2 hip bones o Pelvis includes the hip bones of the appendicular skeleton plus the sacrum and coccyx of the axial skeleton

The Pelvic Girdle (PG 250)

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Consist of paired Hip Bones (Coxal Bones or Pelvic Bones)  Each hip bone forms by the fusion of 3 bones: an Ilium, and a Pubis o The ilia have a sturdy articulation with the auricular surfaces of the sacrum, attaching the pelvic girdle to the axial skeleton o Anteriorly, the medial surfaces of the hip bones are connected by a pad of fibrocartilage at a joint called the Pubic Symphysis o

Acetabulum is a concave socket that articulates with the head of the femur There is a ridge of bone which is incomplete, leaving a gap called the Acetabular notch  The smooth cup-shaped articular surface of the acetabulum is the Lunate Surface 

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The ilium, ischium, and pubis meet inside the acetabulum, as though it were a pie sliced into three pieces

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Bone markings along the margin of the ilium include the iliac spines, which mark at the attachment sites of important muscles and ligaments o The gluteal lines, mark the attachment of large hip muscles o The Greater Sciatic Notch through which a major nerve (Sciatic Nerve) reaches the lower limb

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Ischium forms the posterior, inferior portion of the acetabulum

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Ischial Spine is posterior to the acetabulum It projects superior to the lesser sciatic notch This is where blood vessels and small muscles pass

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Ischial Tuberosity is located at the posterior and lateral edge of the ischium The ischial tuberosities bear your body weight when you are sitting

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The ischial ramus meets the inferior ramus of the pubis  The inferior pubic ramus extends between the ischial ramus and the pubic tubercle, a small, elevated area anterior and lateral to the pubic symphysis.  This is where the inferior pubic ramus meets the superior ramus of the pubis, which originates near the acetabulum

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Pectineal, a ridge that ends at the pubic tubercle, found on the anterior superior surface of the superior ramus o The pubic ramus and ischial ramus encircle the Obturator Foramen o The broadest part of the ilium extends between the Arcuate Line which is continuous with the pectineal line, and the Iliac Crest o Iliac Fossa - the area between the arcuate line and the iliac crest; shallow depression o

Pubic Symphysis 2 pubic bones are attached to a median pad of fibrocartilage o Auricular Surface, posteriorly, articulates with the auricular surface of the sacrum at the Sacroiliac Joint

The Pelvis (PG 250) o o

Pelvis consists of 2 hip bones, the sacrum and the coccyx It may be divided into true (lesser) pelvis and false (greater) pelvis o

True Pelvis: Encloses the pelvic cavity, a subdivision of the abdominopelvic cavity  The superior limit of the true pelvis is a line that extends from either side of the base of the sacrum, along the arcuate line and pectineal line to the pubic symphysis  The bony edge of the true pelvis is called the Pelvic Brim (or Lineal Terminalis)  Pelvic Inlet is the enclosed space  False Pelvis: Consists of the expanded, bladelike portions of each ilium superior to the pelvic brim

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Pelvic Outlet is the opening bounded by the coccyx, the ischial tuberosities, and the inferior border of the pubic symphysis

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Perineum: The surface region bordered by the inferior edges of the pelvis Perineal muscles form the floor of the pelvic cavity and support the organs in the true pelvis

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The Pelvis:  In females, the pelvis is generally smoother and lighter and has lessprominent markings.  Other variations appear to be adaptions for childbearing  The adaptions help support the weight of the developing fetus within the uterus, and the passageway of the newborn through the pelvic outlet during pregnancy  The hormone relaxin, produced during pregnancy, loosens the pubic symphysis and sacroiliac ligaments  The loosening allows movement between the hip bones that can further increase the size of the pelvic inlet and outlet

The Lower Limbs Are Adapted For Movement and Support (PG 254) o

The lower limbs transfer the body weight to the ground

The Femur (PG 254) o 

Femur is the longest and heaviest bone in the body It articulates with the hip bone at the hip joint and with the tibia of the leg at the knee joint.

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Femoral Head, the rounded epiphysis, articulates with the pelvis at the acetabulum o Fovea Capitis, a small pit in the center of the femoral head

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The neck of the femur joins the shaf at an angle of about 125° The greater and lesser trochanters are large, rough projections that originate at the junction of the neck and shaf  The greater trochanter projects laterally  The lesser trochanter projects posteriorly and medially  They develop where large tendons attach to the femur Intertrochanteric, on the anterior surface, marks the edge of the articular capsule  This line continues around to the posterior surface as the Intertrochanteric Crest

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Linea Aspera is a rough ridge that runs along the center of the posterior surface of the femur, marking the attachment site of powerful hip muscles  As it approaches the joint it divides into a pair of ridges that continue to the medial and lateral epicondyles  Medial and lateral condyles are part of the knee joint  The two condyles are separated by a deep intercondylar fossa  The anterior and inferior surfaces of the two condyles are separated by the patellar surface

The Patella (PG 254) o

Patella is a large sesamoid bone that forms within the tendon of the quadriceps femoris, a group of muscles that extend (straighten) the knee o The patellar ligament connects the apex of the patella to the tibia o

The posterior patellar surface has two concave facets for articulation with the medial and lateral condyles of the femur o The patella are cartilaginous at birth  They start to ossify afer the person begins walking, as thigh and leg movements become more powerful  Ossification usually begins at age 2 or 3 and ends around time of puberty  Its direction of movement is superior-inferior (up and down), not medial-lateral (side to side)

The Tibia (PG 256)

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Tibia (or Shinbone), is the largest medial bone of the leg Medial and lateral condyles of the femur articulate with the medial and lateral tibial condyles at the proximal end of the tibia Intercondylar Eminence is a ridge that separates the condyles Tibial Tuberosity marks the attachment of the patellar ligament Anterior Margin is a ridge that begins a the tibial tuberosity Medial Malleolus is a large process familiar to you as the medial bump at the ankle

The Fibula (PG 256) o o o

Fibula parallels the lateral border of the tibia The head of the fibula articulates with the tibia The articular facet is located on the anterior. Inferior surface of the lateral tibial condyle o Interosseous Membrane, extends to the lateral margin of the tibia  This membrane helps stabilize the positions of the two bones, and provides additional surface area for muscle attachment o 

The fibula does not help transfer weight to the ankle and foot It does not articulate with the femur

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Lateral Malleolus, the fibular process, gives lateral stability to the ankle A forceful movement of the foot outward and backward can dislocate the ankle, breaking both the lateral malleolus and the fibula and the medial malleolus of the tibia  This injury is called a Pott's Fracture

The Tarsal Bones (PG 257) o o

The ankle (or Tarsus) consists of 7 Tarsal Bones The large Talus transmits the weight of the body from the tibia toward the toes

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Trochlea, a spool-or pulley shaped articular process  The lateral surface of the trochlea articulates with the lateral malleolus of the fibula

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The calcaneus (or hells bone) is the largest of the tarsal bones When you stand, your weight is transmitted from the tibia, to the talus, to the calcaneus and then to the ground o The posterior portion of the calcaneus is the attachment site for the calcaneal tendon (Achilles Tendon), which arises at the calf muscle.  These muscles can help you stand on your toes.

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Cuboid articulates with the anterior surface of the calcaneus Navicular is an anterior to the talus, on the medial side of the ankle It articulates with the talus and with the 3 Cuneiform Bones (wedge shaped bones arranged in a row, with articulations between them) Named according to their position: Medial Cuneiform, Intermediate Cuneiform, and Lateral Cuneiform Proximally, the cuneiform bones articulate with the anterior surface of the navicular The lateral cuneiform also articulates with the medial surface of the cuboid The distal surfaces of the cuboid and cuneiform bones articulate with the metatarsal bones of the foot

The Metatarsal Bones and Phalanges (PG 258) o

Metatarsal Bones are 5 long bones that form the distal portion of the foot (or Metatarsus) o Are identified by roman numerals I-V, from medial to lateral across the sole  Proximally metatarsal bones I-III articulate with the three cuneiform bones, and metatarsal bones IV and V articulate with the cuboid  Distally, each metatarsal bone ...