Copy and Return to Teacher

Copy and Return to Teacher The Appendicular Skeleton The Appendicular Skeleton  126 bones o Limbs (appendages) o Pectoral girdle (attaches arm to the axial skeleton) o Pelvic girdle (attaches leg to the axial skeleton) The Pectoral (Shoulder) Girdle  Composed of two bones o Clavicle – collarbone o Scapula – shoulder blade  These bones are very light and allow the upper limb to have exceptionally free movement because: 1. Each pectoral girdle attaches to axial skeleton at only 1 point = sternoclavicular joint 2. The loose attachment of the scapula allows it to slide back & forth against the thorax 3. The glenoid cavity is shallow & the shoulder joint is poorly reinforced by ligaments

 Consists of 2 bones: 1. Clavicle (collar bone) = slender, double curved bone o Attaches to manubrium of the sternum medially & to the scapula laterally o Acts as a brace to hold the arm away from the thorax & helps prevent shoulder dislocation 2. Scapula (shoulder blade) = triangular & flare when we move our arms posteriorly (“wings”) o Not directly attached to axial skeleton; held in place by trunk muscles o Flattened body w/ 2 processes: . Acromion process = the enlarged end of the spine of the scapula  Connects w/ the clavicle @ the acromioclavicular joint . Coracoid process = beaklike  Points over the shoulder & anchors some of the arm muscles o Suprascapular notch serves as a nerve passageway o Scapula has 3 borders & 3 angles: . Superior . Medial (vertebral) borders . Lateral (axillary) . Superior . Inferior Angles . Lateral

Bones of the Upper Limb (30)  The arm is formed by a single bone  Humerus o Rounded proximal end fits into glenoid cavity of scapula o Opposite of the head – 2 bony processes = greater & lesser tubercles, sites of muscle attachment o Midpoint of shaft – deltoid tuberosity where the deltoid m. attaches o Radial groove runs obliquely down the posterior shaft o Distal end – medial trochlea (looks like a spool) & lateral ball-like capitulum – both articulate w/ bones of forearm o Above the trochlea anteriorly is a depression – coronoid fossa o On posterior surface is the olecranon fossa o Both are flanked by medial & lateral epicondyles

 Forearm – consists of the radius & ulna o Radius is lateral when the arm is in the anatomical position (on the thumb side) & the ulna is medial o When the hand is rotated, the distal end of the radius crosses over & ends up medial to the ulna. o Radius & ulna articulate @ small radioulnar joints o They are connected along their entire length by a flexible interosseous membrane o Both have a styloid process @ their distal end o Disc-shaped radial head forms a joint w/ the capitulum of the humerus. o Below the head is the radial tuberosity where tendon of biceps m. attaches. o On the ulna’s proximal end are the anterior coronoid process & the posterior olecranon process, which are separated by the trochlear notch.

. These 2 processes grip the trochlea of the humerus in a pliers-like joint.

 Hand consists of carpals, metacarpals & phalanges o 8 carpals arranged in 2 irregular rows of 4 bones each form the part of the hand called the carpus (wrist)

. Bound together by ligaments that restrict movements between them.

o Metacarpals form the palm

. Numbered 1 to 5 from the thumb to the pinky . Clenched fist – heads of the metacarpals = knuckles

o Phalanges (14) are the finger bones (3 in each finger & 2 in the thumb)

Carpals starting Left to Right (pinky to thumb - both rows): Joe took a Hamate and hit poor Pete in the Capitate, breaking it into a Trapezoid and Trapezium. He did it b/c he was Pisiform(d) Triquetral times. The Judge said he was Lunate and sent him to the Scaphoid.

The Bony Pelvis vs. the Pelvic Girdle  Bony Pelvis o Composed of: . Sacrum . Coccyx . Coxal bones (coxae) or ossa coxae (Hip bones)

 Pelvic Girdle o Coxae are composed of three pair of fused bones . Ilium . Ischium . Pubic bone The Pelvic Girdle: Right Coxal Bone

 Coxae are large, heavy & attached securely to the axial skeleton.  Sockets that receive the femur are deep & heavily reinforced w/ ligaments.  Function = bearing weight; total wt. of upper body rests on pelvis.  Reproductive organs, bladder & part of large intestine lie within & are protected by pelvis.  Each coxa is formed by the fusion of 3 bones: 1. Ilium (Large flaring bone - forms most of the coxa)  Connects posteriorly w/ sacrum @ the sacroiliac joint.  Alae - winglike portions of the ilia.  Iliac crest – upper edge of alae that ends anteriorly in the anterior superior iliac spine & posteriorly in the posterior superior iliac spine w/ small inferior spines located below these. 2. Ischium (“sit down bone”)  Most inferior part of coxa.  Ischial tuberosity, a roughened area, receives body wt. when sitting.  Ischial spine, superior to the tuberosity, narrows the outlet through which the baby passes during childbirth.  Greater sciatic notch allows blood vessels & the large sciatic nerve to pass from the pelvis posteriorly into the thigh. 3. Pubis or pubic bone  Most anterior part of the coxa.  Fusion of the rami of the pubis anteriorly & the ischium posteriorly forms a bar of bone enclosing the obturator foramen, an opening through which blood vessels & nerves pass into the anterior part of the thigh.  Pubic bones fuse anteriorly to form a cartilaginous joint called the pubic symphysis.  The ilium, ischium, & pubis fuse @ the deep socket called the acetabulum (“vinegar cup”); it receives the head of the femur. The Bony Pelvis

Male pelvis Female pelvis

 Bony pelvis is divided into 2 regions: o False pelvis, superior to the true pelvis, is the area medial to the flaring portions of the ilia. o True pelvis lies inferior to the flaring parts of the ilia & the pelvic brim. o Dimensions of the true pelvis are important for childbirth – must be large enough for the head to pass. . Outlet is the inferior opening of the pelvis. . Inlet is the superior opening. Differing characteristics between the male & female pelvis  Female inlet is larger & more circular.  Female pelvis as a whole is shallower & the bones are lighter & thinner.  Female ilia flare more laterally.  Female sacrum is shorter & less curved.  Female Ischial spines are shorter & farther apart; thus the outlet is larger.  Female pubic arch is more rounded because the angle of the pubic arch is greater. Bones of the Lower Limbs  Carry our total body weight when standing = thicker & stronger.  The thigh has one bone – femur (thigh bone)  Femur (thigh bone) o Heaviest, strongest bone in the body. o Proximal end has ball-like head, neck and greater & lesser trochanters. Trochanters are separated anteriorly by intertrochanteric line and posteriorly by intertrochanteric crest. o Trochanters, inter.-crest & gluteal tuberosity are sites for muscle attachment. o Slants medially as it runs downward to bring knees in line w/ body’s center of gravity. (more noticeable in females b/c of wider pelvis) o Distally are the lateral & medial condyles – articulate w/ tibia. (condyles separated by condylar fossa) o Anteriorly on distal end is the patellar surface – forms a joint w/ patella (kneecap)  Lower leg has 2 bones – Tibia & Fibula o Connected by interosseous membrane.  Tibia (shinbone) o Larger & more medial o At proximal end – medial & lateral condyles (separated by intercondylar eminence) articlulate w/ distal end of femur to form knee joint. o Patellar ligament attaches to tibial tuberosity (anter.) o Distally, a process called medial malleolus forms inner bulge of ankle. o Anterior surface has sharp ridge – anterior border (unprotected by muscle – so you can feel this)  Fibula o Thin & sticklike o Distally - lateral malleolus forms outer part of ankle.  Foot – composed of tarsals, metatarsals & phalanges o Two important functions: supports body weight & serves as a lever allowing us to propel body forward when walking,etc. o 7 Tarsals . Weight carried by the 2 largest tarsals:  calcaneus (heelbone) &  talus (lies b/n tibia & calcaneus) o 5 metatarsals form the sole o 14 phalanges form the toes (each toe has 3, except the big toe) o Bones are arranged to form 3 strong arches: . 2 longitudinal (medial & lateral), 1 transverse  Ligaments bind foot bones together  Tendons of the foot muscles help to hold bones in arched position but allow for “springiness” – weak arches are referred to as “fallen arches” or “flat feet”