Two Major Regions
Two major regions of the skeleton
- Axial Skeleton:
Frontal Bone, Parietal Bone, Occipital Bone, Temporal Bone, Sphnoid Bone, Ethmoid Bone
Malleus, Incus, Stapes
Cervical Vertebrae (7), Thoracic Vertebrae (12), Lumbar Vertebrae (5), Saccrum, Coccyx
- Appendicular Skeleton:
Humerus, Radius, Ulna, Carpals, Metacarpals, Phalanges
Femur, Patella, Tibia, Fibula, Tarsals, Metatarsals, Phalanges
Typical number of bones
206 in typical adult skeleton (can range 204-207)
- 22 bones joined together by sutures
- Cranial bones surround cranial cavity
- *Frontal Bone** (1)
- *Parietal Bones** (2)
- *Temporal Bone** (1)
- *Occipital Bone **(1)
- *Sphenoid Bone** (1)
- *Ethmoid Bone** (1)
- **Facial bones support teeth and form nasal cavity and orbit **(make up for the other 14 bones)
- *Maxilla** (2)
- *Palatine Bone** (2)
- *Zygomatic Bone** (2)
- *Lacrimal Bone** (2)
- *Nasal Bone** (2)
- *Vomer** (1)
- *Inferior Nasal Concha** (2)
- *Mandible** (1)
- Forms forehead
- Forms roof of the orbit (Eye-socket)
- Contains frontal sinuses (openings in the bone which help lighten the bone)
- Cranial roof and part of its lateral walls
- Temporal lines of temporalis muscle
- One on each side, seperated by the Saggital Suture
Lateral wall and part of floor of cranial cavity
- Squamous part (flat part of bone)
- Tympanic part (external auditory canal/external auditory meatus)
- Mastoid part (mastoid process)
- Petrous portion (rocky, stlyoid process and surface)
Rear and base of skull
- Foramen magnum: Hole located in the mid-section of the occipital bone
- Skull rests on atlas
This bone helps form the base of the cranium, the sides of the skull, and the floors and sides of the orbits (eye sockets).
- Sella Turcica (Turk’s saddle): A saddle-shaped mass along the middle, within the cranial cavity. The depression of this saddle is occupied by the pituitary gland, which hangs from the base of the brain by a stalk.
- Sphenoidal Sinuses: Two sinesus which lie side by side and are separated by a bony septum that projects downward into the nasal cavity.
An anterior cranial bone located between the eyes. It is a very porous and delicate bone.
THREE major portions:
- Vertical Perpendicular Plate: A thin median plate that forms the superior two-thirds of the nasal septum (The lower part is formed by cartilages and the vomer) The septum divides the nasal cavity into right and left air spaces called the nasal fossae. The septum is often curved, or deviated, toward one nasal fossa or the other.
- Cribriform Plate: Horizontal plate, forms the roof of the nasal cavity. This plate has a median crest called the crista galli, an attachment point for the dura mater. On each side of the crista is an elongated depressed area perforated with numerous holes, the cribriform (olfactory) foramina. A pair of olfactory bulbs of the brain, concerned with the sense of smell, rests in these depressions, and the foramina allow passage for olfactory nerves from the nasal cavity to the bulbs.
- Labyrinth: A large mass on each side of the perpendicular plate. The labyrinth is named for the fact that internally, it has a maze of air spaces called the ethmoidal cells.
Malleus, Incus, Stapes
Largest facial bones.
They form the upper jaw and meet each other at a median intermaxillary suture.
- Alveolar Processes: Grow into the spaces between the bases of the teeth.
- Infraorbital Foramen: Just below the orbit, provides passage for a blood vessel to the face and a nerve that receives sensations from the nasal region and cheek.
- Inferior Orbital Fissure: A gash in the maxilla, angles downward and medially. The inferior and superior orbital fissures form a sideways V whose apex lies near the optic foramen. The inferior orbital fissure is a passage for blood vessels and sen- sory nerves from the face.
Located in the posterior nasal cavity.
- Horizontal Plate: (L-shape) form the posterior one-third of the bony palate.
- Perpendicular Plate: (L-shape) A thin, delicate, irregularly shaped plate that forms part of the wall between the nasal cavity and the orbit.
- Palatine Foramen: A nerve passage to the palate.
The zygomatic bones (cheekbones) form the angles of the cheeks inferolateral to the eyes and part of the lateral wall of each orbit; they extend about halfway to the ear.
- Zygomaticofacial Foramen: Inverted T shape on each zygomatic bone near the intersection of the stem and crossbar of the T.
- Zygomatic Arch: Flares from each side of the skull, formed by the union of the zygomatic bone, temporal bone, and maxilla.
The lacrimal bones form part of the medial wall of each orbit. These are the smallest bones of the skull, about the size of a small fingernail.
Lacrimal Fossa: Depression that houses a membranous lacrimal sac. Tears from the eye collect in this sac and drain into the nasal cavity.
Two small rectangular nasal bones form the bridge of the nose and support cartilages that shape the lower portion of the nose.
The vomer forms the inferior portion of the nasal septum. Its name literally means “plowshare,” which refers to its resemblance to the blade of a plow. The superior half of the nasal septum is formed by the perpendicular plate of the ethmoid bone. The vomer and perpendicular plate support a wall of septal cartilage that forms most of the anterior part of the septum.
Inferior Nasal Concha
There are three conchae in the nasal cavity.
- Superior Conchae
- Middle Conchae
- Inferior Nasal Concha: Largest of the three.
Only movable bone
- Holds the lower teeth
- Attachment of muscles for mastication
- Mandibular foramen: Two small holes located on both inner-sides of mandible (for alveolar nerve and vessel)
- Mental foramen: Two small holes located on both outter-sides of mandible (mental nerve and other veins pass through to supply the tissues of the mouth)
- Ramus: The portion of the mandible from the condoyle to the angle.
- Angle: Small corner of the mandible where the bone begins to slop upward toward.
- Body: The portion of the mandible from the angle to the chin.
The Vertebral Column
- 33 vertebrae (Though variations in number of lumbar and sacral vertebrae)
Five vertebral groups
- Cervicle Vertebrae: (7) C1-C7
- Thoracic Vertebrae: (12) T1-T12 (Giraffes)
- Lumbar Vertebrae: (5) L1-L5 (Moose)
- Sacrum: (5) S1-S5
Thoracic (Rib) Cage
- Involved in respiration
Attaches upper extremity to the body
- Scapula and clavicle
- Clavicle attaches medially to the sternum and laterally to the scapula
Brachium and Antebrachium
- Brachium: The arm, specifically the upper arm from shoulder to elbow.
- Antebrachium: The forearm.
Supports trunk on the legs and protects viscera.
Carpals, Metacarpals, Phalanges
Carpal Bones: Bones of the wrist.
- Some - Scaphoid
- Lovers - Lunate
- Try - Triquetrum
- Positions - Pisiform
- That - Trapezium
- They - Trapezoid
- Can’t - Capitate
- Handle - Hamate (has prominent hook)
Metacarpal Bones: Bones of the palm.
- Metacarpal I is located proximal to the thumb
- Metacarpal V is proximal to the little finger
- The proximal end of a metacarpal bone is called the base, the shaft is called the body, and the distal end is called the head. The heads of the metacarpals form the knuckles when you clench your fist.
Phalanges: Bones of the fingers.
- Phalanges are identified by roman numerals preceded by proximal, middle, and distal.
- The three parts of a phalanx are the same as in a metacarpal: base, body, and head.
- The ventral surface of a phalanx is slightly concave from end to end and flattened from side to side; the dorsal surface is rounder and slightly convex from end to end.
Comparison of Male and Female
- Female: Lighter, shallower pubic arch, pubic inlet round or oval
- Male: Heavier, upper pelvis nearly vertical, coccyx more vertical, and pelvic inlet heart-shaped
Femur and Patella
- Femur: Hip bone. The longest and strongest bone of the body.
- Patella: Knee bone.
The larger, medially placed lower leg bone.
The smaller of the two lower leg bones.
(Fib: Small lie - Fibula: Smaller bone).
The Ankle and Foot
Proximal row of tarsal bones
- Calcaneus: Largest tarsal bone. Forms the heel. Its posterior end is the point of attachment for the calcaneal (achilles) tendon from the calf muscles.
- Talus: Second-largest tarsal bone, and the most superior.
It has three articular surfaces:
Inferoposterior: Articulates with the calcaneus.
Superior Trochlear: Articulates with the tibia.
Anterior: Articulates with a short, wide tarsal bone called the navicular.
Distal row of tarsal bones
- Medial Cuneiforms
- Intermediate Cuneiforms
- Lateral Cuneiforms
- Cuboid: The cuboid is the largest.
- Metatarsals I through V from medial to lateral, metatarsal I being proximal to the great toe. Note that roman numeral I represents the medial group of bones in the foot but the lateral group in the hand. In both cases, however, it refers to the largest digit of the limb. Metatarsals I through III articulate with the three cuneiforms; metatarsals IV and V articulate with the cuboid.
Bipedalism and Limb Adaptations
- Humans support their entire body weight on two feet. The tarsal bones are tightly articulated with each other, and the calcaneus is strongly developed.
- The hallux provides the “toe-off” that pushes the body forward in the last phase of the stride.
- Although apes are flat-footed, humans have strong, springy foot arches that distribute the body’s weight between the heels and the heads of the metatarsal bones and absorb stress as the body jostles up and down during walking and running.
Bipedalism and Upright Stance
Bipedalism and Head Position
** Classified by freedom of movement**
Classified how adjacent bones are joined
- Gap between two bones ossifies
- Can occur in either fibrous or cartilaginous joint
- Collagen fibers span the space between bones
Immovable fibrous joints
- Serrated: Interlocking lines
- Lap: Overlapping beveled edges
- Plane: Straight, nonoverlapping edges
Types of Sutures
Attachment of a tooth to its socket
- Held in place by fibrous periodontal ligament
- Some movement while chewing
Two bones bound by ligament only
- Most movable of fibrous joints
Bones are joined by hyaline cartilage
2 bones joined by fibrocartilage
- Only slight amount of movement is possible
Joint in which two bones are separated by a space called a joint cavity
Articular capsule encloses joint cavity
- Synovial fluid = slippery fluid; feeds cartilages
Types of Synovial Joints
- Ball-and-Socket Joints
Smooth hemispherical head fits within a cuplike depression
- Condyloid (ellipsoid) Joints
Oval convex surface on one bone fits into a similarly shaped depression on the next
- Saddle Joints
Each articular surface is shaped like a saddle, concave in one direction and convex in the other
- Gliding Joints
Flat articular surfaces in which bones slide over each other
Limited monoaxial joint
- Hinge Joints
One bone with convex surface that fits into a concave depression on other bone
- Pivot Joints
One bone has a projection that fits into a ringlike ligament of another
First bone rotates on its longitudinal axis relative to the other
Range of Motion
Degrees through which a joint can move
- Structure of the articular surfaces
- Strength and tautness of ligaments, tendons and capsule
- Action of the muscles and tendons
Axes of Rotation
Other joints: monoaxial or biaxial
Types of Movement
The Humeroscapular Joint
Most freely movable joint in the body
- Supportd by ligaments and tendons
(3 glenohumeral, coracohumeral, transverse humeral and biceps tendon)
- Associated with shoulder joint
Stabilizers of the Shoulder Joint
Tendons of Rotator Cuff Muscles
Dissection of Shoulder Joint
The Elbow Joint
Single joint capsule enclosing the humeroulnar and humeroradial joints
The Coaxal (hip) Joint
Head of femur articulates with acetabulum
Dissection of Hip Joint
The Knee Joint
Most complex diarthrosis
Joint capsule anteriorly consists of patella and extensions of quadriceps femoris tendon
(Anterior and Posterior Views)
- Anterior and lateral cruciate ligaments
- Medial and lateral collateral ligaments
Medial and lateral meniscus absorb shock and shape joint
Dissection of Knee Joint
- Arthritis: is a broad term for pain and inflammation
- Osteoarthritis: results from years of joint wear
- Rheumatoid arthritis: is autoimmune attack on joint