1. SKELETAL SYSTEM
Prepared By
Doppalapudi Sandeep
M. Pharmacy,
Assistant Professor
Department of Physiology & Pharmacology
Chebrolu Hanumaiah Institute of Pharmaceutical
Sciences, Chandramoulipuram, Chowdavaram,
Guntur, Andhra Pradesh, India 522019
2. The Skeletal System
Parts of the skeletal system include:
Bones (skeleton)
Joints
Cartilages
Ligaments
Divided into two divisions:
1. Axial skeleton 80 bones
2. Appendicular skeleton 126 bones
3. Functions of Bones
Framework
Supports muscle, fat and skin
Protection
Surrounds vital organs like skull, ribs, pelvis
Movement
Muscles attach to bones to provide movement
Mineral homeostasis
Stores and maintain minerals (Calcium & phosphorus)
Production of blood cells
Red bone marrow produes Red and white blood cells and platelets
Storage
Calcium
Yellow bone marrow has adipocytes stores fat.
4. Classification of Bones
Long bones
Typically longer than wide
Have a shaft with heads at both ends
Contain mostly compact bone
Examples: Femur, humerus
Short bones
Generally cube-shape
Contain mostly spongy bone
Examples: Carpals, tarsals
5. Classification of Bones
Flat bones
Thin and flattened, usually curved
Thin layers of compact bone around a layer
of spongy bone
Examples: Skull, ribs, sternum
Irregular bones
Irregular in shape
Do not fit into other bone classification
categories
Example: Vertebrae and hip
7. Gross Anatomy
of a Long Bone
Diaphysis
Shaft
Composed of compact
bone
Epiphysis
Ends of the bone
Composed mostly of
spongy bone
9. The Axial Skeleton
Forms the longitudinal part of the body
Divided into three parts
Skull
Vertebral column
Bony thorax
10. Skull (Cranium)
Consists of 22 bones
Bones of the skull are grouped into two categories:
Cranial bones - Eight cranial bones form the cranial cavity
Frontal bone,
two parietal bones,
two temporal bones,
the occipital bone,
the sphenoid bone,
ethmoid bone
Facial bones - Fourteen facial bones form the face
Two nasal bones,
two maxillae,
two zygomatic bones,
the mandible,
two lacrimal bones,
two palatine bones,
two inferior nasal conchae and vomer
11. Skull
The cranial and facial bones protect and support
special sense organs and the brain.
Besides forming the large cranial cavity, the skull
also forms several smaller cavities
Nasal cavity
Orbits (eye sockets)
Paranasal sinuses
Small cavities which house organs involved in hearing
and equilibrium
13. Skull
Immovable joints called sutures fuse most of the skull
bones together.
The skull provides large areas of attachment for
muscles that move various parts of the head.
Skull and facial bones provide attachment for muscles
that produce facial expressions.
The facial bones form the framework of the face and
provide support for the entrances to the digestive and
respiratory systems.
14. Skull (Cranial Bones)
Frontal Bone
Forms the forehead
Parietal Bones
Form the sides and roof of the cranial cavity
Temporal Bones
Form the lateral aspects and floor of the cranium
Occipital Bone
Forms the posterior part and most of the base of the cranium
Sphenoid Bone
Lies at the middle part of the base of the skull
Ethmoid Bone
Located on the midline in the anterior part of the cranial floor medial to
the orbits
A major superior supporting structure of the nasal cavity
Contain thin projections called conchae which are lined by mucous
membranes
Increased surface area in the nasal cavity helps to humidify inhaled air
trapping inhaled particles
16. Skull (Facial Bones)
Nasal Bones
Form the bridge of the nose
Maxillae
Form the upper jawbone and most of the hard palate
Separates the nasal cavity from the oral cavity
Zygomatic Bones (Cheek bones)
form the prominences of the cheeks
Lacrimal Bones
Form a part of the medial wall of each orbit
Palatine Bones
Form the posterior portion of the hard palate
Inferior Nasal Conchae
Form a part of the inferior lateral wall of the nasal cavity
17. Skull (Facial Bones)
Vomer
Forms the inferior portion of the nasal septum
Mandible
Lower jawbone and the only movable skull bone
The largest, strongest facial bone
Nasal Septum
Divides the interior of the nasal cavity into right and left sides
Orbits
Eye socket
Foramina
Openings for blood vessels, nerves or ligaments of the skull
21. Paranasal Sinuses
Hollow portions of bones surrounding the
nasal cavity
Functions:
Lighten the skull
Give resonance and
amplification to voice
Warm and moisten
air
22. The Hyoid Bone
The only bone that
does not articulate
with another bone
Serves as a
moveable base for
the tongue
The hyoid bone also
helps to keep the
larynx (voice box)
open at all times
23. Vertebral Column
Also called the spine, backbone, or spinal column
Functions:
Protect the spinal cord
Support the head
Serve as a point of attachment for the ribs, pelvic girdle, and
muscles
The vertebral column is curved to varying degrees in
different locations
Curves increase the column strength
Help maintain balance in the upright position
Absorb shocks during walking, and help protect the vertebrae from
fracture
24. Vertebral Column
Composed of a series of bones called vertebrae
(Adult=26)
7 cervical are in the neck region
12 thoracic are posterior to the thoracic cavity
5 lumbar support the lower back
1 sacrum consists of five fused sacral vertebrae
1 coccyx consists of four fused coccygeal vertebrae
26. Intervertebral Discs
Found between the bodies of adjacent vertebrae
Functions to:
Form strong joints
Permit various movements of the vertebral column
Absorb vertical shock
Vertebrae typically consist of:
A Body (weight bearing)
A vertebral arch (surrounds the spinal cord)
Several processes (points of attachment for muscles)
27. Vertebral Column (Regions)
Cervical Region
Cervical vertebrae (C1C7)
The atlas (C1) is the first cervical vertebra
The axis (C2) is the second cervical vertebra
Thoracic Region
Thoracic vertebrae (T1T12)
Articulate with the ribs
Lumbar Region
Lumbar vertebrae (L1L5)
Provide for the attachment of the large back muscles
Sacrum
The sacrum is a triangular bone formed by the union of five
sacral vertebrae (S1S5)
Serves as a strong foundation for the pelvic girdle
Coccyx
The coccyx, like the sacrum, is triangular in shape
It is formed by the fusion of usually four coccygeal vertebrae
32. Thorax
Thoracic cage is formed by the:
Sternum
Ribs
Costal cartilages
Thoracic vertebrae
Functions to:
Enclose and protect the organs in the thoracic and
abdominal cavities
Provide support for the bones of the upper limbs
Play a role in breathing
33. Thorax
Sternum
Breastbone located in the center of the thoracic wall
Consists of the manubrium, body, xiphoid process
Ribs
Twelve pairs of ribs give structural support to the sides of the
thoracic cavity
True ribs (7 pairs), False ribs (3 Pairs) and floating ribs(2 pairs).
Costal cartilages
Costal cartilages contribute to the elasticity of the thoracic cage
38. Upper Limb
The pectoral girdle consists of two bones,
the scapula and the clavicle
The free part has 30 bones
1 humerus (arm)
1 ulna (forearm)
1 radius (forearm)
8 carpals (wrist)
19 metacarpal and phalanges (hand)
39. The Pectoral (Shoulder) Girdle
Composed of two bones
Clavicle collarbone
Scapula shoulder blade
These bones allow the upper limb to have
exceptionally free movement.
The clavicle is convex in shape anteriorly
near the sternal junction
The clavicle is concave anteriorly on its
lateral edge near the acromion
41. Pectoral Girdle - Scapula
Also called the shoulder blade
Triangular in shape
Most notable features include the spine,
acromion, coracoid process and the
glenoid cavity
43. Features on the Scapula
Spine - a large process on the posterior of
the scapula that ends laterally as the
acromion
Acromion - the flattened lateral portion of
the spine of the scapula
Coracoid process - a protruding projection
on the anterior surface just inferior to the
lateral aspect of the clavicle
Glenoid cavity - shallow concavity that
articulates with the head of the humerus
44. Skeleton of the Arm - Humerus
Longest and largest bone of the free part
of the upper limb
The proximal ball-shaped end articulates
with the glenoid cavity of the scapula
The distal end articulates at the elbow with
the radius and ulna
45. Bones of the Upper Limb
The arm is formed by a single bone- Humerus
46. Skeleton of the Forearm - Ulna
The longer of the two forearm bones
Located medial to the radius
Olecranon - the large, prominent proximal end, the tip of
your elbow
Coronoid process - the anterior lip of the proximal ulna
Trochlear notch - the deep fossa that receives the
trochlea of the humerus during elbow flexion
Styloid process - the thin cylindrical projection on the
posterior side of the ulnas head
47. Radius
Lies lateral to the ulna (thumb side of the forearm)
The head (disc-shaped) and neck are at the
proximal end
The head articulates with the capitulum of the
humerus and the radial notch of the ulna
Radial tuberosity - medial and inferior to neck,
attachment site for biceps brachii muscle
Styloid process - large distal projection on lateral
side of radius
49. Bones of the Upper Limb
The hand
Carpals wrist
Metacarpals
palm
Phalanges
fingers
50. Skeleton of the Hand
The carpus (wrist) consists of 8 small bones
(carpals)
Two rows of carpal bones
Proximal row - scaphoid, lunate, triquetrum, pisiform
Distal row - trapezium, trapezoid, capitate, hamate
Scaphoid - most commonly fractured
Carpal tunnel - space between carpal bones and
flexor retinaculum
51. Metacarpals and Phalanges
Five metacarpals - numbered I-V, lateral to
medial
14 phalanges - two in the thumb (pollex)
and three in each of the other fingers
Each phalanx has a base, shaft, and head
Joints - carpometacarpal,
metacarpophalangeal, interphalangeal
52. Bones of the Pelvic Girdle
Hip bones
Composed of three pair of fused bones
Ilium
Ischium
Pubic bone
The total weight of the upper body rests on the pelvis
Protects several organs
Reproductive organs
Urinary bladder
Part of the large intestine
55. The Ilium
Largest of the three hip bones
Ilium is the superior part of the hip bone
Consists of a superior ala and inferior body which
forms the acetabulum (socket for head of the femur)
Superior border - iliac crest
Hip pointer - occurs at anterior superior iliac spine
Greater sciatic notch - allows passage of sciatic nerve
56. Ischium and Pubis
Ischium - inferior and posterior part of the hip
bone
Most prominent feature is the ischial
tuberosity, it is the part that meets the chair
when you are sitting
Pubis - inferior and anterior part of the hip
bone
Superior and inferior rami and body
59. Skeleton of the Thigh - Femur and Patella
Femur - longest, heaviest, and strongest bone in the
body
Proximally, the head articulates with the acetabulum
of the hip bone forming the hip (coxal) joint
Neck - distal to head, common site of fracture
Distally, the medial and lateral condyles articulate
with the condyles of the tibia forming the knee joint
Also articulates with patella
60. Patella
Largest sesamoid bone in the body
Forms the patellofemoral joint
Superior surface is the base
Inferior, narrower surface is the apex
Thick articular cartilage lines the posterior surface
Increases the leverage of the quadriceps femoris
muscle
62. Tibia (shin bone)
The larger, medial weight-bearing bone of leg
The lateral and medial condyles at the proximal
end articulate with the femur
It articulates distally with the talus and fibula
Tibial tuberosity - attachment site for the patellar
ligament
Medial malleolus - medial surface of distal end
(medial surface of ankle joint)
63. Fibula
The smaller, laterally placed bone of leg
Non-weight bearing
The head forms the proximal tibiofibular
joint
Lateral malleolus - distal end, articulates
with the tibia and the talus at the ankle
64. Bones of Lower Limbs
The foot
Tarsus ankle
Metatarsals sole
Phalanges toes
65. Skeleton of the Foot - Tarsals,
Metatarsals & Phalanges
Seven tarsal bones - talus (articulates with
tibia and fibula), calcaneus (the heel bone,
the largest and strongest), navicular, cuboid
and three cuneiforms
Five metatarsals - (I-V) base, shaft, head
14 phalanges (big toe is the hallux)
Tarsus = ankle