ANAT 315

Pectoralis Major

Origin: Anterior surface of clavicle, anterior surface of sternum, external oblique aponeurosis

Insertion: lateral edge of the intertubercular groove, inferior to the greater tubercle.

Action: Adducts, flexes + medially rotates arm

Innervation: Medial + lateral pectoral nerves

Pectoralis Minor

Origin: Ribs 3-5

Insertion: Coracoid process of scapula

Action: Pulls scapula down and anteriorly

Innervation: Medial pectoral nerve

Pectoralis Major

Origin: Anterior surface of clavicle, anterior surface of sternum, external oblique aponeurosis

Insertion: lateral edge of the intertubercular groove, inferior to the greater tubercle.

Action: Adducts, flexes + medially rotates arm

Innervation: Medial + lateral pectoral nerves

Pectoralis Minor

Origin: Ribs 3-5

Insertion: Coracoid process of scapula

Action: Pulls scapula down and anteriorly

Innervation: Medial pectoral nerve

Subclavius

Origin: 1st Rib

Insertion: Inferior surface of clavicle

Action: Pulls down and stabilizes clavicle

Innervation: C5-C6

Serratus Anterior

Origin: Surface of ribs 1-8

Insertion: Medial surface of scapula on the costal surface

Action: Protracts scapula and elevates ribs

Innervation: Long thoracic nerve

Serratus Posterior Superior

Origin: C7-T3 spinous processes

Insertion: Superior borders of ribs 2-4

Action: Elevates upper ribs

Innervation: T1-T4 ventral rami

Serratus Posterior Inferior

Origin: T11-L2 spinous processes

Insertion: Inferior border of ribs 9-12

Action: Depresses lower ribs

Innervation: T9-T12 anterior rami

External Intercostals

Origin: Inferior border of ribs

Insertion: Superior border of rib below

Action: Elevates ribs

Breathing: Inspiration

Innervation: Intercostal nerves

Internal Intercostals

Origin: Inferior border of ribs

Insertion: Superior border of rib below

Action: Lowers ribs

Breathing: Expiration

Innervation: Intercostal nerves

Innermost Intercostals

Origin: Inferior border of ribs

Insertion: Superior border of rib below

Action: Lowers ribs

Breathing: Expiration

Innervation: Intercostal nerves

External - medial + inferior

Internal - medial + superior

hands in pockEt - external

hands in pIts - internal

Which way do the intercostal muscle fibres point?

Transversus Thoracis

Origin: Pleural surface of ribs 2-6 (anteriorly)

Insertion: Posterior surface of sternum, xiphoid process

Action: Lowers ribs

Breathing: Expiration

Innervation: Intercostal nerves

Subcostales

Origin: Pleural surface of ribs 2-6 (posteriorly)

Insertion: Superior border of rib below

Action: Lowers ribs

Breathing: Expiration

Innervation: Intercostal nerves

Diaphragm

Origin: Xiphoid process of sternum, L1-L4 vertebra, costal arch of ribs 7-12

Insertion: Central tendon of diaphragm

Action & Breathing: Contracts and compresses abdomen (inspiration); relaxes (expiration

Innervation: Phrenic nerve; C3, 4, 5 keeps diaphragm alive

Reference position for anatomical directional terms

Anatomical Position

Anterior/posterior (Front half/Back half)

Coronal/Frontal Plane

Right/left

Sagittal (Mid-Sagittal) Plane

Superior/inferior (Upper half/Lower half)

Transverse/Horizontal Plane

Medial: toward the midline

Lateral: away from midline

Medial & Lateral

Proximal: toward an attached base

Distal: away from an attached base

Proximal & Distal

Posterior: toward the back, behind

Anterior: toward the front, in front of

Posterior & Anterior

Superficial: toward/closer to body surface

Deep: away from body surface/toward interior of body

Superficial & Deep

Superior: higher

Inferior: lower

Superior & Inferior

Axial & Appendicular

The skeleton can be divided into…

• Bones of the skull

• Accessory bones

• Vertebral column

• Thoracic cage (ribs, sternum, thoracic vertebrae)

AXIAL SKELETON

• Upper limbs and pectoral girdle

• Lower limbs and pelvic girdle

APPENDICULAR SKELETON

26 bones

• 24 vertebrae (7 Cervical 12 thoracic 5 lumbar)

• Sacrum

• Соссух

What makes up the vertebral column?

• Column of support

• Protection of spinal cord

• Passage for nerves

• Attachment site for muscles

Functions of the vertebral column

Label

Label + Function

Label

Refers to a joint

Articular

Smooth, flat surface

Facet

Hole

Foramen

Projection

Process

Label + Function

Nucleus pulposus herniates (protrudes) into vertebral canal due to tear or rupture in the annulus fibrosis

How does a Herniated Disc happen?

Label

Size: Small - fine movements

Spinous process: Bifid

Vertebral body: Oval

Other features: Transverse foramen

Cervical Vertebrae

Size: Medium

Spinous process: Downward sloping

Vertebral body: Heart

Other features: Costal facets for ribs

Thoracic Vertebrae

Size: Large - weight bearing

Spinous process: Short, stumpy

Vertebral body: Kidney

Other features: No articular facets for ribs

Lumbar Vertebrae

Label

• Encloses and protects viscera of the thoracic cavity

• Thoracic skeleton acts an anchor for muscles, including those for respiration

• Attachment for muscles that move the upper limb, scapula

Functions of the Thoracic Cage

What makes up the Thoracic Cage?

Label

Label

• Most ribs articulate with sternum via costal cartilage

• Contributes to the elasticity of the thoracic cage

Label + Function

• True ribs 1-7: articulate directly with the sternum via costal cartilage

• False ribs 8-10: articulate indirectly via fused costal cartilage

• Floating ribs 11 & 12: no anterior articulation. Don't wrap all the way around

Label + Explain

Tubercle: articulates with transverse process of thoracic vertebrae

Head: articulates with body of the thoracic vertebrae (via costal facet)

Label

Bumb/Prominence

Tubercle

Relating to ribs

Costal

Primary muscles of inspiration: Diaphragm, External intercostals

Accessory muscles of inspiration: Scalenes, Sternocleidomastoid

Muscles of Inspiration

Primary muscles of expiration: Diaphragm, Internal intercostals Innermost intercostals

Accessory muscles of expiration: Innermost intercostals, Anterior abdominal wall muscles

Muscles of Expiration

Label

Label

Label

• Also referred to as an articulation

• The site where two (or more) bones connect

• Link the skeletal system

• Joints facilitate movement of the skeleton

What is a joint and why do we have them?

The more stable a joint, the less mobile & vice versa

Stability vs Mobility - Joints

Classification of joints

Joined by dense fibrous connective tissue

Fibrous synarthrosis

• Created when bones fuse together

• The boundaries separating the bones disappear upon fusion

Bony Fusion

Bones joined by a wedge of cartilage (allows for some degree of flexibility)

Cartilaginous amphiarthrosis

• Specialized for movement: permit a wider range of motion than other joints

• Typically found at the ends of long bones, such as those of the upper and lower limbs

All synovial joints have the same basic components:

1. Joint capsule

2. Articular cartilage

3. Joint cavity filled synovial fluid

4. Synovial membrane

5. Accessory structures

Synovial Joints

• Surrounds synovial joint, encloses joint cavity

• Made of outer dense connective tissue layer & inner synovial membrane

Joint Capsule

• Lines inner surfaces of the joint (does not cover the articulating bone surfaces)

• Produces synovial fluid

Synovial membrane

• Fills the joint cavity

• Lubricates (reduces friction)

• Absorbs shock

• Distributes nutrients to cells of the articular cartilage

Synovial fluid

• Covers surfaces of articulating bones

• Smooth surface helps reduce friction during movement

People with arthritis will have wearing away articular cartilage

Articular cartilage

Provide support and additional stability

1. Menisci

2. Ligaments

3. Bursae

4. Fat pads

Accessory Structures of Synovial Joints

Menisci (meniscus)

• Fibrocartilage pads between bone

• Reduce friction, disperse weight, protect & cushion joint surface

Label + Explain

Ligaments

• Fibrous connective tissue connecting bone to bone

• Support and strengthen synovial joints

Label + Explain

• Outside (extracapsular)

• Inside (intracapsular)

Relative to the joint capsule, can be located…

Bursa (bursae pl.)

• Small fluid-filled pockets in connective tissue, occur around tendons and bones

• Filled with synovial fluid, lined by a synovial membrane

• Reduce friction

• Act as shock absorbers

Label + Explain

Fat Pads

• Usually found around the periphery of the joint

• Protect articular cartilages

• Cushion joint as a whole

Label + Explain

1. Gliding movements

2. Angular movements

3. Rotational movements

4. Special movements

Types of movement at synovial joints

• Also referred to as: planar/linear movement

• Two opposing (flat) surfaces slide past each other

Gliding movements

Movement that changes the angle between articulating bones

• Flexion & Extension

• Abduction & Adduction

• Circumduction

Angular movements

Flexion: Decrease in the angle between articulating bones

Extension: Increase in the angle between articulating bones

Flexion & Extension

Adduction: Movement of a structure toward the midline

Abduction: Movement of a structure away from the midline

*Fingers (and toes) move away from or toward the middle finger (toe) (not the midline of the body)*

Abduction & Adduction

Combination of:

• Extension, Flexion, Adduction, Abduction

• Best performed at ball and socket joints, such as hip and shoulder

• Can also be performed by other body parts such as: fingers, wrist, and head

Circumduction

• Rotations

• Supination & Pronation

Rotational movements

Right or left rotation

Medial (internal) rotation

• Rotation towards the midline

Lateral (external) rotation

• Rotation away from the midline

Rotations

Supination (think holding up soup)

• Radius in anatomical position

• Rotation of the forearm that makes the palm face anteriorly

Pronation (think pouring soup)

• Radius rolls across anterior surface of ulna

• Rotation of the forearm that makes the palm face posteriorly

Supination & Pronation

Inversion: Sole of foot twists inward

Eversion: Sole of foot twists outward

Dorsiflexion: Elevate sole of foot (decrease angle between dorsum of foot and anterior surface of leg)

Plantar flexion: Elevate heel of foot (decrease angle between plantar surface of foot and posterior surface of leg)

Special Movements: The Foot

Opposition: Thumb moves across palm to touch the tips of the fingers

Reposition: Thumb and fingers move from opposition back to anatomical position

Special Movements: The Thumb

Protraction: Moving part of the body anteriorly in the horizontal (transverse) plane

Retraction: Part of the body moves posteriorly in the horizontal plane

Ex. pulling back shoulder blades toward spine

Special Movements: Protraction & Retraction

Elevation: Structure moves in a superior direction

Depression: Structure moves in an inferior direction

Special movements: Elevation & Depression

Lateral flexion: Vertebral column bends to the side

Flexion/Extension

Rotation (twisting)

Special Movements: Vertebral Column

• Pivot joint

• Hinge joint

• Ellipsoid joint

• Ball and socket joint

• Saddle ioint

• Gliding joint

Types of synovial joints

Flattened or slightly curved surfaces slide across one another

Gliding (plane) joint

Monoaxial: angular movement across one axis (flexion/extension)

• Convex surface of bone fits into a concave surface of a bone

Other hinge joints:

• Ankle joint

• Knee joint

• Interphalangeal (finger) joints

*modified hinge joints, permit some other movements like slight gliding or rotation*

Hinge joint

Monoaxial: permits only rotation

• Pointed surface of bone articulates with a ring (made up of bone and ligament)

Other pivot joints: Proximal radioulnar joint

Pivot joint

Biaxial: permits motion across two axes

• Oval articular face (condyle) sits within a depression on the opposing surface

• Flexion, extension, abduction, adduction (and circumduction)

Ex. Metacarpophalangeal joints 1-5 of the hand

Ellipsoidal (condylar) joint

Biaxial: angular movement across two axes, opposition

• Articular surface of a bone fits into a saddle-shaped bone

Saddle joint

Most mobility

Triaxial: angular and rotational movement across three axes

• Round head of a bone fits into a cup-shaped depression of a bone

• Angular motion, circumduction, rotation

Other ball-and-socket joints: Hip joint

Ball-and-socket joint

Pectoral Girdle

Label (What is the area called?)

Orientation of pectoral girdle

Clavicle - Superior view

Acromial / lateral end

• Articulates with acromion of scapula

Sternal / medial end

• Articulates with sternum

Label + Function

Clavicle - Inferior View

Rough inferior surface

• Attachment sites for muscles and ligaments

Label + Describe

Sternoclaviular Joint

Label

Depression in bone

Fossa

3 fossae of the scapula

Label