WEEK 10
a. Anatomy of the upper arm
b. Anatomy of the lower arm
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ANATOMY OF THE UPPER ARM
The musculoskeletal anatomy of the upper arm includes the pectoral girdle, which is made up the
scapula and the clavicle, and the shoulder joint which is made up of the scapula and the humerus.
Contrac<on of the muscles in this region allow for movement of the shoulders and chest, as well as
the arm. Both muscles and ligaments play a role in stabilising the notoriously unstable shoulder joint.
Blood vessels which supply the upper arm are con<nua<ons of the subclavian vessels we learnt
about last week.
By the end of this module, it is expected that you will be able to:
1. Iden<fy the bones and ligaments of the upper arm
2. Iden<fy the muscles and blood vessels of the upper arm
3. Determine the ac<on(s) created by each muscle during contrac<on
The bones of the upper arm include the clavicle, scapula, and humerus, which together support
shoulder movement and stability. The clavicle, an S-shaped bone, connects the sternum to the
scapula and provides structural support to the shoulder. The scapula is a flat, triangular bone on the
back of the rib cage with key features like the acromion, coracoid process, and glenoid cavity that
ar<culate with the clavicle and humerus. The humerus is the long bone of the upper arm, with a
head that fits into the glenoid cavity, tubercles for muscle aLachment, and a distal end that
ar<culates with the radius and ulna. The shoulder joint complex includes the sternoclavicular,
acromioclavicular, and glenohumeral joints, with the scapulothoracic joint func<oning through
movement between bone and muscle. Stability is maintained by ligaments, the joint capsule, and
especially the rotator cuff muscles (SITS: supraspinatus, infraspinatus, teres minor, subscapularis).
Muscles like the trapezius, deltoid, pectoralis major, and la<ssimus dorsi allow diverse upper limb
movements including flexion, extension, rota<on, and abduc<on. Ligaments such as the
glenohumeral and coracoclavicular further support and stabilise the shoulder.
_____________________________________________________________________
,ANATOMY OF THE UPPER ARM
Clavicle (Collarbone)
• S-shaped long bone connects the sternum (medial) to the scapula (lateral), supports the
shoulder, keeping the scapula in posi<on, only direct bony connec<on of the upper limb to the
axial skeleton.
• Ar<culates at:
⁃ Medial: Sternoclavicular joint (with the manubrium of the sternum).
⁃ Lateral: Acromioclavicular joint (with acromion of scapula).
Scapula (Shoulder Blade)
• Large flat, triangular bone on the posterior thoracic wall, lies between ribs 2–7.
Key Features:
• Spine: Diagonal ridge on posterior side
• Borders: Medial (vertebral), lateral (axillary), superior
• Angles: Inferior angle (muscle aLachment site)
• Acromion: Lateral projec<on; ar<culates with clavicle
• Coracoid Process: Hook-like; muscle/ligament aLachment
• Glenoid Cavity: Ar<culates with humeral head (shoulder joint)
• Fossae (muscle sites):
⁃ Supraspinous: Above spine (supraspinatus)
⁃ Infraspinous: Below spine (infraspinatus)
⁃ Subscapular: Anterior surface (subscapularis)
Humerus (Upper Arm Bone): Long bone of the upper arm.
Proximal Features:
• Head: Fits into glenoid cavity
• Anatomical Neck: Margin around head
• Greater/Lesser Tubercles: Muscle aLachment (e.g. rotator cuff)
• Intertubercular Sulcus: Groove for biceps tendon
Sha]: Deltoid Tuberosity: Lateral rough area for deltoid inser<on
Distal Features:
• Capitulum: Ar<culates with radius
• Trochlea: Ar<culates with ulna
• Epicondyles (medial/lateral): Muscle aLachment
• Olecranon Fossa: Posterior pit for olecranon (ulna)
• Fossa = depression/pit
, LIGAMENTS/JOINTS OF THE UPPER ARM
Sternoclavicular (SC) Joint
• Synovial joint between sternum and clavicle.
• Strong joint allowing shoulder girdle movement.
• Has an ar<cular disc for shock absorp<on.
Acromioclavicular (AC) Joint
• Plane joint between clavicle and acromion.
• Allows small gliding movements.
• Stabilized by acromioclavicular and coracoclavicular ligaments.
Glenohumeral Joint (Shoulder Joint)
• The ball-and-socket joint between the humeral head and glenoid cavity.
• Extremely mobile → prone to disloca<on.
• Stabilized by:
⁃ Rotator cuff muscles
⁃ Glenohumeral ligaments
⁃ Labrum (fibrocar<lage rim deepening the socket)
⁃ Joint capsule
Scapulothoracic "Joint" (Func<onal)
• Not a true joint → movement between the scapula and thoracic cage.
• Allows eleva<on, depression, retrac<on, protrac<on, and upward/downward rota<on.
LIGAMENTS OF THE SHOULDER
Glenohumeral Ligaments • Located inside the joint capsule (anteriorly).
• Three bands: Superior, middle, inferior
• Resist anterior disloca<on of humerus.
Coracohumeral Ligament • From coracoid process to greater tubercle of humerus.
• Supports superior part of joint capsule.
• Helps suspend humerus.
Transverse Humeral Ligament • Spans from greater to lesser tubercle.
• Covers bicipital groove, holding biceps long head tendon in place.
Coracoacromial Ligament • From coracoid process to acromion.
• Forms coracoacromial arch above humeral head.
• Prevents upward disloca<on.
Acromioclavicular Ligament • Connects acromion to clavicle.
• Supports the AC joint.
Coracoclavicular Ligament • Connects coracoid process to clavicle.
• Strong stabilizer of AC joint.
• Two parts: Trapezoid ligament (lateral), Conoid ligament (medial)
a. Anatomy of the upper arm
b. Anatomy of the lower arm
,_____________________________________________________________________
ANATOMY OF THE UPPER ARM
The musculoskeletal anatomy of the upper arm includes the pectoral girdle, which is made up the
scapula and the clavicle, and the shoulder joint which is made up of the scapula and the humerus.
Contrac<on of the muscles in this region allow for movement of the shoulders and chest, as well as
the arm. Both muscles and ligaments play a role in stabilising the notoriously unstable shoulder joint.
Blood vessels which supply the upper arm are con<nua<ons of the subclavian vessels we learnt
about last week.
By the end of this module, it is expected that you will be able to:
1. Iden<fy the bones and ligaments of the upper arm
2. Iden<fy the muscles and blood vessels of the upper arm
3. Determine the ac<on(s) created by each muscle during contrac<on
The bones of the upper arm include the clavicle, scapula, and humerus, which together support
shoulder movement and stability. The clavicle, an S-shaped bone, connects the sternum to the
scapula and provides structural support to the shoulder. The scapula is a flat, triangular bone on the
back of the rib cage with key features like the acromion, coracoid process, and glenoid cavity that
ar<culate with the clavicle and humerus. The humerus is the long bone of the upper arm, with a
head that fits into the glenoid cavity, tubercles for muscle aLachment, and a distal end that
ar<culates with the radius and ulna. The shoulder joint complex includes the sternoclavicular,
acromioclavicular, and glenohumeral joints, with the scapulothoracic joint func<oning through
movement between bone and muscle. Stability is maintained by ligaments, the joint capsule, and
especially the rotator cuff muscles (SITS: supraspinatus, infraspinatus, teres minor, subscapularis).
Muscles like the trapezius, deltoid, pectoralis major, and la<ssimus dorsi allow diverse upper limb
movements including flexion, extension, rota<on, and abduc<on. Ligaments such as the
glenohumeral and coracoclavicular further support and stabilise the shoulder.
_____________________________________________________________________
,ANATOMY OF THE UPPER ARM
Clavicle (Collarbone)
• S-shaped long bone connects the sternum (medial) to the scapula (lateral), supports the
shoulder, keeping the scapula in posi<on, only direct bony connec<on of the upper limb to the
axial skeleton.
• Ar<culates at:
⁃ Medial: Sternoclavicular joint (with the manubrium of the sternum).
⁃ Lateral: Acromioclavicular joint (with acromion of scapula).
Scapula (Shoulder Blade)
• Large flat, triangular bone on the posterior thoracic wall, lies between ribs 2–7.
Key Features:
• Spine: Diagonal ridge on posterior side
• Borders: Medial (vertebral), lateral (axillary), superior
• Angles: Inferior angle (muscle aLachment site)
• Acromion: Lateral projec<on; ar<culates with clavicle
• Coracoid Process: Hook-like; muscle/ligament aLachment
• Glenoid Cavity: Ar<culates with humeral head (shoulder joint)
• Fossae (muscle sites):
⁃ Supraspinous: Above spine (supraspinatus)
⁃ Infraspinous: Below spine (infraspinatus)
⁃ Subscapular: Anterior surface (subscapularis)
Humerus (Upper Arm Bone): Long bone of the upper arm.
Proximal Features:
• Head: Fits into glenoid cavity
• Anatomical Neck: Margin around head
• Greater/Lesser Tubercles: Muscle aLachment (e.g. rotator cuff)
• Intertubercular Sulcus: Groove for biceps tendon
Sha]: Deltoid Tuberosity: Lateral rough area for deltoid inser<on
Distal Features:
• Capitulum: Ar<culates with radius
• Trochlea: Ar<culates with ulna
• Epicondyles (medial/lateral): Muscle aLachment
• Olecranon Fossa: Posterior pit for olecranon (ulna)
• Fossa = depression/pit
, LIGAMENTS/JOINTS OF THE UPPER ARM
Sternoclavicular (SC) Joint
• Synovial joint between sternum and clavicle.
• Strong joint allowing shoulder girdle movement.
• Has an ar<cular disc for shock absorp<on.
Acromioclavicular (AC) Joint
• Plane joint between clavicle and acromion.
• Allows small gliding movements.
• Stabilized by acromioclavicular and coracoclavicular ligaments.
Glenohumeral Joint (Shoulder Joint)
• The ball-and-socket joint between the humeral head and glenoid cavity.
• Extremely mobile → prone to disloca<on.
• Stabilized by:
⁃ Rotator cuff muscles
⁃ Glenohumeral ligaments
⁃ Labrum (fibrocar<lage rim deepening the socket)
⁃ Joint capsule
Scapulothoracic "Joint" (Func<onal)
• Not a true joint → movement between the scapula and thoracic cage.
• Allows eleva<on, depression, retrac<on, protrac<on, and upward/downward rota<on.
LIGAMENTS OF THE SHOULDER
Glenohumeral Ligaments • Located inside the joint capsule (anteriorly).
• Three bands: Superior, middle, inferior
• Resist anterior disloca<on of humerus.
Coracohumeral Ligament • From coracoid process to greater tubercle of humerus.
• Supports superior part of joint capsule.
• Helps suspend humerus.
Transverse Humeral Ligament • Spans from greater to lesser tubercle.
• Covers bicipital groove, holding biceps long head tendon in place.
Coracoacromial Ligament • From coracoid process to acromion.
• Forms coracoacromial arch above humeral head.
• Prevents upward disloca<on.
Acromioclavicular Ligament • Connects acromion to clavicle.
• Supports the AC joint.
Coracoclavicular Ligament • Connects coracoid process to clavicle.
• Strong stabilizer of AC joint.
• Two parts: Trapezoid ligament (lateral), Conoid ligament (medial)
