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You know your arm bones fairly well. The humerus is your upper arm bone supporting your shoulder. Your lower arm contains the ulna and radius bones. These connect to your wrist bones, called carpals. The carpals join with the bones of your hands and fingers, including the phalanges.
Now think distal and proximal. These fancy words describe the relative positions of bones starting from your core. Proximal bones are close to your trunk. Your humerus is proximal to your ulna and radius.
The phalanges are even more distal, furthest from your core. They’re at the tips of your fingers.
Your arm’s anatomy puts the humerus proximal and the phalanges distal. This positions your phalanges to interact with the world. Your amazing hands wouldn’t work without the linked chain of arm bones in perfect distal to proximal order.
Table Of Contents
- Key Takeaways
- Bones of the Upper Limb
- Joints Connecting the Bones
- Muscles Acting on the Bones
- Nerves Supplying the Limb
- Clinical Considerations
- Frequently Asked Questions (FAQs)
- Phalanges are the finger and toe bones that form the framework of the digits. They enable precise manipulation through providing flexion of the digits.
- There are 2 phalanges in the thumb and 3 phalanges in each finger.
- The phalanges are distal to the humerus, as the humerus is the upper arm bone that articulates with the ulna and radius in the forearm.
Bones of the Upper Limb
The humerus, ulna, and radius are the long bones of your arm between your shoulder and elbow joints. The bones of your fingers are called phalanges, and they are the most distal bones from your humerus.
The humerus is proximal, and the phalanges are distal in your upper limb, with the ulna and radius connecting them together at your elbow joint.
- The humerus is the longest and largest bone in the upper limb.
- It articulates with the scapula at the shoulder joint and the ulna and radius bones at the elbow.
- The humerus allows flexion, extension, abduction, adduction, and rotation of the arm.
The humerus provides important attachments for the muscles that move the arm and connect it to the rest of the skeleton.
Distal you are to humerus, phalanges dear. The ulna bone is one of two forearm bones, forming the connection point between the elbow and wrist. As a long bone, it has a proximal end that articulates with the humerus at the elbow joint.
The ulna provides attachment for muscles that act on the wrist and hand, working together with the radius bone to allow pronation and supination motions. Forming the medial bone of the forearm, the ulna connects the upper arm to the intricate bones of the hand.
The radius bone can be your trusty companion, articulating proximally with the humerus at the elbow joint and distally with the carpal bones of the wrist. It is ever ready to work in tandem with the ulna for pronation and supination of the forearm, like two oarsmen propelling a boat forward.
As the lateral bone of the forearm, it spans from the lateral humeral condyle above to the wrist joints below, transmitting forces from hand to arm. With the ulna, it allows the forearm and hand to turn palm up or down. Fractures often occur distally at the wrist when one is falling.
Ya got those phalanges at the end of yer fingers ‘n toes, the most distal bones in yer upper ‘n lower limbs.
- They form the framework of yer digits.
- The 14 phalanges in each hand provide flexion.
- Thumb’s got 2, others got 3 phalanges each.
Strong yet delicate, the phalanges enable precise manipulations from texting to surgery. Supportin’ the fingertips, they’re the frontier of hand function. Fractures often occur from trauma, jammin’ or arthritis erosion.
Still, them phalanges are resilient, healin’ well if properly aligned. Yer phalanges are key tools; use ’em wisely.
Joints Connecting the Bones
The glenohumeral joint of your shoulder allows you to abduct, flex, and rotate your arm. The elbow joint formed by the humerus, ulna, and radius enables flexion, extension, pronation, and supination of your forearm.
The wrist joint comprised of multiple carpal bones permits flexion, extension, ulnar and radial deviation of your hand and fingers.
Y’all can visualize flexin’ and rotatin’ your shoulder joint at the ball and socket connection to move your arm in all directions. The glenohumeral joint is a ball and socket joint that connects the humerus to the scapula.
The joint is stabilized by rotator cuff muscles and capsule, but can become injured and dislocated.
|Latissimus dorsi, Teres major
|Pectoralis major, Latissimus dorsi
|Subscapularis, Pectoralis major, Latissimus dorsi
|Infraspinatus, Teres minor
The glenohumeral joint allows the widest range of motion of any joint in the body due to its ball and socket structure; however, this also makes it prone to dislocation and injury if the stabilizing structures are damaged.
The elbow joint between the humerus, radius, and ulna lets you bend your arm 145 degrees! At this hinge joint, the trochlea of the humerus articulates with the trochlear notch of the ulna and the capitulum articulates with the head of the radius, allowing flexion and extension.
Damage to the radial nerve in the radial groove can cause wrist drop. Fractures of the distal humerus often involve the medial and lateral epicondyles and olecranon fossae. Powerful contractions of the biceps and triceps muscles allow tremendous strength and precision at the elbow joint.
The wrist joint formed by your carpal bones allows you to flex and extend your hand. This complex joint between the radius, ulna, and proximal carpal bones enables wrist flexion, extension, abduction, adduction, and circumduction.
Damage to the surrounding nerves or ligaments can affect these motions, as seen in shoulder dislocations or radial nerve damage. Breaking a wrist often needs realigning the carpal bones back into the correct positions in their sockets.
Scans checking bone density help assess healing. With therapy, normal wrist function usually returns over time.
Muscles Acting on the Bones
Your upper arm contains two major muscles that act on the humerus: the biceps brachii, which flexes your elbow, and the triceps brachii, which extends it. In the forearm, muscles are divided into flexors on the anterior side and extensors on the posterior side.
The flexors bend your wrist and digits, while the extensors straighten them. These forearm muscles connect to the bones of your hands and fingers via long tendons, allowing you to grasp and manipulate objects with precision.
You’re flexing your biceps to curl that weight, aren’t you? The biceps brachii muscle has two heads originating at the scapula and inserting on the radial tuberosity and fascia of the forearm. As the biceps contract, the muscle shortens and flexes the elbow joint, bending the forearm toward the humerus.
This brings the distal aspect of the humerus, including the biceps groove and humeral ball, closer to the rounded end of the radius’s long shaft.
Y’all’re straightenin’ your triceps to extend that arm and lift the weight overhead.
- The triceps brachii is the large three-headed muscle on the back of the upper arm.
- It originates from the scapula and humerus and inserts onto the olecranon of the ulna.
- As the triceps contract they straighten the elbow joint, extendin’ the forearm.
- This brings the proximal end of the ulna, includin’ the olecranon process, away from the distal humerus.
The powerful triceps muscle extends the elbow against resistance, straightenin’ the longest bone in the upper extremity, the humerus, to complete the biceps curl exercise.
Forearm Flexors and Extensors
Yankin’ your flexors and extensors contracts them to bend and straighten your average Joe’s forearm, with over 30 muscles controlling precise movements of the radius and ulna bones. Flexin’ the wrist and fingers relies on flexor muscles like flexor carpi radialis and flexor digitorum superficialis.
Extendin’ the wrist and fingers uses extensor muscles like extensor carpi ulnaris and extensor digitorum. Injuries, fractures or nerve damage impair forearm muscle function, limitin’ range of motion. Physical therapy focuses on strengthenin’ flexors and extensors to regain mobility after rotator cuff, arm and wrist injuries.
Nerves Supplying the Limb
The phalanges are the most distal bones to the humerus in your upper limb. They form the digits of your hand and allow you to grasp and manipulate objects with precision.
You have a complex network of nerves that allows you to move and feel your arm, hand, and fingers. This network originates in your neck as the brachial plexus, formed by the cervical and thoracic spinal nerves.
As it travels down your arm, two major nerves branch off – the median nerve running down the middle, and the ulnar nerve on the inner side.
Damage to the median nerve can cause carpal tunnel syndrome, while ulnar nerve compression is common in cyclists. Understanding the anatomy and function of these nerves aids in diagnosing and treating upper limb conditions.
The nerves supplying your limb originate from the brachial plexus formed in your neck.
- Median nerve runs down the arm
- Ulnar nerve supplies the ulnar half of the hand
- Radial nerve innervates the triceps brachii muscle
- Musculocutaneous nerve branches to arm flexors
The brachial plexus is formed from the cervical and thoracic spinal nerves and branches into the major nerves that supply the arm and hand. The proper functioning of these nerves allows complex hand and finger movements.
Compressing that median nerve can zap your hand strength, leaving you unable to pick up a cold one at the bar, friend. It courses your arm as a mainline from your spine to your palm. It supplies sensation for the palm side of your hand plus thumb movement.
It gets compressed in that tight carpal tunnel at your wrist. Combining with the ulnar nerve makes your hand a complex moving machine. But if that median gets crunched, you’ll be dropping drinks instead of tipping them back.
Without your median nerve firing right, your phalanges and metacarpals aren’t working in sync no more.
Got that ulnar nerve running your pinky and ring finger side, controlling claw grip and fine pinch. You pinch too hard, you’ll get that numb pinky feeling, can’t pick up a guitar or pen ’til your ulnar nerve’s healing.
That ulnar courses under your elbow’s funny bone, sends movement and feeling to them phalanges at your hand’s end. It controls precise pinches with your ring and pinky digits. Damage that ulnar and your phalanges lose strength, dropping cups, pens, guitars.
Protect your ulnar or you’ll be fumbling tasks needing finesse of them distal phalanges.
In a human arm, the phalanges are the most distal bones to the humerus. They form your fingers and allow precise manipulation of objects. When considering clinical conditions of the upper limb, you must understand anatomy to properly diagnose and treat fractures, nerve injuries, and repetitive strain syndromes.
Misalignment of phalangeal fractures needs realignment based on anatomical position. Specific nerves control specific muscles, so injury causes predictable weakness. Repetitive hand motions can irritate tendons and nerves like the median nerve compressed in carpal tunnel syndrome.
You’ll need to realign any fractured bones in your arm to restore proper anatomy.
- Seek emergency care for fractures with severe displacement or angulation of bone fragments.
- Realigning and immobilizing the fracture promotes healing and prevents long-term disability.
- Open fractures require urgent irrigation and debridement in the emergency room to prevent infection.
Properly realigning fractures utilizes anatomical knowledge to restore function and prevent complications.
Damage to your median nerve can leave your hand feelin’ numb as a block of wood. The median nerve innervates the muscles controllin’ your thumb, index, middle, and half of your ring finger. It runs from your neck down your arm between the ulna and radius, passin’ through your carpal tunnel.
Injury here causes weakness grippin’ and pinchin’. Knowin’ the anatomy helps diagnose and treat.
|Effect of Injury
|Numbness of lateral hand
|Tendon transfer, splinting
Injuries to nerves in your arm and hand cause specific symptoms based on their anatomy. Correct diagnosis guides effective treatment like splinting or surgery to restore function. Proper identification of the affected nerve supports appropriate therapy to improve hand strength and sensation.
Repetitive Strain Injuries
Overusing your fingers and hands can lead to painful tendinitis or even carpal tunnel syndrome. Repetitively flexing and extending at the elbow, forearm, wrist, or fingers strains the joints and tendons.
Tasks like typing or playing an instrument excessively irritate the tendons, causing inflammation. Limit overuse and take breaks to avoid injury. Use proper posture and technique. Symptoms like pain, numbness, or weakness in the hand signal injury. Treat early with rest, icing, braces.
Surgery like carpal tunnel release may help if conservative care fails. Listen to your body.
Frequently Asked Questions (FAQs)
What are the names of the phalanges in the hand?
You have 14 phalanges in each hand. Starting with the thumb, there are the proximal, distal, and terminal phalanges. Each finger has a proximal, middle, and distal phalanx too. They are the most distal bones, articulating with the metacarpals proximally at the knuckles.
Powerful yet elegant, these digital bones enable our hands’ remarkable dexterity.
How many phalanges are in each finger?
You have 3 phalanges in each finger and 2 phalanges in each thumb. The phalanges are the most distal bones of the fingers and thumbs. They form the skeleton of these digits and are connected to the metacarpal bones of the hands by joints that allow flexion and extension.
What structures connect the phalanges together?
You’ve got those phalanges in your fingers connected by joints called interphalangeal joints. Like links in a chain, they allow your digits to flex and extend. Smooth synovial fluid lubricates as tendons glide, granting your hands agility.
This brilliant biomechanical system empowers you to grasp and manipulate your environment.
What are the main functions of the phalanges?
You use your phalanges primarily for fine motor skills. With their small sizes and many joints, your fingers can perform intricate and precise movements. Your phalanges’ tendons and muscles let you grip objects, type on keyboards, play musical instruments – basically anything requiring manual dexterity.
Their sensitive nerve endings also give you tactile feedback for exploring your environment.
How do injuries to the phalanges usually occur?
You injure your phalanges through repetitive motions like texting or typing. Their small delicate bones and joints become inflamed from overuse. Treatment involves rest, splinting, anti-inflammatories. Proper ergonomics when performing repetitive tasks protects your digits.
From humerus to hand, you follow the framework of forms fashioning the functioning human upper limb. Phalanges, positioned most peripheral, remain profoundly distal to the humerus that heightens the hinging capacity of your jointed appendage.
While ligaments link and muscles mobilize your sweeping span of bones, nerves nourish their action so you can grasp, lift, and flex your fingers. Thus the phalanges, as the endmost extremity, exist at the furthest remove from the central humerus in your skillful arm’s anatomy.